Size Of Microspheres Research Articles

Microfluidic Precision Manufacture of High Performance Liquid Chromatographic Microspheres.

A key bottleneck in developing chromatographic material is the chemically entangled control of morphology, pore structure, and material chemistry, which holds back precision material manufacture in order to pursue advanced separation performance. In this work, a precision manufacture strategy based on droplet microfluidics was developed, for production of highly efficient chromatographic microspheres with independent control over particle morphology, pore structure and material chemistry. The droplet-synthesized microspheres display extremely narrow particle size distribution (CV<3 %), enabling a 100 % production yield due to complete elimination of sieving steps. More importantly, the size of the droplet-synthesized microspheres is freely adjustable without the need for re-optimizing chemical recipes or reaction conditions. The resulting materials exhibit excellent separation efficiencies, achieving a reduced plate height of hmin=1.67. This precision manufacture strategy also allows for flexible pore design and continuous pore size adjustment across three orders of magnitudes, providing a novel vehicle for resolution fine-tuning targeting protein separation. Besides traditional silica, organic-inorganic hybrid silica, zirconia, and titania microspheres can also be precisely synthesized on the same platform, supporting various separation applications and operating conditions. Powered by precision manufacture, super-throughput production, and versatile chemistry, the high-performance droplet-synthesized separation material will pave the way towards green and precision chromatographic industry.

Human milk fat globule size distributions: comparison between laser diffraction and 3D confocal laser scanning microscopy

Milk fat globules (MFGs) in human milk provide energy to breastfed infants and support infant development. Accurate measurements of MFG size distributions are important to better understand MFG function and origin, as well as the influence of MFG size on milk composition analysis methods. Nevertheless, commonly used laser diffraction systems have never been thoroughly validated for size distribution measurements in human milk. Here, we introduce a new method for determining the size distribution of milk fat globules in human milk, using 3D confocal laser scanning microscopy (CLSM) in combination with fluorescent labeling of MFGs. We validate and compare 3D CLSM to laser diffraction (Mastersizer 2000, Malvern Panalytical), using polystyrene microsphere size standards. Next, we apply both methods to evaluate MFG size distributions in human milk. We show that 3D CLSM can be used to obtain more accurate size distributions between 500 nm and 10 μm compared to laser diffraction. Importantly, MFG size distributions obtained with 3D CLSM contain no secondary population around 1 μm, in contrast to laser diffraction measurements. This suggests that the bimodal MFG distribution obtained by laser diffraction can be an artifact of the built-in fitting algorithm, instead of an actual feature of human milk. This work demonstrates that care should be taken when interpreting size distributions of MFGs measured with laser diffraction and that 3D CLSM is an accurate alternative for measuring size distributions in lactation and dairy research.

Theoretical study of size and shell composition effect of TiO2 core-shell mesoporous microsphere on UV absorption effectivity for photocatalytic application

Microdispersed photocatalysts based on titanium dioxide (TiO2) in the form of hollow core-shell microspheres (microcapsules) with mesoporous structure are widely demanded in modern critical technologies related to the catalysis of various chemicals, solving environmental problems, and obtaining cheap fuel. To date, a number of experimental works are known, showing that geometrical parameters of microcapsules (size, shell thickness), as well as microstructural composition (nanosized metal additives, additional inner dielectric core- the "yolk") noticeably affect their photocatalytic activity. At the same time, a valuable physical description of the optical properties of porous microcapsules has not been presented in the literature so far. Using the finite element method, we perform a full-wave theoretical simulation of the optical field inside a hollow microsphere whose shell is randomly self-assembled from multiple TiO2 nanoparticles forming an irregular nanoporous structure. We provide a unified physical explanation of the published experimental data on the optical activity of titanium-dioxide microcapsules and show that the existing theoretical models do not always give a correct interpretation of the observed empirical behaviors.

The induction of bone formation by 3D-printed PLGA microsphere scaffolds in a calvarial orthotopic mouse model: a pilot study.

Polymeric biodegradable microspheres are readily utilized to support targeted drug delivery for various diseases clinically. 3D printed tissue engineering scaffolds from polymer filaments with embedded microspheres or nanoparticles, as well as bulk microsphere scaffolds, have been investigated for regenerative medicine and tissue engineering. However, 3D printed scaffolds consisting only of a homogenous microsphere size with an optimized architecture that includes a unique micro- and macroporosity, have been challenging to produce and hence, have not been assessed in the literature yet. Utilizing our recently established 3D-MultiCompositional Microsphere-Adaptive Printing (3D-McMap) method, the present study evaluated the effectiveness of 3D-printed poly (lactic-co-glycolic acid) (PLGA) microsphere scaffolds, consisting of microsphere sizes 50, 100, or 200μm, on the induction of bone formation when implanted in the calvarial murine regeneration model. Our results showed that PLGA microsphere scaffolds possess unique properties that support bone regeneration by supporting osteoconduction and stimulating, in our opinion, true spontaneous osteoinduction. The study demonstrated that PLGA microsphere-based scaffolds support bone growth in the absence of additional growth factors and promote osteogenesis primarily via their unique geometric configuration. The larger the microspheres were, the greater de novo bone formation was. This proves that bone tissue engineering scaffolds 3D printed from microspheres, enabled by the 3D-McMap method, are superior over bulk material printed scaffolds, as they possess the unique capability of spontaneous induction of new bone formation. With the addition of encapsulated modulatory bone-forming biomolecules they can substantially improve the spatiotemporal control of tissue morphogenesis, potentially leading to new innovative clinical tissue repair therapies that regenerate bone in large defects correctly and fully.

Controllable preparation of hexanitrostilbene (HNS) microspheres with multi-cavity structure to enhance safety and combustion performance

Controlling the structure to meet the demand for high-energy, low-sensitivity energetic materials in modern military and civilian applications is an effective method. In this study, hexanitrostilbene (HNS) microspheres with a multi-cavity structure were prepared using nitrocellulose (NC) and fluororubber (F2604) as binders via microjet droplet technology. The effects of flow rate, receiving liquid temperature, and suspension concentration on the morphology, particle size, and cavity of the HNS microspheres were investigated. Furthermore, the impact of the multi-cavity structure on the microspheres' specific surface area, dispersibility, thermal properties, safety performance, and combustion performance was studied. Results showed that the multi-cavity HNS microspheres retained the raw materials' crystal structure while exhibiting improved dispersibility, higher activation energy, and shorter ignition delay. Moreover, the multi-cavity structure outperformed the solid structure in terms of specific surface area, safety performance, and combustion performance. This study opens up a new direction for the preparation of multi-structured energetic microspheres.

Rapid fabrication of gold microsphere arrays with stable deep-pressing anisotropic conductivity for advanced packaging

Smooth metal microspheres with uniform sizes are ideal for constructing particle-arrayed anisotropic conductive films (ACF), but synthesis is hindered by challenges in controlling anisotropic metal growth. Here, we present a positioned transient-emulsion self-assembly and laser-irradiation strategy to fabricate pure gold microsphere arrays with smooth surfaces and uniform sizes. The fabrication involves assembling gold nanoparticles into uniform colloidosomes within a pre-designed microhole array, followed by rapid transformation into well-defined microspheres through laser heating. The gold nanoparticles melt and merge in a layer-by-layer manner due to the finite skin depth of the laser, leading to a localized photothermal effect. This strategy circumvents anisotropic growth, enables tunable control of microsphere size and positioning, and is compatible with conventional lithography. Importantly, these pure gold microspheres exhibit stable conductivity under deep compression, offering promising applications in soldering micro-sized chips onto integrated circuits.

Effect of seasonal changes in temperature on capture efficiency in the blue mussel, Mytilus edulis, fed seston and microplastics

AbstractSuspension‐feeding bivalve molluscs are dominant benthic fauna in many near‐shore environments, with phytoplankton often being their main prey type. Feeding, which involves hydrosol filtration and mucociliary processes to capture particles and process them for digestion, occurs at low Reynolds numbers. Changes in water temperature have been shown to affect feeding processes of bivalves as a result of altered physiological processes or temperature‐dependent changes in kinematic viscosity of water. Most studies, however, have focused on feeding rates and have manipulated temperature under laboratory conditions. In this study, experiments were conducted using ambient seawater and acclimatized blue mussels, Mytilus edulis, to examine particle capture efficiency over a 1‐year period. During this period, water temperature decreased from ~18°C to 5°C with a concomitant increase in viscosity of ~41%. The capture of a wide variety of bacteria and phytoeukaryotes (0.8–8 μm), as well as two sizes of polystyrene microspheres (1 and 6 μm), was quantified to calculate capture efficiency. Data demonstrate that temperature, and the concomitant change in water viscosity, had no significant effect on capture efficiency. Cyanobacteria were captured at significantly higher rates than other bacteria of similar size. These results suggest that the laterofrontal cirri of blue mussels act as paddles rather than sieves because capture efficiency was constant over a range of viscosities and Reynolds numbers. Additionally, the efficient capture of some bacteria and smaller phytoeukaryotes by the mussels suggests that these plankters could play a larger role in the diet of M. edulis than previously considered. The ecological impact of these findings, especially regarding differences in capture efficiency of different bacterial cells, warrants further study.

Experimental Study of Synergy between Polymeric Microspheres and Nanoemulsions for Profile Control and Water Plugging.

The development of low-porosity and low-permeability oil reservoirs in the Changqing oilfield presents a significant challenge due to the high injection pressure and limited space for profile control and pressure raising. Therefore, the synergistic profile control and flooding technology of polymer microspheres (PMs) and nanoemulsions is proposed, which makes use of the plugging performance of PMs and the pressure-reducing and oil-driving properties of nanoemulsions, with the objective of controlling the water-absorbing profile and increasing the recovery rate. The paper assessed the properties of nanoemulsions and PMs and evaluated their suitability for reservoirs. The construction parameters of profile control and flooding were optimized on an experimental basis. The experimental results demonstrate that the initial particle size of microspheres can more closely match the pore diameter of the formation and that the core exhibits a higher plugging rate after hydration and expansion. Moreover, the nanoemulsion can effectively reduce the interfacial tension, thereby exerting a beneficial effect on pressure reduction. The construction parameters of microspheres and nanoemulsions were optimized by alternately injecting them with 2:1 multistage plugs, and the injected pressure was lowered by 43%, with a high plugging rate and value-added recovery rate of up to 26.5%. Based on the experimental study, 8 well sets of field tests were conducted, and the results demonstrated that the efficiency rate of profile control reached 50%. Furthermore, the average injection pressure of the injected wells decreased by 1.7 MPa, the rise in water content decreased by 2.27%, and the petroleum production increased by 1110.2 tons. The validity period reached 162 days, indicating a positive application effect.

Microsphere as a Novel Drug Delivery System : A Review

Microspheres play a very important role as particulate drug delivery system because of their small size and other efficient properties. Microspheres have been proved to be a suitable bridge to scale the distance over to formulate an effective dosage form, to simulate controlled drug release. Microspheres are characteristically free flowing solid powders, which consist of proteins or synthetic polymer, which are biodegradable in nature[1]. Microsphere size ranges Between 1 to 1000 um . It can be administered By oral, Parentral ,Transdermal, ophthalmic, nasal ,colonal routes etc. Microspheres received much attention not only for prolonged release, but also for targeting of anticancer drugs. In future by combining various other strategies, microspheres will find the central place in novel drug delivery, particularly in diseased cell sorting, diagnostics, gene &amp; genetic materials, safe, targeted and effective in vivo delivery and supplements as miniature versions of diseased organ and tissues in the body[2]

Water-in-water emulsions stabilized by nano-chitin

A water-in-water (W/W) emulsion consists of microdroplets was formed by the spontaneous liquid–liquid separation by mixing polyacrylic acid and chitosan oligosaccharide in water, and these microdropletes were stabilized by nano-chitin, formed water-in-water Pickering emulsions. By taking the advantage of interfacial adsorption of nano-chitin, the W/W emulsion droplets composed of polyacrylic acid/chitosan oligosaccharide (COS/PAA) polyelectrolyte coacervate were successfully stabilized. Research results indicated that composite microspheres were formed by the nano-chitin stabilized COS/PAA emulsion, and the size of these composite microspheres was related to the concentration and morphology of the nano-chitin. As the concentration of nano-chitin increases, the size of the composite microspheres first increases and then decreases, gradually becoming more uniform; whereas a decrease in the length of nano-chitin will lead to an increase in the size of the composite microspheres. The formation of composite microspheres may be due to the electrostatic interactions between nano-chitin and the emulsion droplets. In addition, the composite microspheres exhibit the best release effect for berberine hydrochloride at a pH value of 3.

Fabrication of ZMF@PS composite microspheres as T2 contrast agents with enhanced contrast performance and magnetic properties

The impacts of nanoplastics on the environment and organisms are gradually increasing, using MRI to detect the metabolic pathways of nanoplastics has low sensitivity and requires magnetic particles for enhanced visualization. In this study, we used Mn0.6Zn0.4Fe2O4 nanoparticles as magnetic particles and coated them with polystyrene to afford polystyrene composite microspheres (ZMF@PS) with enhanced contrast performance. The effects of the polymerization parameters on the morphology and loading rate of the magnetic ZMF@PS composite microspheres were investigated. In addition, the effect of the magnetic contrast agent (ZMF particles) on the magnetic properties of the ZMF@PS composite microspheres was examined. The results show that when MAA and KPS quantities are 1 mL and 0.02 g, respectively, ZMF was uniformly distributed in the ZMF@PS composite microspheres exhibiting a good coating effect, with an average microsphere size of only 151.09 nm. Regarding the contrast performance, an increase in the ZMF content increased the loading rate, saturation magnetization intensity, and relaxation rate of the ZMF@PS composite microspheres.

Hydrogel Composition Effects on Performance as Single-Walled Carbon Nanotube Purification Media.

Hydrogel microsphere media allows for postsynthetic purification of single-walled carbon nanotubes (SWNTs), affording characterization and application of their unique (n,m) chirality-dependent properties. This work reports the characterization of five hydrogel resins, Sephacryl S-100, S-200, S-300, S-400, and S-500, and the implementation of each as a SWNT purification medium. The physiochemical properties of each resin were explored spectroscopically through elemental analyses and with both light and electron microscopy. Both surface porosity and hydrogel swelling ratio were found to increase as the concentration of component allyl dextran (aDEX) decreased, each with an increasing Sephacryl S-number. Conversely, invariant properties included a hydrogel microsphere size distribution and concentrations of components methylenebisacrylamide and ammonium persulfate. When employed within gel-based SWNT purification schemes in overloading conditions, Sephacryl formulations of larger S-number adsorbed fewer SWNTs, but the chirality dependence of SWNT adsorption and elution was approximately consistent across all resins. In underloading conditions, approximately one-third of introduced SWNTs passed through each resin unabsorbed, while the resins showed varying chirality-dependent adsorption efficiencies. These observations collectively identify aDEX-rich gel regions as being responsible for SWNT purification, along with a SWNT-exclusive parameter other than chirality (speculated as length) that convolutes the effectiveness of gel-based single-chirality purification.

Predicting effective thermal conductivity of HGM composite using ML

Data-driven materials research can be used as an effective tool to supplement conventional approaches in designing new materials. Hollow glass microsphere (HGM) composites are widely used for high-temperature thermal insulation applications, and their synthesis is traditionally done by varying parameters of the constituents on a trial-and-error basis. In this work, a prediction tool based on a supervised machine learning (ML) model is developed to predict the effective thermal conductivity (ETC) of an HGM composite by tailoring the composition and parameters of the constituents to reduce the time and cost involved. A comprehensive database containing the various input features is generated from previous experimental investigations conducted on various HGM composites. ML models, namely random forest regression (RF), K-nearest neighbor (KNN), support vector regression (SVR), and artificial neural network (ANN), are used to predict the ETC of HGM composites. Feature importance analysis showed that the matrix material’s thermal conductivity and the composite’s bulk density have the highest impact on the ETC of the HGM composite, followed by porosity and average microsphere size. ANN emerged as the best model to predict HGM composite ETC with the lowest root mean square error and highest R2 value for predictions. Moreover, a systematic approach for key feature selection using ANN shows that adding or omitting additional features beyond an optimal combination degrades the model’s predictive accuracy.

How substrate surface area and surface curvature determine kinetics and titanate formation during non-hydrothermal alkali treatment of titanium microspheres

Titanium surface nanostructuring using alkali treatment gains significant attention in a wide range of fields, such as biomaterials, (photo)catalysis, (metal/ion) sorption, CO2 capture, electrochromism and sodium-ion batteries. Even though the physicochemical properties and application potentials of the surface nanostructures are fairly well understood, there is still debate about their exact formation mechanism, limiting knowledge based structural control through altered synthesis conditions. Moreover, this knowledge is largely focused on hydrothermal synthesis conditions, whereas non-hydrothermal conditions might provide benefits towards industrial application. Also the impact of substrate properties, rather than chemical reaction conditions, on the nanostructure formation is only limitedly reported in literature. This work reveals new fundamental knowledge of non-hydrothermal alkali treatment of titanium, using microspheres by implementing, for the first time, in-situ hydrogen measurement during alkali treatment in combination with the ex-situ determination of the sodium and oxygen content in the recovered alkali treated samples, providing critical information on the role of dissolution apart from the precipitation process. The effect of surface area and surface curvature on the dissolution and precipitation process, and the resulting impact on the physicochemical properties of the obtained titanate layer is studied. This shows the much larger impact on dissolution in contrast to precipitation, knowledge that is lacking in literature, but important when implementing alkali surface nanostructuring on complex (e.g. 3D printed) substrates, and considering the prospective shift from lab-scale to industry. The Ti dissolution step was found to be mainly controlled by the total surface area, while the rate determining step was found to be the titanate precipitation, not influenced by either surface area or particle size.The changes in oxygen content in the samples after transformation of titanate into TiO2 provided a novel method for its quantification. The microspheres were analysed chemically (Raman), structurally (XRD) and morphologically (SEM, MIP), screening the effect of surface area, particle size and reaction time on the growth behaviour of the titanate layer. The porous layer structurally corresponds to Na2Ti2O4(OH)2 for all evaluated conditions, with pores in the range of 10–600 nm. Increasing surface area and particle size results in local and non-uniform titanate growth, while titanate nanowire and strut formation between the microspheres were enhanced by reduced microsphere size and prolonged reaction times.

Research on permeable self-restoring proppant for in-layer reinforcement and sand control

Weakly consolidated sandstone (WCS) is a common reservoir used in petroleum development. Owing to its loose structure, sand production and formation collapse frequently occur during oil and gas extraction, posing significant challenges in the petroleum industry. To address these issues, some researchers have proposed in-layer reinforcement sand control methods for weakly consolidated sandstones. To implement this approach, developing a permeability-self-restoring proppant (PSRP) for in-layer reinforcement is essential. The aim is to support the fractures created by fracturing, ensuring that the curable working fluid is not displaced and that the curable liquid does not infiltrate the voids of the PSRP, thereby preventing a substantial reduction in permeability. In this study, a new structure and principle for the PSRP are proposed. Polylactic acid (PLA) was selected as the filling material due to its alkaline solubility. The size and quantity of hollow microspheres were optimised based on the permeability of the consolidated body. The optimal microsphere size was determined to be 50–80 mesh, with an optimal dosage of 10%. Subsequently, the PSRP was developed and incorporated into a permeable curing liquid system prepared by other experts. The permeability of the obtained consolidated body was measured as 25.47 × 10−3 μm2 after 1 d and 22.46 × 10−3 μm2 after 7 d at 15 °C and 20 MPa. The compressive strength after 1 d was 6.88 MPa. Compared to conditions without PSRP addition, the permeability of the consolidated body increased by 35.12% after 1 d and by 134.47% after 7 d. This research lays the foundation for applying sand-control methods in in-layer reinforcement.

Preparation of poly(acrylonitrile-co-styrene) microspheres by reflux precipitation polymerization

Poly(acrylonitrile-co-styrene) microspheres are utilized in several applications due to their superior mechanical properties, excellent chemical stability, and tunable surface modification. In this work, poly(acrylonitrile-co-styrene) microspheres were synthesized in ethyl acetate usingreflux precipitation polymerization. The average particle size and morphology of microspheres were carefully measured to investigate the responding influencing factors. In the growth process of these microspheres, the average particle size of poly(AN-co-St) microspheres changed a little after 180 min. However, the yield of the microspheres continued to increase until 420 min. The properties of the solvents had a significant impact on both the average particle size and the morphology of the poly(AN-co-St) microspheres. The concentrations of the initiator and the cross-linker have minimal effect on the average particle size of poly(AN-co-St) microspheres. By controlling the monomer content at 25 wt%, the yield of these microspheres could reach 82%. The method is straightforward to operate andthe prepared microspheres exhibithigh sphericity and uniformity. As a result, it shows great promise for thepreparation of submicron poly(AN-co-St) microspheres.

Fabrication of Cross‐Linked Polyimide Hollow Microspheres With Lightweight, Thermal Resistance and Controllable Size

AbstractPolyimide (PI) hollow microspheres possess lightweight and excellent thermal resistance, which are widely used in microreactors, catalysis, adsorption separation, high‐temperature insulation, and so on. In this manuscript, PI hollow microspheres are fabricated by constructing a crosslinked structure combined with gradient heating. The formation of PI hollow microspheres includes gas nucleation, expansion, and imidization. The PI hollow microspheres size is controlled by adjusting polyester ammonium salts size, and microspheres size is distributed in 309–956 µm. PI hollow microspheres have lightweight, excellent heat resistance and carbonization performance, bulk density, initial decomposition temperature, and weight residue at 800 °C is 87.3–178.6 kg m−3, 533.6 °C and 59.8%. The PI hollow microspheres have potential applications in high‐temperature resistant and multifunctional composite materials preparation. Moreover, this method is simple, efficient, and highly operable, which can be used for large‐scale production of PI hollow microspheres.

Experimental study on optimizing tailwater reinjection technology for weakly consolidated sandstone geothermal reservoirs

The difficulty of recharging the weakly consolidated sandstone geothermal reservoirs (WCSGR) is a macroscopic manifestation of the interplay of multiple factors associated with both fluids and formation properties. However, current studies predominantly focus on the influence mechanisms of individual factors on the reinjection of WCSGR. To address this limitation, a high temperature–pressure core flow experimental platform, combined with an orthogonal experimental design, is employed to investigate the dynamic reinjection process of WCSGR under the combined effects of multiple factors. The research indicates that high temperatures significantly impact the movement of 3 μm microspheres, leading to a rapid decrease in core permeability. Additionally, in experiments conducted at flow rates of 2 mL/min, 3 mL/min, and 4 mL/min, the pH stabilization time of the outflow solution decreased, while both the pH value and turbidity of the outflow solution increased, compared to the experiments conducted at flow rate of 0.5 mL/min and 1 mL/min. The permeability damage rate (%) was used as the experimental evaluation index. The primary and secondary order of influence of each factor on the permeability is: microsphere size > flow rate > turbidity > confining pressure > temperature. The optimal levels for each factor are 5 μm, 4 mL/min, 2 mg/L, 1.4 MPa, and 25 °C, respectively. Consequently, the reinjection technology of GT in WCSGR is optimized.

Zinc phosphate glass microspheres promoted mineralization and expression of BMP2 in MC3T3-E1 cells.

Degradable phosphate glasses have shown favorable properties for tissue engineering. By changing the composition of the glasses, the degradation rate, and ion release are controllable. Zinc oxide can function as a glass network modifier and has been shown to play a positive role in bone formation. Also, phosphate glasses can easily be processed into microspheres, which can be used as microcarriers. This study aims to develop zinc phosphate glasses microspheres and explore the optimized size and composition for applications in bone tissue engineering. Zinc-titanium-calcium-sodium phosphate glasses with 0, 1, 3, 5, or 10 mol % zinc oxide were prepared and processed into microspheres. The smaller microspheres ranged in size from 50 to 106 μm, while the larger ones ranged from 106 to 150 μm. The characteristics of glasses were examined. The osteoblastic cell line MC3T3-E1 was cultured on the surface of microspheres and the cell viability was examined. To evaluate osteogenic differentiation, Alizarin Red S staining, quantitative reverse transcription polymerase chain reaction, and western blot analysis were performed after 14 days. Different sizes of zinc phosphate glass microspheres were successfully made. The glass microspheres with <10 mol % zinc oxide were able to support the adhesion and proliferation of MC3T3-E1 cell lines. The relative gene expression of BMP2 was significantly upregulated in the smaller glass microspheres containing 3 mol % zinc oxide (26-fold, p < .001) and both sizes of microspheres containing 5 mol % zinc oxide (smaller: 27-fold, p < .001; larger: 35-fold, p < .001). Additionally, cluster formation was observed in glass microspheres after 14 days, and the mineralization of MC3T3-E1 cell lines was promoted. Based on these findings, the glass microspheres containing 3-5 mol % of zinc oxide can promote osteogenic differentiation for MC3T3-E1 cells.

Mechanical Properties, Drug Release, Biocompatibility, and Antibacterial Activities of Modified Emulsified Gelatin Microsphere Loaded with Gentamicin Composite Calcium Phosphate Bone Cement In Vitro.

Bone defects are commonly addressed with bone graft substitutes; however, surgical procedures, particularly for open and complex fractures, may pose a risk of infection. As such, a course of antibiotics combined with a drug carrier is often administered to mitigate potential exacerbations. This study involved the preparation and modification of emulsified (Em) crosslinking-gelatin (gel) microspheres (m-Em) to reduce their toxicity. The antibiotic gentamicin was impregnated into gel microspheres (m-EmG), which were incorporated into calcium phosphate bone cement (CPC). The study investigated the effects of m-EmG@CPC on antibacterial activity, mechanical properties, biocompatibility, and proliferation and mineralization of mouse progenitor osteoblasts (D1 cells). The average size of the gel microspheres ranged from 22.5 to 16.1 μm, with no significant difference between the groups (p > 0.05). Most of the oil content within the microspheres was transferred through modification, resulting in reduced cytotoxicity. Furthermore, antibiotic-impregnated m-EmG did not compromise the intrinsic properties of the microspheres and exhibited remarkably antibacterial effects. After combining with CPC (m-EmG@CPC), the microspheres did not significantly hinder the CPC reaction and produced the main product, hydroxyapatite (HA). However, the compressive strength of the largest microsphere content of 0.5 wt.% m-EmG in CPC decreased significantly from 59.8 MPa of CPC alone to 38.7 MPa of 0.5m-EmG@CPC (p < 0.05). The 0.5m-EmG@CPC composite was effective against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) in drug release and antibacterial tests. Compared with m-EmG alone, the 0.5m-EmG@CPC composite showed no toxicity to mouse fibroblast cells (L929). Additionally, the proliferation and mineralization of mouse osteoblastic osteoprogenitor cells (D1 cells) did not have a negative impact on the 0.5m-EmG@CPC composite over time in culture compared with CPC alone. Results suggest that the newly developed antibacterial 0.5m-EmG@CPC composite bone cement did not negatively affect the performance of osteoprogenitor cells and could be a new option for bone graft replacement in surgeries.