Production Of Microspheres Research Articles

Production of more ideal uranium trioxide microspheres for the sol-gel microsphere pelletization process without the use of carbon

Renewed interest by the U.S. Department of Energy in the sol-gel microsphere pelletization process led to an evaluation of dried uranium trioxide (UO3) microspheres produced without the use of carbon by the internal gelation process at Oak Ridge National Laboratory. An earlier study has shown that less dense UO3 microspheres led to uranium dioxide pellets with higher densities. This effort identified feed formulations that produced dried UO3 microspheres with the lowest tap densities for gelation temperatures of 333, 343, 353, and 363 K. The tap densities of these dried UO3 microspheres ranged from 680 to 820 kg/m3, which were significantly lower than the previously reported low UO3 density of 900 kg/m3. This study confirmed an earlier observation that the effects of gelation conditions on the properties of the gel sphere are complex since only two of the four best formulations were similar in composition. The need to age the wet gel spheres in the gelation medium for 20 min at the end of the experiment was also confirmed.

Physicochemical processing of polyphenylsulfone: Optimization of processing parameters for microsphere production via spray drying using a response surface model

AbstractThis article describes the processing of polyphenylsulfone (PPSU) into microspheres via the physicochemical method called spray drying (SD). Polymeric microspheres have a potential in various fields of research like diagnostics, separations, thermal insulations, pigments, and additive manufacturing like selective laser sintering (SLS). These microspheres have the potential to be used as building material for SLS provided they have spherical morphology and have a submicrometer particle size. The effects of the different processing parameters on these two response factors have been investigated in SD of PPSU by design of experiment. A plot is predicted in which size and morphology are optimized and combined in order to find the ideal parameter set for production. The effect of polymer concentration, solution feed rate, atomization flow rate, inlet temperature, and polymer grade was optimized using a five‐factor three‐level factorial design. Through the statistical model, particles with a mean particle size of 13.27 μm can be obtained of which 19% are of adequate sphericity and roundness according to Powers’ scale for the low viscous grade (R5600, Radel® R5600 Solvay polymer, low viscous grade (or very high melt flow grade) of PPSU). In the case of the high viscous grade (R5000, Radel® R5000 Solvay polymer, high viscous grade of PPSU), a best particle size of 12.48 μm with 12.5% spherical particles can be achieved.

A Droplet-Based Microfluidic Approach and Microsphere-PCR Amplification for Single-Stranded DNA Amplicons.

Droplet-based microfluidics enable the reliable production of homogeneous microspheres in the microfluidic channel, providing controlled size and morphology of the obtained microsphere. A microsphere copolymerized with an acrydite-DNA probe was successfully fabricated. Different methods such as asymmetric PCR, exonuclease digestion, and isolation on streptavidin-coated magnetic beads can be used to synthesize single-stranded DNA (ssDNA). However, these methods cannot efficiently use large amounts of highly purified ssDNA. Here, we describe a microsphere-PCR protocol detailing how ssDNA can be efficiently amplified and separated from dsDNA simply by pipetting from a PCR reaction tube. The amplification of ssDNA can be applied as potential reagents for the DNA microarray and DNA-SELEX (Systematic evolution of ligands by exponential enrichment) processes.

Modeling phase behavior of Poly(ɛ-caprolactone) solutions at high pressure

Poly(ɛ-caprolactone) (PCL) is a biocompatible and biodegradable polymer and is widely used in controlled drug-delivery applications. For the production of polymeric microspheres loaded with pharmaceutical products, the supercritical fluid technology using carbon dioxide (CO2) is favored because of its non-toxic nature. In this work, the phase behavior of PCL in various supercritical solvents such as CO2, CHClF2, dimethyl ether (DME), 1-butene, and propylene is described by the PC-SAFT model. The effects of the molecular weight of PCL, the type of solvent, pressure, temperature, and the concentration of the cosolvent are investigated. The solubility of PCL in supercritical solvents is accurately described over a wide range of temperatures (from 293.15 to 503 K) and for pressures up to 300 MPa. CO2 shows the poorest solubility, while CHClF2 shows the highest solubility. The predicted cloud-point pressures show an increasing tendency with an increase of the molecular weight of the PCL. The addition of cosolvents, i.e., DME and CHClF2, to the PCL/CO2 solution increases of the dissolving power of the mixed solvent. The results predicted with the PC-SAFT equation of state are in good agreement with the experimental data.

Carnauba wax as a wall material for urea microencapsulation

The high ureolytic activity of rumen microbiota is a concern when urea is used in ruminant feed, because it leads to fast urea conversion, resulting in possible intoxication and lower nitrogen utilization. This study intended to microencapsulate urea using carnauba wax to obtain slow-release systems in the rumen. The experiment was conducted in a randomized block design, arranged in a 3 × 2 factorial, with the urea encapsulated with carnauba wax in ratios of 1 : 2; 1 : 3, and 1 : 4 (UME 2; UME 3, and UME 4) and two particles sizes (small, PS ; and large, PL ). All formulations showed excellent properties, including inhibition of urea hygroscopicity. The formulation UME 2 exhibited the greatest yield (91.6%) and microencapsulation efficiency (99.6%) values, whereas the formulation UME 4 presented the greatest thermal stability (259.5 °C) and lowest moisture content (1.81%). The UME 2 formulation presented a slower release than the other UME formulations studied. The production of urea microspheres using carnauba wax was successful for all microencapsulated systems developed, evidencing the promising potential for use in ruminant animal diets. The UME 2 formulation with large particles is the most recommended because it permitted greater resistance to microbial attack, allowing a slower release of urea into the rumen, reducing the risk of intoxication or ruminal alkalosis. © 2018 Society of Chemical Industry.

Dual-crosslinked homogeneous alginate microspheres for mesenchymal stem cell encapsulation

A smart hydrogel material was used in combination with custom microfluidic devices (MFDs) to create microspheres for human mesenchymal stem cell (MSC) encapsulation. Methods for fabricating homogeneous stimuli-responsive microspheres for MSC encapsulation and cell delivery have gained interest to increase viability and manipulate microencapsulation within microspheres 10-1000 µm in diameter. Herein, MFDs were combined with non-toxic smart hydrogel materials to tune both the size and mechanics of the microspheres. Traditional hydrogels have a single input/stimulus for crosslinking, utilize potentially toxic ultraviolet radiation, and fail to mimic surrounding musculoskeletal tissue mechanics. Thus, it is highly beneficial to encapsulate MSCs inside a mechanically-stable microsphere made from naturally-derived materials. The objectives of this research were to optimize microsphere fabrication techniques using custom microfluidic devices (MFDs), and to encapsulate viable MSCs within visible-light crosslinked smart-alginate microspheres, with tunable mechanical properties. Microsphere production was characterized optically, and MSC viability, post-encapsulation, was verified using a standard florescence assay. Cell viability was maintained in chemically-modified alginate homogenous microspheres post encapsulation, and after subsequent crosslinking via green light exposure.

Effect of hydrothermal conditions on production of coal organic microspheres

Coal organic microspheres (COM), a novel material originated from the organic components of coal, were obtained from brown coal directly using a one-step treatment in a flow of water. Here, we studied in detail the effect of hydrothermal conditions on morphology, yield, elemental composition, functional groups, and molecular composition of COM, at temperatures of 250, 300, 350, and 380 °C, pressures of 4, 10, 20, and 24 MPa, and holding times of 0, 30, 60, and 90 min. The holding time influences COM production: longer holding time leads to higher yields and larger particle size. The hydrothermal temperature and pressure, which control the properties of water, have a significant influence on the yield, shape, and particle size of COM. The properties of water affect the COM yields as follows: 1) when the phase of water is liquid, the lower density, viscosity, and static dielectric constant gives higher yields; 2) the yield obtained in supercritical water is higher than that in subcritical water; 3) phase transformation of water from liquid to gas decreases the yield. Additionally, the particle size of COM can be controlled by the temperature, and the pressure affects the shape of COM greatly; even nano-sized particles are produced at 350 °C and 10 MPa. From the molecular composition results, low-molecular weight compounds with small double bond equivalents decompose under supercritical water condition. Large amounts of organic compounds in brown coal are thermally decomposed and extracted under hydrothermal conditions, and then spherical COM particles form and grow from small to big during the cooling process. These results are helpful for clarifying the formation mechanism of COM, and enable control of COM yield and properties.

Characterization of mechanical parameters of microbeads by means of analytical centrifugation

Microcapsules, microspheres and microbeads are widely used in the food industry, pharmacy, agriculture, cosmetics, construction, textile industry and printing to protect immobilized substances against harsh conditions or to mask bad taste, as well as to enable and control the release of substances e.g. active pharmaceutical ingredients. The knowledge of the mechanical properties is a key parameter in development, application and control of processing. The paper focuses on the experimental determination of the stiffness of alginate beads (about 400 μm) in terms of bulk compressional behaviour by using a commercial available multisample analytical centrifuge (LUMiSizer). The basic principle consists in applying an increasing centrifugal force on an alginate bead column in a measuring cell and to record the height of the bead column (volume) in dependence on the applied force during centrifugation. The packing/compression of beads is quantified by the decreased column volume in relation to the applied force. It was shown that beads made of alginate of high α-l-guluronic acid (G) content are more stable compared to alginate types of high ß-d-mannuronic acid (M) content. In contrast, gelling cations and their concentrations have less influence on the mechanical behaviour. The described ensemble method is sensitive, reproducible, easy to perform and, due to the simultaneous analysis of up to 12 samples, time saving. The new method is especially suitable for quality control during microsphere production.

CONJUGATE HEAT TRANSFER IN THE PRODUCTION OF GLASS MICROSPHERES IN A GAS-FLAME REACTOR

A model for the process of glass microsphere production in a recuperative gas-flame reactor was proposed. Based on the described mathematical model of heating and motion of particles in a high-temperature gas stream, which takes into account conjugate heat exchange between the reactor’s operating environment and the recuperator, the appropriate processes were modeled and optimized by geometric and regime parameters. The particle location time in the reactor at a temperature above 1400 °С, which was determined by data of differential scanning colorimetry, was used as an optimized charac- С, which was determined by data of differential scanning colorimetry, was used as an optimized charac- , which was determined by data of differential scanning colorimetry, was used as an optimized characteristic.As a result of optimization calculations, the reactor parameters (diameter and height, natural gas flow rate, air flow rate in the recuperator) were found, as well as regime parameters (diameter and flow rate of glass particles), under which microspheres can be formed. The information obtained can be a basis for designing an effective gas-flame reactor for production of glass microspheres.

Modeling phase behavior of poly(lactic acid) in supercritical fluids

Poly (lactic acid) (PLA) is typical biocompatible polymer, and is widely used in drug delivery application. For the production of polymeric microspheres loaded with the pharmaceutical, the supercritical fluid technology using carbon difoxide (CO2) is favor because of non-toxic nature. In this work, the phase behaviors of PLA in various supercritical solvents such as dimethyl ether (DME), CO2, chlorodifluoromethane (HCFC-22), difluoromethane, trifluoromethane (HFC-23), 1,1,1,2-tetrafluoroethane, 1,1-difluoroethane are described by PC-SAFT model. One binary interaction parameter without considering temperature-dependency is used over a wide range of temperature and pressure. CO2 shows the poorest solubility, while HCFC-22 and DME show the highest solubility. The predicted cloud-point pressure shows the increasing tendency with an increase of PLA's molecular weight. In addition, the pressure-temperature isopleths for the dl-PLA/CO2 solutions with DME, HCFC-22, and HFC-23 as a cosolvent are investigated. The predicted results for three ternary systems with PC-SAFT model show a good agreement with experimental data.

Production of monodisperse cerium oxide microspheres with diameters near 100 µm by internal-gelation sol–gel methods

Internal-gelation sol–gel methods have used a variety of sphere-forming methods in the past to produce metal oxide microspheres, but typically with poor control over the size uniformity at diameters near 100 µm. This work describes efforts to make and measure internal-gelation, sol–gel microspheres with very uniform diameters in the 100–200-µm size range using a two-fluid nozzle. A custom apparatus was used to form aqueous droplets of sol–gel feed solutions in silicone oil and heat them to cause gelation of the spheres. Gelled spheres were washed, dried, and sintered prior to mounting them on glass slides for optical imaging and analysis. Microsphere diameters and shape factors were determined as a function of silicone oil flow rate in a two-fluid nozzle and the size of a needle dispensing the aqueous sol–gel solution. Nine batches of microspheres were analyzed and had diameters ranging from 65.5 ± 2.4 µm for the smallest needle and the fastest silicone oil flow rate to 211 ± 4.7 µm for the largest needle and the slowest silicone oil flow rate. Standard deviations for measured diameters were less than 8% for all samples and most of them were less than 4%. Microspheres had excellent circularity with measured shape factors of 0.9–1. However, processing of optical images was complicated by shadow effects in the photoresist layer on glass slides and by overlapping microspheres. Based on the calculated flow parameters, microspheres were produced in a simple dripping mode in the two-fluid nozzle. Using flow rates consistent with a simple dripping mode in a two-fluid nozzle configuration allows for very uniform oxide microspheres to be produced using the internal-gelation sol–gel method.

Porous calcium phosphate glass microspheres for orthobiologic applications

Orthobiologics is a rapidly advancing field utilising cell-based therapies and biomaterials to enable the body to repair and regenerate musculoskeletal tissues. This paper reports on a cost-effective flame spheroidisation process for production of novel porous glass microspheres from calcium phosphate-based glasses to encapsulate and deliver stem cells. Careful selection of the glass and pore-forming agent, along with a manufacturing method with the required processing window enabled the production of porous glass microspheres via a single-stage manufacturing process. The morphological and physical characterisation revealed porous microspheres with tailored surface and interconnected porosity (up to 76 ± 5%) with average pore size of 55 ± 8 µm and surface areas ranging from 0.34 to 0.9 m2 g−1. Furthermore, simple alteration of the processing parameters produced microspheres with alternate unique morphologies, such as with solid cores and surface porosity only. The tuneable porosity enabled control over their surface area, degradation profiles and hence ion release rates. Furthermore, cytocompatibility of the microspheres was assessed using human mesenchymal stem cells via direct cell culture experiments and analysis confirmed that they had migrated to within the centre of the microspheres. The novel microspheres developed have huge potential for tissue engineering and regenerative medicine applications. Statement of SignificanceThis manuscript highlights a simple cost-effective one-step process for manufacturing porous calcium phosphate-based glass microspheres with varying control over surface pores and fully interconnected porosity via a flame spheroidisation process. Moreover, a simple alteration of the processing parameters can produce microspheres which have a solid core with surface pores only. The tuneable porosity enabled control over their surface area, degradation profiles and hence ion release rates. The paper also shows that stem cells not only attach and proliferate but more importantly migrate to within the core of the porous microspheres, highlighting applications for bone tissue engineering and regenerative medicine.

Study of the organic solvent template double emulsions for porous microspheres production with adjustable structures

In this study, the method of Hansen solubility parameters was applied to identify a solvent substitution less toxic than dichloromethane used in a microencapsulation process. A theoretical approach was developed to investigate the influence of solvent type on water permeation across the solvent film in w/o/w template double emulsions. Analysis showed that water solubility in the solvent was a key factor in deciding water permeability across the solvent film, which could vary significantly with different solvents. Besides high water permeability, experiments showed that dichloromethane and ethyl acetate films in double emulsion also featured very low film robustness due to their high water permeability and poor film robustness. To improve film robustness, the influence of polymer and surfactant concentration in the film phase was studied. Results showed that increased viscosity and non-Newtonian conversion induced by polymers dissolved in the film phase could significantly improve the stability of the template double emulsion; the addition of hydrophobic surfactant Span 80 in the film phase significantly destabilized double emulsion with twofold effects: at low concentration water permeation was promoted while at high concentration deformation and breakup of the oil film were facilitated. Further study showed that different internal structures, i.e., microspheres of single- and multi-compartments, could be effectively tailored by employing the water permeation characteristics as predicted by the permeation model. The large cavity of the hollow single-compartment microspheres makes them particularly suitable as delivery vehicle systems.

Production of self-immobilised enzyme microspheres using microfluidics

Self-immobilisation of enzymes is a useful way of producing particulate biocatalysts that are easy to recover while still retaining high specific activity. The spherezyme microsphere immobilisation technique is useful in that it provides structured enzyme micro-particles within a specific size range. Herein an alternative micro-fluidics spherezyme production technology is evaluated. Spherezymes of Pseudomonas fluorescens lipase were successfully produced using a new continuous microfluidic method involving the two sequential steps of emulsion formation and subsequent protein cross-linking. The microchannel design with two flow-focussing junctions provided uniform enzyme microspheres with a particle diameter of 50 μm and a size distribution within 3% as determined by a microscopic image analysis method. The size of the particles could be finely controlled as a function of the microreactor flow rate and monitored in real time. The structure of the particles were analysed using focused ion beam scanning electron microscopy (FIB-SEM), which showed that the external structure was less porous, with pores of up to 492 nm, while internal structure had a much greater porosity with a maximum pore size of 1735 nm. The activity retention of the lipase after immobilisation was 65% on hydrolysis of p-nitrophenyl butyrate (PNPB) and the micro-particle biocatalyst could be recycled multiple times. Using microfluidics provides a superior method to scale up production of lipase spherezymes with a very narrow size distribution.

Preparation of “Open/closed” pores of PLGA-microsphere for controlled release of protein drug

Poly(D,L-lactic-co-glycolic acid) has been extensively used as a controlled release carrier for drug delivery due to its good biocompatibility, biodegradability, and mechanical strength. In this study, porous PLGA microspheres were fabricated by an emulsion-solvent evaporation technique using poly ethylene glycol (PEG) as an extractable porogen and loaded with protein (lysozyme) by suspending them in protein solution. For controlled release of protein, porous microspheres containing lysozyme were treated with water-miscible solvents in aqueous phase for production of pore-closed microspheres. The surface morphology of microspheres were investigated using scanning electron microscopy (SEM) for confirmation of its porous microstructure structure. Protein property after release was observed by enzymatic activity assay. The pore-closing process resulted in nonporous microspheres which exhibited sustained release patterns over an extended period.

High-throughput double emulsion-based microfluidic production of hydrogel microspheres with tunable chemical functionalities toward biomolecular conjugation.

Chemically functional hydrogel microspheres hold significant potential in a range of applications including biosensing, drug delivery, and tissue engineering due to their high degree of flexibility in imparting a range of functions. In this work, we present a simple, efficient, and high-throughput capillary microfluidic approach for controlled fabrication of monodisperse and chemically functional hydrogel microspheres via formation of double emulsion drops with an ultra-thin oil shell as a sacrificial template. This method utilizes spontaneous dewetting of the oil phase upon polymerization and transfer into aqueous solution, resulting in poly(ethylene glycol) (PEG)-based microspheres containing primary amines (chitosan, CS) or carboxylates (acrylic acid, AA) for chemical functionality. Simple fluorescent labelling of the as-prepared microspheres shows the presence of abundant, uniformly distributed and readily tunable functional groups throughout the microspheres. Furthermore, we show the utility of chitosan's primary amine as an efficient conjugation handle at physiological pH due to its low pKa by direct comparison with other primary amines. We also report the utility of these microspheres in biomolecular conjugation using model fluorescent proteins, R-phycoerythrin (R-PE) and green fluorescent protein (GFPuv), via tetrazine-trans-cyclooctene (Tz-TCO) ligation for CS-PEG microspheres and carbodiimide chemistry for AA-PEG microspheres, respectively. The results show rapid coupling of R-PE with the microspheres' functional groups with minimal non-specific adsorption. In-depth protein conjugation kinetics studies with our microspheres highlight the differences in reaction and diffusion of R-PE with CS-PEG and AA-PEG microspheres. Finally, we demonstrate orthogonal one-pot protein conjugation of R-PE and GFPuv with CS-PEG and AA-PEG microspheres via simple size-based encoding. Combined, these results represent a significant advancement in the rapid and reliable fabrication of monodisperse and chemically functional hydrogel microspheres with tunable properties.

Production of alginate microspheres of various sizes under the influence of an electrostatic field with the help of electrospray method

Background: Microspheres obtained from polymers, both natural and synthetic origin, have found application in chemical-pharmaceutical, food industries and in agriculture. Despite this, various methods of obtaining them are actively developing. The main requirements for the preparation of microspheres are low cost, homogeneity of the end product, mild conditions of their obtaining. One of the promising methods to produce the microspheres, which meets the stated requirements, is the electrospray method. At the present time, a large number of studies have been carried out to study the effect of an inhomogeneous electric field on the dimensions of microspheres from polymeric materials, while at the same time there are practically no published reports devoted to the investigation of the influence of a homogeneous electric field on their dimensions. Objectives: The purpose of this study was the investigation of the influence of the electrostatic field uniformity on the size of the sodium alginate microspheres obtained by means of electrospray. Materials and methods: The sodium alginate microspheres were prepared by the electrospray method, on the condition of homogeneity of electrostatic field formed between the contacts of the device. Sodium alginate of low viscosity (15·10-3–25·10-3 Pa·s) was used in the work. As a gel solution, a 2% solution of CaCl2 was used. The sizes of the microspheres were evaluated with a confocal microscope AxioObzerver Z1 (Carl Zeiss, Germany). Results: During the study, there were revealed the main parameters of the experimental setup, which affected the sizes of the obtained microspheres. These include the magnitude of the voltage applied to the plates determining the shape of the field, the distance between the plates, and the rate of the polymer supplying. The most important parameters comprise the magnitude of the applied voltage since it was the change in this value that led to the largest change in the sizes of the alginate microspheres. Conclusions: Upon using the uniform electrostatic field it is possible to obtain the sodium alginate microspheres with a diameter from 900±5 μm to 2071±15 μm, on the condition of maintaining the spherical shape of the particles.

Ultrasound-induced Microencapsulation of Simvastatin for Gastro Retention and Controlled Delivery

The objective of this study is to demonstrate an effective technique with potential for commercialization for microsphere production. Ultrasound-assisted ionic gelation of sodium alginate was used to encapsulate simvastatin. Chitosan was used as a mucoadhesive polymer for gastro-retention of microsphere. Sodium alginate solution was sonicated using probe sonicator at a frequency of 20±3 KHz and ultrasonic power of 130 W with an input voltage range of 170-270 AC, 50 Hz, at a temperature of 50°. The influence of ultrasound waves on drug entrapment efficiency, yield and particle size dispersion was studied in comparison to mechanical stirring method. Mucoadhesiveness, release pattern and kinetics of drug release were also characterized. Ultrasound treatment caused small fissures and depressions on the surface of alginate as evidenced in SEM. Ultrasound of 20±3 KHz for 12 min duration was the optimum frequency and time in the experimental set up to obtain microspheres with uniform and smaller microparticles. The encapsulation efficiency of simvastatin was directly proportional to the sonication effect, concentration of alginate and extent of its cross linkage with calcium ions. DSC studies revealed that ultrasound treatment did not alter the structural integrity of the drug component. Formulation was found to be dissolution efficient and drug release pattern was concentration dependent, which followed non-Fickian diffusion mechanism with an ‘n’ value of 0.8. Therefore, it could be concluded that ultrasound can be used as an efficient technology to develop drug-entrapped microsphere for controlled delivery.

Engineering of cell-laden gelatin-based microgels for cell delivery and immobilization in regenerative therapies.

Cell-based therapies often face the challenge of low cell retention and viability upon transplantation. Hence, biomaterials, which can immobilize transplanted cells, while at the same time support cell viability, are essential for successful clinical application. Noteworthy, biomaterials in the micrometer range such as microcapsules or microspheres have the advantage of a minimally invasive introduction into tissue.Hence, we established an approach to generate gelatin-based cell carriers in the form of microspherical hydrogels. Fibroblasts were microencapsulated in glycidylmethacrylate (GMA)-functionalized gelatin by photopolymerization. While the degree of GMA-functionalization was kept constant, the hydrogel cross-linking density was adjusted by varying the time of irradiation or the average gelatin-chain length.Stable microspheres were synthesized from 10 wt% GMA-gelatin solutions for all irradiation periods tested (0.5 -2 min). Evaluation of cell viability revealed that microgels with the same weight content of biopolymer but with decreased cross-linking densities and thus decreased storage and E modulus, resulted in best cell support. Noteworthy, encapsulated cells partially migrated out of the microspheres and attached to the spherical surface.10 wt% GMA-gelatin-based hydrogels with E moduli comparable to the native cellular niche proved to be a promising biomaterial suitable for the production of cell-laden microspheres and shall be evaluated further for biomedical application.

Synthesis and luminescent properties of uniform monodisperse LuPO4:Eu3+/Tb3+ hollow microspheres.

Uniform monodisperse LuPO4:Eu3+/Tb3+ hollow microspheres with diameters of about 2.4 µm have been successfully synthesized by the combination of a facile homogeneous precipitation approach, an ion-exchange process and a calcination process. The possible formation mechanism for the hollow microspheres was presented. Furthermore, the luminescence properties revealed that the LuPO4:Eu3+ and LuPO4:Tb3+ phosphors show strong orange-red and green emissions under ultraviolet excitation, respectively, which endows this material with potential application in many fields, such as light display systems and optoelectronic devices. Since the synthetic process can be carried out at mild conditions, it should be straightforward to scale up the entire process for large-scale production of the LuPO4 hollow microspheres. Furthermore, this general and simple method may be of much significance in the synthesis of many other inorganic materials.