Bovine Serum Albumin Gels Research Articles

Load-bearing columns inspired fabrication of ductile and mechanically enhanced BSA hydrogels

Currently, protein-based hydrogels are widely applied in soft materials, tissue engineering and implantable scaffolds owing to their excellent biocompatibility, and degradability. However, most protein-based hydrogels are soft brittle. In this study, a ductile and mechanically enhanced bovine serum albumin (BSA) hydrogel is fabricated by soaking the a 1-(3-dimethylaminopropyl)-3ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) induced BSA hydrogel in (NH4)2SO4 solution. An EDC/NHS coupling reaction induce protein coupling reactions that cause the BSA skeleton to resemble architectural load-bearing walls, protecting the integrity of the hydrogel and preventing collapse. The effects of the BSA and (NH4)2SO4 concentrations on the hydrogel mechanics are evaluated, and the possible strengthening mechanism is discussed. Besides, the highly kosmotropic ions greatly enhance the hydrophobic interaction within BSA gels and dehydration effect and their mechanical properties were significantly enhanced. The various mechanical properties of hydrogels can be regulated over a large window by soaking hydrogels into various ions. And most of them can be washed away, maintaining high biocompatibility of the protein. Importantly, the protein hydrogels prepared by this strategy could also be modified as strain sensors. In a word, this work demonstrates a new, universal method to provide multi-functional, biocompatible, strength enhanced and regulable mechanical pure protein hydrogel, combining the Hofmeister effect with -NH2/-COOH association groups.

Effect and Mechanism of Soluble Starch on Bovine Serum Albumin Cold-Set Gel Induced by Microbial Transglutaminase: A Significantly Improved Carrier for Active Substances.

Soluble starch (SS) could significantly accelerate the process of bovine serum albumin (BSA) cold-set gelation by glucono-δ-lactone (GDL) and microbial transglutaminase (MTGase) coupling inducers, and enhance the mechanical properties. Hardness, WHC, loss modulus (G″) and storage modulus (G') of the gel increased significantly, along with the addition of SS, and gelation time was also shortened from 41 min (SS free) to 9 min (containing 4.0% SS); the microstructure also became more and more dense. The results from FTIR, fluorescence quenching and circular dichroism (CD) suggested that SS could bind to BSA to form their composites, and the hydrogen bond was probably the dominant force. Moreover, the ability of SS to bind the original free water in BSA gel was relatively strong, thereby indirectly increasing the concentration of BSA and improving the texture properties of the gel. The acceleration of gelling could also be attributed to the fact that SS reduced the negative charge of BSA aggregates and further promoted the rapid formation of the gel. The embedding efficiency (EE) of quercetin in BSA-SS cold-set gel increased from 68.3% (SS free) to 87.45% (containing 4.0% SS), and a controlled-released effect was detected by simulated gastrointestinal digestion tests. The work could put forward new insights into protein gelation accelerated by polysaccharide, and provide a candidate for the structural design of new products in the food and pharmaceutical fields.

Robust Protocol for the Synthesis of BSA Nanohydrogels by Inverse Nanoemulsion for Drug Delivery.

In a highly efficient and reproducible process, bovine serum albumin (BSA) nanogels are prepared from inverse nanoemulsions. The concept of independent nanoreactors of the individual droplets in the nanoemulsions allows high protein concentrations of up to 0.6% in the inverse total system. The BSA gel networks are generated by the 1-ethyl-3-[3-dimethylaminopropyl]carbodiimide hydrochloride coupling strategy widely used in protein chemistry. In a robust work-up protocol, the hydrophobic continuous phase of the inverse emulsion is stepwise replaced by water without compromising the colloidal stability and non-toxicity of the nanogel particles. Further, the simple process allows the loading of the nanogels with various cargos like a dye (Dy-495), a drug (ibuprofen), another protein [FMN-binding fluorescent protein (EcFbFP)], and oligonucleotides [plasmid DNA for enhanced GFP expression in mammalian cells (pEGFP c3) and a synthetic anti-Pseudomonas aeruginosa aptamer library]. These charged nanoobjects work efficiently as carriers for staining and transfection of cells. This is exemplarily shown for a phalloidin dye and a plasmid DNA as cargo with adenocarcinomic human alveolar basal epithelial cells (A549), a cell revertant of the SV-40 cancer rat cell line SV-52 (Rev2), and human breast carcinoma cells (MDA-MB-231), respectively.

Design of surface tailored carboxymethyl dextran-protein based nanoconjugates for paclitaxel: Spectroscopical characterizations and cytotoxicity assay

Paclitaxel (PTX) is an essential anticancer drug from the biopharmaceutical classification system (BCS) class IV. Unfortunately, PTX has some drawbacks including low solubility, cell toxicity, adverse cell reaction, etc. Therefore, folic acid (FA) tailored carboxymethyl-dextran (CMD), and bovine serum albumin (BSA) mediated nanoconjugates of paclitaxel (PTX) (FA-CMD-BSA-PTX) were designed. At first, esterification reaction between FA and CMD resulted in FA-CMD conjugate whereas FA-CMD-BSA conjugate was synthesized via the Maillard reaction. Finally, FA-CMD-BSA conjugates of PTX were achieved via hydrophobic interaction and gelation of BSA. Herein, heating offers the gelation of BSA that furnishes the cross-linking wherein PTX gets fixed inside BSA. Thermogram of FA-CMD-BSA-PTX showed the absence of PTX peak that concluding PTX has been molecularly dispersed in polymer matrix and entrapment inside polymeric conjugate. As an effect, surface decorated FA-CMD-BSA-PTX showed low hemolytic toxicity over free PTX. Cytotoxicity assay on A549 human lung cancer cells shows cell viability decreased from 60 % to 10 % with increasing concentration from 1 to 5 μg/mL. In conclusion, CMD facilitates the circulation time of PTX and BSA acts as a carrier to target tumor locations effectively. The nano-conjugate formulation significantly reduces toxicity and can be used for the treatment of lung cancer.

Detection of o‐nitro aniline by bovine serum albumin based self‐fluorescent hydrogel via FRET process

AbstractSelective and sensitive detection of nitroaromatic compounds is recent concern for both security purpose and pollution control. Nitroaromatics are either explosive in nature or used in preparation of explosives and they inherently carry the toxic property. Herein, a selective and rapid detection of ortho nitro aniline (o‐NA) by glutaraldehyde cross‐linked bovine serum albumin (BSA) protein functionalized auto fluorescent hydrogel (BG) in aqueous medium is reported. The hydrogel is characterized by Scanning electron microscope, rheology, Fourier transform infrared spectroscopy and dynamic light scattering. The change in conformation due to gelation of BSA is supported by FTIR with alternation of peak intensity and position, DLS with increased average particle size, UV–vis spectra having different kind of peaks after gelation and SEM image with porous morphology. A good linear relationship of fluorescence detection of o‐NA is observed in range of 0–3 × 10−4 (M) with the detection limit of 35 μM. The sensing procedure is performed by involving dried BG gel in aqueous medium. The possible quenching process is established via FRET mechanism between BG gel and o‐NA showing high selectivity and sensitivity towards the detection of o‐NA over the other nitroaromatics and common ions present in water.

Subcritical water treatment of bovine serum albumin pathway to produce superabsorbent biomaterial as green technology

Four different types of bovine serum albumin (BSA)-based biomaterials (BSA-based running gel, hydrogel, nanoparticles and two-phase) were formed in different subcritical water treatment (SCWT) conditions. In SCWT temperature range of 80–100°C the running BSA-based gels appeared which were distinguished by visual inspection. Stable hydrogel network can also form by SCWT without using any additives or cross-linking agent to yield superabsorbent hydrogels (SAHs) that were non-toxic. A detailed investigation of BSA-based biomaterials pathway under SCWT on the formation and reversible steps of these gels was carried out using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy. The optimum SCW gelation temperature of BSA hydrogels was found to lie between 100 and 120°C. All synthesized BSA-based superabsorbent hydrogels (BSAHs) showed a Fickian water diffusion mechanism and second order swelling kinetic model. Moreover, the initial water contents were 48, 46 and 41 g/g for BSAH100-9, BSAH110-9 and BSAH120-9 respectively. It could be found that, 44, 45 and 40% of trapped water retained from the swollen BSAH100-9, BSAH110-9 and BSAH120-9 respectively after 1 month, which is superior to that of any reported SAH. Remarkably, WRs still were more than 30% after 2 months, indicating super excellent water release capability of such BSAH. This good water release capability is ascribed to this novel structures of such BSAHs which had been prepared under SCWT. Overall, our approach demonstrates a rapid, crosslinker-free thermoresponsive BSA gelation approach with control on the material property, which is highly desirable in many applications such as drug delivery applications and agriculture.

Multilayered Porous Titanium-Based 3rd Generation Biomaterial Designed for Endosseous Implants.

This work proposes a novel complex multi-layered material consisting of porous titanium as a substrate and a complex coating consisting of a chitosan film engulfing microsphere loaded with growth factors such as BMP2 (bone morphogenic protein 2) and IGF1 (insulin-like growth factor-1). The microspheres were obtained through deposition of dual layers of calcium cross linked pectin–chitosan/pectin polyelectrolyte onto a BSA (bovine serum albumin) gel core. The multilayer was conceived to behave like a 3rd generation biomaterial, by slow delivery of viable growth factors around implants, and to assist the healing of implantation wound and the development of new vital bone. The biologic effect of the delivery of growth factors was studied in vitro, on MSC-CD1 mesenchymal stem cells, and in vivo, on CD1 mice. Proliferation and differentiation of cells were accelerated by growth factors, especially IGF1 for proliferation and BMP2 for differentiation. In vivo tests analyzed histologically and by MicroCT show a more structured tissue around BMP2 samples. The present concept will give the best clinical results if both growth factors are delivered together by a coating film that contains a double population of microcarriers.

Thermoresponsive BSA hydrogels with phase tunability

Amyloids are fibrillar structures formed due to protein aggregation or misfolding when the molecules undergo a conformational change from α-helix to β-sheet. Although this self-assembly is associated with many neurodegenerative diseases in vivo, the highly ordered amyloidic structures formed in vitro are ideal scaffolds for many bionanotechnological applications. Amyloid fibrillar networks under specific stimuli can also form stable hydrogels. We have used bovine serum albumin (BSA) as a model amyloidogenic protein to obtain thermally-induced hydrogels that display tunable sol-gel-sol transitions spanning over minutes to days. High concentrations of BSA (14–22% w/v) were heated at 65 °C for less than 3 min without any cross-linking agent to yield soft, injectable gels that were non-toxic to mammalian cells. A detailed investigation of temperature, concentration, incubation time and ionic strength on the formation and reversal of these gels was carried out using visual inspection, rheology, electron microscopy, fluorescence spectroscopy, UV–visible spectroscopy and circular dichroism spectroscopy. The optimum gelation temperature (Tg) for phase reversal of BSA gels was found to lie between 60 and 70 °C. An increase in protein concentration led to a reduction in the gelation time and increase in the gel-to-rev sol transition time. Gels heated for longer duration than their minimum gelation time yielded irreversible gels suggesting that low incubation periods were favourable for partial protein denaturation and hydrogel formation. This was supported by time-resolved secondary and tertiary structural ensemble studies. Further, the hydrogel networks demonstrated a zero-order drug release kinetics and the rev sol was found to be cytocompatible with HaCaT skin cell lines. Overall, our approach demonstrates rapid, crosslinker-free thermoresponsive BSA gelation with wide tunability and control on the time and material property, ideal for topical drug delivery applications.

Influence of amino acids on thermal stability and heat-set gelation of bovine serum albumin

This study investigated the parallels in the influence of amino acid additives on thermal denaturation temperature (Td) and heat-set gelation of bovine serum albumin (BSA). Complete denaturation of BSA occurred only when the gelation temperature (TG) was 14 °C above Td. Under these conditions, the relative effects of various amino acid additives on elevation of Td and gel strength followed a particular order. Further, while zwitterionic amino acids increased both the strength of junction zones and participation of protein in the gel network, sucrose increased the gel strength primarily by strengthening the existing junction zone. The net increase in Td of BSA was linearly correlated with the net increase in gel strength (ΔGS), indicating that the underlying molecular mechanism in both cases might be same. The results suggest that the rheological properties of protein gels can be enhanced by using amino acids, instead of polyols and sugars, as additives.

Histotripsy Liquefaction of Large Hematoma for Intracerebral Hemorrhage Using Millisecond-Length Ultrasound Pulse Groups Combined With Fundamental and Second Harmonic Superposition: A Preliminary Study

Intracerebral hemorrhage is a life-threatening acute cerebrovascular disease characterized by a 30-d mortality rate of 40% and substantial disability for those who survive. The objective of this study is to investigate the feasibility of histotripsy-mediated efficient and fine liquefaction of large-volume hematoma by utilizing a protocol of millisecond-length ultrasound pulse groups combined with fundamental and second harmonic superposition. Experiments were initially performed in an in vitro hematoma phantom, using a two-element confocal-annular array. Results showed that a single ellipsoid shape, histotripsy lesion with major dimensions of 10.8 ± 1.2 mm axially and 4.8 ± 0.2 mm laterally was successfully generated. Controllability of the lesion shape and size could be realized by modulating treatment parameters in single-spot experiments. Large-volume hematomas were efficiently and finely liquefied through multisonications via a treatment strategy under the relatively optimized treatment parameters. Liquefied contents were evacuated and analyzed using a particle sizing system. The size of the lysates for the most part ranged from 4–8 μm, with more than 99% of them being smaller than 10 μm. Experiments were then conducted in an optically transparent tissue phantom to explore the liquefaction mechanisms. The phantom was composed of polyacrylamide hydrogel, embedded with bovine serum albumin (BSA), and a thin phantom layer consisted of red blood cells in the BSA polyacrylamide gel was inlayed in the BSA gel phantom. The related mechanisms, such as the frequent boiling that occurred at multiple positions and the enhanced cavitation, revealed the quick development of the lesion in the phantom and the efficient liquefaction of the clot. These results indicated that the proposed histotripsy approach is feasible for the efficient, precise and fine liquefaction of large-volume hematoma and may be developed as a useful tool for intracerebral hemorrhage treatment.

Bovine serum albumin gel/polyelectrolyte complex of hyaluronic acid and chitosan based microcarriers for Sorafenib targeted delivery

AbstractThe development of systems for targeted delivery of Sorafenib in unresectable hepatocellular carcinoma to reduce the systemic toxicity is a challenge. In our article, we successfully prepared core‐shell microcapsules based on bovine serum albumin gel with polyelectrolyte complex multilayer shell of polysaccharides with opposite charges, hyaluronic acid, and chitosan, encapsulating Sorafenib, as targeting delivery system for improved hepatocellular carcinoma therapy. A bovine serum albumin gel core was formed by a method based on a sacrificial CaCO3 template, followed by the multilayer shell build‐up of Ca2+ cross‐linked hyaluronic acid hydrogel, and subsequently alternating multilayers of the polyelectrolyte complex formed between hyaluronic acid and chitosan. The following techniques: Fourier‐transform infrared and UV–Vis spectroscopy, X‐ray diffraction, differential scanning calorimetry, confocal laser scanning microscopy, atomic force microscopy, and scanning electron microscopy were used for the physicochemical characterization. These tests revealed the spherical shape of core‐shell type, the micro‐size, as well as the composition of microcapsules after their synthesis and proved the successful encapsulation and release of the drug. The promising results regarding encapsulation efficiency, Sorafenib release profile and cytotoxicity on HepG2 and mesenchymal stem cells, recommend Sorafenib loaded microcapsules as suitable targeted drug carriers for further in vivo studies for hepatocellular carcinoma therapy.

High-intensity focused ultrasound beam path visualization using ultrasound imaging

In High-Intensity Focused Ultrasound (HIFU) treatment, effective localization of HIFU focus is important for developing a safe treatment plan. While Magnetic Resonance Imaging guided HIFU (MRIgHIFU) can visualize the ultrasound path during the treatment for localizing HIFU focus, it is challenging in ultrasound imaging guided HIFU (USIgHIFU). In the present study, a real-time ultrasound beam visualization technique capable of localizing HIFU focus is presented for USIgHIFU. In the proposed method, a short pulse, with the same center frequency of an imaging ultrasound transducer below the regulated acoustic intensity (i.e., Ispta < 720 mW/cm(2)), was transmitted through a HIFU transducer whereupon backscattered signals were received by the imaging transducer. To visualize the HIFU beam path, the backscattered signals underwent dynamic receive focusing and subsequent echo processing. From in vitro experiments with bovine serum albumin gel phantoms, the HIFU beam path was clearly depicted with low acoustic intensity (i.e., Ispta of 94.8 mW/cm(2)) and the HIFU focus was successfully localized before any damages were produced. This result indicates that the proposed ultrasound beam path visualization method can be used for localizing the HIFU focus in real time while minimizing unwanted tissue damage in USIgHIFU treatment.

In vitro study of BSA gel/polyelectrolite complexes core shell microcapsules encapsulating doxorubicin for antitumoral targeted treatment

The aim of this study is to develop core shell microcapsules of bovine serum albumin (BSA) gel with a complex polyelectrolite multilayer shell of natural polysaccharides with opposite charges, pectin (P), chitosan (Chi), and hyaluronic acid (HA) respectively, encapsulating Doxorubicin (Dox) as a carrier for targeted anti-tumoral treatment of hepatic cell carcinoma (HCC). A sacrificial CaCO3 template method was used in order to obtain microcapsules with a BSA gel core and a layer-by-layer (Lbl) deposition technique of polyelectrolite complexes formed between P/Chi in the inner layers and HA/Chi in the outer shell layers. The preformed microcapsules, BSA gel/P/Chi/HA, noted as ms, have been applied for Dox encapsulation (ms-Dox). Dox encapsulation and release in different pH media were studied in order to elucidate the interactions between pH dependently charged species involved in the Dox loading/releasing processes. The structure characterization of ms/ms-Dox was evaluated by FTIR and UV-Vis spectroscopy, X-ray diffraction, thermal analy sis, optical microscopy, confocal laser scanning microscopy, and scanning electron microscopy. The in vitro study for citotoxicity assessment on normal and tumoral cells of both ms and ms-Dox was performed using mesenchymal stem cells (MSCs) and Hep2G HCC cell lines. Results of physical-chemical analyses confirm the successful encapsulation of Dox in ms, and the in vitro biological study recommends ms-Dox as a candidate for future in vivo research as a targeted anti-tumoral treatment modality applications.

Rheo-kinetics of bovine serum albumin in catanionic surfactant systems

The effects of catanionic surfactant systems consisting of mixtures of cationic cetyltrimethylamonium bromide (CTAB) and anionic sodium dodecyl sulfate (SDS) on the rheological properties and kinetics of bovine serum albumin (BSA) were investigated. The ionic strength of the solution was varied by using different mixing ratio of SDS and CTAB. Gelation curves observed in dynamic viscoelastic measurements were fitted with gelation kinetics models to describe the gelation under isothermal and non-isothermal conditions. Overall, the gelation of BSA in cationic-rich solutions was found to be more energetically favorable when compared with BSA solvated in anionic-rich solutions. Consequently, highest gel temperature (Tgel) and time (tgel) were observed for anionic-rich solutions with SDS/CTAB molar ratio of 4.0 (i.e., SDS/CTAB=4.0), while lowest gel temperature and time were found for cationic-rich solutions with SDS/CTAB molar ratio of 0.25 (SDS/CTAB=0.25). BSA in equal molar ratio of the mixed surfactants (SDS/CTAB=1.0) showed a gel temperature and time in the halfway between the anionic and cationic-rich regions. Interestingly, under isothermal and non-isothermal conditions, BSA in equimolarly mixed and anionic-rich solutions showed a heat-dependent protective effect against thermal denaturation and gelation. The protective effect on BSA gelation in equimolar and anionic-rich solutions was diminished by increasing the catanionic concentration under non-isothermal conditions, while under isothermal conditions, protective effect on BSA gelation increased with catanionic concentration. On the other hand, cationic-rich solutions did not protect BSA from thermal denaturation and gelation, and therefore the gelation rate increased with catanionic concentration in all heating conditions examined.

Effects of anionic and cationic surfactants on the rheological properties and kinetics of bovine serum albumin hydrogel

The effects of the anionic surfactant, sodium dodecyl sulfate (SDS), and of the cationic surfactant cetyltrimethylammonium bromide (CTAB) on the gelation kinetics of bovine serum albumin (BSA) hydrogel were investigated by rheological measurements using surfactant concentrations of 0–0.05 M, and BSA concentrations of 5, 7, and 10 wt%. It was found while an increase in CTAB concentration accelerated the rate of gelation of BSA solution under temperature jump and temperature ramp conditions, BSA solutions containing SDS exhibited a heat-dependent protective effect against thermal denaturation and gelation. Under temperature ramp conditions, inhibition of BSA gelation by SDS was diminished by increasing SDS concentration, while under temperature jump conditions, inhibition of BSA gelation increased with SDS concentration. That is, gel temperature (Tgel) under temperature ramp decreased with increasing CTAB and with SDS concentration, but under temperature jump the gel time (tgel) decreased with increasing CTAB concentration but increased with SDS concentration. Furthermore, BSA/CTAB solutions were found to gel more rapidly than BSA/SDS solutions, which was in line with the lower activation energy of BSA/CTAB gel. In support of experiments, molecular dynamics (MD) simulations and dynamic light scattering (DLS) revealed the faster rate of BSA denaturation in the presence of CTAB was responsible for the increased gelation rate of BSA/CTAB solutions, whereas BSA was found to be protected by SDS against thermal denaturation leading to the slower gelation rate of BSA/SDS solutions.

Chitosan-alginate BSA-gel-capsules for local chemotherapy against drug-resistant breast cancer.

Background and objectPolyelectrolyte microcapsule is a promising candidate for multifunctional drug delivery system. However, the lack of reports about animal experiments have greatly slowed down their development for drug delivery. We engineered biodegradable chitosan–alginate polyelectrolyte multilayer capsule filled with bovine serum albumin gel (BSA-gel-capsule). Herein, we demonstrated their applicability for local chemotherapy, a means of treating local or regional malignancies by direct administration of anti-tumor agents to tumor sites.MethodDoxorubicin (DOX) was loaded in BSA-gel-capsules and DOX-resistant cell line (MCF-7/ADR cells) was employed for antitumor studies in vitro. The cytotoxicity, cellular uptake and distribution of DOX from BSA-gel-capsules were studied. Afterwards, MCF-7/ADR xenografts tumor model was established in nude mice. The in vivo antitumor efficacy of DOX-loaded BSA-gel-capsules by intratumor injection was then evaluated.ResultCompared with free DOX, more effective cytotoxicity against MCF-7/ADR cells after treatment with DOX-loaded BSA-gel-capsules was revealed, demonstrating the positive reversal effect on drug-resistance. Thereafter, the more cellular uptake and nucleus distribution of DOX from BSA-gel-capsules in MCF-7/ADR cells provided convincing explanation for the reversal effect. DOX-loaded BSA-gel-capsules displayed remarkably more antitumor efficacy than free DOX in MCF-7/ADR cell-xenografted mice. Finally, the high DOX accumulation and prolonged retention in tumor site after local administration of DOX-loaded BSA-gel-capsules was demonstrated, displaying the unique advantages of BSA-gel-capsules for local chemotherapy.ConclusionThese findings indicate that DOX-loaded BSA-gel-capsules should be considered a potential candidate for the treatment of drug-resistant breast cancer. This paper provides a feasibility for the local chemotherapy of polyelectrolyte microcapsules, which will be a big step towards their application as drug delivery vehicles.

Characterization of transglutaminase from Bacillus subtilis and its cross-linking function with a bovine serum albumin model.

Finding new crosslinking enzymes for enzyme-mediated protein conjugation is a great need in the food industry. In this research, the properties of Bacillus subtilis transglutaminase (BTG) were characterized in detail and its protein crosslinking functions with bovine serum albumin (BSA) as a model were studied. Compared to the commercial transglutaminase from Streptoverticillium mobaraense, BTG was more stable in a broad range of temperatures (30-60 °C) and pH values (pH 5.0-9.0), with its maximum enzymatic activity at 60 °C and pH 8.0. The protein function evaluation results demonstrated that the BTG-modified BSA showed better emulsifying and foaming properties (p < 0.05) compared with the native one. Additionally, significant improvements (p < 0.05) were observed in the rheological properties, water holding capacity, and textural properties of the BTG-treated BSA gels. With good thermal and pH stability and excellent crosslinking effects, BTG would be a potential enzyme for food structure engineering to improve the functional properties of food proteins and expand their applications.

Integrated Experimental and Modeling Study of Enzymatic Degradation Using Novel Autofluorescent BSA Microspheres.

Autofluorescent bovine serum albumin (BSA) hydrogel microspheres were prepared through the spray-drying of glutaraldehyde cross-linked BSA nanoparticles and then used for a proteinase K based degradation study in an aqueous solution. Experimental results and empirical models are presented to characterize the kinetics of BSA hydrogel microsphere degradation, as well as the accompanying release of synthesized fluorophore. The BSA gel degradation dynamics is primarily controlled by the concentration of proteinase K within the Tris buffer. The coupling of swelling dynamics and the transient distributions of fluorophore are traced by confocal microscopy. Models are developed based on the linear theory of elastic deformation coupled to enzyme and fluorophore transport. This study represents a fundamental investigation of the degradation and release kinetics of protein-based materials, which can potentially be applied for the dynamic and photostable tracking of relevant in vivo systems.

Dissolution of bovine serum albumin hydrogels in alkali

Heat-induced protein gelled deposits, occurring during dairy processing, are industrially cleaned with caustic-based solutions. In order to develop general dissolution mechanisms of protein hydrogels, in analogy to general gelation mechanisms for globular proteins, different protein systems must be characterized. We report the first characterization of the dissolution behaviour of heat-set pure bovine serum albumin (BSA) hydrogels. At low alkali concentrations (<0.2 M NaOH), the formed BSA gels were dissolved as observed for whey protein mixtures or pure β-lactoglobulin gels. The key rate limiting step is suggested to be the destruction of inter-protein non-covalent interactions. At higher NaOH concentrations (>0.2 M) the dissolution rate of BSA gels was fairly constant, unlike seen before. Activation energy estimations of the rate yield very low value in certain conditions, again unlike seen before. It is suggested that mass transfer limitations occur during dissolution due to the large BSA size.

Effect of urea on heat-induced gelation of bovine serum albumin (BSA) studied by rheology and small angle neutron scattering (SANS)

This paper reports the effects of urea on the heat-induced gelation of bovine serum albumin (BSA), which was studied by the tube inversion method, rheological measurements, and small-angle neutron scattering (SANS). An increase in the urea concentration accelerated the rate of gelation because the protein molecules have already been unfolded to some extent during sample preparation in the urea solution. In addition, the BSA solution in the presence of urea underwent a sol-gel-sol transition during the time sweep test at a constant temperature of 80oC. On the other hand, the BSA solution without urea turned into a hard and brittle gel that did not return to the solution state during isothermal heating at a constant temperature of 80oC. Aggregation and re-bonding of the denatured and unfolded protein chains led to gel formation. Urea added to the protein denatures its tertiary and secondary structures by simultaneously disrupting the hydrogen bonds, hydrophobic interactions, and altering the solvent properties. Furthermore, urea induces thermoreversible chemical interactions in BSA solutions leading to the formation of a gel with dynamic properties under these experimental conditions.