Release Rate Of Bovine Serum Albumin Research Articles

Exfoliated clay-polymer nanocomposite as a promising delivery system for bovine serum albumin

ABSTRACT The pH-sensitive exfoliated clay-alginate composite was investigated for the controlled oral delivery of bovine serum albumin (BSA). The X-ray diffraction analysis and transmission electron microscopy analysis revealed the exfoliated structure of clay in the composite. The degree of exfoliation was increased with sonication and it was optimised that the maximum exfoliation of clay in the aqueous medium occurred for 150 min of sonication. The maximum adsorption of BSA in the clay-alginate was detected at a pH of 4.5. The in-vitro release study of BSA from the exfoliated clay and the clay-alginate composite was analysed at simulated gastric and simulated intestinal pH conditions which suggested that the adsorption and release of BSA could be controlled simply by adjusting the solution pH condition. In the in-vitro release study, it was noted that there was no release of BSA from the clay-alginate composite up to 30 min in gastric pH conditions. But, there was a slow release rate of BSA within 10 h from the clay-alginate composite in the intestinal pH condition. The release profile from the clay–alginate composite was more fitted to the Peppas kinetic model.

Amphiphilic sodium alginate-vinyl acetate microparticles for drug delivery

To overcome the fast or burst release of hydrophilic drugs from hydrophilic alginate-based carriers, hydrophobic molecule (vinyl acetate, VAc) was grafted on alginate (Alg), which was further used to prepare drug carriers. Amphiphilic Alg-g-PVAc hydrogel beads were firstly prepared by emulsification/internal gelation technique for the loading of bovine serum albumin (BSA). Then, chitosan was coated on the surface of beads to form novel amphiphilic Alg-g-PVAc/chitosan (Alg-g-PVAc/CS) microcapsules. The BSA-loading amphiphilic Alg-g-PVAc/chitosan (Alg-g-PVAc/CS) microcapsules display similar morphology and size to the hydrophilic alginate/chitosan (AC) microcapsules. However, the drug loading and loading efficiency of BSA in Alg-g-PVAc/CS microcapsules are higher, and the release rate of BSA from Alg-g-PVAc/CS microcapsules is slower. The results demonstrate that the introduction of hydrophobic PVAc on alginate can effectively help retard the release of BSA, and the higher degree of substitution is, the slower the release rate is. In addition, the complex membrane can also be adjusted to delay the release of BSA. As a whole, amphiphilic sodium alginate-vinyl acetate/CS microparticles could be developed for macromolecular drug delivery.

Fabrication of Quaternized Chitosan Nanoparticles Using Tripolyphosphate/Genipin Dual Cross-Linkers as a Protein Delivery System.

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with genipin. The formation of QCS nanoparticles was optimized as a function of monomer grafting yield, QCS/TPP weight ratio, and QCS/genipin weight ratio by Box-Behnken design and response surface methodology. The results showed that QCS nanoparticles prepared with a grafting yield of 50%, QCS/TPP weight ratio of 7.67, and QCS/genipin weight ratio of 60 had a particle size of 193.68 ± 44.92 nm, polydispersity of 0.232, zeta potential of +23.97 mV and BSA encapsulation efficiency of 46.37 ± 2.89%, which were close to the predicted values from mathematical models. In vitro drug release studies at pH 1.2 and pH 7.4 exhibited that the release rate of BSA was significantly decreased and the release period was significantly prolonged after QCS nanoparticles cross-linking with genipin. Therefore, QCS nanoparticles cross-linked with TPP/genipin dual cross-linkers may be a promising protein drug carrier for a prolonged and sustained delivery.

ECM based injectable thermo-sensitive hydrogel on the recovery of injured cartilage induced by osteoarthritis

Intra-articular injection of anti-inflammatory drugs can be a promising strategy for recovery of injured articular cartilage. We prepared a series of injectable thermo-sensitive composite hydrogels, composed of Pluronic F127, glycosaminoglycan (GAG) and bone morphogenetic protein (BMP-2), which was designed to mimic extracellular matrix (ECM). The rheological properties and dissolution rate of composite hydrogels containing chondroitin sulfate or with different hyaluronic acid molecular mass (10k, 90k, 800k) were investigated. Meanwhile, bovine serum albumin (BSA) or FITC-BSA was chosen as model drug loaded into PF/GAG hydrogels to study their sustained release behavior in vitro. The results showed that hydrogels could maintain shapes for more than 16 days and the release rate of BSA in PF/GAG composite gels was much slower than in PF127 gels, due to the affinity between BSA and GAG. Furthermore, increasing the molecular weight of hyaluronic acid correspondingly increased hydrogel dissolution rate and BSA release in the hydrogels. Subsequently, MTT experiments were performed to investigate the toxicity of the hydrogels on mouse pre-osteoblast cell MC3T3-E1. In vivo anti-inflammation results showed that PF/GAG@BMP-2 composite hydrogels had the most efficient efficacy on recovery of injured cartilage, which is induced by osteoarthritis, compared to the control groups (PF127@BMP-2 or BMP-2 saline solution).

Fabrication and characterization of dual drug-loaded poly (lactic-co-glycolic acid) fiber-microsphere composite scaffolds

ABSTRACTThe purpose of this work is to develop dual drug-loaded poly (lactic-co-glycolic acid) (PLGA) fiber-microsphere composite scaffolds with desired morphologies and dual drug loading properties, and to investigate the release kinetics of the dual drugs, both hydrophobic and hydrophilic, from the composite scaffolds. In this study, simvastatin (SIM) and bovine serum albumin (BSA) were used as model drugs, which were incorporated into the composite scaffolds by performing electrospinning and emulsion electrospraying simultaneously. The optimum condition for electrospraying (solution concentration: 0.06 g/mL; applied voltage: 15 kV; and flow rate: 0.6 mL/h) has been obtained to prepare PLGA microspheres. The release rate of SIM and BSA from the composite scaffolds fit the first order kinetics and the Higuchi model, respectively. The results indicated that fiber-microsphere composite scaffolds had the ability to load two types of drug, suggesting the scaffolds have great potential in the field of tissue engineering and combined therapies.

Chitosan-Based Thermo/pH Double Sensitive Hydrogel for Controlled Drug Delivery.

A series of thermo/pH sensitive N-succinyl hydroxybutyl chitosan (NSHBC) hydrogels with different substitution degrees of succinyl are prepared for drug delivery. Rheology analysis shows that the gelation temperature of NSHBC hydrogels is 3.8 °C higher than that of hydroxybutyl chitosan (HBC) hydrogels. A model drug bovine serum albumin (BSA) is successfully loaded and released. NSHBC hydrogels show excellent pH sensitivity drug release behaviors. After incubation for 24 h, 93.7% of BSA is released from NSHBC hydrogels in phosphate buffer saline (PBS) (pH 7.4), which is significantly greater than that of 24.6% at pH 3.0. In contrast, the release rate of BSA from HBC is about 70.0% at pH 3.0 and 7.4. Thus, these novel hydrogels have the prominent merits of high adaptability to soluble drugs and pH sensitivity triggered release, indicating that NSHBC hydrogels have promising applications in oral drug delivery.

Modulating the release of proteins from aloaded carrier of alginate/gelatin porous spheres immersed in different solutions.

A biodegradable porous particle for the controlled biofactor delivery which assembly of pores in scaffolds can improve the permeation and diffusion of drugs or growth factors. Porous-spheres in millimeter scale were prepared by mixing sodium alginate and gelatin interpenetrating networks with cross-linkers; interconnected open pores were fabricated through solvent casting and particulate leaching. Morphological characteristics, degradation, and bovine serum albumin (BSA) release rates of the porous-spheres immersed in three different solutions, namely, deionized distilled water, simulated body fluid (SBF), and phosphate-buffered saline (PBS), were detected. Porous-spheres with a large amount of gelatin exhibited an increase in water absorption rates without affecting scaffold strength and no cytotoxicity was elicited. Highly interconnected pores with a diameter of 100-200µm were uniformly distributed in scaffolds. The weight loss in PBS was faster than that in other solutions; the highest release rate of BSA in SBF was observed for 2h. The release rates also exhibited linear patterns from 2h to 24h in all of the groups. After 1 d of immersion in solutions, BSA release rates in scaffolds logarithmically decreased for 14 d. The degradation of porous-spheres also showed an inverse pattern.

Determining dominant driving forces affecting controlled protein release from polymeric nanoparticles.

Enzymes play a critical role in many applications in biology and medicine as potential therapeutics. One specific area of interest is enzyme encapsulation in polymer nanostructures, which have applications in drug delivery and catalysis. A detailed understanding of the mechanisms governing protein/polymer interactions is crucial for optimizing the performance of these complex systems for different applications. Using a combined computational and experimental approach, this study aims to quantify the relative importance of molecular and mesoscale driving forces to protein release from polymeric nanoparticles. Classical molecular dynamics (MD) simulations have been performed on bovine serum albumin (BSA) in aqueous solutions with oligomeric surrogates of poly(lactic-co-glycolic acid) copolymer, poly(styrene)-poly(lactic acid) copolymer, and poly(lactic acid). The simulated strength and location of polymer surrogate binding to the surface of BSA have been compared to experimental BSA release rates from nanoparticles formulated with these same polymers. Results indicate that the self-interaction tendencies of the polymer surrogates and other macroscale properties may play governing roles in protein release. Additional MD simulations of BSA in solution with poly(styrene)-acrylate copolymer reveal the possibility of enhanced control over the enzyme encapsulation process by tuning polymer self-interaction. Last, the authors find consistent protein surface binding preferences across simulations performed with polymer surrogates of varying lengths, demonstrating that protein/polymer interactions can be understood in part by studying the interactions and affinity of proteins with small polymer surrogates in solution.

Surface Modification of Titanium Using BSA-Loaded Chitosan and Chitosan/Gelatin Polymers

The integration of titanium-based implants with the surrounding bone tissue needs to be improved to increase their service life. This work presents a surface modification technique to increase the osteointegration of titanium implants. The studies were conducted in three main steps: (i) surface modification of titanium using bovine serum albumin (BSA)-loaded chitosan and chitosan/gelatin polymers, (ii) studies of BSA release from these surfaces, (iii) effect of porosity and polymer composition on osteoblast cell proliferation. TiO2 and COOH groups were formed on titanium surfaces. Then, chitosan and chitosan (C)/gelatin (G) with various ratios (G:C = 0.5:1, 1:1, 1:0.5) were mixed with BSA and fixed to the surface via carbodiimide chemistry (EDC/NHS). After the immobilization process, samples were exposed to either air or freeze-drying. Characterization studies were conducted using Fourier transform-infrared spectroscopy and scanning electron microscopy. Finally, BSA release studies in phosphate-buffered saline (0.1 M, 37 °C) and cell (osteoblast) proliferation studies using MTS assay were conducted. BSA-loaded porous structures were obtained on chitosan- and chitosan/gelatin-containing surfaces after freeze-drying, while smooth surfaces were obtained after air-drying. The BSA release rate was directly correlated with increasing gelatin amount in the chitosan/gelatin coatings. MTS analysis was not conclusive because of the absorption properties of polymer coatings. However, absorbed color density in chitosan/gelatin (G:C = 1:1) polymers under freeze-drying conditions was more dominant, indicating better cell proliferation. This method may be used to release growth factors for controlled cell proliferation and differentiation or for the local delivery of antimicrobial drugs to prevent contamination during implementation in hard tissue applications.

Investigation of 3D ordered macroporous carbon with different polymer coatings and their application as an oral vaccine carrier

3-D ordered macroporous carbon with different polymer coatings were developed as new oral vaccine immunological systems. Poly dimethyl diallyl ammonium (PDDA), polyethyleneimine (PEI) and chitosan (CTS), three different polymers with electropositive or adsorption-promoting properties, were chosen as the coating materials to endow the vaccine delivery systems with different surface properties. The bovine serum albumin (BSA) was used as a model vaccine. The three different polymer coated systems exhibited similar release rate which minimized the influence of release rate. The measured value of immunoglobulin G (IgG) titers suggested that the sustained release rate of BSA from polymer coated systems exhibited no strengthened effect on the immune response but could delay the appearance of the peak of the IgG titers compared with uncoated system. The electrostatic attraction between the mucosal and positively charged carrier would be useful during the whole immune experiment. In addition, using the coating material with the ability of enhancing mucosal adsorption was important in the mid-late period of immune. The immunoglobulin A (IgA) titers induced by the polymer coated systems were significantly higher than that induced by the oral BSA solution or i.m. BSA with Freund’s complete adjuvant (FCA) which suggested the successful mucosal immune response of the three different coated systems. Overall, this work provides valuable information for the development of oral vaccine delivery system.

Solution combustion synthesis of calcium phosphate particles for controlled release of bovine serum albumin.

Four different phase compositions of calcium phosphate (CaP) particles were prepared via a solution combustion method. X-ray diffraction (XRD) and Rietveld analysis results revealed that the variations in the nominal Ca/P (molar) ratios were found to provide a favorable control in the different proportions of CaP materials. Bovine serum albumin (BSA) was used as a model protein to study the loading and release behavior. The release profile indicated that the BSA release rates depended on the phase compositions of the CaP particles, and showed an order of TCP-BSA>BCP-1-BSA>BCP-2-BSA>HA-BSA. The results suggested that the BSA protein release rate can be controlled by varying the phase compositions of CaP carriers. Moreover, the release process involved two stages: firstly surface diffusion via ion exchange and secondly intraparticle diffusion.

Rod-shaped hydroxyapatite with mesoporous structure as drug carriers for proteins

Rod-shaped hydroxyapatite (HAp) with mesoporous structure was synthesized by a hydrothermal method using Pluronic block co-polymer F127 as the template. The rod-shaped HAp was then tested as protein drug carriers by investigating their protein adsorption/release properties. Bovine serum albumin (BSA) and lysozyme (LSZ) were used as the model drugs. Various instrumental methods were used to characterize the structure, morphology, texture and protein drug adsorption/release properties of the samples. The amounts of BSA or LSZ adsorbed onto the rod-shaped HAp and their release profiles were evaluated in a simulated body fluid (SBF). The synthesized rod-shaped HAp had irregular mesostructures with lengths of 75–125nm and diameters of about 25nm. The rod-shaped HAp exhibited a higher loading capacity for BSA than for LSZ in the SBF. This adsorption behavior can be explained by the morphology of the rod-shaped HAp, which grew along the c-axis, leading to an a(b)-plane area that is larger than the c-plane area. Consequently, the number of positive charges on the surface of the rod-shaped HAp increased relative to the number of negative charges. The BSA release rate in SBF was slower than that of LSZ which is a result of the HAp surface properties.

Regulating drug release from pH- and temperature-responsive electrospun CTS-g-PNIPAAm/poly(ethylene oxide) hydrogel nanofibers

Temperature- and pH-responsive polymers have been widely investigated as smart drug release systems. However, dual-sensitive polymers in the form of nanofibers, which is advantageous in achieving rapid transfer of stimulus to the smart polymeric structures for regulating drug release behavior, have rarely been explored. In this study, chitosan-graft-poly(N-isopropylacrylamide) (CTS-g-PNIPAAm) copolymer was synthesized by using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxy succinimide (NHS) as grafting agents to graft carboxyl-terminated PNIPAAm (PNIPAAm-COOH) chains onto the CTS biomacromolecules, and then CTS-g-PNIPAAm with or without bovine serum albumin (BSA) was fabricated into nanofibers through electrospinning using poly(ethylene oxide) (PEO, 10 wt%) as a fiber-forming facilitating additive. The BSA laden CTS-g-PNIPAAm/PEO hydrogel nanofibers were tested to determine their drug release profiles by varying pH and temperature. Finally, cytotoxicity of the CTS-g-PNIPAAm/PEO hydrogel nanofibers was evaluated by assaying the L929 cell proliferation using the MTT method. It was found that the synthesized CTS-g-PNIPAAm possessed a temperature-induced phase transition and lower critical solution temperature (LCST) at 32° C in aqueous solutions. The rate of BSA release could be well modulated by altering the environmental pH and temperature of the hydrogel nanofibers. The CTS-g-PNIPAAm/PEO hydrogel nanofibers supported L929 cell growth, indicative of appropriate cytocompatibility. Our current work could pave the way towards developing multi-stimuli responsive nanofibrous smart materials for potential applications in the fields of drug delivery and tissue engineering.

Controlled protein release from monodisperse biodegradable double-wall microspheres of controllable shell thickness

Biodegradable polymer microparticles are promising delivery depots for protein therapeutics due to their relatively simple fabrication and facile administration. Double-wall microspheres (DWMS) comprising a core and shell made of two distinct polymers may provide enhanced control of the drug release profiles. Using precision particle fabrication (PPF) technology, monodisperse DWMS were fabricated with model protein bovine serum albumin (BSA)-loaded poly(lactide-co-glycolide) (PLG) core and drug-free poly(d,l-lactic acid) (PDLL) shell of uniform thickness. Monolithic single-wall microspheres were also fabricated to mimic the BSA-loaded PLG core. Using ethyl acetate and dichloromethane as shell- and core-phase solvents, respectively, BSA was encapsulated selectively in the core region within DWMS with higher loading and encapsulation efficiency compared to using dichloromethane as core and shell solvents. BSA in vitro release rates were retarded by the presence of the drug-free PDLL shell. Moreover, increasing PDLL shell thickness resulted in decreasing BSA release rate. With a 14-μm thick PDLL shell, an extended period of constant-rate release was achieved.

Alginate/BSA/montmorillonite composites with enhanced protein entrapment and controlled release efficiency

Novel pH sensitive alginate–protein–clay composite beads were investigated for the in vitro oral delivery of the model protein, bovine serum albumin (BSA). X-ray diffraction (XRD) results revealed that BSA enter between layers of montmorillonite (MMT) by expanding interlayer distance and finally an exfoliated structure forms in the alginate hydrogel. MMT incorporation increases protein entrapment efficiency to 78%, compared to 40% of conventional alginate beads. The release ratio of BSA from composite beads is 9–13% depending on MMT contents after around a 2h stay in gastric fluid. More importantly, no BSA release is detected until 60–90min after the first contact time of beads with gastric solution. The presence of clay in alginate beads prevents burst release in higher pH of intestine by slowing release rate of BSA to 45–55% within around 9h, resulting in a potential matrix for intestinal release of protein drugs.

Layer-by-layer assembled polyaspartamide nanocapsules for pH-responsive protein delivery

Biodegradable shell cross-linked nanocapsules were prepared via layer-by-layer assembly of PADH (tertiary amine and hydrazide grafted polyaspartamide) and PACA (carboxyl and aldehyde grafted polyaspartamide) on silica spheres. Both of the polyaspartamide derivatives are water-soluble and biodegradable polymers with a protein-like structure, and obtained by aminolysis reaction of polysuccinimide. The latter is prepared by thermal polycondensation of aspartic acid. Dynamic light scattering and zeta potential measurements were used to analyze the layer-by-layer assembly process. Bovine serum albumin (BSA), as a model protein, was entrapped in the nanocapsules via electrostatic adsorption. Nanocapsules encapsulating BSA were prepared via layer-by-layer assembly on protein-entrapping amino-functionalized silica spheres, hydrazone cross-linking and silica core removal. The BSA release profiles exhibited a pH-dependent behavior. BSA release rate increased significantly as the ambient pH dropped from the physiological pH to acidic. Cell viability study suggests that the obtained polymeric nanocapsules have good biocompatibility. These kinds of novel composite nanocapsules may offer a promising delivery system for proteins.

Evaluation of BSA protein release from hollow hydroxyapatite microspheres into PEG hydrogel

Implants that simultaneously function as an osteoconductive matrix and as a device for local drug or growth factor delivery could provide an attractive system for bone regeneration. In our previous work, we prepared hollow hydroxyapatite (abbreviated HA) microspheres with a high surface area and mesoporous shell wall and studied the release of a model protein, bovine serum albumin (BSA), from the microspheres into phosphate-buffered saline (PBS). The present work is an extension of our previous work to study the release of BSA from similar HA microspheres into a biocompatible hydrogel, poly(ethylene glycol) (PEG). BSA-loaded HA microspheres were placed in a PEG solution which was rapidly gelled using ultraviolet radiation. The BSA release rate into the PEG hydrogel, measured using a spectrophotometric method, was slower than into PBS, and it was dependent on the initial BSA loading and on the microstructure of the microsphere shell wall. A total of 35–40% of the BSA initially loaded into the microspheres was released into PEG over ~14days. The results indicate that these hollow HA microspheres have promising potential as an osteoconductive device for local drug or growth factor delivery in bone regeneration and in the treatment of bone diseases.

Chitosan-g-PEG nanoparticles ionically crosslinked with poly(glutamic acid) and tripolyphosphate as protein delivery systems

In the present study chitosan grafted copolymers with poly(ethylene glycol) (CS-g-PEG) were prepared and studied using PEG with molecular weights 2000 and 5000g/mol. The materials were characterized using 1H NMR, FTIR and WAXD techniques. These polyelectrolytes were ionically crosslinked with tripolyphosphate (TPP) and poly(glutamic acid) (PGA) at different polymer/crosslinking agent ratios (1:1, 2:1, 3:1 and 4:1, w/w) for the nanoencapsulation of bovine serum albumin (BSA). Prepared nanoparticles are spherical in shape with a mean diameter ranging from 150 to 600nm. The size depends mainly to the molecular weight of the PEG and the crosslinking agent used. The PEG molecular weight also seems to affect the release rate of BSA especially the first burst effect which appears to be high in copolymers containing PEG5000, compared with copolymer prepared with PEG2000, and it is also higher when PGA was used as crosslinking agent, instead of TPP.

Preparation and characterization of PEM-coated alginate microgels for controlled release of protein

In this study, calcium-alginate microgels coated with a polyelectrolyte multilayer (PEM) were fabricated as a controlled-release system. This system was constructed via an electrostatic droplet generation technique followed by a layer-by-layer (LbL) self-assembly technique. The electrostatic droplet generation technique was reported as an easy method of preparing microgels, due to their mild preparation conditions and ability to preserve the biological activity of the encapsulated drugs. With the LbL self-assembly technique, the PEM could be fabricated on the microgels attributed to the electrostatic attraction between positive-charged chitosan (Chi) and negative-charged dextran sulfate (Dex). The properties of the prepared microgels were investigated using dynamic laser scattering (DLS), scanning electron microscopy (SEM), x-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectrum and zeta potential analyzer. In vitro release study indicated that the initial burst release of the bovine serum albumin (BSA) from PEM-coated microgels was less compared to the uncoated microgels (19% versus 31% in 24 h). In addition, the sustained release of BSA from the PEM-coated microgels was recorded up to 1 month without any damage to BSA integrity. Thus, our results demonstrated that the PEM-coated microgels not only prolonged the release time, but also relieved the initial burst problem to some degree and preserved the biological activity of the encapsulated drugs. Moreover, the release rate of BSA could be regulated by controlling the number of deposited layers. In conclusion, this study presented an easy yet effective method for the controlled, sustained release of biological macromolecules.

Influence of PEG in PEG–PLGA microspheres on particle properties and protein release

The aim of the present study was to compare different commercial available types of Poly(d,l-lactide-co-glycolide) (PLGA), multiblock copolymers of PLGA and polyethylene gylcol (PEG) as well as blends of PLGA and PEG regarding the preparation of microparticles and the release behavior of encapsulated protein. Microspheres were prepared by the solvent evaporation technique using the same conditions for each formulation. The encapsulation rate of bovine serum albumin (BSA) was unaffected by the different polymer types, and the mean was 79±4%. Microspheres composed of blends of PLGA and PEG showed a porous structure, a higher specific surface area, an inhomogenous distribution of protein and a higher release rate of BSA than microspheres consisting of PLGA, whereas the release profiles were the same. The specific surface area of microparticle formulations composed of diblock copolymers was the highest with 8.57±0.07m2/g emphasized by a highly porous, sponge-like structure. The triblock copolymer formulation revealed nearly spherical particles with a slightly uneven surface. Although the triblock copolymer consists of 10% PEG, the specific surface area was the lowest of all formulations. The rapid hydration due to PEG leads to a swollen matrix, which released the protein in a slow and continuous way.