Microparticle Formation Research Articles

Sterically Stabilized Diblock Copolymer Nanoparticles Enable Convenient Preparation of Suspension Concentrates Comprising Various Agrochemical Actives.

It is well known that sterically stabilized diblock copolymer nanoparticles can be readily prepared using polymerization-induced self-assembly. Recently, we reported that such nanoparticles can be employed as a dispersant to prepare micron-sized particles of a widely used fungicide (azoxystrobin) via ball milling. In the present study, we examine the effect of varying the nature of the steric stabilizer block, the mean nanoparticle diameter, and the glass transition temperature (Tg) of the core-forming block on the particle size and colloidal stability of such azoxystrobin microparticles. In addition, the effect of crosslinking the nanoparticle cores is also investigated. Laser diffraction studies indicated the formation of azoxystrobin microparticles of approximately 2 μm diameter after milling for between 15 and 30 min at 6000 rpm. Diblock copolymer nanoparticles comprising a non-ionic steric stabilizer, rather than a cationic or anionic steric stabilizer, were determined to be more effective dispersants. Furthermore, nanoparticles of up to 51 nm diameter enabled efficient milling and ensured overall suspension concentrate stability. Moreover, crosslinking the nanoparticle cores and adjusting the Tg of the core-forming block had little effect on the milling of azoxystrobin. Finally, we show that this versatile approach is also applicable to five other organic crystalline agrochemicals, namely pinoxaden, cyproconazole, difenoconazole, isopyrazam and tebuconazole. TEM studies confirmed the adsorption of sterically stabilized nanoparticles at the surface of such agrochemical microparticles. The nanoparticles are characterized using TEM, DLS, aqueous electrophoresis and 1H NMR spectroscopy, while the final aqueous’ suspension concentrates comprising microparticles of the above six agrochemical actives are characterized using optical microscopy, laser diffraction and electron microscopy.

Influence of thermoinduced magnetoelastic effect on domain structure of planar Ni microparticles

Results of studying the domain structure of planar Ni microparticles formed on single-crystal substrates from the lithium niobate and from the potassium titanyl phosphate at different temperatures are presented. The dependence of domain sizes on the sample temperature was studied. It is shown the observed change of the domain structure is caused by the magnetoelastic effect, which arises due to the difference in the thermal expansion coefficients of the substrate and microparticles as the sample temperature changes. It is shown, the sizes of magnetic domains, up to the creation of a state with a quasi-homogeneous magnetization may be set by the substrate temperature during the microparticles formation. Keywords: magnetoelastic effect, magnetic force microscopy, remagnetization, lithium niobate, potassium titanyl phosphate, temperature.

Влияние термоиндуцированного магнитоупругого эффекта на доменную структуру планарных Ni-микрочастиц

Results of studying the domain structure of planar Ni microparticles formed on single-crystal substrates from the lithium niobate and from the potassium titanyl phosphate at different temperatures are presented. The dependence of domain sizes on the sample temperature was studied. It is shown the observed change of the domain structure is caused by the magnetoelastic effect, which arises due to the difference in the thermal expansion coefficients of the substrate and microparticles as the sample temperature changes. It is shown, the sizes of magnetic domains, up to the creation of a state with a quasi-homogeneous magnetization may be set by the substrate temperature during the microparticles formation.

MicroRNA-363-3p/sphingosine-1-phosphate receptor 1 axis inhibits sepsis-induced acute lung injury via the inactivation of nuclear factor kappa-B ligand signaling.

Infection-associated inflammation and coagulation are critical pathologies in sepsis-induced acute lung injury (ALI). This study aimed to investigate the effects of microRNA-363-3p (miR-363-3p) on sepsis-induced ALI and explore the underlying mechanisms. A cecal ligation and puncture-induced septic mouse model was established. The results of this study suggested that miR-363-3p was highly expressed in lung tissues of septic mice. Knockdown of miR-363-3p attenuated sepsis-induced histopathological damage, the inflammation response and oxidative stress in lung tissues. Furthermore, knockdown of miR-363-3p reduced the formation of platelet-derived microparticles and thrombin generation in blood samples of septic mice. Downregulation of miR-363-3p suppressed sphingosine-1-phosphate receptor 1 (S1PR1) expression in lung tissues and subsequently inactivated the nuclear factor kappa-B ligand (NF-κB) signaling. A luciferase reporter assay confirmed that miR-363-3p directly targeted the 3’-untranslated region of the mouse S1pr1 mRNA. Collectively, our study suggests that inactivation of NF-κB signaling is involved in the miR-363-3p/S1PR1 axis-mediated protective effect on septic ALI.

Hollow protein microparticles formed through cross-linking by an Au3+ initiated redox reaction.

Hollow microparticles (MPs) are of great relevance in the materials industry for a wide range of applications, such as catalysis, coatings, and delivery of theranostics. Here, we report the formation of hollow MPs through the assembly of lipoproteins in CaCO3 templates. Proteins interact in the pores of CaCO3 templates through attractive hydrophobic forces and form dense edges of hollow MPs. To further cross-link the proteins, Au3+ was added to initiate a redox reaction, where proteins were oxidized forming inter- and intramolecular covalent bonds, while Au3+ was reduced and gold nanoparticles (AuNPs) were formed. The obtained protein-based hollow MPs have a diameter of 6 μm and the AuNPs are embedded on their surface. Through this research, we suggest a new route to design biobased Au-protein hollow MPs in simple steps, which can allow new possibilities for carrying functional molecules and bioimaging.

Morphology and Degradation of Multicompartment Microparticles Based on Semi-Crystalline Polystyrene-block-Polybutadiene-block-Poly(L-lactide) Triblock Terpolymers.

The confinement assembly of block copolymers shows great potential regarding the formation of functional microparticles with compartmentalized structure. Although a large variety of block chemistries have already been used, less is known about microdomain degradation, which could lead to mesoporous microparticles with particularly complex morphologies for ABC triblock terpolymers. Here, we report on the formation of triblock terpolymer-based, multicompartment microparticles (MMs) and the selective degradation of domains into mesoporous microparticles. A series of polystyrene-block-polybutadiene-block-poly(L-lactide) (PS-b-PB-b-PLLA, SBL) triblock terpolymers was synthesized by a combination of anionic vinyl and ring-opening polymerization, which were transformed into microparticles through evaporation-induced confinement assembly. Despite different block compositions and the presence of a crystallizable PLLA block, we mainly identified hexagonally packed cylinders with a PLLA core and PB shell embedded in a PS matrix. Emulsions were prepared with Shirasu Porous Glass (SPG) membranes leading to a narrow size distribution of the microparticles and control of the average particle diameter, d ≈ 0.4 µm–1.8 µm. The core–shell cylinders lie parallel to the surface for particle diameters d < 0.5 µm and progressively more perpendicular for larger particles d > 0.8 µm as verified with scanning and transmission electron microscopy and particle cross-sections. Finally, the selective degradation of the PLLA cylinders under basic conditions resulted in mesoporous microparticles with a pronounced surface roughness.

Study of the properties of the ovarian fluid of the Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833) during freezing

The process of freezing the ovarian fluid of the Russian sturgeon (Acipenser gueldenstaedtii Brandt, 1833) was analyzed. With gradual cooling from 22°C to -196°C at a rate of 10° per minute, the process of freezing, formation and change of ice microparticles was observed. The ovarian liquid was glazed at -5°C and only at -70°. With the microparticles of ice began to form. From that moment, up to the temperature of liquid nitrogen (-196°C), the microparticles were crushed into smaller ones. The high content of intracellular water in the ovarian fluid of female Russian sturgeon contributes to the formation of the bulk of microparticles of ice, which is confirmed by their shape. These particles, which have sharp edges, are able to damage the thin shells of eggs during deep freezing.

The improvement of the physicochemical properties and bioaccessibility of lutein microparticles by electrostatic complexation

In this study, biopolymer microparticles were fabricated for the encapsulation and delivery of lutein by electrostatic complexation of sodium caseinate (NaCas) and sodium alginate (ALG) to improve its physicochemical stability and bioaccessibility. The lutein microparticles were determined by analysis of the particle size, zeta-potential, physical stability and microstructure. The formation mechanism of lutein microparticles was examined by Fourier transform infrared spectroscopy (FTIR) analysis. Moreover, the crystalline structure change of lutein was characterized by X-ray diffraction (XRD) and Differential scanning calorimetry (DSC). Bioaccessibility of lutein was also investigated in a simulated gastrointestinal tract (GIT) model. Lutein microparticles were rough irregular structures with larger mean particle size of 1750 ± 2.24 nm, higher physical stability and negative zeta-potential (−54.03 ± 0.38 mV) when the optimized concentration of NaCas and ALG were 2.0 wt%, respectively. FTIR analysis indicated the electrostatic interaction between the amino group of the caseinate and the carboxyl group of the alginate in the formation of microparticles. XRD and DSC analysis confirmed that lutein was encapsulated in microparticles as an amorphous state. Meanwhile, the microparticles effectively reduced the decomposition of lutein during 22 d storage at 37 °C. GIT studies showed that the microparticles presented higher free fatty acid (FFA) release and lutein bioaccessibility (51.27 ± 0.78%) than emulsions (12.83 ± 1.43%). This study provided a broad prospect for the formulation of lutein-fortified functional foods and beverages.

POTENTIOMETRIC STUDY OF KINETICS AND MECHANISM FORMATION OF SILVER NANOPARTICLES STABILIZED BY SYNTHETIC FULVATES

Silver nanoparticles are actively studied due to their unique properties and wide use in various fields. In this study, silver nanoparticles were obtained by reacting Ag+ ions with synthetic fulvic acids derived from quercetin. Synthetic fulvic acids perform a dual function: a reducer of silver ions and a stabilizer of the formed nanoparticles The presence of silver nanoparticles in the solution is confirmed by the presence of a maximum in the absorption spectrum at 400 nm, which is due to the phenomenon of surface plasmon resonance. The parameters of the crystal lattice were established using the X‑ray diffraction method. The average nanoparticle size calculated by the Scherrer formula is 28 nm. The kinetics and mechanism formation of silver nanoparticles were studied by potentiometry, which allows direct and continuous control of the consumption of silver ions in the synthesis process. It is established that the mechanism of the process depends on the pH of the medium. In particular, at high pH values of the reaction medium there is a heterogeneous mechanism, while at low – homogeneous. The heterogeneous mechanism of formation of silver nanoparticles is characterized by the presence of three stages, in particular: 1) formation of Ag2O microparticles after mixing reagents, 2) reduction of Ag+ ions by synthetic fulvic acids from quercetin on the surface of formed Ag2O microparticles, which are heterogeneous nucleation centers. 3) reduction of Ag+ ions from solution on the surface of silver nanoparticles after complete dissolution of Ag2O microparticles (this process is described by first-order kinetics by Ag+). Activation parameters for different stages of silver nanoparticle formation using quercetin fulvic acids were calculated. A potentiometric study of the influence of the degree of aeration of the medium on the kinetics of changes in the pAg system was performed.

Study of the Role of the Tyrosine Kinase Receptor MerTK in the Development of Kidney Ischemia-Reperfusion Injury in RCS Rats.

Renal ischaemia reperfusion (I/R) triggers a cascade of events including oxidative stress, apoptotic body and microparticle (MP) formation as well as an acute inflammatory process that may contribute to organ failure. Macrophages are recruited to phagocytose cell debris and MPs. The tyrosine kinase receptor MerTK is a major player in the phagocytosis process. Experimental models of renal I/R events are of major importance for identifying I/R key players and for elaborating novel therapeutical approaches. A major aim of our study was to investigate possible involvement of MerTK in renal I/R. We performed our study on both natural mutant rats for MerTK (referred to as RCS) and on wild type rats referred to as WT. I/R was established by of bilateral clamping of the renal pedicles for 30′ followed by three days of reperfusion. Plasma samples were analysed for creatinine, aspartate aminotransferase (ASAT), lactate dehydrogenase (LDH), kidney injury molecule -1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) levels and for MPs. Kidney tissue damage and CD68-positive cell requirement were analysed by histochemistry. monocyte chemoattractant protein-1 (MCP-1), myeloperoxidase (MPO), inducible nitric oxide synthase (iNOS), and histone 3A (H3A) levels in kidney tissue lysates were analysed by western blotting. The phagocytic activity of blood-isolated monocytes collected from RCS or WT towards annexin-V positive bodies derived from cultured renal cell was assessed by fluorescence-activated single cell sorting (FACS) and confocal microscopy analyses. The renal I/R model for RCS rat described for the first time here paves the way for further investigations of MerTK-dependent events in renal tissue injury and repair mechanisms.

Novel ezetimibe-loaded fibrous microparticles for enhanced solubility and oral bioavailability by electrospray technique

This study developed a novel electrospray-based fibrous microparticle for increased water solubility and enhanced oral bioavailability of a poorly water-soluble drug, ezetimibe. Ezetimibe-loaded fibrous microparticles were prepared by an electrospray technique using polyvinylpyrrolidone (PVP) and Cremophor RH40 as carriers. Nine different formulations were prepared with varying ratios of the drug and carrier. These were then evaluated for water solubility and dissolution. The formation of ezetimibe-loaded fibrous microparticles was confirmed by differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), particle size measurement, and scanning electron microscopy (SEM) analyses. Pharmacokinetic evaluation of the optimized ezetimibe-loaded fibrous microparticles was conducted in rats and compared with that of the drug alone. All of the electrospray-based fibrous microparticles had significantly improved water solubility and dissolution compared to the drug. An optimized ezetimibe-loaded fibrous microparticle composed of ezetimibe/PVP/Cremophor RH40 at 1/5/0.1 (w/w) had 26.3- and 4.6-fold higher solubility and dissolution, respectively, than ezetimibe powder. Solid state characterization showed that ezetimibe exists in the amorphous state within the fibrous microparticles and exhibits smaller particles (less than 20 μm) as compared to the ezetimibe powder. For electrospray-based fibrous microparticles, the in vivo pharmacokinetic parameters AUC and Cmax were 2.1- and 2.6-fold higher, respectively, than those of the ezetimibe powder. The results of this study showed that electrospray-based fibrous microparticles could improve water solubility and bioavailability, which provides a novel approach for the poorly water-soluble ezetimibe.

Carbon sources driven supernatant micro-particles differentiate in submerged anaerobic membrane bioreactors (AnMBRs)

Recently, micro-particles with a size range of 0.45–10 μm in anaerobic membrane bioreactors (AnMBRs), were rich in microorganisms and characterized as a significant source to membrane fouling. Nevertheless, little is known about the formation of the micro-particles associated microorganisms as well as their metabolic functions, which could be largely impacted by carbon sources in the influent. Here, protein and glucose were chosen to be two different carbon sources fed into two identical AnMBRs (i.e., AnMBR-P and AnMBR-G), and a comprehensive comparison of the micro-particles formed in corresponding reactors was made. Size-dependent fractionation and fluorescent staining assay showed that micro-particles with the size range of 0.45–1 μm possessed the highest contents (41.4%) in the AnMBR-P and presented as vibrios and coccus, while the 5–10 μm micro-particles with filamentous morphologies were the prevailing fraction (61.9%) in the AnMBR-G. According to the results of high-throughput 16S rRNA gene sequencing, the Lentimicrobiaceae, D8A-2 and Syntrophorhabdus prevailed in the AnMBR-P micro-particles, while the SJA-15 showed overwhelming predominance than the other genera in the AnMBR-G micro-particles. Metagenomic sequencing further revealed that the micro-particles in the AnMBR-P possessed higher abundance in specific functional genes for nitrogen metabolism (nirB), sulfur metabolism (cysK) and cysteine and methionine metabolism (mtaD), as well as in the cell mobility as chemotaxis (rbsB) and flagellar assembly (fliC). In comparison, the micro-particles obtained from the AnMBR-G encoded abundant genes for converting glucose to metabolites in the next level, such as glk (glucokinase), pfk (ATP-dependent phosphofructokinase), and PGK (phosphoglycerate kinase). Overall, our findings provided new insights into the formation of micro-particles in the supernatant of AnMBRs, which could facilitate to propose related fouling alleviation methods from the perspective of carbon sources regulation and/or pretreatment of the influent.

Deep Learning Based Image Analysis of Pearl Chain Formation in a Dielectrophoretic System

Deep learning has achieved exceptional success in image analysis in recent years and has become one of the most trusted tools, swiftly invading and altering various study domains. Using state-of-the-art deep Convolutional Neural Networks (CNNs), this research proposes a deep learning technique for detecting and analyzing Pearl Chains Formation (PCF) of micro-particles. According to experimental findings, the PCF process in Dielectrophoresis (DEP) is highly influenced by the voltage and frequency given to electrodes, but only weakly by particle sizes, which contradicts theoretical expectations. To better understand the above phenomenon, we use micrographs of the beads collected during low voltage DEP tests to estimate the rate of PCF and DEP force. To conduct our study, we rely on pre-trained CNN models. This finding will serve as the foundation for the development of an application for automatic PCF identification and DEP force on a lab-on-a-chip device in the field. We validate the scaling laws of the DEP force and electro-mechanics in the PCF by comparing experimental and numerical results. Figure 1

Initial Formation of the Skin Layer of PLGA Microparticles.

Poly(lactide-co-glycolide) (PLGA) has been extensively used in making long-acting injectable formulations. The critical factors affecting the PLGA formulation properties have been adjusted to control the drug release kinetics and obtain desirable properties of PLGA-based drug delivery systems. The PLGA microparticle formation begins as soon as the drug/PLGA-dissolved in the organic solvent phase (oil phase) is exposed to the water phase. The initial skin (or shell) formation on the oil droplets occurs very quickly, sometimes in the matter of milliseconds, and studying the process has been difficult. The skin formation on the PLGA emulsion droplet surface that can affect the subsequent hardening steps is examined. PLGA droplets with different compositions are prepared. Using collimated light and a high-speed camera made it possible to detect the diffusion of acetonitrile from the oil phase into the water phase during the oil droplet formation. Although the skin formation is not visible on the surface of the oil phase droplet with the current setup, the droplet shapes, solid strand formation, and the difference in the spreading time suggest that the initial contact time between the oil and water phases in the range of a few seconds is critical to the properties of the skin.

Pea protein microparticulation using extrusion cooking: Influence of extrusion parameters and drying on microparticle characteristics and sensory by application in a model milk dessert

Microparticulated proteins are potential fat replacers to reduce the caloric value of foods. In contrast to whey protein, knowledge on the formation of microparticles based on pea protein using extrusion cooking is limited. This research aimed at evaluating the impact of extrusion parameters and subsequent effects of spray- and freeze-drying on the physico-chemical and sensorical characteristics of the resulting `functionalized´ pea protein microparticles. A method for pea protein microparticulation is presented. Extrusion parameters could be varied such that particles suitable for fat replacement in terms of size range were formed. Particle size was mainly dependent on extrusion temperature and residence time. The screw speed was of negligible influence. Post-extrusion spray- or freeze-drying did not affect the particle size. To assess the aggregation mechanism of particulation, the stabilizing forces were investigated by applying a protein interaction assay. It was found that pea protein microparticles were mainly stabilized by hydrophobic interactions. The ability of functionalized pea proteins to replace fat while maintaining authentic dairy flavour was tested sensorically in a model milk dessert. The incorporation of microparticles in a fat-reduced milk dessert resulted in almost the same creamy perception compared to the full-fat milk dessert as control. An important finding was that drying of the microparticles lowered undesired grassy/beany off-flavours, which are currently typical disadvantages of pea protein usage within food.

Subclinical markers of cardiovascular toxicity of benzene inhalation in mice

Benzene is a ubiquitous environmental pollutant. Recent population-based studies suggest that benzene exposure is associated with an increased risk for cardiovascular disease. However, it is unclear whether benzene exposure by itself is sufficient to induce cardiovascular toxicity. We examined the effects of benzene inhalation (50 ppm, 6 h/day, 5 days/week, 6 weeks) or HEPA-filtered air exposure on the biomarkers of cardiovascular toxicity in male C57BL/6J mice. Benzene inhalation significantly increased the biomarkers of endothelial activation and injury including endothelial microparticles, activated endothelial microparticles, endothelial progenitor cell microparticles, lung endothelial microparticles, and activated lung and endothelial microparticles while having no effect on circulating levels of endothelial adhesion molecules, endothelial selectins, and biomarkers of angiogenesis. To understand how benzene may induce endothelial injury, we exposed human aortic endothelial cells to benzene metabolites. Of the metabolites tested, trans,trans-mucondialdehyde (10 μM, 18h) was the most toxic. It induced caspases-3, -7 and -9 (intrinsic pathway) activation and enhanced microparticle formation by 2.4-fold. Levels of platelet-leukocyte aggregates, platelet macroparticles, and a proportion of CD4+ and CD8+ T-cells were also significantly elevated in the blood of the benzene-exposed mice. We also found that benzene exposure increased the transcription of genes associated with endothelial cell and platelet activation in the liver; and induced inflammatory genes and suppressed cytochrome P450s in the lungs and the liver. Together, these data suggest that benzene exposure induces endothelial injury, enhances platelet activation and inflammatory processes; and circulatory levels of endothelial cell and platelet-derived microparticles and platelet-leukocyte aggregates are excellent biomarkers of cardiovascular toxicity of benzene.

Photonic Particles Made by the Confined Self-Assembly of a Supramolecular Comb-Like Block Copolymer.

Approaches that enable the preparation of robust polymeric photonic particles are of interest for the development of nonfading and highly reflective pigments for applications such as paints and display technologies. Here, the preparation of photonic particles that display structural color in both, aqueous suspension and the dry solid state is reported. This is achieved by exploiting the confined self-assembly of a supramolecular comb-like block copolymer (BCP) that microphase separates into a well-ordered lamellar morphology with dimensions that promote a photonic bandgap in the visible range. The comb-like BCP is formed by robust ionic interactions between poly(styrene-b-4-vinyl-pyridine) (PS-b-P4VP) BCP and dodecylbenzene sulfonic acid (DBSA), which selectively interacts with P4VP blocks. The components are combined in chloroform, and an aqueous emulsion is prepared. Evaporation of the organic solvent leads to the formation of solid microparticles with an onion-like 3D morphology. These photonic pigments display brilliant colors with reflectance spectra featuring pronounced optical bandgaps across the entire visible wavelength range with a peak reflectivity of 80-90%.

Preparation of physically crosslinked polyelectrolyte Gelatin-Tannic acid-κ-Carrageenan (GTC) microparticles as hemostatic agents

In humans, excessive bleeding during civilian accidents, and surgery account for 40% of the mortality worldwide. Hence, the development of biocompatible hemostatic materials useful for rapid hemorrhage control has become a fundamental research problem in the biomedicine community. In this study, we prepared biocompatible gelatin-tannic acid-κ-carrageenan (GTC) microparticles using a facile Tween 80 stabilized water-in-oil (W/O) emulsion method for rapid hemostasis. The formation of GTC microparticles occurs via polyelectrolyte interactions between gelatin and k-carrageenan as well as hydrogen bonding from tannic acid. In addition, the GTC microparticles formulated in our study showed high water adsorption ability with a low volume-swelling ratio for a particle size of 46 μm. In addition, the GTC microparticles displayed >80% biocompatibility in NIH 3T3 cells and <5% hemocompatibility in hemolysis ratio tests. Notably, the GTC microparticles induced rapid blood clotting in 50 s and blood loss of approximately 46 mg in the femoral artery of BALB/c female mice with a 100% survival rate that was significantly better than the control group (blood clot time:250 s; blood loss: 259 mg). Thus, the findings from our study collectively suggest that GTC microparticles may play a promising clinical role in medical applications to tackle hemorrhage control.

Mimicking Low pH Virus Inactivation Used in Antibody Manufacturing Processes: Effect of Processing Conditions and Biophysical Properties on Antibody Aggregation and Particle Formation.

Low pH virus inactivation (VI) step is routinely used in antibody production manufacturing. In this work, a mimic of the VI step was developed to focus on evaluating adverse effects on product quality. A commercially available lab-scale glass reactor system was utilized to assess impacts of process and solution conditions on process-induced monoclonal antibody particle formation. Flow imaging was found to be more sensitive than light obscuration in detecting microparticles. NaOH as a base titrant increased protein microparticles more than Tris. Both stirring and NaCl accelerated particle formation, indicating that interfacial stress and protein colloidal stability were important factors. Polysorbate 80 was effective at suppressing particle formation induced by stirring. In contrast, trehalose led to higher microparticle levels suggesting a conformational stabilizer may have other adverse effects during titration with stirring. Additionally, conformational and colloidal stability of antibodies were characterized to investigate the potential roles of antibody physicochemical properties in microparticle formation during VI. The stability data were supportive in rationalizing particle formation behaviors, but they were not predictive of particle formation during the mimicked viral inactivation steps. Overall, the results demonstrate the value of testing various solution and processing conditions in a scaled-down system prior to larger-scale VI bioprocesses.

Preparation, characterization of SF- HPMC blend films and SF microparticles

The aim of this study was to synthesis silk fibroin (SF) micro particles which could be used as carrier of drug by simple blending of silk fibroin solution with low molecular weight Hydroxy Propyl Methyl Cellulose (HPMC) under mild processing conditions. Firstly SF/HPMC blend films were prepared with variable proportions of SF and HPMC using solvent evaporation technique. The phase separation structure of the blend films was examined by scanning electron microscope (SEM). In the next step the blend films were dissolved in predetermined volume of ultra-pure water, shaken well for ten minutes followed by centrifugation twice to get the silk micro particles. SF particles were in disc or oval shape with diameters almost less than 10 μm with predominant beta sheet structure. When sonication was performed on some sets of SF/HPMC blend solutions using probe sonicator at amplitude of 20% for 30 s, resulted in silk microparticles with minimum surface roughness than other samples. The formation of silk microparticles of oval or disc shape was confirmed by scanning electron microscope (SEM) and Fourier transform infrared (FTIR) analysis.