荧光碳点，四环素检测，细胞器靶向成像

Phosphate pollution leads to the deterioration of water quality, posing a serious threat to human health. Tetracycline hydrochloride (TC), a class of broad-spectrum bacteriostatic agents, has garnered attention due to its extensive use and potential toxicity. Therefore, developing a highly selective and sensitive fluorescent probe for the detection of phosphates and TC is of significant importance. Herein, to enhance the conversion and utilization of high-value biomass waste, biomass-derived carbon dots (LZ-NCDs) emitting green fluorescence with a quantum yield of 44 % were synthesized in a one-step hydrothermal process using chestnut shell biomass waste as a carbon source and nitrogen doping technology. Based on the dynamic quenching mechanism, a highly sensitive method for effectively identifying PO43- using LZ-NCDs fluorescence probe was constructed, with a linear range of 0.1-10 µmol/L and a detection limit of 43.0 nmol/L. A quenched fluorescent probe, LZ-NCDs for the determination of TC, was fabricated through the synergistic effects of inner filter effect and static quenching, exhibiting a linear range from 0.05 to 10 µmol/L with a detection limit of 16.8 nmol/L. The successful determination of PO43- and TC in actual samples was achieved. The two different quenching mechanisms indicate that LZ-NCDs are expected to become potential sensing materials for the real-time monitoring of PO43- and TC in organisms and food, which is very important for our health.

No abstract available

No abstract available

No abstract available

Excessive exposure to fluoride and tetracycline can cause severe dental damage, including tetracycline-induced tooth discoloration and dental fluorosis. Herein, we introduce a dual-mechanism sensing strategy using red-emitting carbon dots (R-CDs) for the independent detection of fluoride and tetracycline. A key advantage of R-CDs as sensors is their ability to selectively identify both analytes through long-wavelength emission with a large Stokes shift. For fluoride detection, we developed a fluorescence-enhanced sensor based on R-CDs-Fe3+ via a competitive binding mechanism. Meanwhile, tetracycline detection was achieved using a fluorescence-quenching sensor leveraging static quenching and the internal filter effect (IFE). The successful quantification of fluoride and tetracycline in food matrices demonstrates the practical potential of R-CDs in food safety monitoring. Additionally, this study presents a novel framework for designing multi-target detection systems using a single type of carbon dots across different sensing mechanisms.

Synchronous regulation of the photoluminescence and physicochemical characteristics of multicolor carbon dots (CDs) can fully realize their application potential in multicomponent imaging. Herein, by utilizing an acid-regulated synthetic strategy, green-emissive and orange-emissive CDs that target lipid droplets (LDs) and mitochondria (Mito) have been developed for fluorescence visualization of LD-Mito interactions. The finding of different molecular fluorophores reveals that the precursor undergoes different reaction pathways in neutral and acidic conditions, which alters the size of sp2-conjugated domain and surface properties for the successful regulation of photoluminescence properties and organelle-targeting ability. Moreover, the one-step fabrication of these two CDs was also realized by lowering the dosage of acid. Therefore, the multicolor imaging of LDs and Mito has been achieved with one-step staining, disclosing that their interaction frequency decreases during the lipotoxicity process. This work successfully demonstrates the high coupling potential between multicolor CDs and organelle-interaction visualization, which would provide guidance on the correlation between photoluminescence features and other properties of multicolor CDs for extending application space.

No abstract available

Over the years, the abuse of antibiotics has increased, leading to their presence in the environment. Therefore, a sustainable method for detecting these substances is crucial. Researchers have explored biomass-based carbon dots (CDs) to detect various contaminants, due to their low cost, environmental friendliness, and support of a circular economy. In our study, we reported the synthesis of CDs using pinecones (PCs) and pinebark (PB) through a sustainable microwave method. We characterized the PCCDs and PBCDs using X-ray diffraction, Raman spectroscopy, Transmission Electron Microscope, and Fourier transform infrared, Ultraviolet-visible, and photoluminescence (PL) spectroscopy. The PCCDs and PBCDs were tested for the detection of amoxicillin (AMX) and tetracycline (TC). The results indicated that the sizes of the PCCDs and PBCDs were 19.2 nm and 18.39 nm, respectively, and confirmed the presence of the 002 plane of the graphitic carbon structure. They exhibited excitation wavelength dependence, good stability, and quantum yields ranging from 6% to 11%. PCCDs and PBCDs demonstrated “turn-off” detection for TC and AMX. The limits of detection (LOD) for TC across a broader concentration range were found to be 0.062 µM for PCCDs and 0.2237 µM for PBCDs. For AMX detection, PBCDs presented an LOD of 0.49 µM.

Tetracycline (TC), a commonly used antibiotic, presents significant health risks to both humans and animals when found in various samples. In this research, carbon dots (CDs) were created through a one‐step hydrothermal process using chamomile leaves as the precursor material. The presence of TC caused a quenching of fluorescence (FL) in the synthesized CDs. Upon excitation at a peak wavelength of 345 nm, the CDs exhibit blue fluorescence with an emission at 420 nm. The sensor exhibited impressive analytical capabilities for detecting TC, with detection limits (LOD) of 6.13 µM and quantitation limits (LOQ) of 18.58 µM, respectively. Additionally, the probe showed high efficacy in analyzing TC presence in tap water and milk samples. To evaluate the environmental impact of the method, two green metrics, AGREE and BAGI, were applied, and the results confirmed its excellent environmental sustainability. This research provides valuable advancements in the areas of food safety, analytical chemistry, and monitoring of environmental conditions.

No abstract available

The development of a sensitive sensing platform for monitoring tetracycline hydrochloride (TCH) is of particular significance for safeguarding human health and food safety. Herein, a ratiometric nanofluorescent probe called Eu/N, S-CDs was designed by the combination with N, S-doped carbon dots (CDs) and europium ions (Eu3+). TCH could lead to blue fluorescence (FL) emission at 464 nm quenched through static quenching, while could enhance red FL emission at 617 nm via the antenna effect. The proposed sensor had a wider linear detection range of 0.05-45 μM and a lower detection limit (LOD) of 5.92 nM for monitoring TCH. Moreover, the Eu/N, S-CDs-loaded test strips endowed a visual and convenient detection with a smartphone-assisted equipment based on TCH-induced FL color transition from blue to red. Importantly, satisfactory recoveries were achieved for actual sample analysis, indicating the great potential applications for food quality protection and public health safeguarding.

No abstract available

No abstract available

Tetracycline (TC), a widely used broad-spectrum antibiotic, can accumulate in ecosystems through environmental release, posing risks to ecological security and human health. This study presents a green and efficient microwave-assisted method for synthesizing fluorescent carbon quantum dots (B-CQDs) using spent coffee grounds as a precursor. The as-prepared B-CQDs were employed as a fluorescent probe for the highly selective detection of TC in water. Characterization results revealed that the B-CQDs possess good water dispersibility, high fluorescence stability, and a relatively high quantum yield of 11.2%. Under optimal conditions, B-CQDs exhibited a highly selective fluorescence quenching response towards TC, with a linear detection range of 0–140 µmol L−1 and a low detection limit (LOD) of 0.36 µmol L−1. Mechanistic investigations indicated that the quenching process is primarily attributed to the synergistic effect of the inner filter effect (IFE) and static quenching. The practicality of the method was demonstrated by analyzing TC in real water samples (tap water, lake water, and swine farm wastewater), achieving satisfactory spike recoveries of 98.8–105.5% with relative standard deviations (RSD) below 3.53%, confirming its good accuracy and practical applicability. Furthermore, the greenness of the proposed method was evaluated using the Greenness Evaluation Metric for Analytical Methods (GEMAM) system, yielding an excellent comprehensive score of 8.536 out of 10, which underscores its superior environmental friendliness. This work not only demonstrates a pathway for the valorization of waste biomass but also provides a green detection methodology and a potential high-performance sensing material foundation for the environmental monitoring of tetracycline antibiotics.

The selective and highly sensitive detection of trace tetracycline antibiotic residues is crucial for ensuring food safety and maintaining organismal health. In the present study, we describe a novel method for tetracycline detection utilizing phosphorus-doped carbon quantum dots (P-CQDs) synthesized via solid-phase pyrolysis as fluorescent probes. Phosphorus doping significantly amplifies the fluorescence intensity by a factor of 8.1, and the resulting P-CQDs exhibit superior optical stability. The excitation and emission maxima of the P-CQDs are located at 340 nm and 440 nm, respectively. The fluorescent probe detects tetracycline based on the inner filter effect, demonstrating high selectivity and strong interference resistance. It has a wide detection range of 0–80 μM and a low detection limit of 0.120 μM. This method has been effectively applied to the analysis of real samples, yielding satisfactory results.

No abstract available

No abstract available

Fluorescent carbon dots (CDs), as a class of carbon nanomaterials with unique physicochemical properties, show great potential for sensing applications. This study introduces a novel approach for synthesizing proline‐derived blue‐emitting CDs (B‐CDs) via a one‐step hydrothermal method using L‐proline and L‐tryptophan as precursors, and demonstrates their application as fluorescent probes for tetracycline (TC) determination. The synthesized B‐CDs exhibit strong fluorescence emission at 446 nm with a quantum yield of 10.2%, along with excellent stability against photobleaching, pH variations (3–11), and ionic strength. Selectivity assays reveal high specificity toward TC over other antibiotics and amino acids, with a linear determination range from 0 to 80 µL (R2 = 0.9973) and a limit of detection (LOD) of 8.238 µM. Water sample analysis show recoveries between 100%–111%, indicating practical applicability. This work presents a facile, cost‐effective, and environmentally friendly strategies for TC sensing, offering promising applications in environmental monitoring, food safety, and clinical diagnostics.

No abstract available

In this paper, a ratiometric fluorescent sensor based on double emitting carbon dots (DE-CDs) and molecularly imprinted polymers (MIP) was constructed. The sensor was successfully applied for the detection of tetracycline (TC) by using the ratio of two emission peaks of DE-CDs as the response signal, combined with the selectivity of MIP. Under the optimal conditions, the linear range of TC was 0.05-25 μM, and the detection limit was 0.03 μM. The practicality of the developed sensor was evaluated in the detection of real samples such as lake water, milk, and egg, and the recoveries were in the range of 98.0-105.2 % with RSD less than 3.2 %, which indicated that its application for the detection of tetracycline yielded satisfactory results.

Highlights What are the main findings? Novel carbon dots with excellent fluorescence were prepared from agricultural waste tomato straw. A fluorescence sensor made of CDs@SiO2-MIPs was constructed via molecularly imprinted SiO2-confined carbon dots. What are the implications of the main findings? The developed sensor exhibited high selectivity, a wide linear range, and a low detection limit for TC detection. Abstract In this work, novel biomass-derived carbon dots (CDs) with superior fluorescent properties were prepared from tomato straws. A selective, eco-friendly tetracycline (TC) sensor was fabricated by immobilizing a SiO2 molecularly imprinted polymer (MIP) layer onto CDs, forming a CDs@SiO2-MIP composite. This sensor combined highly selective adsorption properties with the sensitivity of fluorescence detection, with the sensing mechanism stemming from the off-fluorescent signal after molecular imprinting specifically recognizing the target substance. Under optimal conditions, the sensor exhibited a linear response to TC concentrations ranging from 1.00 × 10−7 to 5.00 × 10−4 mol/L, with fluorescence intensity decreasing as concentration increased. The detection limit of TC was 9.33 × 10−8 mol/L. This work provides novel biomass-derived CDs and a simple molecularly imprinted fluorescence sensing method for the detection of environmental organic pollutants.

Thermally activated delay fluorescence (TADF) has great potential for information encryption, temperature detection, and bioimaging due to its long‐lived luminescence, temperature‐sensitive and high signal‐to‐noise ratio. However, it is still a challenge to establish TADF in aqueous environments. In this study, the composite with TADF (M‐FNCDs) is prepared using fluorine‐nitrogen co‐doped carbon dots (FNCDs) and melamine. It is worth mentioning that the M‐FNCDs show stable TADF under long‐wavelength excitation (470 nm) in aqueous environments. Moreover, the M‐FNCDs has distinctive temperature‐responsive properties and exhibit good linear relationships in the temperature range of 77–370 K. Simultaneously, M‐FNCDs suspension as the ink is utilized to realize information encryption/decryption due to their afterglow cannot be quenched in an aqueous solution. More importantly, M‐FNCDs with biocompatibility can target the mitochondria and lysosomes of living cells, and for the first time achieve the high signal‐to‐noise ratio and low background signal afterglow imaging of organelles. This work proposes a new strategy to prepare the stable TADF in aqueous solutions under long‐wavelength excitation and extend the TADF material potential applications in the future.

No abstract available

No abstract available

No abstract available

No abstract available

Tetracycline (TC) contributes to the spread of antibiotic resistance, leading to ecological imbalances and negative environmental impacts. Achieving multifunctional applications that allow for specific recognition and in-situ degradation of tetracycline...

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

Herein, we report an eco-friendly biomass based completely greener microwave assisted synthesis of carbon dots from wild lemon leaves having superior photo-luminescent properties with moderately good quantum yield. The carbon dots synthesized (LLCDs) were characterized by high resolution transmission electron microscopy, fluorescent, UV-vis absorption, Fourier transform infrared and Raman spectroscopic techniques. The quenching of native fluorescence of LLCDs observed with tetracycline antibiotic was made use to make it as a fluorescent probe. Tetracycline is widely used as a drug to treat various bacterial infections and as a growth promoter in variety of farming fields like aquaculture and feedstock's. The excessive usage of this antibiotic in farming fields caused severe water pollution and micro level detection of tetracycline in water system is highly demanded for the protection of health and environment. Based on the selective interaction of tetracycline with LLCDs, a simple and cost effective analytical method was proposed to detect tetracycline in water with satisfactory parameters. The limit of detection is 0.42 µM with a linear range of 0 to 27. 27 µM. The mechanism of quenching was investigated through various experiments and finally accredited to static quenching. Furthermore, the same method has been practically applied for tetracycline detection in natural water resources with acceptable recoveries ranging from 95.56 % to 101.93 %.

The controllable design of red-emitting carbon dots and further exploration of their application in the trace determination of environmental pollutants remains a tremendous challenge. Herein, the novel strategy for red fluorescent carbon dots (R-CDs) with a higher quantum yield of 58.9% was proposed by doping small-molecule urea into the bio-dye of resazurin for the first time, which can retain the luminophore of precursors and exhibit exceptional optical, advantageous reversibility and outstanding photostability. Importantly, the R-CDs exhibit a remarkable fluorescence reduction towards tetracyclines (TCs) accompanied by a noticeable color change of R-CDs solution from red to yellow, which can realize the trace detection of TCs at strelatively low levels, including tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC). The linear range of TC, CTC, and OTC are 3-40 μM, 4-50 μM, and 2-50 μM, and the corresponding detection limits are 38.5 nM, 64.6 nM, and 45.4 nM, respectively (S/N = 3). Furthermore, the R-CDs demonstrate sensitivity to the physiological pH in the linear range of 4.0-5.0 and 5.0-6.2 with a pKa of 5.61. As a multifunctional fluorescent sensor, R-CDs can provide a new perspective for the preparation of long-wavelength CDs, and further realize the trace determination of environmental pollutants.

In this work, nitrogen and sulfur dual-doped carbon quantum dots (N,S-CDs) from naturally renewable biomaterial fungus fibers were prepared by a biosynthesis and hydrothermal method. The N,S-CDs displayed good water solubility, excellent stability, high quantum yield (QY = 28.11%) as well as remarkable features for fluorescence quenching-based detection and cellular imaging of cancer cells. It was worth mentioning that the heteroatoms doped carbon quantum dots made from the fungus fibers had a satisfactory QY and could be used as a selective, efficient, and sensitive fluorescent probe to determine tetracyclines by the synergistic effects of static quenching and internal filtration effect. The probe demonstrated a wide linear range and low detection limit. For tetracycline, the linear range was 0.5 μM to 47.6 μM, and the corresponding detection limit was 15.6 nM. Significantly, the test papers prepared by using N,S-CDs could detect tetracyclines in aquiculture wastewater rapidly. The produced N,S-CDs did not affect the cell viability and showed great promises for cellular imaging.

The bio-sensing activity of fluorescence based nanoprobes is one of the most significant aspects to scrutinize the analytical pursuance in modern security and lateral flow assays. Herein, potent transmogrification of waste cigarette tobacco into fluorescent carbon quantum dots (CQDs) has been achieved by calcination approach. The waste transformation to CQDs holds diverse benefits, comprising high quantum yield, low toxicity and scale up synthesis. The developed CQDs were able to identify tetracycline with phenomenal selectivity and sensitivity through fluorescence based method. The sensing mechanism was fully explored using Density Functional Theory (DFT) and Molecular docking studies. Governing features comprising tetracycline concentration, interfering studies, and real water analysis on the identification of tetracycline were also investigated. Along with, the prepared CQDs act as colorimetric probe, facilitating the detection of tetracycline with the naked eye. The lateral flow device was constructed for the on-site detection of tetracycline in real water samples. To the best of our knowledge, the present work represents a novel approach to designing CQDs and demonstrates their significant potential for application in anticounterfeiting measures and lateral flow devices. This work holds significant prospective as the prepared CQDs was fully utilized to its maximum usage in developing films and fluorescent anti-counterfeiting applications. Concisely, current work opens up distinctive opportunities for rapid on-site, real-time and visualized surveillance of tetracycline using CQDs prepared with a quite simple green approach.

Tetracycline (TC), as a widely used antibiotic, is very useful in treating bacterial infections. However, its residues in animal foodstuffs can enter the human body through the food cycle and causes severe and chronic diseases. On the other hand, due to its weak non-biodegradability, it is considered a threat to the environment. In this regard, the development of sensing methods to detect and measure TC is need of the hour. Herein, a dual-emission fluorescence sensor based on porous aluminosilicate structure (ASS) with rough surface hexagonal shape morphology and pore diameter less than 2 nm was prepared. The porous AAS was modified by post-modification method with blue carbon dots (CDT) and rhodamine B (RB) as two fluorophores to develop the ratiometric fluorescence (RF) sensor (CDT-AAS/RB). Nanostructured CDT-AAS/RB emitted two resolved peaks at 445 and 585 nm , which were dramatically quenched in the presence of TC. The RF sensor, with excellent sensitivity, was able to measure TC over the linear range of 0.001-150 μM with a limit of detection of 5.4 nM in the aqueous phosphate buffer. Moreover, the AAS component granted high selectivity and anti-interference ability to the sensor. In addition, the stability of the sensor was greatly improved due to the non-accumulation of CDT nanoparticles and RB molecules in the presence of the AAS. The proposed method was able to determine TC in complex real samples with satisfactory recovery, and the obtained results were validated with standard high-performance liquid chromatography technique.

No abstract available

No abstract available

No abstract available

Carbon dots have emerged as one of the most promising materials with various potential applications derived from their unique photophysical and chemical properties. The present work investigates the electrochemical and photochemical properties of one-pot synthesized carbon dots for environmental sustainability. Facile microwave-assisted pyrolysis of urea and glucose yielded nitrogen doped carbon dots (N-doped carbon dots) with blue fluorescence and a quantum yield of 14.9%. As synthesized N- doped carbon dot had intense fluorescence, stability, water solubility, and biocompatibility. In the sensing studies, N-doped carbon dots appeared as a dual sensor for drug tetracycline with excellent sensitivity and selectivity. Beyond sense, the carbon dots have the potential to act as a photocatalyst for the degradation of tetracycline. Further, N-doped carbon dot could bring exhaustive degradation of tetracycline (>95%) within 10 min in the absence of any additives. This is the first time report on the utilization of raw non-metal doped carbon dots as a photocatalyst for the degradation of tetracycline.

Doxycycline (DOXY) is a broad-spectrum tetracycline antibiotic. It is widely used in the treatment of various infectious diseases. However, the excessive use of doxycycline may result in the emergence of antibiotic-resistant bacteria, environmental contamination, and drug residues in food products. Therefore, developing a sensitive and efficient method is crucial for the accurate detection and monitoring of DOXY. In this study, a novel fluorescent probe based on nitrogen and phosphorus co-doped carbon dots (N,P-CDs) was synthesized with solvothermal processing. The resulting N,P-CDs showed a uniform particle size distribution, excellent water solubility, and high stability, with a fluorescence quantum yield of 34.7 %. The dual-signal sensing system was in the "ON" state when the N,P-CDs exhibited a fluorescence peak at 474 nm (under the optimal excitation wavelength of 380 nm) and a UV-vis absorption peak at 334 nm. Upon the introduction of DOXY, the fluorescence intensity of the N,P-CDs decreased significantly. At the same time, the absorbance increased notably, corresponding an "ON-OFF" transition in fluorescence and an enhanced colorimetric response. Meanwhile, sodium fluoride (NaF) was introduced into the system as a masking agent to suppress ferric ion (Fe3+) interference, thereby improving the recognition ability toward DOXY. Based on this, a dual-signal fluorescence-colorimetric sensing system using N,P-CDs was constructed for DOXY detection. The fluorescence sensing system exhibited a good linear range from 3.348 to 109.308 μM with a detection limit of 1.5273 μM (LOD, S/N = 3). The colorimetric sensing system showed a linear range from 1.609 to 31.448 μM with a detection limit of 0.0295 μM(LOD, S/N = 3). This dual-signal sensing platform was successfully applied to detect DOXY in real samples including human serum, Beichuanhe River, laboratory water, milk, and orange juice. The results demonstrated its promising potential for environmental monitoring and bioanalytical applications.

No abstract available

Polarity switching photoelectrochemical (PEC) sensing effectively addresses the issue of false positive or negative results that arise from single signal on or off in PEC systems. In this study, a novel core-shell ternary composite material of S-TiO2/CDs/PCN-224 was constructed by growing PCN-224 on the surface of spherical titanium dioxide (S-TiO2) while simultaneously confining carbon quantum dots (CDs). This ternary composite can produce cathodic and anodic PEC signals under visible (420-800 nm) and ultraviolet (UV)-Vis (320-800 nm) excitation, respectively. Leveraging this characteristic, we constructed a polarity switching PEC sensing system by integrating a tetracycline (TC) molecular imprinting polymer (MIP), enabling dual signals for self-calibration of TC detection results. Notably, the suppression of the cathodic signal due to steric hindrance mitigates interference, while the anodic signal resulting from the advanced oxidation of TC facilitates signal amplification and self-cleaning of the electrode interface, enhancing the reusability of the molecularly imprinted polymer photoelectrochemical (MIP-PEC) sensor. Ultimately, the developed MIP-PEC sensor demonstrates a cathodic mode detection range of 5.00 × 10-13-1.00 × 10-8 mol/L with a limit of detection (LOD) of 3.07 × 10-13 mol/L, and an anodic mode detection range of 5.00 × 10-12-5.00 × 10-6 mol/L, with an LOD of 3.14 × 10-12 mol/L under optimal conditions. Furthermore, it exhibits excellent dual-signal stability, reproducibility, and reusability. This study presents a sustainable and efficient PEC sensing platform capable of achieving polarity switching self-calibration, self-cleaning, and high analytical performance for detecting environmental organic pollutants.

No abstract available

No abstract available

No abstract available

No abstract available

No abstract available

This study reports a straightforward one-step synthesis of carbon quantum dots (CQDs) derived from neem fruit flesh, a readily accessible natural biosource.

Carbon quantum dots (CQDs) were synthesized from Trachyspermum ammi seeds through a green hydrothermal method. The CQDs exhibited strong fluorescence, high stability, and abundant surface functionalities. They showed dual functionality by enabling selective detection of toxic metal ions and temperature-dependent photoluminescence for nanothermometry. This eco-friendly approach provides a sustainable route to multifunctional nanomaterials with promising applications in environmental monitoring and analytical sensing.

No abstract available

Carbon dots (CDs) exhibit exceptional biocompatibility and programmable amphiphilicity, establishing them as transformative nanomaterials for subcellular visualization with exceptional resolution. However, existing CD-based probes lack the spatiotemporal precision required for real-time organelle tracking, particularly in mitochondrial-targeted imaging via ultrafast, wash-free protocols. To overcome these limitations, this study describes the solvent-free, high-temperature (280 °C) and short-time (2 h) preparation of green-emitting CDs (GCDs) with distinctive amphiphilic architectures utilizing benzoylurea and citric acid in a sealed high-pressure reactor. GCDs may form micelle-like structures driven to hydrophobic interactions, producing long-wavelength emission in contrast to blue emission in low-polar solvents. They also simultaneously activate the synergy of numerous endocytotic modes, achieving ultrafast (<5 s) and wash-free imaging. GCDs can also effectively target the mitochondria, more significantly, in both normal and cancer cells (Person's value ≈ 0.90/0.91), which is explained by the minor adjustment of mitochondrial membrane potential. This work describes assembly mechanisms of amphiphilic CDs while establishing potential design principles for mitochondria-targeted nanostructures with wash-free, ultrafast tracking.

The valorization of biomass waste represents an important direction in green chemistry. This study successfully prepared blue fluorescent carbon dots (BP-CDs) from waste banana peels via a one-step hydrothermal method, establishing a dual-functional platform for both pollutant detection and cellular imaging. The resulting material exhibited uniform particle size (~2.05 nm), good water dispersibility, and strong fluorescence emission at 445 nm under 360 nm excitation. It maintained over 93% of its initial fluorescence intensity after 20 days, demonstrating excellent stability. Based on the inner filter effect, the probe enabled a highly selective detection of tetracycline with a detection limit of 0.191 µM and two wide linear ranges (0–15 µM, R2 = 0.996; 15–95 µM, R2 = 0.991). Cellular experiments confirmed the good biocompatibility of BP-CDs (cell viability > 84%) and their successful application in cell imaging. More importantly, the probe achieved visual observation and semi-quantitative analysis of the distribution and content of tetracycline in living cells, providing a direct tool for studying the cellular behavior of antibiotics. This work not only offers a new strategy for banana peel valorization but also develops a green fluorescence imaging platform suitable for tracking intracellular pollutants.

No abstract available

No abstract available

We developed a technique that detects Al3+ in milk/bio-samples, and reversibly applied to recognize tetracycline (TC) in milk, enhancing the fluorescence intensity without interference from other cations (Cd2+, Ni2+, Co2+, Sr2+, Mg2+, Fe3+, K+, Sm3+, Ag+, Na+, Ba2+, Cr3+, Zn2+ and Mn2+); the limit of detection (LOD) is found to be 0.00022 mM with r2 = 0.9439. The detection of Al3+ is tested in milk as well as in living cells (Saccharomyces cerevisiae and Debaryomyces spp.) by TC or by its quantum dots. This is consistent with the molecular orbital, revealing that the lowering of the energy of HOMO (Highly Occupied Molecular Orbital) discourages the electron transfer from HOMO of fluorophore to HOMO of excited states of Al-complex that increases the fluorescent intensity. Interestingly, carbon dots (CDs) generated from TC also recognize Al3+ as its LOD is as low as to 0.00050 mM with r2 of 0.9404.

No abstract available

No abstract available

No abstract available

No abstract available

Mitochondria are recognized as essential organelles that form a dynamic network responsible for energy production, calcium homeostasis, and cell signalling for cell metabolism. Dysfunction in mitochondria results in many diseases, such as Alzheimer’s, Muscular dystrophy, Diabetes, and Parkinson’s. As a result, it is of great significance to directly visualize mitochondria inside cellular environment for therapeutic target. Carbon dots (CDs) are one of the probes with low toxicity and high biocompatibility that have been utilized for mitochondrial visualization. However, till date, CDs are synthesized using multi‐step synthesis and most of them emit in the blue to green region thus limiting their application in bioimaging. Herein, we synthesized orange emissive mitochondria‐specific CDs via a one‐pot method using 3‐(carboxypropyl) triphenylphosphonium bromide (TPP) and citric acid as precursors. Synthesized CDs have excellent photoluminescence properties to stain and image mitochondria in different cancerous and non‐cancerous mammalian cells.

No abstract available

The commercial production of carbon dots will be concerned with the simplicity and energy consumption. Herein, maleic acid and m-phenylenediamine form elegantly simple sources for carbon dots. The two precursors are dissolved in formamid (abbreviated as FA) or N,N-dimethylformamide (abbreviated as DMF) and the dehydration-condensation processes have been performed at 30 min or 120 min under room temperature. No external energy/irradiations, reactants or high temperature will be required and the afforded carbon dots (abbreviated as CDs) are collected by extraction, centrifugation, dialysis and column chromatography. It has been found for the first time the choice of organic solvents has been correlated with emission color. The blue-emitting CDs (abbreviated as B-CDs) and green-emitting CDs (abbreviated as G-CDs) are yielded in FA and DMF respectively. Facts support that the increase of -CONH- units causes red-shift in emissions. The optical sensing of tetracycline has been explored and the detection limit of blue-emitting CDs is as low as 25 nM. Live cells exposed to B-CDs and G-CDs (0.5 mg/ml) show no apparent changes via both Cell Counting Kit-8 and Annexin V/7-AAD analysis. The blue and green fluorescent signals can be easily tracked in cells. It has been demonstrated that the two carbon dots can be fabricated as multiple-color light-emitting diodes (abbreviated as LEDs).

A miniature device was design for the point-of-care testing (POCT) of tetracycline (TC) including a ratio fluorescence test strip, a sample slot, a UV lamp and a smartphone. The nitrogen and sulfur co-doped carbon dots (N, S-CDs) and Eu3+ were dropped onto the filter paper to construct the ratio fluorescence test strips for the specific detection of TC. Under the excitation at 390 nm, the fluorescence emission of N, S-CDs at 530 nm decreases through inner filter effect (IEF) after addition of Eu3+. When the further addition of TC, the emission of N, S-CDs at 530 nm kept unchanged while the emission of Eu3+ at 616 nm was obviously enhanced for the antenna effect (AE) between Eu3+ and TC. The ratio changes of the two-fluorescence emission realized the quantitative detection of TC. In addition, the test strips with different concentrations of TC showed different fluorescence color from green to red under a 365 nm UV lamp. The miniature device was designed as a fluorescence photo reader with the merits of the powerful functions of smartphones and the portability of test strips. The smartphone camera takes a fluorescent color image of the test strips and the photos are recognized by a color recognizer on the smartphone to obtain RGB (red-greenblue) values which reflect the concentrations of the analytes. Therefore, we established a fast, sensitive and efficient POCT of TC. In particular, the proposed nanomaterial-based POCT platform will open a new route towards the development of ratio fluorescence probe for TC analysis for environment samples.

Investigating the interactions between various organelles can effectively reveal the corresponding biological problems. Currently, studies of organelle interactions typically employ multiple fluorescent probes that can concurrently target different organelles. However, the simultaneous use of multiple probes is complicated to operate, and the probes can interact with each other, affecting the imaging results. Therefore, targeting multiple organelles using a single probe can enhance the process of studying organelle interactions. Carbon dots (CDs), with their abundant surface groups, are expected to solve the abovementioned problems. Herein, we successfully used m-aminophenol and ethylenediamine to prepare high anti-interference capability and triple targetability CDs (n-CDs) with hydrothermal method. The co-localization experiments with commercial probes confirmed that it can target nucleolus, mitochondria and Lysosome at the same time. The preparation of n-CDs provides a new and convenient strategy to study the interaction between various organelles for solving corresponding biological problems, thus revealing the mysteries of life.

Aluminum and tetracyclines (TCs) are important environmental pollutants, and the development of simple and efficient analytic techniques is of great significance. In this work, an economical nitrogen-doped carbon dots (N-CDs) from chitosan and 4-hydroxycoumarin was prepared through one-step hydrothermal process. The N-CDs with blue fluorescence emission exhibited satisfactory water solubility, stability and biocompatibility. When the addition of Al3+ or TCs, the N-CDs solution presents obvious fluorescence enhancing or quenching, Al3+ can make the fluorescence in the N-CDs-TCs system recover. The N-CDs sensor platform shows satisfactory selectivity and sensitivity in detection of Al3+, tetracycline, oxytetracycline and chlortetracycline, and their low detection limits are 0.857 μM, 120 μM, 127 μM, and 117 μM, respectively. The N-CDs sensor can be applied for the detection of trace Al3+ and TCs in real samples such as tap water and milk, moreover, possible mechanisms on the combination of N-CDs with Al3+ and TCs also were investigated by IR, UV, XPS analysis and DFT calculations. In addition, the N-CDs with good water solubility and biocompatibility can be used to observe the hatching process for medaka fish embryo and fluorescence bio-imaging to indicate that it may have good application potential in biomedical field.

Doxycycline (DOX), widely used in human medicine and animal feed, poses health and environmental risks due to residue accumulation, emphasizing the need for reliable detection methods. Unlike conventional methods relying on single- or dual-detection strategies, our approach enables the selective detection of DOX among tetracycline antibiotics through a triple-mode system (fluorescence, electrochemical, and colorimetric), achieving an exceptionally low detection limit. To expand their utility, red-emitting carbon dots (R-CDs) were embedded in PMMA to form solid films, where restricted intramolecular motion and surface structure conferred stable fluorescence for effective colorimetric sensing. The low limits of detection for DOX were found to be 15 nM for visual detection, 31.44 nM for fluorescence detection, and 17.9 nM for electrochemical detection. For supporting antimicrobial resistance control, detection of DOX residues was also done in tap water, milk, and egg samples. Owing to their excellent biocompatibility and minimal toxicity, the R-CD system was effectively employed as a "turn-off" fluorescent probe for intracellular imaging in HeLa cells. This work highlights the ability of the synthesized single probe to enable the detection of DOX via three distinct sensing modalities, each of which provides complementary evidence for the presence of DOX.

In situ visualization of lipid composition diversity in lipid droplets (LDs) is essential for decoding lipid metabolism and function. However, effective probes for simultaneously localizing and reflecting the lipid composition of LDs are currently lacking. Here, we synthesized full-color bifunctional carbon dots (CDs) that can target LDs as well as respond to the nuance in internal lipid compositions with highly sensitive fluorescence signals, due to lipophilicity and surface state luminescence. Combined with microscopic imaging, uniform manifold approximation and projection, and sensor array concept, the capacity of cells to produce and maintain LD subgroups with varying lipid composition was clarified. Moreover, in oxidative stress cells, LDs with characteristic lipid compositions were deployed around mitochondria, and the proportion of LD subgroups changed, which gradually disappeared when treated with oxidative stress therapeutics. The CDs demonstrate great potential for in situ investigation of the LD subgroups and metabolic regulations.

Mitochondria play a significant role in many cellular processes. Precise long-term tracking of mitochondrial status and behavior is very important for regulating cell fate and treating mitochondrial diseases. However, developing probes with photostability, long-term tracking capability, and tunable long-wavelength fluorescence has been a challenge in mitochondrial targeting. Carbon dots (CDs) as new fluorescent nanomaterials with low toxicity and high stability show increasing advantages in bioimaging. Herein, the mitochondria tracking CDs (MitoTCD) with intrinsic mitochondrial imaging capability and tunable long-wavelength fluorescence from green to red are synthesized where the lipophilic cation of rhodamine is served as the luminescent center of CDs. Due to the excellent photostability, superior fluorescence properties and favorable biocompatibility, these MitoTCD are successfully used for mitochondrial targeting imaging of HeLa cells in vitro and can be tracked as long as six passages, which is suitable for long-term cell imaging. Moreover, these MitoTCD can also be used for zebrafish imaging in vivo.

Multicolor carbon dots (CDs) have been developed recently and demonstrate great potential in bio-imaging, sensing, and LEDs. However, the fluorescence mechanism of their tunable colors is still under debate, and efficient separation methods are still challenging. Herein, we synthesized multicolor polymeric CDs through solvothermal treatment of citric acid and urea in formamide. Automated reversed-phase column separation was used to achieve fractions with distinct colors, including blue, cyan, green, yellow, orange and red. This work explores the physicochemical properties and fluorescence origins of the red, green, and blue fractions in depth with combined experimental and computational methods. Three dominant fluorescence mechanism hypotheses were evaluated by comparing time-dependent density functional theory and molecular dynamics calculation results to measured characteristics. We find that blue fluorescence likely comes from embedded small molecules trapped in carbonaceous cages, while pyrene analogs are the most likely origin for emission at other wavelengths, especially in the red. Also important, upon interaction with live cells, different CD color fractions are trafficked to different sub-cellular locations. Super-resolution imaging shows that the blue CDs were found in a variety of organelles, such as mitochondria and lysosomes, while the red CDs were primarily localized in lysosomes. These findings significantly advance our understanding of the photoluminescence mechanism of multicolor CDs and help to guide future design and applications of these promising nanomaterials.

No abstract available

No abstract available

No abstract available

In this work, a sustainable method was developed for the production of water-soluble carbon quantum dots employing a green approach. The synthetic protocol was employed using the microwave pyrolysis technique, while lemon peel served as a carbon precursor. Fabrication of highly fluorescent lemon-peel-derived CQDs (LP-CQDs) having inherent nitrogen functionality was validated by X-ray photoelectron spectroscopy, FTIR, X-ray diffraction, Raman spectroscopic analysis, and TEM techniques. The average particle size of fabricated LP-CQDs was 4.46 nm. LP-CQDs yielded a remarkable quantum yield of 49.5%, which displayed excellent salinity, photostability, storage time, conditions, and pH stability. LP-CQDs displayed encouraging results for tetracycline (TC) detection using a PL turn-off approach. The sensitivity of LP-CQDs toward TC was seen in a nanomolar range having a detection limit of 50.4 nM. Method validation was comprehensively studied to ensure the precision of the nanosensor. A complete analysis of different photophysical parameters of LP-CQDs was performed with TC to gain a deeper understanding of the sensing mechanism. Fabricated LP-CQDs showed fluorescence quenching toward TC, elucidated by the inner filter effect (IFE) mechanism. The synthesized nanoprobe demonstrated a lesser detection limit with a broad linear range, enabling facile, cheap, environmentally friendly, and fast detection of TC. Practicality of the detection method was assessed through analysis of real samples, resulting in satisfactory recovery percentage and relative standard deviation with respect to the developed probes. Furthermore, LP-CQDs were used as fluorescent inks and to fabricate paper-based fluorescent strips. This study lays the door for the sensing platform of LP-CQDs toward detection of TC, which may impact the potential role of environmental sustainability.

A ratiometric fluorescent probe based on N/S doped carbon dots (N/S-CQDs) and mercaptoacetic acid capped CdTe quantum dots (TGA-CdTe QDs) with sensitized and self-calibration functions was constructed to sensitively detect multiple tetracycline antibiotics (TCs). N/S-CQDs could attach stably to TGA-CdTe QDs and form a new composite ratiometric fluorescent probe that had a more than tenfold increase in sensitivity to TCs compared with each single QD. The probe could detect four common TCs as the color of the probe changed from bright red to dark red, and the limit of detection (LOD) was 1.47 × 10-2-1.78 × 10-2 mg/L. Practical applications of the probe in food and urine were also verified with recovery rates of 95.21%-104.97%. Due to the abundant spectral fingerprints provided by both QDs, this novel probe could accurately recognize not only different single TCs but also mixed TC samples even in actual samples combined with chemometrics.

In recent years, antibiotic residues in food have been of great concern to regulators and consumers. In this study, a novel fluorescent sensor based on S, N-doped carbon quantum dots (S, N-CQDs) was established for rapid detection of tetracycline antibiotics (TCs). Through the internal filter effect (IFE), QDs fluorescence can be effectively quenched by TCs, endowing it an "off" condition. Under the optimal conditions, the TC concentration in the range of 1.88-60 μmol/L had a good linear relationship with the change of QDs fluorescence intensity, and the limit of detection (LOD) was calculated as 0.56 μmol/L (S/N = 3). Furthermore, the proposed "Turn-off" sensor could be employed to quickly and accurately quantify TCs residues even in milk, honey and tap water. The recovery rate was as high as between 93.61% and 102.31%. The established sensor has great application value in the fields of food safety and drug analysis, and provides broad prospects for the future food industry.

No abstract available

Tetracyclines (TCs) prevent the growth of peptide chains and the synthesis of proteins, and they are widely used to inhibit Gram-positive and -negative bacteria. For the detection of tetracyclines in cell and in vitro, a convenient and simple detection system based on nitrogen-doped cyan carbon quantum dots (C-CQDs) was developed. C-CQDs have excellent excitation-independent properties, the best optimal excitation peak is 360 nm and the best emission peak is 480 nm. Based on the inner filter effect (IFE), the fluorescence intensity of C-CQDs in solution decreases with the increase of tetracyclines. In the range of 0–100 μM, C-CQDs present a good linear relationship with three tetracyclines (CTC, TET, OCT), with R2 all greater than 0.999. C-CQDs can detect tetracycline in milk samples with recovery in the range of 98.2–103.6%, which demonstrates their potential and broad application in real samples. Furthermore, C-CQDs exhibit excellent lysosomal targeting, as indicated by a Pearson's coefficient of 0.914 and an overlap of 0.985. The internalisation of C-CQDs was mainly affected by lipid raft-mediated endocytosis in endocytic pathway experiments. These experiments indicate that C-CQDs can be effectively used to detect TC content and target lysosomes as an alternative to commercial dyes.

No abstract available

In this study, a novel, sensitive, and cost‐effective spectrofluorimetric approach was established for the estimation of two important tetracycline antibiotics, tetracycline and doxycycline, without any pre‐treatment procedures or harsh reaction conditions, for the first time. The proposed methodology is based on the quantitative quenching effect of each tetracycline and doxycycline on the native fluorescence of nitrogen and sulfur co‐doped carbon quantum dots (NS‐CQDs). A simple and ultrafast approach was applied to synthesize NS‐CQDs using thiosemicarbazide and citric acid as starting materials after incubation in a microwave for only 1 min. Utilizing an excitation wavelength of 360 nm, NS‐CQDs showed maximum emission peak at 430 nm. Calibration curves revealed excellent linearity within the ranges of 1.0–10.0 and 0.8–12.0 μg/mL with detection limits of 0.20 and 0.09 μg/mL for tetracycline and doxycycline, respectively. Due to the method's high sensitivity and selectivity, the proposed approach was applied for the determination of the studied drugs in their capsules and human plasma samples with high %recoveries. The developed approach was validated according to ICHQ2(R2) guidelines. GAPI and AGREE metric tools were used to verify the method's greenness and eco‐friendliness, suggesting its use as a green substitute for the analysis of the studied drugs.

No abstract available

No abstract available

Herein, a "lab-on-an-AIE@Ln/ICP" sensor array was constructed by employing aggregation-induced emission carbon quantum dots (AIE-CQDs) as the guest and Eu/GMP ICP as the host. Based on the antenna effect (AE) and reductive photo-induced electron transfer (r-PET) between CQDs@Eu/GMP ICPs and tetracyclines (TCs), the as-constructed sensor produced satisfactorily dual-emitting fluorescence. By combining pH regulation with principal component analysis (PCA), the underlying fingerprinting patterns realized the specific identification and quantitation of six TCs in animal farm wastewater, milks and milk-derivative products. Through the aggregation-induced quenching of CQDs@Eu/GMP ICPs on test strips, the discernible fluorescence alterations were successfully utilized for developing smartphone-based visual assay. To sum up, the prominent novelty of this study lies in that based on the comprehensive principles of AE and r-PET along with combination of pH-adjustment and PCA, the pioneered sensor assay achieves specifically identifying and sensing individual TCs for their rapid and on-site detection in animal-derived matrices.

Nitrogen-doped carbon quantum dots (N-CQDs) were successfully synthesized using rice residue and glycine as carbon and nitrogen sources by one-step hydrothermal method. High quantum yield (23.48%) originated from the effective combination of nitrogen with various functional groups (CO, NH, CN, COOH and COC). The N-CQDs showed a fluorescence with the wavelength varied from 420 to 500 nm and the maximum emission wavelength being at 440 nm. N-CQDs have been importantly applied as probe to detect Fe3+ and tetracycline (TCs) antibiotics with remarkable performance. Using the linear relationship between fluorescence intensity and Fe3+ concentration, the N-CQDs could be employed as a simple, efficient sensor for ultrasensitive Fe3+ detection ranging from 3.32 to 32.26 µM, with a limit of detection (LOD) of 0.7462 µM. The N-CQDs showed the applicability to detect TCs. The detection limits of tetracycline, terramycin and chlortetracycline were 0.2367, 0.3739 and 0.2791 µM, respectively. The results of TC by fluorescence method in real water samples were in good agreement with standard Ultraviolet-visible (UV-vis) method. The N-CQDs have various potential applications including sensitive and selective detection of Fe3+ and TCs, and cellular imaging with low cytotoxicity, good biocompatibility and high permeability.

No abstract available

Tetracycline (TC) residues not only endanger human health, but also are detrimental to the sustainable development of aquaculture and animal husbandry. Herein, a novel fluorescence sensor with high sensitivity and selectivity was developed based on nitrogen-doped carbon dots embedded in zinc-based metal-organic frameworks and incorporating molecularly imprinted polymer (ZIF-8&N-CDs@MIP). The physical and chemical properties of the ZIF-8&N-CDs@MIP had been characterized by SEM, TEM, FTIR, XRD, BET, TGA, etc. Under optimal conditions, the limit of detection (LOD) of the novel sensor was 0.045 μg mL-1 with the concentration of TC in the range of 0.1-4.0 μg mL-1. In addition, the prepared imprinted polymers showed superior adsorption selectivity to tetracycline compared with non-imprinted polymers, and the quenching mechanism of ZIF-8&N-CDs@MIP was demonstrated to be attributed to the inner filter effect (IFE). This work provided an effective and reliable method for the specific detection of tetracycline and was successfully applied in milk and egg samples with satisfactory recoveries (80.67-95.22%).

Sudan dyes are strictly prohibited from being added to edible products as carcinogens and tetracycline hydrochloride (TC) remaining in animal-derived food may cause harm to the human body. Therefore, it is necessary to establish a high-sensitivity, simple and convenient method for the detection of Sudan dyes and TC in foods for safety purposes. In this work, multifunctional blue fluorescent carbon dots (B-CDs) were prepared by a one-step hydrothermal synthesis using glucose as the carbon source. The results show that the fluorescence intensity of B-CDs was significantly affected by the acidity of the solution and can be quenched by Sudan I, IV and TC through selective studies. Interestingly, the fluorescence quenching intensities of B-CDs have a good linear relationship with the concentration of Sudan I and IV at pH = 3–7. The wide range of pH is beneficial to broaden the application of B-CDs in a practical samples analysis. The method has been successfully applied to real food samples of tomato paste, palm oil and honey, and the detection limits are 26.3 nM, 54.2 nM and 31.1 nM for Sudan I, Sudan IV and TC, respectively. This method integrates Sudan dyes and TC into the same multifunctional B-CDs, which shows that the sensor has a great potential in food safety detection.

A novel fluorescent probe based on molecularly imprinted polymers (MIPs) coupled with N-doped carbon dots (CDs) was prepared and used for specific recognition and sensitive determination of tetracycline (TC). N-doped CDs were synthesized using citric acid as a carbon source and ethylenediamine as a nitrogen source by a microwave assisted pyrolysis method. The determination conditions such as the solvents, material amount, pH value, and temperature were optimized. The CDs-MIPs have the best quenching on TC in water. The proposed method used for TC determination in milk powder samples had a detection limit of 0.054 μg mL−1 and a wide range of 0.5–30 μg mL−1. Meanwhile, satisfactory recoveries were obtained ranging from 95 to 108%. Oxytetracycline, chlorotetracycline and most of the coexisting substances showed no obvious interference indicating that the CDs-MIP probe exhibited high selectivity due to the presence of imprinted sites. Charge transfer from CDs-MIPs to TC may be through the mechanism of fluorescence quenching. This work gives a feasible strategy for the synthesis of N-doped carbon dot based molecularly imprinted polymers used as a fluorescent sensor in the food analysis field.

Monitoring and eliminating pollutants are critical for environmental remediation. In this study, nitrogen- and sulfur-co-doped nanocarbon dots (NS-NCDs) were synthesized via a hydrothermal method using ascorbic acid and thiosemicarbazide as precursors. The introduction of nitrogen and sulfur atoms through doping altered the electron configuration and nanostructure of the carbon dots, resulting in strong blue fluorescence (quantum yield: 11.32%). These NS-NCDs functioned as dual-functional agents for both detecting and degrading tetracycline antibiotics (TCs). Under UV light, the fluorescence color of the NS-NCDs transitioned from blue to colorless with increasing TCs concentration. Fluorescence quenching of NS-NCDs by TCs was mediated synergistically by the inner filter effect (IFE) and electron transfer, with IFE contributing 76%, 75%, and 71% of the total quenching efficiency for tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), respectively. This dual-mechanism enabled ultrasensitive detection of TCs, achieving limits of detection (LODs) as low as 0.21 μM (TC), 0.28 μM (OTC), and 0.16 μM (CTC), which are well below regulatory thresholds for environmental antibiotic residues. The NS-NCDs probe also exhibited high selectivity and anti-interference performance in complex matrices. Furthermore, NS-NCDs serve as a catalyst to rapidly activate peroxymonosulfate (PMS) under sunlight for the degradation of TCs, achieving degradation rates exceeding 90% within 60 min. TCs degradation is driven by the oxidation of free radicals and electron transfer from TCs to PMS, facilitated by NS-NCDs. This study demonstrates the bifunctional role of NS-NCDs in real-time monitoring and photocatalytic degradation of TCs, providing an innovative strategy to combat antibiotic contamination.

The tetracycline (TC) residue in water environment has caused serious public safety issue. Thus, efficient sensing of TC is highly desirable for environmental protection. Herein, biomass-derived nitrogen-doped carbon dots (N-CDs) synthesized from natural Ophiopogon japonicus f. nanus (O. japonicus) were used for TC detection. The unique solvent synergism efficiently enhanced detection sensitivity, and the detailed sensing mechanism was deeply investigated. The blue fluorescence of N-CDs was quenched by TC via static quenching and inner filter effect. Moreover, the enhancement of green fluorescence from deprotonated TC was firstly proposed and sufficiently verified. The solvent effect of N-methyl pyrrolidone (NMP) and the fluorescence resonance energy transfer (FRET) with N-CDs achieved an instantaneous enhancement of the green emission by 64-fold. Accordingly, a ratiometric fluorescence method was constructed for rapid and sensitive sensing of TC with a low detection limit of 6.3 nM within 60 s. The synergistic effect of N-CDs and solvent assistance significantly improved the sensitivity by 7-fold compared to that in water. Remarkably, the biomass-derived N-CDs displayed low cost, good solubility, and desired stability. The deep insights into the synergism with solvent can provide prospects for the utilization of biomass-based materials and broaden the development of advanced sensors with promising applications.

Carbon dots (CDs) with room-temperature phosphorescence (RTP) attract the numerous explorations owing to their promising prospects in multiple fields, howbeit, their phosphorescence in aqueous barely lasts for long due to the quenching effects originated from the dissolved oxygen, and thus it is of a great challenge to acquire the water-soluble phosphorescent CDs. We here proposed one kind of solid-state RTP CDs through a microwave strategy using tetraethylenepentamine and phosphoric acid as the precursors. Significantly, we further employed tetraethoxysilane (TEOS) as the matrix, which could encapsulate the previous CDs, thus facilitating the formation of the compact structure and activating their long-lived and high-efficiency phosphorescence in aqueous. On the basis of their fluorescence and phosphorescence, a dual-signal strategy of detecting tetracycline by CDs@TEOS was successfully established, and this detection exhibited a fluorescent linear-range of 2 nM to 90 μM as well as a phosphorescent linear-range of 30 nM to 300 μM towards assaying tetracycline, broadening the dual-signal ways of assaying tetracycline. Additionally, the CDs prepared here showed the great potential of serving as the RTP ink for the information encryption.

The requirement of simple, efficient and accurate detection of tetracycline (TC) in water environments poses new challenges for sensing platform development. Here, we report a simple method for TC sensing via fluorescence detection based on metal–organic coordination polymers (MOCPs, (4-Hap)4(Mo8O26)) coated with nitrogen-doped carbon dots (NCDs). These NCDs@(4-Hap)4(Mo8O26) composites showed excellent luminescence features of NCDs with stable bright-blue emission under UV light. The results of the sensing experiment showed that the fluorescence of NCDs@(4-Hap)4(Mo8O26) can be quenched by TC (166 µM) with 94.1% quenching efficiency via the inner filter effect (IFE) in a short time (10 s), with a detection limit (LOD) of 33.9 nM in a linear range of 8–107 µM. More significantly, NCDs@(4-Hap)4(Mo8O26) showed a high selectivity for TC sensing in the presence of anions and metal cations commonly found in water environments and can be reused in at least six cycles after washing with alcohol. The potential practicality of NCDs@(4-Hap)4(Mo8O26) was verified by sensing TC in real water samples with the standard addition method, and satisfactory recoveries from 91.95% to 104.72% were obtained.

Nitrogen-doped carbon dots (N-CDs) were synthesized hydrothermally using abundantly accessible pitaya peel and 1,2-ethylenediamine as precursors. N-CDs exhibited favorable photostability, which can serve as a multifunctional nano-sensor for detection of three tetracycline antibiotics (TCs) based on fluorescence (FL) dual-mode sensing strategy. The FL intensity of N-CDs could be rapidly quenched by tetracycline (TC) and oxytetracycline (OTC) based on bandgap transition, inner filter effect (IFE), static quenching (SQ) and electrostatic interaction. While a new finding that FL of N-CDs demonstrated a remarkable enhancement in the presence of chlortetracycline (CTC) with the same detection mechanisms as TC and OTC, also including the aggregation-induced emission (AIE). Furthermore, an easily extensible fluorescence sensor array was developed based on multiple CDs for identifying multiple TCs in real samples. Therefore, the constructed N-CDs provides a new perspective for choosing extensive natural biomass to synthesize CDs, further developing a novel sensor to realize their versatile sensing application.

Tetracyclines (TCs), widely used in livestock farming, accumulate in ecosystems and pose health risks due to their persistence. Existing detection methods suffer from high cost, complex procedures, and insufficient specificity. Herein, a dual-emission fluorescent composite (CDs@ZIF-8) was designed by encapsulating carbon dots (CDs) into zeolitic imidazolate framework-8 (ZIF-8). The composite material exhibits distinct dual emission peaks at 332 nm (ZIF-8) and 492 nm (CDs), and achieves ratiometric fluorescence sensing and differentiation between two structurally analogous antibiotics tetracycline (TC) and chlortetracycline (CTC) by quenching the ZIF-8 peak and enhancing the CD peak. The sensor achieves low detection limits of 7.13 nM for TC and 7.25 nM for CTC, with excellent selectivity and anti-interference capability over other antibiotics. A colorimetric logic gate and smartphone-based RGB analysis platform were developed for visual discrimination and quantitative detection, demonstrating high accuracy in real-sample analysis. This work provides a robust, low-cost strategy for on-site monitoring of TC antibiotics.

Tetracyclines residues, particularly oxytetracycline (OTC) and tetracycline (TC), have raised extensive concern because of their serious adverse effects on human health. Herein, a dual-response fluorescent probe based on nitrogen-doped carbon dots (N-CDs) and Eu3+ hybrid (N-CDs-Eu3+) was developed to selectively determine OTC and TC. The N-CDs act as ancillary ligands of Eu3+ and recognition units of OTC/TC, while the Eu3+ ions chelated with N-CDs can also specifically recognize OTC/TC. Upon inclusion of OTC/TC, an enhancement in Eu3+ emission occurs due to the energy transfer from OTC/TC to Eu3+ and the efficient elimination of quenching effect caused by H2O molecule, which is attributed to the incorporation of N-CDs; while the blue fluorescence emitted by the N-CDs decreases under the inner filter effect and static quenching effect caused by OTC/TC. Based on the double and reverse response signals, the ratiometric detection of OTC and TC in the range of 0.1-45 μΜ and 0.1-30 μΜ is achieved with a detection limit of 0.017 and 0.041 μM, respectively. In addition, the noticeable variation in fluorescence color of the probe is integrated with a smartphone-assisted analysis device for the rapid on-site quantitative assay of OTC, where the detection limit is 0.15 μΜ. The results show that this probe performs with excellent specificity and anti-interference for both OTC and TC, and satisfactory detection results are obtained in lake water, milk, and honey samples, thereby confirming that the probe exhibits promising application in food safety and environmental monitoring.

No abstract available

A highly sensitive, selective, and rapid spectrofluorometric method has been developed using fluorescence sensors. This method is based on the highly fluorescent graphene quantum dots coated with silica molecularly imprinted polymers (GQDs-SMIPs) for the determination of tetracycline HCl (TET) and metronidazole (MET). Upon excitation of the GQDs-SMIPs at 260.0 nm for TET and 245.0 nm for MET, strong fluorescence emissions at 292.0 nm were produced for both sensors. Such fluorescence was quenched by the addition of their corresponding molecularly imprinted polymer (MIPs) templates. The quenching effect was linear over the concentration ranges of 15.0–120.0 µM and 15.0–140.0 µM for TET and MET, respectively. Limits of detection (LOD) were 3.55 µM, and 4.48 µM while limits of quantification (LOQ) were 10.75 µM and 13.57 µM for TET and MET, respectively. The fabricated GQDs-SMIPs were characterized using scanning electronic microscopy, Fourier-transform IR spectroscopy, and X-ray diffraction. Selectivity of the method was investigated against potentially interfering substances, including two official impurities of TET and MET. Additionally, this fluorescent technique was successfully applied for the determination of these drugs in pharmaceutical dosage forms and spiked human plasma samples. This approach provides a selective and sensitive fluorometric platform for the determination of the studied drugs in complex matrices and quality control laboratories.

The widespread presence of tetracyclines in the environment has raised concerns about the potential risks to ecosystems and human health. The ratiometric fluorescence sensor for detecting tetracyclines was developed using europium-doped carbon dots (Eu-CDs) as probes under alkaline conditions. The sensing mechanism of sensor for tetracyclines was considered as inner filter effect (IFE), antenna effect (AE), and self-quenching effect (SQE). The sensor had a wide linear detection range than the reported europium ions-based tetracyclines sensors. The linear detection ranges of oxytetracycline (OTC), tetracycline (TC), doxycycline (DC) and chlorotetracycline (CTC) were respectively 0.00-603.75 μM, 0.00-623.82 μM, 0.00-594.61 μM and 0.00-601.54 μM, and the corresponding detection limits were respectively 9.50 nM, 15.80 nM, 10.40 nM and 90.30 nM. The smartphone with RGB Color Picker was further employed to analyze the concentration of tetracyclines, which provided a new method for visual tetracyclines detection. The application of Eu-CDs test paper was also explored, and the results showed that the Eu-CDs test paper has great potential application in the visual detection of tetracyclines. In addition, the accuracy of the established tetracyclines sensor was compared with that of the China national standard method by high-performance liquid chromatography (HPLC), and the results showed that the established method in this work has similar accuracy to the China national standard method. The sensor has been employed to detect tetracyclines in the actual samples with satisfactory results, which indicated that this method has promising applications in the real-time monitoring tetracyclines of food and environment.

Enhanced blue fluorescent carbon nitride quantum dots (g-C3N4QDs) were synthesized by a simple solvothermal “tailoring” process from bulk g-C3N4 and analyzed by various characterization methods. The as-obtained g-C3N4QDs were successfully applied in the determination of tetracycline (TC) with a good linear relationship in the range of 0.23–202.70 μM. The proposed fluorescent sensor shows excellent stability, good repeatability, high selectivity and outstanding sensitivity to TC with a low detection limit of 0.19 μM. The fluorescence quenching mechanism of g-C3N4QDs with TC was mainly governed by static quenching and the inner filter effect. The method was successfully applied to monitor TC in tap water and milk powder samples.

No abstract available

No abstract available

No abstract available

A quadruple-channel fluorescent sensor array based on label-free carbon dots (CDs) was fabricated to detect and discriminate a series of tetracyclines (TCs), including chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC) and doxycycline (DOX). Blue-emitting carbon dots (B-CDs) and green-emitting carbon dots (G-CDs) were prepared to serve as four sensing elements. When the TCs were directly mixed with CDs, the fluorescence quenching phenomenon appeared. Since different TCs exhibited different affinities for sensing elements, the sensor array displays a distinct fluorescence pattern of the fluorescence intensity variation (F0 - F)/F0 for each of these TCs, which is further analyzed by principal component analysis (PCA). The present fluorescent sensor array has the capacity to differentiate TCs at a low concentration of 1 μM. Meanwhile, quantitative detection with a lower limit (0.30 μM) for TCs could be achieved by applying a single element. Moreover, a high accuracy (100%) examination of unknown samples is acquired. Finally, the fluorescent sensor array performs well in distinguishing binary mixtures and could also recognize TCs in milk.

In this study, we present an intelligent electromagnetic-actuated microfluidic chip integrated with a G-quadruplex DNAzyme-based biocatalysis platform for rapid and sensitive tetracycline (TC) detection. In this sensing system, TC significantly quenches fluorescent magnetic carbon dots (M-CDs) via the internal filtration effect and dynamic quenching (the excitation and emission wavelength at 350 and 440 nm, respectively). Then, the G-quadruplex on the M-CDs-Aptamer is exposed and bound with hemin to form hemin-G-quadruplex DNAzyme, catalyzing the conversion of 3,3',5,5'-tetramethylbenzidine to produce blue color. This enables the fluorescence/colorimetric detection of TC. Importantly, an automatic electromagnet-integrated microfluidic chip was designed to control the shuttling of magnetic materials in each function slot according to a programmed sequence. Under the optimal conditions, the detection limits of TC for fluorescence and colorimetric methods were 11 and 43 μmol/L, respectively. The detection results for tilapia (Oreochromis nilotica) were comparable to those of traditional high-performance liquid chromatography. This platform offers excellent performance for TC determination and potential for portable, intelligent detection of trace pollutants in food and the environment.

The antibiotic tetracycline can be efficiently used as medicine for the deterrence of bacterial infections in humans, animals, and plants. However, the unprecedented use of tetracycline is of great concern owing to its low biodegradability, extensive usage, and adverse impacts on the environment and water quality. In this study, a sensitive spectrofluorometric method was proposed for the direct determination of tetracycline, based on biocompatible fluorescent carbon dots (CDs). The synthesis of CDs was performed by adopting a green hydrothermal procedure from carrot juice without requiring surface passivation or outflowing any environmentally hazardous waste. X-ray diffraction analysis and transmission electron microscopy revealed amorphous spherical-shaped CDs that exhibited blue emission under blue illumination. The fabricated fluorescent probe directly detected tetracycline in the concentration range of 4.00 × 10-6 to 1.55 × 10-5 mol L-1 with an LOD of 1.33 × 10-6 mol L-1. The performance of the probe was assessed in a tap water sample, with recovery values between 80.70 and 103.60%. The method's greenness was evaluated using the Analytical Green metric approach (AGREE) and confirmed to be within the green range. The developed method is facile, rapid, cost-effective, and offers a wide linear range and satisfactory selectivity, making it potentially suitable for determining tetracycline in water applications.

Terbium- and nitrogen-doped carbon quantum dots (Tb,N@CQDs) were greenly created employing microwave synthesis from plum juice with terbium nitrate. The synthesis of Tb,N@CQDs was fast (7 min) with a high quantum yield (35.44%). Tb,N@CQDs were fully characterized using transmission electron microscopy, Zeta potential analysis, fluorescence, and ultraviolet spectroscopy. Omadacycline (OMC) is a broad-spectrum tetracycline that has been recently approved by the United States Food and Drug Act (FDA) in October 2018. OMC is the first oral aminomethylcycline class antibiotic drug that was authorized for the treatment of acute skin structure infections and community-acquired pneumonia. Tb,N@CQDs exhibited emission at 440 nm after excitation at 360 nm, where their fluorescence intensity showed a reduction upon addition of OMC. The experimental parameters were further studied and optimized. The linear range was between 40 and 60 parts per billion (ppb), with (limit of quantitation) equal to 34.78 ppb. The proposed approach was validated for bioanalytical purposes using FDA guidelines and proved to be straightforward, cheap, highly sensitive, and very selective, which can be used in clinical studies. The developed approach proved to be green using some current assessment metrics and was applied successfully for the determination of OMC in human plasma, milk, and pharmaceutical formulations as well as pharmacokinetic study. Graphical Abstract This is a visual representation of the abstract.

No abstract available

No abstract available

Recently, fluorescent sensors have gained considerable attention due to their high sensitivity, low cost and noninvasiveness. Among the different materials that can be used for this purpose, carbon dots (CDs) represent valuable candidates for applications in sensing. These, indeed, are easily synthesized, show high quantum yield and are highly biocompatible. However, it was pointed out that the photoluminescence properties of these nanomaterials are strictly dependent on the synthetic and purification methods adopted. The presence of halloysite nanotubes (HNTs), a natural, low cost and biocompatible clay mineral, has been found to be efficient in obtaining small and highly monodispersed CDs without long and tedious purification techniques. Herein, we report the comparison of synthetic pathways for obtaining halloysite-N-doped CDs (HNTs-NCDs) that could be used in biological sensing. One was based on the synthesis of N-doped CDs by a bottom-up approach on HNTs’ surface by a MW pyrolysis process; the other one was based on the post-modification of pristine N-doped CDs with halloysite derivatives. The evaluation of the best synthetic route was performed by different physico-chemical techniques. It was found that the bottom-up approach led to the formation of N-doped CDs with different functional groups onto the HNTs’ surface. This evidence was also translated in the different fluorescence quantum yields and the existence of several functional groups in the obtained materials was investigated by potentiometric titrations. Furthermore, the ability of the synthesized nanomaterials as sensors for Fe3+ ions detection was assessed by spectroscopic measurements, and the cellular uptake was verified by confocal/fluorescence microscopies as well.

Nitrogen doped carbon dots (N-CDs) have been prepared via a one-pot hydrothermal method by using formamide and o-phenylenediamine as the carbon precursors. The as-fabricated N-CDs display excellent water dispersibility, good biocompatibility and anti-photobleaching properties. A strong emission band with an emission maximum (λflmax) of 556 nm is observed under 450 nm excitation, and a large Stokes shift of 106 nm is presented. However, the fluorescence is quenched by the addition of Fe3+; a good linearity is shown in the range of 0–65 μM with a detection limit as low as 0.85 μM. Fortunately, the quenched fluorescence could be recovered rapidly by the addition of monohydrogen phosphate (HPO42−) due to the formation of the stable [N-CDs–Fe3+–HPO42−] complex, and a good linearity is exhibited in the range of 0–60 μM with a low detection limit of 0.80 μM for HPO42−. A novel “on–off–on” fluorescence response is seen with an obvious color change from yellow-crimson-yellow by the naked eye. In addition, the confocal microscopy images suggest that the as-synthesized N-CDs could serve as a sensitive nanosensor for Fe3+ and HPO42− detection, implying the diverse potential application of N-CDs in the biomedical field.

The development of biocompatible, widely applicable fluorescent imaging probe, with emission beyond the cellular and tissue autofluorescence interference, is a challenging task. In this regard, a series of 28 different fluorescent carbon dots (CDs) were synthesized using carbohydrates as carbon and cysteine (Cys) and o-phenylenediamine (OPD) as nitrogen source. The screened CDs showed photostability with bright blue (∼505-520 nm) and red (∼588-596 nm) emission and high fluorescence quantum yield (QY = 72.5 ± 4.5%). FTIR and NMR studies suggested presence of carboxylate and ester group for Cys- and OPD-based CDs, respectively. HRTEM results showed particle size of ∼3.3-5.8 nm for all the developed CDs. The antibacterial studies suggested that the developed CDs showed preferential antibacterial activity against Escherichia coli, with IC50 value of ∼200 μg/mL. Cytotoxicity and confocal microscopy studies of HeLa cells reflected that these CDs showed both anticancer activity and imaging ability. Agarose gel electrophoresis, together with SOSG assay and thiol estimation studies, suggested oxidative stress induced DNA degradation to be the primary cause for cell death. These hemocompatible CDs can thus be used as simultaneous imaging probe and photo dynamic therapeutic agent for both antibacterial and anticancer activity.

In this study, carbon dots synthesized from bamboo leaf cellulose were used simultaneously as a staining agent and for doxorubicin delivery to target cancer cells. Owing to their nontoxic properties, the production of carbon dots from bamboo leaves is a green approach involving optimized application of bamboo tree waste. For multifunctional applications, the carbon dots were modified with 4-carboxybenzylboronic acid and doxorubicin to improve target specificity and drug delivery to HeLa tumor cells. The resulting modified carbon dots were characterized using different analytical techniques, which showed that they were biocompatible, nontoxic, and highly stable over a wide range of pH values and at high ionic strengths. Furthermore, in vitro confocal microscopy studies demonstrated their blue fluorescence and cellular pathway for entering HeLa cells via folate receptor-mediated endocytosis. Cell viability data and flow cytometry results also confirmed the selective uptake of the carbon dots by HeLa cells, which significantly enhanced cell cytotoxicity.

No abstract available

The preparation of functional long-wavelength-emitting nanomaterials and the researches on their applications in antibacterial and antibiofilm fields have important significance. This paper reports the preparation of yellow-green-fluorescent and high- quantum yield carbon dots (4-ACDs) with 4-aminosalicylic acid and polyethylene imine as raw materials through one-step route, and the impacts of raw material structure and the reaction conditions upon the optical properties of the products have been investigated. 4-ACDs exhibit excellent broad-spectrum antibacterial activity, and their good biocompatibility ensures them as ideal fluorescent nano-probe for cell imaging. However, 4-ACDs could not effectively eliminate the biofilm of Staphylococcus aureus (S. aureus). CDs-LZM complex was prepared through the coupling between 4-ACDs and lysozyme (LZM) and the complex showed strong antibacterial activity against Gram-positive bacteria, particularly with MIC against S. aureus at 5 μg mL-1. Besides, CDs-LZM showed excellent ability against the biofilm of S. aureus. At the concentration of 60 μg mL-1, its inhibition rate against the growth of biofilm was 86 %, and elimination rate against biofilm reached 76 %. CDs-LZM exhibited obvious antibiofilm ability through removing extracellular matrix of biofilm, greatly reducing the thickness of biofilm under confocal microscopy. The application of novel long-wavelength-emitting nanomaterial in eliminating pathogenic bacteria is of great significance.

No abstract available

This study introduces an environmentally friendly and cost-efficient approach for producing carbon quantum dots (CQDs) from Citrus nobilis deliciosa via a microplasma-assisted technique. The obtained CQDs demonstrated excitation-dependent fluorescence accompanied by a red shift, which can be ascribed to quantum size effects and the influence of surface chemical functionalities. The synthesized CQDs demonstrated remarkable antibacterial properties, achieving growth inhibition rates of 99.24% against Staphylococcus aureus and 98.12% against Escherichia coli at a concentration of 50 μg mL−1. The antibacterial mechanism was primarily driven by membrane destabilization and oxidative stress induction, making CQDs a promising alternative to conventional antimicrobial agents. Additionally, the CQDs served as highly responsive fluorescent probes for Cd(ii) ion detection, exhibiting a linear response range spanning 1–14 μg mL−1, a minimum detectable concentration of 0.12 μg mL−1, and a Stern–Volmer quenching constant (KSV) of 0.45 μg mL−1. These findings highlight the dual functionality of CQDs as potent antibacterial agents and efficient fluorescence-based sensors for heavy metal detection. The eco-friendly synthesis, combined with the excellent biocompatibility and adjustable optical characteristics of CQDs, highlights their potential for applications in biosensing, environmental monitoring, and biomedical fields.

Normally, electrostatic-dependent mitochondria localization can cause a decrease/loss of mitochondrial membrane potential (MMP), leading to the corresponding abnormal behaviors. So, achieving subcellular organelle localization and imaging with as little interference on their physiological activity is of significance for understanding cell activity. Herein, we discover and demonstrate that "polarity" can independently act as a novel kind of target for labeling at the organelle level. On this basis, mitochondria and lysosomes are precisely fluorescently imaged by two kinds of polarity-targeted carbon dots (C-dots), respectively. The two C-dots, named C-dots-1 and C-dots-2, have almost identical size and morphology as well as surface chemistry. The subtle difference is their polarity property: both of them are amphiphilic, with 1.54 and 0.95 for the log P values. Different from commonly used cationic-based organelle probes, both of the two C-dots possess slightly negatively charged surfaces (ζ-potential values ∼ -2.5 to -7.5 mV) at physiological conditions. Interestingly, the C-dots-1 and C-dots-2 have the capacity for highly selectively labeling and imaging mitochondria and lysosomes, whether cancer cells or normal cells. Because the targeting processes do not rely on electrostatic attraction effects, the MMP is not changed during localization processes. So, the corresponding cell abnormal behaviors caused by MMP diminishing, for example, the autophagy phenomenon, can be effectively avoided.

Due to the serious detrimental impact on human health, antibiotic pollution particularly tetracyclines residues has become a serious problem. Herein, a multiple response fluorescent probe consisted of dual-emission carbon dots and Eu3+ (D-CDs@Eu3+) is designed for the determination and discrimination of tetracyclines (TCs). Specifically, the carboxyl and amidogen group of dual-emission carbon dots (D-CDs) can coordinate with Eu3+ to form the D-CDs@Eu3+. Upon adding TCs, the fluorescence intensities of D-CDs at 405 nm and 495 nm are quenched due to inner filter effect (IFE) and the localization of fluorescence resonance energy transfer (L-FRET) between the D-CDs@Eu3+ and TC. Simultaneously, the D-CDs@Eu3+ may chelate with TCs to enhance the occurrence of antenna effect, while the characteristic peaks of Eu3+ at 590 nm and 615 nm are enhanced. On these bases, the TCs detection is achieved with low detection limits from 46.7 to 72.0 nM. Additionally, through the distinct efficiencies of L-FRET, the discrimination of TCs is achieved. Moreover, a novel centrifugated lateral flow assay strips (CLFASs) device is developed by integrating the D-CDs@Eu3+, lateral flow assay strips and smartphone using RGB variations for TCs detection, achieving remarkable recoveries (98.6-103.7 %) in real samples. Therefore, this CLFASs device provides a reliable approach for the TCs detection, demonstrating potential applications.

Metal organic frameworks (MOFs) possess a large surface area, inherent porosity and high crystallinity. Nevertheless, they lack electron acceptors, which limit the exploitation of their photocatalytic properties. Carbon dots (CDs) known for excellent optical properties can serve as localized electron acceptors. As a novel hybrid nanomaterial, the structure of CDs@MOFs effectively facilitates charge separation and carrier transfer, bring about a marked improvement of photocatalytic activity. In this study, yellow-emission carbon dots (YCDs) were encapsulated within zirconium-based metal organic framework (UiO-66) via a dynamic adsorption method. Compared with blue carbon dots (BCDs), the YCDs@UiO-66 exhibited superior degradation performance. It demonstrates that incorporation of YCDs broadens the UV absorption range of UiO-66, thereby enhancing light utilization. The degradation efficiency of YCDs@UiO-66 was 92.6%, whereas UiO-66 alone achieved only 63.1%. Notably, the results of the radical quenching experiment and electron paramagnetic resonance (EPR) revealed that h+ and •O2- played a prominent role in the photodegradation of tetracycline hydrochloride (TCH). This study highlights that the introducing YCDs in MOFs-mediated photocatalytic reactions is a viable strategy to improve catalytic efficiency.