Particle Size Of Microspheres Research Articles

Fabrication of chitosan-coated konjac glucomannan/sodium alginate/graphene oxide microspheres with enhanced colon-targeted delivery.

Microspheres play an increasingly important role in the food and medicine industries. In this study, konjac glucomannan (KGM)/sodium alginate (SA)/graphene oxide (GO) solution was injected into CaCl2 solution under high-voltage static electricity assistance to fabricate microspheres. Then, chitosan (CS) was coated on the surface of the microspheres to enhance their stability. SEM images confirmed that increasing voltage decreased the particle size of microspheres obviously. Furthermore, GO was beneficial in maintaining the full structure of freeze-dried microspheres, and the CS membrane improved the surface of the microspheres with no relatively obvious gully. Results indicated that KGM interacted with SA by hydrogen bond, and GO improved this interaction in microspheres. Furthermore, swelling tests showed that the microspheres exhibited different swelling properties in different media, and the CS membrane could improve the stability of microspheres in simulated intestinal fluid and simulated colon fluids. Moreover, GO could greatly improve the ciprofloxacin (CPFX) loading efficiency of microspheres, and achieving a sustained release effect of CPFX. Thus, CS-coated KGM/SA/GO microspheres showed great potential application in drug and/or nutrition factor colon-targeted delivery.

Liquid jet breakup: A new method for the preparation of poly lactic-co-glycolic acid microspheres

The purpose of this study was to apply the phenomenon of liquid jet breakup to the preparation of sustained-release microspheres. The mechanisms of liquid jet breakup in different jet states were investigated and the single factor method was used to study the effect of each process parameter on the particle size and size distribution of microspheres. Meantime, the prepared microspheres were characterized by morphology, drug loading, encapsulation efficiency and in vitro release. The results indicated that the process of liquid jet breakup could have 5 different states. The laminar flow state dominated when the Reynolds number (Re) was low, and the prepared microspheres had larger particle sizes. When the Re was high, the turbulent state was dominant and the microspheres had smaller particle sizes. And during the transition state from the laminar flow to the turbulence, the microspheres had a wide particle size distribution. Different process parameters could affect the particle size and distribution of microspheres by changing the Re, surface tension coefficient and viscosity. The microspheres prepared by liquid jet breakup were smooth and round with the drug loading of 35% and the encapsulation efficiency of 88%. In addition, when the polymeric carrier materials were different, the microspheres could have various drug release models such as sustained release with a lag phase, sustained release with no lag phase, pulsed release and so on, which could be applied widespread in the future.

A new route to synthesize calcium carbonate microspheres from phosphogypsum

In this work, monodisperse spherical vaterite calcium carbonate (CaCO3) was synthesized at room temperature and atmospheric pressure through a simple and efficient ‘phase transfer-precipitation’ route using phosphogypsum (PG) as raw material, sodium gluconate(SG) as phase transfer agent and CO2 as precipitator. CaCO3 samples were characterized by Field-emission scanning electron microscopy (FE-SEM), x-ray diffraction (XRD), and Dynamic light scattering (DLS). The composition of the as-obtained sample was almost monodisperse spherical vaterite CaCO3 by adjusting the concentration of SG and other operational conditions. The effects of SG and STP on the formation of CaCO3 microspheres were investigated. The results indicated that the existence of SG inhibited the nucleation and growth of calcite but promoted the formation of vaterite. The effects between SG and Ca2+ played a key role in the formation process of monodisperse spherical vaterite CaCO3. The existence of STP can effectively control the further growth and enhance the uniformity of the particle size of CaCO3 microspheres. These studies are promising for the industrial preparation and further commercial applications of monodisperse spherical vaterite CaCO3.

Experimental design approach in erythropoietin-alginate microsphere preparation with different concentrations of drug and polymer

Background: Microspheres as drug delivery system has been selected to increase stability of Erythropoietin (EPO) to achieve efficacy. Aim: Aim of this research was to determine effect of polymer and EPO concentrations on the characteristics. Materials and Method: Microspheres involved sodium alginate as polymer and CaCl2 as a crosslinker. The concentrations of sodium alginate used were 2% and 3%, and EPO were 5000 IU and 10000 IU. Formula of microspheres which consist of 2% and 3% of alginate and 5000 IU EPO were called F1 and F2 respectively, whereas microspheres using 2 and 3% alginate and 10000 IU EPO was named F3 and F4 respectively. Characterization including morphology, particle size, swelling index, and yield of microspheres prepared by ionotropic gelation aerosolization technique. Design of Experiment (DoE) was used to analyze the formula. Results: Results showed that particle sizes of EPO-alginate microspheres were 3.36 ± 0.126μm, 3.42 ± 0.098μm, 3.88 ± 0.131μm and 3.95 ± 0.151μm for F1, F2, F3 and F4 respectively. The swelling index measurement based on mass and particle size of microspheres of all formulas showed an index of less than 10. Respectively, yield was 77.84 ± 0.290%, 86.65 ± 0.191%, 91.89 ± 0.210%, and 94.65 ± 0.252% for F1 to F4. Using the ANOVA factorial design, it was found that increasing sodium alginate concentration significantly increased yield, while increasing EPO concentration significantly increased particle size and yield of microspheres. Both sodium alginate and EPO concentrations did not affect swelling index of microspheres. Range concentrations of sodium alginate and EPO that produced optimal characteristics of microspheres can be observed in the feasible area of design space overlaid contour plot generated from DoE study. Conclusion: EPO-alginate microspheres demonstrated the prospective as carrier and DoE is potential for further optimized formulations.

Design and development of microparticulate delivery system for Curcumin

Background: Curcumin has been associated with remarkable beneficial effects; despite having a broad spectrum of activities, curcumin is characterized by poor water solubility and low bioavailability. Objective: The objective of this study is to enhance the solubility of curcumin using polyethylene glycol 400 (PEG400) and establish a microparticulate drug delivery system in a sodium alginate polymer matrix (microspheres containing curcumin triturated with PEG400 [Cur-PEGMS]) to improve the bioavailability of curcumin. Materials and Methods: The microspheres were formulated using the ionic gelation technique. Nine batches (F1 to F9) were prepared using 32 factorial design. The amount of sodium alginate and calcium chloride was selected as a formulation variable. The prepared Cur-PEGMS were characterized by Fourier-transform infrared spectroscopy, scanning electron microscope, differential scanning calorimeter, ultraviolet spectrophotometer, and high-performance thin-layer chromatography (HPTLC). The pharmacokinetics of curcumin was characterized in rats using high-performance liquid chromatography, and calculations were performed using WinNonlin standard edition version 1.1 software. Results: We found that solubility was affected by the use of cosolvent. All F1–F9 batches were investigated for entrapment efficiency, and batch F5 was found to be optimum batch which was further evaluated. HPTLC chromatogram of Cur-PEGMS shows peak retention for curcumin. The particle size of microspheres was found to be in the range of 384–468 μm. Remarkable improvement in maximum plasma concentration and bioavailability was observed. Maximum the time after administration of a drug when maximum plasma concentration is reached (Tmax) was found to be 0.5 h, and AUC0–24was found to be 374.75 ng/ml and 622 ng/ml for curcumin suspension and curcumin microspheres, respectively. Conclusion: The developed formulation enhances the bioavailability of the drug. This enhanced oral absorption of Cur-PEGMS may provide a practical formulation to conduct a correlative pharmacodynamic study.

Preparation of surface-modified monodisperse polystyrene microspheres with cationic functional comonomer

A two-stage synthesis of surface-functionalized monodisperse polystyrene (PS) microspheres in ethanol/water medium by introducing methacryloyloxyethyl dodecyl dimethyl ammonium bromide (QDMDB) to dispersion polymerization of styrene is reported. Polyvinylpyrrolidone (PVP) and fatty alcohol polyoxyethylene ether (AEO-9) are used as dispersion stabilizers. The novel microspheres are characterized by FT-IR, SEM, GPC, TGA, water contact angle (WCA), etc. The dispersion polymerization goes through successfully with the solid content up to 58.75%, in which the water content in the medium is 20%. The water content in the medium has a certain effect on the particle size and molecular weight of microspheres. Under the experimental conditions, the average diameters of the obtained microspheres are approximately 550–1200 nm with the number average molecular weight of up to 5.8 × 105. The introduction of QDMDB improves the wettability and thermal stability of the poly(St-co-QDMDB) microspheres. A mechanism of dispersion copolymerization based on XPS and 1H NMR is proposed.

Formulation and evaluation of erythropoietin-alginate microspheres at different amount of drug

This research formulate erythropoietin-alginate microspheres and to evaluate characteristics of erythropoietin-alginate microspheres at different amount of drug using aerosolization. Amount of erythropoietin are 10.000 IU (F1); 20.000 IU (F2); 60.000 IU (F3). The mixture of erythropoietin-alginate was sprayed into CaCl2 and was stirred at 1000 rpm for 30 minutes. Formulas resulted spherical shape of microspheres. The size of microspheres was 2.77 µm for F1; 3.89 µm for F2; and 4.42 µm for F3. The results of swelling index showed that swelling index of microspheres increased by increasing the concentration of erythropoietin. The results were in accordance with the size of the microspheres that increased with increasing concentration of drug. The yields of microspheres obtained were respectively 91.92%; 87.53%; 86.50% for F1, F2 and F3. It can be concluded that the particle size of microspheres, swelling index increased by increasing concentration of erythropoietin. In contrast, yield of microspheres decreased by increasing drug concentration. In conclusion, formula of microspheres were potential in terms of characteristics and may recommend for further in vivo study.

Antagonistic Effect of Azoxystrobin Poly (Lactic Acid) Microspheres with Controllable Particle Size on Colletotrichum higginsianum Sacc.

Size-controlled azoxystrobin-poly (lactic acid) microspheres (MS) were prepared by an oil/water emulsion solvent evaporation approach. The hydrated mean particle sizes of the MS1, MS2, and MS3 aqueous dispersions were 130.9 nm, 353.4 nm, and 3078.0 nm, respectively. The drug loading and encapsulation efficiency of the azoxystrobin microspheres had a positive relationship with particle size. However, the release rate and percentage of cumulative release were inversely related to particle size. The smaller-sized microspheres had a greater potential to access the target mitochondria. As a result, the more severe oxidative damage of Colletotrichum higginsianum Sacc and higher antagonistic activity were induced by the smaller particle size of azoxystrobin microspheres. The 50% lethal concentrations against Colletotrichum higginsianum Sacc of MS1, MS2, and MS3 were 2.0386 μg/mL, 12.7246 μg/mL, and 21.2905 μg/mL, respectively. These findings reveal that particle size is a critical factor in increasing the bioavailability of insoluble fungicide.

Quasi-Static and Impact Response of Graded Aluminium Matrix Syntactic Foams

The behaviour of aluminium matrix syntactic foams (AMSFs) with homogeneous and graded structures have been studied under quasi-static compression and impact. Particle size of ceramic microspheres and impact velocity had significant effects on the static and impact responses. Smaller microspheres led to higher strength but lower toughness. The compressive yield stress, plateau stress and specific energy absorption of the graded AMSF specimens were approximately the averages of the constituent layers, following the rule of mixture, although the order of the layers had some influence on the compressive behaviour. The syntactic foams were brittle under impact, no matter whether they were brittle or ductile in quasi-static compression. They had higher peak stresses and absorbed more energy in impact than in quasi-static compression. The location of the most brittle layer of the small ceramic microspheres had a significant effect on the impact failure pattern and sequence of the three-layer graded AMSFs.

RIZATRIPTAN BENZOATE LOADED NATURAL POLYSACCHARIDE BASED MICROSPHERES FOR NASAL DRUG DELIVERY SYSTEM

Objective: The objective of this research was to formulate and evaluate the different grades of rizatriptan benzoate loaded polysaccharide based microspheres for the nasal drug delivery system.Methods: The polysaccharide was extracted from the seed of Trigonella foenum-graecum and microspheres were prepared by emulsification, followed by crosslinking using epichlorohydrin. A 32 full factorial design was employed in formulating the microspheres with polymer concentration (X1), and stirring rate (X2) as independent variables and particle size (Y1) and entrapment efficiency (Y2) were dependent variables.Results: The microspheres were discrete and free-flowing. The mean particle size (Y1) of microspheres ranged from 40.82+12 µm to 62.48+0.41 µm and the encapsulation efficiency (Y2) was found to be increased from 60.7+0.2% to 79.22+0.2% as the drug polysaccharide ratio increased. A 32 full factorial design confirmed that the X1 and X2 both effect on particle size whereas X1 alone effect on entrapment efficiency. SEM revealed the smooth spherical surface of microspheres whereas kinetic model revealed that drug release followed the case II transport. FTIR indicated good compatibility of the excipients with rizatriptan benzoate. Stability studies were carried out for formulation F7 at 4°C ambient, 25+2°C/60+5%, 40+2°C/75+5% relative humidity revealed that the physical drug appearance, entrapment efficiency were within the permissible limits.Conclusion: The result obtained in this research work indicate a promising potential of control release rizatriptan benzoate loaded microspheres whereas the Trigonella foenum-graecum polysaccharide used as rate controlling polymer for the effective treatment of migraine patients.

Fabrication of Monodisperse Porous Silica Microspheres with a Tunable Particle Size and Pore Size for Protein Separation.

Monodisperse porous silica microspheres with a tunable particle size and pore size were fabricated by utilizing porous polymer microspheres as a novel hard template during the sol-gel process followed by calcination to remove the polymer. The particle size and pore size could be simply tuned by the feature of the polymer template and reaction conditions such as different functionalization of the parent polymer template, particle size of polymer template, and amount of TEOS during the sol-gel process. EDA (ethylenediamine), APTES (3-aminopropyl)triethoxysilane, and TMA (trimethylamine hydrochloride) functionalization of porous poly(GMA-co-EGDMA) microspheres were carried out to study their effect on the synthesized porous silica microspheres. The TMA-functionalized polymer microspheres led to a higher yield, smaller silica nanoparticles, and no self-nucleation of TEOS due to their positive surface charge. Furthermore, no addition of NaOH during TMA functionalization and the amount of TEOS during the sol-gel process played key roles in determining the pore size and particle size of porous silica microspheres. Then, through poly(aspartic acid) coating of the APTES-functionalized monodisperse porous silica microspheres, the modified monodisperse porous silica microspheres were explored as the stationary phase of HPLC for protein separation. The effects of particle size and pore size on the chromatographic behavior were discussed. When the protein mixture composed of transferrin, hemoglobin, ribonuclease A, cytochrome C, and lysozyme was used as the model analytes, the as-prepared silica microspheres exhibited an excellent separation performance with a high protein recovery and good reproducibility.

EVALUATION OF STABILITY OF ROPINIROLE HYDROCHLORIDE AND PRAMIPEXOLE DIHYDROCHLORIDE MICROSPHERES AT ACCELERATED CONDITION

Objective: The objective of the present work was to conduct accelerated stability study as per international council for harmonisation (ICH) guidelines and to establish shelf life of controlled release dosage form of ropinirole hydrochloride and pramipexole dihydrochloride microspheres for a period of 6 mo.Methods: Most optimized batch of ropinirole hydrochloride and pramipexole dihydrochloride (F12 and M12 respectively) were selected and subjected to exhaustive stability testing by keeping the sample in stability oven for a period of 3 and 6 mo. Various parameters like surface morphology, particle size, drug content, in vitro drug release and shelf life were evaluated at 3 and 6 mo period. The surface morphology of the formulated microspheres was determined by scanning electron microscopy (SEM). The particle size of the microspheres was estimated by optical microscopy method. The drug content was assayed by the help of ultra-violet spectrophotometer (UV). The in vitro drug release was performed by using Paddle II type dissolution apparatus and the filtrate was analyzed by UV spectrophotometer. The shelf life of the optimized microspheres was calculated by using the rate constant value of the zero-order reaction.Results: A minor change was recorded in average particle size of F12 and M12 microspheres after storage for 6 mo. For F12 and M12, initially the particle size was 130.00 µm and 128.92 µm respectively and after 6 mo it was found to be 130.92 µm and 128.99 µm respectively. There was no change in surface morphology of F12 and M12 microspheres after 6 mo of storage. The shape of microspheres remained spherical and smooth after 6 mo. An insignificant difference of drug content was recorded after 6 mo compared to the freshly prepared formulation. For F12 and M12, 94.50% and 93.77% of the drug was present initially and after 6 mo 94.45% and 93.72% of the drug was recorded. In vitro drug release was recorded after 6 mo for F12 and M12. Initially, 97.99% and 97.69% of the drug was released till 14th hour respectively for F12 and M12. After 6 mo, 98.23% and 97.99% of the drug was released respectively. The percentage residual drug content revealed that the degradation of microspheres was low. Considering the initial percentage residual drug content as 100%, 99.94% of the drug was recorded for both F12 and M12. The shelf life for F12 and M12 was found to be 10 y 52 d and 10 y 70 d respectively which were determined by the zero-order kinetic equation.Conclusion: A more or less similar surface morphology, particle size, drug content and percent of drug release before and after stability study confirmed the stability of F12 and M12 microspheres after storage for 6 mo and prove the efficacy of the microspheres in the site-specific delivery of drugs in Parkinson’s disease.

Densely-stacked N-doped mesoporous TiO2/carbon microsphere derived from outdated milk as high-performance electrode material for energy storages

Spherical N-doped mesoporous TiO2/C (MTC) composite micro-particles are produced by spray drying (SD) and carbonization process. The particle size of MTC microsphere is between 2 and 3.4 µm, and the N-doped amorphous C around TiO2 could provide a conductive matrix, and buffer the volume change. When evaluated as electrodes for Li-ion batteries (LIBs) and Li-S batteries (LSBs), the MTC microsphere exhibits relatively high discharge-voltage plateau, excellent capacity retention and rate capability. As anode for LIBs, after 200 cycles, a reversible capacity more than 230 mA h g−1 can achieved at 1 C. And for LSBs, a specific capacity of 1317.7 mA h g−1 at 1 C and the capacity retention of 73.8% after 500 cycles. The superior electrochemical performance is ascribed to robust scaffolding architecture and conductive N-doped carbon matrix. The excellent electrochemical performance and process ability of the MTC microspheres make them very attractive as electrode materials for use in high rate battery application.

Formulation and Evaluation of Acyclovir Microspheres

The present study is to formulate and evaluate Acyclovir (ACV) microspheres using natural polymers like chitosan and sodium alginate. ACV is a DNA polymerase inhibitor used in treating herpes simplex virus infection and zoster varicella infections. Acyclovir is a suitable candidate for sustained-release (SR) administration as a result of its dosage regimen twice or thrice a day and relatively short plasma half-life (approximately 2 to 4 hours). Microspheres of ACV were prepared by an ionic dilution method using chitosan and sodium alginate as polymers. The prepared ACV microspheres were then subjected to FTIR, SEM, particle size, % yield, entrapment efficiency, in vitro dissolution studies and release kinetics mechanism. The FTIR spectra’s revealed that, there was no interaction between polymer and ACV. ACV microspheres were spherical in nature, which was confirmed by SEM. The particle size of microspheres was in the range of 23.8µm to 39.4µm. 72.9% drug entrapment efficiency was obtained in the formulation F3 (1:3 ratio) with a high concentration of calcium chloride (4% w/v). The in vitro performance of ACV microspheres showed sustained release depending on the polymer concentration and concentration of calcium chloride. The release data was best fitted with zero order kinetics and Korsemeyer -Peppas release mechanism and diffusion exponent ‘n’ value of was found to be Non-Fickian.

Influencing Factors in the Test Procedure of Hydrated Microsphere Particle Size

Microsphere profile control is a new deep profile control technology in oilfield, which has developed in recent years. The particle size distribution of hydrated microsphere is an important basis for its application in formation pore throat, which has direct influence on the effect of profile control. First, the existing problems in current particle measurement of hydrated microsphere were studied through analyzing the results of the hydrated particle size, which were obtained from the static laser particle size analyzer. Results showed that there were two main problems in the current test methods of hydrated particle size. One was the poor reproducibility of the test results, and the other was the unrecognized particle size distribution of the truly hydrated microsphere. In addition, the test factors of hydrated microsphere particle size were studied through analyzing the morphology and the composition of microsphere. Results showed that the main influential factors of the hydrated particle size testing were the organic solvent and the emulsifier, which existed in the aqueous solution of microsphere with a variety of forms. Finally, some specific suggestions were put forward about the measurement of testing the hydrated particle size, which was removing the organic solvent and emulsifier from the aqueous solution of microsphere before measuring the hydrated particle size.

Problems in the Test Procedure of Hydrated Microsphere Particle Size

Microsphere profile control is a new deep profile control technology in oilfield, which has developed in recent years. The particle size distribution of hydrated microsphere is an important basis for its application in formation pore throat, which has direct influence on the effect of profile control. First, the results of hydrated microsphere particle size were obtained from the current testing method, which was based on the static laser particle size analyzer. And then, the existing problems in current particle measurement of hydrated microsphere were studied. Results showed that there were two main problems in the current test methods of hydrated microsphere particle size. One was the poor reproducibility of the test results, and the other was the unrecognized particle size distribution of the truly hydrated microsphere. Finally, the suggestion of analyzing the influencing factors during the test procedure of hydrated microsphere particle size was given.

Self-assembled microspheres feasibility study for conformance control in high temperature and high salinity reservoirs

This paper investigated the micro-structure and swelling and heat tolerance of DCA (divinylbenzene-co-acrylamide) microsphere and its self-assembly ability at high temperature, high salinity, oil-water system. Heterogeneous cores have been used in displacement experiment to evaluate the conformance control effectiveness of DCA microsphere. The result suggested that DCA microsphere has a hollow structure and many oligomer chain segment on the microsphere surface extending into the aqueous solution. The particle size of microsphere has strong stability. DCA microsphere can tolerate temperature up to 260 °C and still self-assemble in an oil-water system at high temperature and high salinity condition; DCA microsphere can self-assemble in the core into microspherical clusters used for conformance control of injected water, resulted in subsequent water flooding pressure increase of tenfolds and oil recovery enhancement of 9.53%; DCA microsphere exhibit effective conformance control of CO2 and control well CO2 channeling. CO2 displacement with conformance control using DCA microspheres has 15.8% higher oil recovery than direct CO2 displacement. DCA self-assembled microsphere can improve development of high–temperature, high-salinity heterogeneous reservoir and provide an aid for enhanced oil recovery.

Synthesis, Self-Assembly, and Drug-Release Properties of New Amphipathic Liquid Crystal Polycarbonates.

New amphiphilic liquid crystal (LC) polycarbonate block copolymers containing side-chain cholesteryl units were synthesized. Their structure, thermal stability, and LC phase behavior were characterized with Fourier transform infrared (FT-IR) spectrum, 1H NMR, gel permeation chromatographic (GPC), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), polarizing optical microscope (POM), and XRD methods. The results demonstrated that the LC copolymers showed a double molecular arrangement of a smectic A phase at room temperature. With the elevating of LC unit content in such LC copolymers, the corresponding properties including decomposition temperature (Td), glass temperature (Tg), and isotropic temperature (Ti) increased. The LC copolymers showed pH-responsive self-assembly behavior under the weakly acidic condition, and with more side-chain LC units, the self-assembly process was faster, and the formed particle size was smaller. It indicated that the self-assembly driving force was derived from the orientational ability of LC. The particle size and morphologies of self-assembled microspheres loaded with doxorubicin (DOX), together with drug release tracking, were evaluated by dynamic light scattering (DLS), SEM, and UV–vis spectroscopy. The results showed that DOX could be quickly released in a weakly acidic environment due to the pH response of the self-assembled microspheres. This would offer a new strategy for drug delivery in clinic applications.

Preparation and evaluation of naringin-loaded polycaprolactone microspheres based oral suspension using Box-Behnken design

The objective of the current investigation was to study the outcome of the concentration of polycaprolactone (PCL), the concentration of polyvinyl alcohol (PVA) and the concentration of hydroxypropyl methylcellulose (HPMC) on the average particle size of microspheres and the drug entrapment efficiency of naringin-loaded polycaprolactone microspheres based oral suspension. Naringin-loaded polycaprolactone microspheres based oral suspension were prepared by solvent evaporation method. Further, in this work optimization of the formulation was done using a three factors, three levels Box-Behnken design (BBD). Drug-loaded microsphere suspension was prepared by employing solvent evaporation technique. Fourier transform infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) analysis was carried out to determine any incompatibility between the naringin and other components used in the formulations. Polymer alone (PVA concentration) or interaction effects of polymers (PCL-HPMC, PCL-PVA, HPMC-PVA, and PCL in higher order) have a substantial influence on particle size of microspheres. Amount of PVA and HPMC have a significant effect on entrapment efficiency of microspheres. The optimal conditions of PCL concertation were 7.7% w/v; HPMC concentration was 3.2% w/v and PVA concentration was 0.081% w/v. The optimized suspension showed particle size of 24μm with drug entrapment efficiency 96%. As a result, due to uniform distribution of microspheres, drug entrapment efficiency was achieved in optimized suspension.

Influence of crosslinker concentration on the characteristics of erythropoietin-alginate microspheres

Context: Microspheres have several advantages including protecting proteins from degradation and clearance after administration and produce a long-term therapeutic effect. Erythropoietin as a neuroprotectant agent has protein-like properties, which are susceptible to degradation and have low in vivo bioavailability. Microspheres formulations is one of potential drug delivery system for erythropoietin. Aims: To evaluate the effect of CaCl2 concentration on the characteristics (particle size, morphology, swelling index, and yield) of erythropoietin-alginate microspheres. Methods: Erythropoietin-alginate microspheres prepared by ionotropic gelation method with aerosolization technique using sodium alginate as polymer and CaCl2 as crosslinker were dried using freeze drying method with maltodextrin as lyoprotectant. The concentrations of alginate used were 2%, and CaCl2 concentrations were 0.5 M(F1), 0.75 M(F2) and 1 M(F3). Results: Results showed smooth and spherical microspheres for all formula with average particle size were 3.23 ± 0.05 μm (F1); 2.99 ± 0.07 μm (F2); and 2.86 ± 0.03 μm (F3). Mass swelling index at 24 h were 1.25 ± 0.10 (F1), 1.18 ± 0.11 (F2), and 1.11 ± 0.10 (F3); at 30 h were 2.00 ± 1.25 (F1), 1.85 ± 0.14 (F2), and 1.72 ± 0.15 (F3) while particle size swelling index at 24 h were 1.15 ± 0.10 (F1), 1.11 ± 0.10 (F2), and 0.97 ± 0.10 (F3); at 30 h were 1.81 ± 0.09 (F1), 1.73 ± 0.15 (F2), and 1.54 ± 0.14 (F3). Respectively yield percentages were 77.76 ± 6.49, 80.01 ± 3.53, and 82.97 ± 4.22. By using One Way ANOVA, it was found that there were significantly differences between three formulas. Conclusions: The particle size of formulas decreased by increasing concentration of CaCl2, whereas no significant difference on swelling index and yield from microspheres with increasing CaCl2 concentration simultaneously.