溶胶凝胶制备UC微球的研究进展、难点与技术指标

The development of functional biomaterials with real-time monitoring of mineralization processes, drug release and biodistribution has potential applications but remains an unsolved challenge. Herein, erbium- and ytterbium- containing mesoporous bioactive glass microspheres (MBGs:Er/Yb) with blue and red emission at an excitation wavelength of 980 nm were synthesized by a sol-gel combined with organic template method. As the concentration of Yb3+ ions gradually increases, the emission intensity of the MBGs:Er/Yb exhibits a clear concentration quenching effect. Combined with in vitro bioactivity tests, the optimal molar ratio of Er3+/Yb3+ was determined to be 4:3. Therefore, MBGs:4Er/3Yb was selected for in vitro biomineralization and drug release monitoring. The results of biomineralization monitoring show that the upconversion luminescence intensity is closely related to the degree of biomineralization. The upconversion luminescence intensity of MBGs:4Er/3Yb is quenched with the increase of the degree of biomineralization. The degree of luminescence quenching during biomineralization can be semiquantized. Drug release monitoring experiments showed that the anticancer drug doxorubicin hydrochloride (DOX) was successfully loaded into MBGs:4Er/3Yb and selectively quenched the green emission. When DOX was released, the green emission recovered stably, and It/I0 increased gradually. Moreover, there was a linear relationship between It/I0 and cumulative drug release, indicating that DOX-MBGs:4Er/3Yb is highly sensitive to DOX release, and monitoring the It/I0 values of DOX-MBGs:4Er/3Yb can achieve real-time tracking of the DOX release process to a certain extent. In conclusion, MBGs:4Er/3Yb has potential application as an upconversion luminescence biomonitoring material in the field of bone tissue engineering. STATEMENT OF SIGNIFICANCE: Mesoporous bioactive glasses have great potential for applications in bone tissue repair due to their excellent biological properties, but the effective information of the repair process cannot be grasped in a timely manner. Therefore, real-time monitoring of mineralization and drug release processes will be beneficial to obtain the degree of healing and optimize the amount and distribution of drugs to improve targeted therapeutic effects. For biomaterials, in vitro biological properties determine their biological properties in vivo, where the environment is more complex and diverse, and thus in vitro biological performance monitoring is particularly crucial. The organic combination of physical properties and biological properties will also provide a feasible idea for the development of biological materials.

Silica microspheres have been demonstrated as the optical micro-cavity for laser generation based on whispering-gallery modes (WGM). They can achieve a high-quality factor (Q) within a tiny volume. Traditionally, complex processes are needed to process a coating containing photoluminescent elements, with enough thickness and uniformity, for laser generation. We developed a novel sol-gel fabrication method of Er3+/Yb3+doped silica microspheres with a homogeneous doping concentration over the entire microsphere volume. The sol-gel precursors were doped with 1–2 mol% Er3+ and/or Yb3+. The viscosity of the precursor was controlled at around 4000 cP, and gel fibers can be conveniently drawn from the precursor. After firing at 1000 °C for 1 h, transparent fibers with diameters of 40–180 µm were obtained. The fiber tips were quickly melted into microspheres using a CO2 laser. The diameters of microspheres were determined by the fiber diameter and laser parameters, such as laser power and irradiation time duration. Typically, the microspheres had diameters between 90 to 160 µm. The emission spectrum under 357 nm and 527 nm excitation showed characteristic Er3+ emission peaks, that match the literature well. The UV-VIS spectra confirm the photoluminescence results and showed both Er3+ and Yb3+ characteristic absorptions. The optical behaviors of the microspheres indicate that the Er3+ and Yb3+ were well dispersed in the silica matrix and the microspheres had typical optical activities of Er3+/Yb3+ glasses. Silica microspheres, fabricated using laser melting, with homogeneously doped Er3+/Yb3+. No need for multiple layers of Er3+/Yb3+ sol-gel coatings. Microspheres demonstrated strong optical activities with Er3+/Yb3+ doping. Silica microspheres, fabricated using laser melting, with homogeneously doped Er3+/Yb3+. No need for multiple layers of Er3+/Yb3+ sol-gel coatings. Microspheres demonstrated strong optical activities with Er3+/Yb3+ doping.

… The drug release process of MTO was successfully monitored by upconversion luminescence. Cell experiments confirmed that 7Li-MBGs:2Er/2Yb-0.75MTO has a certain long-term …

Er3+/Yb3+-doped TiO2 up-conversion (UC) phosphors were prepared by spray pyrolysis, and the UC luminescence properties were optimized by changing the calcination temperature and the concentration of Er3+ and Yb3+ dopants. TiO2:Er3+/Yb3+ showed green and red emissions due to the 2H11/2/4S3/2 → 4I15/2 transition and the 4F9/2 → 4I15/2 transition of Er3+ ions, respectively. The R/G ratio between red (R) and green (G) emissions does not change significantly with Er concentration but increases linearly with increasing Yb3+ concentration. The dependence of UC luminescence intensity on 980 nm IR pumping power showed that both the red and green UC luminescence of TiO2:Er3+/Yb3+ occurred through a typical two-photon process. In terms of achieving the highest red UC emission intensity, the optimal Er3+ and Yb3+ contents are 0.3% and 7.0%, respectively. The UC intensity of TiO2:Er3+/Yb3+ particles increases until they are calcined at temperatures up to 600 °C and then decreases rapidly above 800 °C. This is because when the calcination temperature is 800 °C and higher, not only does the phase transition of TiO2:Er3+/Yb3+ occur from anatase to rutile, but also the Yb2Ti2O7 impurity phase is formed. According to SEM and TEM/EDX analysis, the prepared TiO2:Er3+/Yb3+ UC powders have an average particle size of 680 nm, a spherical shape with a dense structure, and Er and Yb are uniformly dispersed throughout the particles without local separation. A mark prepared using TiO2:Er3+/Yb3+ powder was found to have a UC emission high enough to be visually observed when irradiated with a portable 980 nm IR lamp.

… 3+ /Ho 3+ codoped La 2 O 3 microspheres with up-conversion emission property have been … The formation process and the physicochemical properties of the hollow microspheres have …

In the present work, Er/Yb co-doped silica hollow spheres are prepared in a two-step process. In a first step, polystyrene-core is silica coated in situ by a modified Stöber sol–gel method …

… The first lanthanide-doped sol-gel silica glasses were samples … [36] prepared highly luminescent SiO 2 microspheres with an Eu… Despite the simplicity of the procedure, the …

… We report the synthesis of silica nanoparticles and microspheres doped with Pr 3+ and Er 3… doped silica microspheres using the sol–gel microencapsulation method. Journal of Sol-Gel …

… In this paper, the performance of Eu 3+ doped Al 2 O 3 hollow microspheres by sol-gel … core-shell structure can be prepared by sol gel method and template method. After adding Eu 3+ …

Multifunctional nanocomposites that integrate lanthanide photophysics with iron oxide magnetism represent a rapidly expanding class of materials for precision bioimaging and theranostics. Lanthanide-based iron oxide nanoparticles (Ln-IONPs) uniquely combine the narrow f–f emissions, long-lived excited states, and UC/DC luminescence of lanthanides with the superparamagnetism, high relaxivity, and magnetic field responsiveness of Fe3O4/γ-Fe2O3. However, their rational design remains challenging due to interfacial energy transfer, concentration-dependent cross-relaxation, and fluorescence quenching induced by iron oxide. This review provides the first systematic overview of Ln-IONPs, covering their fundamental luminescent and magnetic mechanisms, ligand and host engineering, and factors influencing their optical and magnetic performance, such as particle size, dopant distribution, surface chemistry, pH, temperature, and solvent effects. Synthetic strategies, including coprecipitation, thermal decomposition, hydro(solvo)thermal growth, sol–gel assembly, microwave-mediated crystallization, and polymer-integrated architectures, are critically evaluated with respect to phase control, heterointerface engineering, and quenching suppression via inert buffer layers. We further highlight recent advances in multimodal bio-applications, including high-resolution UC imaging, magnetically guided drug delivery, photothermal/photodynamic therapy, and integrated opto-magnetothermal theranostics. Persistent challenges, such as optimizing core–shell energy barriers, balancing luminescence efficiency with magnetic moment retention, and improving in vivo stability and clearance, are discussed alongside future opportunities for designing next-generation Ln-IONPs with enhanced optical–magnetic coupling and clinical translational potential.

… method, coprecipitation method, and sol–gel process, have shown powerful controllability in the … Thereby, the PL colors of TbBO 3 :Eu microspheres can be tuned from green (Tb 3+ ), to …

… previously produced by melting (or sol–gel technique) as shown in … obtained by coating silica microspheres with silica–hafnia … attempts to use such lanthanide-doped materials and it is …

… Researchers have used upconversion nanoparticles (UCNPs… a layer of dense or mesoporous silica to the outer surface of … dense silica, mesoporous silica, or hollow mesoporous silica. …

… Up-conversion measurements under 980 nm excitation … use of sol–gel routes to encapsulate compounds in silica [5] … loaded by the aminofunctionalized silica spheres were checked and …

… In this paper, ordered mesoporous silica encapsulating upconversion luminescence … -assistant sol−gel coating method under a basic condition. The obtained silica shell mesostructure …

… by a multistep procedure including precipitation and sol–gel processes from rare-earth nitrates, … in sol–gel process [20]. The average size of Gd 2 O 3 :Er 3+ 2 mol% @ silica spheres …

… sol–gel reaction to form mesoporous silica. The removal of CTAB surfactants resulted in the formation of mesoporous silica nanospheres embedded with single upconversion …

… 3+ @nSiO 2 @mSiO 2 nanospheres were prepared by coating mesoporous SiO 2 layers with different thicknesses on NaYF 4 :Yb 3+ /Er 3+ nanoparticles via a simple two-step sol–gel …

A new facile approach, namely chemical-assisted sol-gel growth (CASGG), was successfully developed to induce the formation of fine CaF2:Yb3+, Tm3+ nanocrytals within the pore channels of mesoporous silica (mSiO2) nanoparticles. A series of upconversion photoluminescent crystalline CaF2:Yb3+,Tm3+@mSiO2 nanospheres with controlled diameters from ~65 nm to ~290 nm were fabricated. All nanospheres presented sound cyto-compatibility and unique ratiometric spectral monitoring functionalities for drug release kinetics. The nanospheres with smallest dimension (UCNP-2.5, ~65nm) induced the most sustained DOX release kinetics. More importantly, the in-vitro study demonstrated that the DOX loaded UCNP-2.5 nanopheres presented the strongest anti-cancer efficacy to MCF-7 human breast cancer cells due to its stronger penetration ability to cell nuclei due to the size effect.

… silica using CTAB as template through a sol–gel process. The obtained core-shell structured composite material possesses bright up-conversion … by the up-conversion luminescence. …

This letter reports on long-band (L band) lasing whispering-gallery modes (WGMs) in microspheres based on sol-gel silica-alumina glasses doped with high concentration of erbium ions (Er+3 from 1250 to 15 000 ppm). The sol-gel method for making these Er-doped silica-alumina glasses is described. The microspheres with diameters from 40 to 200μm were built by electrical arc. The experimental results show that laser oscillations with high gain at L band were obtained with different coupling schemes, especially with forward pumping and/or backward pumping coupling. The collected laser output power of one WGM could reach to −5dBm in the L band of 1570–1610 nm.

Upconverting nanoparticles (UCNPs) doped with Yb3+ and Tm3+ are near-infrared (NIR) to ultraviolet (UV) transducers that can be used for NIR-controlled drug delivery. However, due to the low quantum yield of upconversion, high laser powers and long irradiation times are required to trigger this drug release. In this work, we report the one-step synthesis of a nanocomposite consisting of a LiYbF4:Tm3+@LiYF4 UCNP coated with mesoporous UV-breakable organosilica shells of various thicknesses. We demonstrate that a thin shell accelerates the breakage of the shell at 1 W/cm2 NIR light exposure, a laser power up to 9 times lower than that of conventional systems. When the mesopores are loaded with hydrophobic vitamin D3 precursor 7-dehydrocholesterol (7-DH), shell breakage results in subsequent cargo release. Its minimal toxicity in HeLa cells and successful internalization into the cell cytoplasm demonstrate its biocompatibility and potential application in biological systems. The tunability of this system due to its simple, one-step synthesis process and its ability to operate at low laser powers opens up avenues in UCNP-powered NIR-triggered drug delivery toward a more scalable, flexible, and ultimately translational option.

… The TEM images (Figure 2, C, D) show that the silica coating is uniform with a thickness of about 8 nm. Finally, the mesoporous silica shell was formed from simultaneous sol–gel …

… Therefore, an alternative and technically simpler sol–gel method has … 2 spherical nanocrystals dissolved in silica glass have been prepared using room temperature sol–gel processing …

Abstract Oxides based upconversion hosts are highly desirable due to their chemical stability and low cost. In this paper, Bi2Ti2O7:Er nanoparticles with different molar ratios of Bi3+ and Er3+ (Bi3+:Er3+ = 1:1, 3:1, 6:1, 8:1 and 10:1) were fabricated by sol-gel method. By annealing powder samples at different temperatures, the best heat treatment temperature was 800 °C. The upconversion property of Bi2Ti2O7:Er was studied under a 980 nm laser extinction. The results revealed that the color of Bi2Ti2O7 nanoparticles changed from green to red with increasing concentration of Er3+. The green and red emission can be attributed to the transition of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. All the luminescence can be seen by naked eyes even the laser power as low as 40 mW.

A fluorolytic sol-gel method was used for the fast and simple synthesis of small cubic-phase SrF2:Yb3+,Er3+ upconversion (UC) nanocrystals (UCNC) of different composition at room temperature. Systematic studies of the crystal phase and particle size of this Yb3+,Er3+-concentration series as well as excitation power density (P)-dependent UC luminescence (UCL) spectra, UCL quantum yields (ΦUCL), and UCL decay kinetics yielded maximum UCL performance for doping amounts of Yb3+ of 13.5% and Er3+ of 1.3% in the studied doping and P-range (30-400 W cm-2). Furthermore, ΦUCL were determined to be similar to popular β-NaYF4:Yb3+,Er3+. The relative spectral UCL distributions revealed that all UCNC show a strong red emission in the studied doping and P-range (30-400 W cm-2) and suggest that the UCL quenching pathway for unshelled cubic-phase SrF2:Yb3+,Er3+ UCNC differs from the commonly accepted population and depopulation pathways of β-NaYF4:Yb3+,Er3+ UCNC. In SrF2:Yb3+,Er3+ UCNC the 4S3/2 → 4I13/2 transition exhibits a notably stronger sensitivity towards P and reveals increasing values for decreasing Yb3+-Yb3+ distances while the 4I9/2 → 4I15/2 transition is significantly less affected by P and energy migration facilitated UCL quenching. These results emphasize the complexity of the UC processes and the decisive role of the crystal phase and symmetry of the host lattice on the operative UCL quenching mechanism in addition to surface effects. Moreover, the room temperature UCNC synthesis enabled a systematic investigation of the influence of the calcination temperature on the crystal phase of powder-UCNC and the associated UCL properties. Calcination studies of solid UCNC of optimized doping concentration in the temperature range of 175 °C and 800 °C showed the beneficial influence of temperature-induced healing of crystal defects on UCL and the onset of a phase separation connected with the oxygenation of the lanthanide ions at elevated temperature. This further emphasizes the sensitivity of the UC process to the crystal phase and quality of the host matrix.

This work reports on the preparation of materials based on Yb3+/Er3+ co-doped SiO2-Gd2O3 via sol-gel process. The 0.4mol%of Er3+ ions was fixed and the amount of Yb3+ ions changed as 1.8, 5 and 9mol%in order to evaluate the photoluminescence properties as a function of the Yb3+ ions concentration. The prepared xerogels were heat-treated at 900, 1000 and 1100°C for 8 h. X-ray diffraction analyses of the heat-treated materials confirmed the formation of the Gd2O3 cubic phase embedded in the SiO2 host, demonstrating the effective incorporation of RE3+ ions in the structure. The Scherrer’s equation verified that the sizes of Gd2O3 nanocrystallite are between 31 and 69 nm and directly dependent on the heat-treatment temperature. Under excitation at 980 nm all materials showed upconversion phenomena, and the intensities of the emissions in the green and red regions showed to be directly dependent on power pump of laser, quantity of Yb3+ ions and heat-treatment temperature. The materials also showed emission in the infrared region with the maximum around 1530 nm, assigned to the transition of 4I13/2 → 4I15/2 of the Er3+ ions, region known as technological C-telecom band used in optical amplification.

… 2a and b consists of nearly spherical nanoparticles with an average size of around 20 nm and 80 nm for the X1 and X2 types, respectively. The average particle sizes of the powders …

Abstract The current study delineates the synthesis and characterization of CaF2 based Oxy-fluoride glass-ceramics with Erbium (1 mol%) and with varying Ytterbium concentration (1 mol% and 5 mol%) doping of fluoride source. The influence of yb3+ concentration on thermal, structural, and luminescence properties were investigated and analyzed through a sol-gel process. The differential thermal analysis (DTA) specified that the glass transition (Tg) temperature decreases with the increase of Yb3+concentration in the prepared glass-ceramics. The microstructural study performed by transmission electron microscope (TEM), indicates the core-shell structure of glass-ceramics nanoparticles in between 10 to 50 nm range. The incorporation of Er3+ and Yb3+ into the crystalline matrix was confirmed and analyzed from X-ray diffraction (XRD) analysis. The increased crystal size according to increased temperatures shows the CaF2 crystal growth. The up-conversion luminescence properties of the prepared nano-glass ceramics were tested by using a 980 nm laser. The photoluminescence emission showed two peaks at green (548 nm and 528 nm) emission and one at red emission (626 nm). Additionally, the cell viability study of the Er3+-Yb3+ doped CaF2 nano glass-ceramics was performed using MG-63 osteoblast cells and it shows significant cell growth as compared to control over a period of 24 hours. The result confirmed that the prepared nano-glass-ceramics can be a potential optical material for bio-imaging.

… anatase-TiO 2 nano-spherical particles (diameter < 50 nm) … by hydrothermal-assisted sol-gel method, followed by their … applications, the upconversion nanoparticles are deposited …

… White up conversion emission has been observed in sol–gel derived α-Y 2 Si 2 O 7 … nanoparticles. The TEM image (Fig. 2a) of the sample consists of nearly spherical nanoparticles with …

Uniform monodisperse YbPO4 hollow microspheres have been successfully synthesized via … ), and up-conversion (UC) luminescence spectroscopy. It is noted that the polystyrene (PS) …

… /upconversion emissions. Such a facile … monodisperse YF 3 :Ln 3+ nano/microspheres and octahedrons with controllable size can be obtained, and the morphology and monodispersity …

… 3 hollow microspheres exhibit bright down- and upconversion … Monodisperse MF colloidal microspheres were prepared … (22a, 24) In a typical synthesis, a solution of formaldehyde (9.8 …

Micron-sized lasers fabricated from upconverting nanoparticles (UCNP) coupled to whispering gallery mode (WGM) microresonators can exhibit continuous-wave anti-Stokes lasing useful for tracking cells, environmental sensing, and coherent stimulation of biological activity. The integration of these microlasers into organisms and microelectronics requires even smaller diameters, however, which raises threshold pump powers beyond practical limits for biological applications. To meet the need for low lasing thresholds and high fidelity fabrication methods, we use correlative optical and electron microscopy to uncover the nanoparticle assembly process and structural factors that determine efficient upconverted lasing. We show that 5 μm microspheres with controlled submonolayer UCNP coatings exhibit, on average, 25-fold lower laser thresholds (1.7 ± 0.7 kW/cm2) compared to the mean values of the lowest threshold UCNP lasers, and variability is reduced 30-fold. WGMs are observed in the upconversion spectra for TiO2-coated microspheres as small as 3 μm, a size at which optical losses had previously prevented such observations. Finally, we demonstrate that the WGM signatures of these upconverting microlasers can be imaged and distinguished through tissue-mimicking phantoms. These advances will enable the fabrication of more efficient upconverting lasers for imaging, sensing, and actuation in optically complex environments.

… , monodisperse spheres of Gd 2 SiO 5 :Ce 3+ @SiO 2 (GSO:Ce 3+ @SiO 2 ) were synthesized via … Core-shell monodisperse spheres with a particle size of approximately 170 nm were …

Fabrication and evaluation of chitosan/NaYF4:Yb3 +/Tm3 + upconversion nanoparticles composite beads based on the gelling of Pickering emulsion droplets - ScienceDirect …

… /Er 3+ microspheres were synthesized through a facile hydrothermal method. The as-prepared monodispersed NaYF 4 :Yb 3+ /Er 3+ microspheres were treated by the sol–gel … emulsion …

The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation information technology, optical communication, bioimaging, and therapy. However, the inherent upconversion luminescent properties of UCNPs are influenced by various parameters, including the size, shape, crystal structure, and chemical composition of the UCNPs, and even the chosen synthesis process and the surfactant molecules used. This review will provide a complete summary on the synthesis methods and the surface modification strategies of UCNPs reported so far. Firstly, we summarize the synthesis methodologies developed in the past decades, such as thermal decomposition, thermal coprecipitation, hydro/solvothermal, sol-gel, combustion, and microwave synthesis. In the second part, five main streams of surface modification strategies for converting hydrophobic UCNPs into hydrophilic ones are elaborated. Finally, we consider the likely directions of the future development and challenges of the synthesis and surface modification, such as the large-scale production and actual applications, stability, and so on, of the UCNPs.

… -situ polycondensation in a non-aqueous emulsion templating system. The scanning electron … emission intensity of the cyan-colored up-conversion and purple-colored down-conversion …

… process (sol-gel) [59]. The sol-gel method was utilized by Patra and his team to produce Er 3+ -doped ZrO 2 nanocrystals. In order to create a water-in-oil (w/o) micro-emulsion, they …

A recyclable, aqueous-phase functioning, and biocompatible photon upconverting system is developed. Hollow mesopo-rous silica microcapsules (HMSMs) with ordered radial mesochannels were employed, for the first time, as vehicles for the post-encapsulation of oil-phase triplet-triplet annihilation upconversion (TTA-UC), with the capability of homogene-ous suspension in water. In-depth characterization of such upconverting oil-laden HMSMs (UC-HMSMs) showed that the mesoporous silica shells reversibly stabilized the encapsulated UC oil in water to allow efficient upconverted emission, even under aerated conditions. In addition, the UC-HMSMs were found to actively bind to the surface of human mesen-chymal stem cells (hMSCs) without significant cytotoxicity and displayed upconverted bright blue emission under 640 nm excitation, indicating a potential of our new TTA-UC system in biophotonic applications. These findings reveal the great promise of UC-HMSMs to serve as ideal vehicles not only for ultralow-power in vivo imaging, but also for stem cell labeling, to facilitate the tracking of tumor cells in animal models.

… The monodisperse polystyrene microspheres were made by the emulsifier-free emulsion … with higher upconversion efficiency can be formed in inverse opal structures through sol-gel …

… , including soft ones such as surfactants, emulsion droplets, micelles, vesicles, ionic solvents … The core–shell Y(OH)CO 3 @SiO 2 microspheres were prepared via a modified sol–gel …

… micelles formed in emulsions as the reactors for growing nanocrystals. The sol–gel process was … such as colloidal gold or colored latex beads was achieved. In a parallel development, …

Luminescent Janus nanoparticles refer to a special category of Janus-based nanomaterials that not only exhibit dual-asymmetric surface nature but also attractive optical properties. The introduction of luminescence has endowed conventional Janus nanoparticles with many alluring light-responsive functionalities and broadens their applications in imaging, sensing, nanomotors, photo-based therapy, etc. The past few decades have witnessed significant achievements in this field. This review first summarizes well-established strategies to design and prepare luminescent Janus nanoparticles and then discusses optical properties of luminescent Janus nanoparticles based on downconversion and upconversion photoluminescence mechanisms. Various emerging applications of luminescent Janus nanoparticles are also introduced. Finally, opportunities and future challenges are highlighted with respect to the development of next-generation luminescent Janus nanoparticles with diverse applications.

Rare-earth doped oxyfluoride glass ceramics represent a new generation of tailorable optical materials with high potential for optical-related applications such as optical amplifiers, optical waveguides, and white LEDs. Their key features are related to the high transparency and remarkable luminescence properties, while keeping the thermal and chemical advantages of oxide glasses. Sol-gel chemistry offers a flexible synthesis approach with several advantages, such as lower processing temperature, the ability to control the purity and homogeneity of the final materials on a molecular level, and the large compositional flexibility. The review will be focused on optical properties of sol-gel derived nano-glass ceramics related to the RE-doped luminescent nanocrystals (fluorides, chlorides, oxychlorides, etc.) such as photoluminescence, up-conversion luminescence, thermoluminescence and how these properties are influenced by their specific processing, mostly focusing on the findings from our group and similar ones in the literature, along with a discussion of perspectives, potential challenges, and future development directions.

Spherical SiO 2 particles have been coated with rare earth oxide layers by a Pechini sol–gel process, leading to the formation of core-shell structured SiO 2 @RE 2 O 3 (RE=rare earth …

… typhimurium) in real-time samples by embedding superparamagnetic beads modified with … using the sol-gel method, allowing the nanoscale size of the upconversion particles and …

The development of up-converting phosphor reporter particles has added a powerful tool to modern detection technologies. Carefully constructed phosphor reporters have core-shell structures with surface functional groups suitable for standard bio-conjugations. These reporters are chemically stable, possess the unique property of infrared up-conversion, and are readily detected. In contrast to conventional fluorescent reporters, up-converting phosphor particles do not bleach and allow permanent excitation with simultaneous signal integration. A large anti-Stokes shift (up to 500 nm) separates discrete emission peaks from the infrared excitation source. Along with the unmatched contrast in biological specimens due to the absence of autofluorescence upon infrared excitation, up-converting phosphor technology (UPT) has unique properties for highly-sensitive particle-based assays. The production and characteristics of UPT reporter particles as well as their application in various bioassays is reviewed.

… The titania beads prepared using sol-gel chemistry within the … With the aid of a microfluidic flow reactor,106-108 Ogawa and … transfer up-conversion process promoted by the Yb 3+ . …