Bovine Serum Albumin Concentration Research Articles

L-arginine-grafted halloysite nanotubes as a sustainable excipient for antifouling composite coating

Halloysite Nanotubes (Hal) are aluminosilicate nanotubes that have been commonly used as reinforcements in different coatings. Their tunable surface chemistry allows them to be a receptive surface for the attachment of various molecules. Amino acids are a particular class of biomolecules known for their zwitterionic nature. This zwitterionic nature allows them to have excellent antifouling abilities. In this study, Hal has been used as supports for the attachment of l-Arginine (Arg), which is a zwitterion. The amino acid-functionalized Hal has been further characterized using SEM, TEM, FTIR, XRD, DSC, and Zeta Potential Analysis. This amino acid-functionalized Hal was compared with 3-aminopropyltriethoxysilane (APTES) modified Hal (A-Hal) and pristine Hal. The % immobilization of amino acid loaded on Hal functionalized with divinyl sulfone was the highest (89.31%). The antifouling ability of the nanocomposite was tested against Bovine Serum Albumin (BSA) as a model foulant while comparing it with Hal and A-Hal. Arg-DVS-A-Hal showed the highest antifouling ability (84.5%). This study was also conducted with variable concentrations of BSA and nano supports, pH, and temperature. Through this study, it was found that amino acid-functionalized Hal could be used as a potential antifouling excipient in various coatings.

Preparation and Characterization of PLG Microparticles by the Multiple Emulsion Method for the Sustained Release of Proteins.

Rapid release and diminished stability are two of the limitations associated with the growth factors that are essentially used in dental applications. These growth factors are employed to enhance the quality and quantity of tissue or bone matter during regeneration. Therefore, drug delivery devices and systems have been developed to address these limitations. In this study, bovine serum albumin (BSA), as a representative growth factor, was successfully sustained by encapsulation with the medium-absorbable copolymer, poly(L-lactide-co-glycolide) (PLG) 70:30% mol, via the multiple emulsion method. Different PLG, PVA, and BSA concentrations were used to investigate their effects on the BSA encapsulation efficiency. The suitable ratios leading to a better characterization of microparticles and a higher encapsulation efficiency in producing encapsulated PLG microparticles were 8% (w/v) of PLG, 0.25% (w/v) of PVA, and 8% (w/v) of BSA. Furthermore, an in vitro release study revealed a bursting release of BSA from the encapsulated PLG microsphere in the early phase of development. Subsequently, a gradual release was observed over a period of eight weeks. Furthermore, to encapsulate LL-37, different proteins were used in conjunction with PLG under identical conditions with regard to the loading efficiency and morphology, thereby indicating high variations and poor reproducibility. In conclusion, the encapsulated PLG microparticles could effectively protect the protein during encapsulation and could facilitate sustainable protein release over a period of 60 days. Importantly, an optimal method must be employed in order to achieve a high degree of encapsulation efficiency for all of the protein or growth factors. Accordingly, the outcomes of this study will be useful in the manufacture of drug delivery devices that require medium-sustained release growth factors, particularly in dental treatments.

Voltammetric immunoassay based on MWCNTs@Nd(OH)3-BSA-antibody platform for sensitive BSA detection

Anelectrochemical approach is presentedbased on multiwall carbon nanotubes (MWCNTs) and neodymium(III) hydroxide (Nd(OH)3) nanoflakes for detection of bovine serum albumin (BSA). The materials were characterized morphologically (XRPD, SEM, and HR-TEM) and electrochemically (DPV, EIS). The MWCNTs@Nd(OH)3 composite was used as support for bovine serum albumin polyclonal antibody (anti-BSA). After the antibody immobilization on the electrochemical platform and antigen/antibody binding time (optimum 60min), the proposed approach shows a linear voltammetric response toward BSA concentration in the range 0.066 to 6.010ngmL-1 at maximum peak potential of 0.13V (vs. Ag/AgCl). Limit of detection (LOD) and limit of quantification (LOQ) were 18pgmL-1 and 61pgmL-1, respectively. The precision of the method calculated as relative standard deviation (RSD) of five independent measurements was better 3%. The selectivity of the optimized method regarding structurally similar proteins (human serum albumin and human hemoglobin), ions (Na+, K+, Ca2+, and NO2-), or compounds (glucose, ascorbic acid, dopamine, uric acid, paracetamol, and glycine) was found to be satisfactory, with the current changes of less than 5% in the presence of up to 1 × 105 times higher concentrations (depending on the compound) of the listed potentialinterfering compounds. Practical applicability of immunosensor for BSA determination in cow whey sample, with recovery values in the range 97 to 103%, shows that the developed method has highpotential for precise and accurate detection of BSA, as well as exceptional miniaturization possibilities for on-site and equipment-free sensing.

Triphenylphosphonium-functionalized BODIPY derivatives for mitochondria-targeted cell imaging and fluorescence turn-on sensing with protein selectivity

Triphenylphosphonium (TPP) cations endow fluorophores with improved hydrophilicities and mitochondria targeting abilities. Evidently, the number of cationic moieties can influence the behavior of fluorophores in different environments. Two water-soluble BODIPY fluorophores, 3TPP and 5TPP, were constructed with three and five TPP groups, respectively, in their structure. Both showed maximum absorption and emission at 640–700 nm wavelengths; however, 5TPP showed a fluorescence quantum yield 10 times higher than that of 3TPP in an aqueous medium, highlighting the beneficial effect of two additional TPP groups on the photophysical properties. While both fluorophores showed excellent stabilities and mitochondrial imaging abilities with low cytotoxicities in HeLa and MCF-7 cells, 5TPP permeated into the mitochondria better than 3TPP. Interestingly, 5TPP demonstrated a 90-fold increase in “turn-on” fluorescence in the presence of bovine serum albumin (BSA) in relation to that of four other proteins (i.e., lysozyme, esterase, transferrin, and fibrinogen). Notably, the fluorescence intensity of 5TPP increased with increasing BSA concentration. The present work is the first report on BODIPY sensors with multiple bulky cationic moieties and provides insights on the applicability of 5TPP as a novel biomaterial for mitochondrion tracking and light-up fluorescence protein sensing.

Superior corrosion resistance and anti-biofouling performance via electrodeposited graphene oxide/silane composite coating with special wettability

Layered double hydroxide (LDH) coating fails to provide stable anti-corrosion ability and anti-biofouling performance on metals. In this work, by exploiting the 2D graphene oxide and silane molecule, an eco-friendly and facile electrodeposition strategy for preparation of fluoride-free superhydrophobic coating (LDH-GO/DTMS) is developed, in which the aforementioned challenges can be addressed. Electrochemical test and bovine serum albumin (BSA) adsorption experiment of the LDH-GO/DTMS coating are investigated. As results, the LDH-GO/DTMS coating exhibits a high protection efficiency (99.98 ± 0.10 %) and corrosion current density (Icorr) decreases by ~4 orders of magnitude compared to bare Al alloy. The adsorption content of BSA on the coating decreases by ~9-fold compared to bare Al alloy. Furthermore, impedance modulus at 0.01 Hz (|Z|0.01 Hz) of the composite coating (4.05 ± 0.05 MΩ·cm2) is still ~2 orders of magnitude higher than Al alloy after immersion in 3.5 wt% NaCl solution over 30 days. The special wettability, physical barrier and the labyrinth effect endow the coating with good anti-corrosion and anti-biofouling property. This eco-friendly and fluorine-free strategy provides new insights for developing anti-corrosive and anti-biofouling coatings on metals used in marine environment.

Optimized protocols for sperm cryopreservation and in vitro fertilization in the rat.

Laboratory rats have been used in biomedical research for over 170 years. Recently, genome editing technology has facilitated the generation of genetically modified rats worldwide. This development has increased the demand for efficient preservation and production of rat resources. Sperm cryopreservation is the most efficient and robust means to archive genetic resources, and this technique reduces the number of animals required for colony management. Previously, we have reported a protocol for rat sperm cryopreservation and in vitro fertilization using frozen-thawed sperm. Here we describe an improved in vitro fertilization protocol to enhance the fertilization rate of cryopreserved sperm in major strains of rats. In this optimized protocol, treatment of frozen-thawed rat sperm with a high concentration of bovine serum albumin (40 mg/ml) results in a high in vitro fertilization rate. This protocol consists of three main steps: preparation of cryopreserved sperm, in vitro fertilization using cryopreserved sperm and embryo transfer. This process takes approximately 1 month to produce live pups from cryopreserved sperm. This protocol can be easily implemented by researchers and technicians with experience in reproductive engineering technology; it can also be used, albeit with some practice, by researchers and technicians who have no experience in reproductive techniques. This sperm cryopreservation and in vitro fertilization protocol for rats will provide an efficient system for the archiving and production of genetically modified rats for the transgenic community.

Cryopreservation of rabbit semen: impacts of permeable and non-permeable mixture of cryoprotectant, male group individuality, freezing rate, semen package size and antioxidant bovine serum albumin on rabbit semen freezability

In the present study, three experiments were designed to identify the most appropriate technique for freezing rabbit semen. Experiment 1 aimed to determine the optimal levels of dimethyl sulfoxide (DMSO) contents in freezing medium and their effects on individual bucks. Semen ejaculates for each buck (n=15 bucks) were mixed and split into three portions for extension with a freezing medium containing varying concentrations of DMSO (0.75, 1.0, and 1.4 M). Diluted semen samples were packaged in 0.25 mL straws and suspended above liquid nitrogen (LN) for 10 min, then dipped in LN. A few days after freezing, post-thaw semen evaluation was assessed, and according to the results, six bucks and an extender containing 0.75 M of DMSO were used for experiments 2 and 3. In experiment 2, the pooled semen from 6 bucks was divided into two portions for packaging in two straw sizes (0.25 and 0.50 mL). Each straw size was divided into five groups and suspended at different heights above LN (2, 4, 6, 8, and 10 cm) for 10 minutes before being preserved in LN. In experiment 3, the pooled semen was divided into four portions for dilution with freezing medium containing different concentrations of bovine serum albumin (BSA; 0, 2.5, 5.0, and 7.5 mg/mL). Semen samples were packaged in a 0.50 mL straw and suspended 10 min, 4 cm above LN for freezing. Pre-freezing and post-thawing, semen samples were evaluated for semen quality. Results showed that the extender containing 0.75 M DMSO had higher significant values for post-thaw sperm motility, longevity, acrosome integrity and sperm plasma membrane permeability. Bucks’ individuality had significant effects on post-thaw motility, acrosome and sperm plasma membrane integrity. A significant interaction was recorded between DMSO concentrations and bucks’ individuality on sperm longevity. Semen package sizes had no significant effects on the evaluated parameters. Semen was frozen at 2 and 4 cm above LN had significantly better post-thaw quality. BSA at concentrations 5 and 7.5 mg/mL improved recovery rates of acrosome integrity and sperm membrane permeability. DMSO 0.75 M and freezing 4 cm above LN seem to be more adequate for rabbit semen cryopreservation. The appropriate level of DMSO differs between bucks, as the post-thaw sperm longevity is affected. BSA enhanced acrosome and sperm membrane integrity. Results obtained will need further investigation to be confirmed in the field.

Effects of Different Concentrations of BSA on In Vitro Corrosion Behavior of Pure Zinc in Artificial Plasma

When medical metallic materials are implanted in the body and come into contact with the body fluid environment, proteins will be rapidly adsorbed on the surface and affect the corrosion process of the material. Currently, there is no uniform understanding of the effect of protein adsorption on the corrosion behavior of materials due to the limitations of the nature of metal materials, protein concentrations, and different media environments. The effect of various bovine serum albumin (BSA) concentrations in artificial plasma (AP) on the corrosion behavior of pure Zn during 14 days of immersion was investigated in this research. The corrosion rate of pure Zn was slowed down by the addition of BSA, and the decelerating effect of lower protein concentration on the corrosion rate of Zn was more significant in the initial stage of immersion. With prolonging the immersion time, the corrosion rate of pure Zn in different media slowed down and stabilized, and the corrosion rates of pure Zn showed a decreasing trend with an increase of BSA concentration. Furthermore, the Langmuir adsorption isotherm model was utilized to study the relationship between the BSA concentration and corrosion behavior of pure Zn and to analyze the role of proteins in the degradation mechanism of pure Zn. This work could be useful for further exploration of potential clinical applications of zinc alloys.

Label-free monitoring of proteins in optofluidic hollow-core photonic crystal fibres

The fluorescent detection of proteins without labels or stains, which affect their behaviour and require additional genetic or chemical preparation, has broad applications to biological research. However, standard approaches require large sample volumes or analyse only a small fraction of the sample. Here we use optofluidic hollow-core photonic crystal fibres to detect and quantify sub-microlitre volumes of unmodified bovine serum albumin (BSA) protein down to 100 nM concentrations. The optofluidic fibre’s waveguiding properties are optimised for guidance at the (auto)fluorescence emission wavelength, enabling fluorescence collection from a 10 cm long excitation region, increasing sensitivity. The observed spectra agree with spectra taken from a conventional cuvette-based fluorimeter, corrected for the guidance properties of the fibre. The BSA fluorescence depended linearly on BSA concentration, while only a small hysteresis effect was observed, suggesting limited biofouling of the fibre sensor. Finally, we briefly discuss how this method could be used to study aggregation kinetics. With small sample volumes, the ability to use unlabelled proteins, and continuous flow, the method will be of interest to a broad range of protein-related research.

Analysis of reaction between vitamin B6 and bovine serum albumin based on a terahertz metamaterial sensor.

A four-peak terahertz metamaterial sensor was used to detect the reaction between different concentrations of vitamin B6 (VB6) and bovine serum albumin (BSA), which achieves a concentration range (0.015-0.125 mg/µl) of VB6 and a maximum binding concentration (0.05 mg/µl) of VB6 and 0.0875 mg/µl BSA. To understand the combination of VB6 and BSA, the reactants between VB (VB1, VB3, and VB5) with the same concentration (0.05 mg/µl) and a BSA solution with a concentration of 0.0875 mg/µl were carried on the surface of the sensor. Experimental results show that the reactants cause the four resonance peaks of the sensor to produce the coincident redshift, which is the same as the order of their binding coefficients determined by the fluorescence method. The experimental process indicates that it is feasible to use terahertz metamaterials to detect the reaction process of organic matter.

Quantification of organic fluorophores in absorbing media by solid-phase fluorescence excitation–emission matrix (SPF-EEM) spectroscopy of modeled mixtures containing bovine serum albumin (BSA) and colorants

Solid-phase fluorescence excitation–emission matrix (SPF-EEM) spectroscopy is beneficial for investigating the characteristics of natural organic matter (NOM) in the solid phase without extraction procedures. However, inner filter effect (IFE) due to the presence of dark components in samples can make it difficult to quantify the fluorophore concentration. To establish a new method to determine unknown concentrations of a fluorescent material in a sample containing various absorbing materials by SPF spectroscopy, modeled mixtures containing bovine serum albumin (BSA) and colorants at different ratios were examined. Fluorescence intensities of BSA against various concentrations afforded different saturation curves for different colorants in the mixtures, suggesting that it is difficult to use the SPF intensity for quantifying the concentration of fluorescent samples in which IFE has occurred, because one cannot obtain a single calibration curve that does not depend on the absorbing medium that it is mixed in. However, products of the fluorescence intensity and Kubelka–Munk (KM) function at the excitation wavelength were proportional to the first order of BSA weight concentrations, regardless of the colorant type. By using this trend as a calibration curve, it may be possible to quantify the amount of BSA from its SPF-EEM spectrum. In this study, the KM function was obtained using an ultraviolet–visible (UV–Vis) spectrometer with an integrating sphere. To reduce the labor and equipment cost of UV–Vis spectroscopy, a substrate of the KM function also was obtained from the Rayleigh scattering in an SPF-EEM spectrum, which could be used as a parameter for calibration curves that quantify the BSA concentration. Although further studies are required, this study proposed that the product of the SPF intensity and KM function at the excitation wavelength can be partially used for an empirical formula to quantify a variety of fluorescent materials mechanically mixed with various absorbing materials.

Factors affecting robustness of anion exchange chromatography: Selective retention of minute virus of mice using membrane media

Mobile and stationary phase factors were investigated in order to identify conditions for effective capture of minute virus of mice (MVM), a potential adventitious contaminant in biomanufacturing, using anion exchange membrane chromatography (AEX). The initial study was conducted for Membrane A for a range of feed conditions using bovine serum albumin (BSA) as a model protein mimicking acidic host-cell proteins (HCPs) competitive for virus binding. The effects of pH (6–8), salt concentration (0–150 mM NaCl) and level of BSA (0–10 g/L) were systematically investigated. It was found that higher BSA concentration has the most negative impact on MVM binding followed by the increased conductivity of the feed solution. The effect of pH on MVM binding is also detected but has a less impact compared to other two factors in the range of feed conditions investigated. In addition to Membrane A, three other AEX membranes (Membrane B, C and D) were investigated for MVM binding at a selected feed condition. Based on properties of the membranes investigated, it was found that ligand charge density has the most significant impact on MVM binding performance of AEX membranes from stationary phase perspective.

A NIR light-activated PLGA microsphere for controlled release of mono- or dual-drug

Microspheres produced from biodegradable poly (D, L-lactic-co-glycolic acid) (PLGA) have been studied widely as drug delivery carriers for therapeutics. This study aimed to develop a near-infrared (NIR) light-activated PLGA microsphere loaded with two kinds of drugs with different molecular weights respectively or simultaneously by the double emulsion method (bovine serum albumin (BSA) and tetracycline hydrochloride (TH) as the drug model agents, indocyanine green (ICG) as the NIR responsive component). To optimize the incorporation of drugs and particle size for PLGA microspheres loaded single drug, the effect of three processing parameters, including the amount of polymer, initial ICG content, and initial BSA or TH content on the drug entrapment efficiency (EE), drug loading and the particle size were investigated. The PLGA microspheres were spherical and ranged from 5 to 10 μm in diameter. The EE of ICG and BSA in PLGA@ICG-BSA was 78.41 ± 0.71% and 69.88 ± 5.14%, respectively. The EE of ICG and TH in PLGA@ICG-TH was 71.52 ± 5.07% and 28.39 ± 3.39%. The PLGA microspheres exhibited desirable biodegradability and low cytotoxicity. Based on the optimized processing of single drug-loaded microspheres, dual-drug-loaded microspheres containing both large and small molecule drugs were further prepared. The EE of ICG, BSA, and TH was 83.37 ± 0.59%, 52.65 ± 3.48%, and 12.88 ± 2.53%; the particle size was ∼7.21 μm. All the NIR-responsive PLGA microspheres exhibited an efficient photothermal property and enhanced photothermal stability under multiple NIR irradiation cycles. The drugs from the different PLGA microspheres were released continuously over 18 days, mainly determined by Fick's diffusion. Furthermore, the drugs can be controlled released through a NIR light trigger, resulting in a dosage increase at a specific time point.

Generating Lifetime-Enhanced Microbubbles by Decorating Shells with Silicon Quantum Nano-Dots Using a 3-Series T-Junction Microfluidic Device

Long-term stability of microbubbles is crucial to their effectiveness. Using a new microfluidic device connecting three T-junction channels of 100 μm in series, stable monodisperse SiQD-loaded bovine serum albumin (BSA) protein microbubbles down to 22.8 ± 1.4 μm in diameter were generated. Fluorescence microscopy confirmed the integration of SiQD on the microbubble surface, which retained the same morphology as those without SiQD. The microbubble diameter and stability in air were manipulated through appropriate selection of T-junction numbers, capillary diameter, liquid flow rate, and BSA and SiQD concentrations. A predictive computational model was developed from the experimental data, and the number of T-junctions was incorporated into this model as one of the variables. It was illustrated that the diameter of the monodisperse microbubbles generated can be tailored by combining up to three T-junctions in series, while the operating parameters were kept constant. Computational modeling of microbubble diameter and stability agreed with experimental data. The lifetime of microbubbles increased with increasing T-junction number and higher concentrations of BSA and SiQD. The present research sheds light on a potential new route employing SiQD and triple T-junctions to form stable, monodisperse, multi-layered, and well-characterized protein and quantum dot-loaded protein microbubbles with enhanced stability for the first time.

Microwave Measurement of Bovine Serum Albumin Solutions Based on High-Q/High-Resolution Resonator

Progressive techniques that enable reagent-free detection and analysis of low-concentration and low-volume chemical samples are of great interest for scientific and technological investigations in biochemical and physiological areas. Highly sensitive microwave-based sensors are promising approaches among such techniques. In this work, we present a novel microwave-based noncontact sensing method to determine the concentration of standard bovine serum albumin (BSA) solution. It is demonstrated that the modal suppression technique can excite a split-ring resonator by two independent microstrip lines with reversed phase, resulting in high quality factor and resolution. The quality factor exceeding <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.5\times 10^{5}$ </tex-math></inline-formula> with lossy-liquid loaded can be achieved at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 4.3$ </tex-math></inline-formula> GHz. The obtained high resolution in frequency is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 20$ </tex-math></inline-formula> kHz for the concentration of BSA from 0 to 1 mg/mL. The measured concentration level ranges from 1 to 200 mg/mL in 0.9% sodium chloride, which covers most commercial standard BSA solutions. An equivalent circuit model is built to study and explain its working principle. Using the fit premeasurement data of standard solutions, the concentration and permittivity of an unknown BSA solution can be estimated.

Turn-on fluorescence of davydov-split aggregate particles for protein detection

The turn-on fluorescence of supramolecular aggregates of organic dyes through the interaction with specific proteins is highly desirable for the development of a high signal-to-noise fluorescence probe for biomedical applications. In this paper, we use the self-assembly of 3,3′-ditetradecyloxacarbocyanine (DiOC14(3)) in the methanol/water mixture with/without NaOH to form Davydov-split aggregate particles. We show that the crystalline Davydov-split aggregate particles formed in the presence of NaOH failed to respond to bovine serum albumin (BSA). While the non-crystalline Davydov-split aggregate particles formed in the absence of NaOH gradually disassembled through the interaction with BSA. The disassembled DiOC14(3) molecules complex with BSA in the monomer and twisted H-dimer forms, consequently turning on fluorescence. The turn-on fluorescence is highly specific to BSA and linearly increases with the increase of BSA concentrations. Furthermore, we show that the turn-on fluorescence behavior of non-crystalline Davydov-split aggregate particles by BSA can also be achieved in synthetic urine, which highlights their potential for the detection of urinary albumin.

Microwave Treatment of Calcium Phosphate/Titanium Dioxide Composite to Improve Protein Adsorption.

Calcium phosphate has attracted enormous attention as a bone regenerative material in biomedical fields. In this study, we investigated the effect of microwave treatment on calcium phosphate deposited TiO2 nanoflower to improve protein adsorption. Hierarchical rutile TiO2 nanoflowers (TiNF) fabricated by a hydrothermal method were soaked in modified simulated body fluid for 3 days to induce calcium phosphate (CAP) formation, followed by exposure to microwave radiation (MW). Coating the dental implants with CAP/TiNF provides a means of improving the biological properties, as the structure, morphology, and thickness of the composites can be controlled. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR), respectively. The composites were identified to be composed of aggregated nano-sized particles with sphere-like shapes, and the calcium phosphate demonstrated low crystallinity. The ability of bovine serum albumin (BSA) to adsorb on MW-treated CAP/TiNF composites was studied as a function of BSA concentration. The Sips isotherm was used to analyze the BSA adsorption on MW-treated CAP/TiNF composites. The MW-treated samples showed high protein adsorption capacity, thereby indicating their potential in various biomedical applications.

Macro- and Nanoscale Effect of Ethanol on Bovine Serum Albumin Gelation and Naproxen Release.

We report extended ethanol-induced gelation procedures of bovine serum albumin (BSA) at 37 °C and investigate the release behavior of a spin-labeled naproxen derivative (SL-NPX) from these hydrogels. The macroscopic mechanical properties of these gels during formation were studied using rheology, while a nanoscopic, more molecular view was obtained by analyzing the secondary structure of the protein during gelation via infrared (ATR-IR) spectroscopy. To evaluate the potential use of BSA hydrogels in controlled drug delivery, SL-NPX-BSA interaction was investigated in detail by continuous-wave electron paramagnetic resonance (CW EPR) spectroscopy, which provides information on the interaction of the small drug molecules and the hydrogel. In addition to CW EPR spectroscopy, dynamic light scattering (DLS), which provides insight into the size and nature of released components, was applied to characterize the combined influence of incubation time, ethanol, SL-drug, and BSA concentration on release behavior. It was found that the alteration of initial drug loading percentage, hydrogel incubation time as well as BSA and alcohol concentrations affect and thus tune the release rate of SL-NPX from BSA hydrogels. These results lead to the conclusion that BSA hydrogels as controlled release systems offer a remarkable fine-tuning capability for pharmaceutical applications due to the variety of gelation parameters.

HYDROGEN PEROXIDASE ENZYME ACTIVITY AT DIFFERENT CONCENTRATIONS OF BSA

Cross-linked enzymes are more stable at a certain temperature than free enzymes. Bovine serum albumin (BSA), which has a large number of amine groups, provides a strong binding between enzyme aggregates, thus leading to increased activity and stability of the bioactive layer. The enzyme-BSA mixture becomes more stable after covalent bonding with a crosslinking agent such as glutaraldehyde. The HRP enzyme was immobilized on the gold electrode together with BSA, gelatin and glutaraldehyde with the help of UV light. Four different electrodes were prepared using different amounts of BSA at 7.5 mg, 15 mg, 30 mg and 60 mg concentrations for each electrode Using four different electrodes prepared, 16 electrochemical measurements were performed with four different ferrous iron analytes. Glutaraldehyde binds to the BSA polymer, which has a higher affinity than the enzyme, reducing the tight covalent cross-links caused by BSA on the HRP and ensuring the continuation of the enzyme activity. It was observed that different BSA concentrations significantly affected the enzyme activity. The concentration of polymers to be used for crosslinking enzymes is an important factor in electrochemical studies.

Fabrication of Carboxylated Carbon Nanotube Buckypaper Composite Films for Bovine Serum Albumin Detection

The salient point of this study is to fabricate carbon nanotube (CNT) buckypaper composite films prepared through the methods of pumping filtration and spin coating. Firstly, carboxylated CNTs were used to make the original buckypaper specimen and further modify the buckypaper surface by incorporating different surface modifiers. Then, all of original (unmodified) and modified buckypaper composite films had different concentrations of bovine serum albumin (BSA) added, and differential pulse voltammetry (DPV) electrochemical measurement was used to measure the characteristics of the various buckypaper composite films, after adding different concentrations of BSA. The experimental results show that the contact angles for four modified specimens are smaller than that of the original unmodified S–BP specimen (62°). These results indicate that the four modifiers used in this study can improve the hydrophilic properties of the original, unmodified S–BP specimen, and benefit the subsequent bonding of a modified specimen with aqueous BSA. In addition to the improvement of the hydrophilic properties of the modified specimen, which affects the bonding with BSA, the bonding type produced by the modifier also plays an essential role in the bonding between specimen and BSA. Therefore, the S–BP–EDC/NHS and S–BP–TA specimens have better linear dependence between log (BSA concentration) and oxidation current data.