BSA Films Research Articles

Measurement of Dilational Modulus of an Adsorbed BSA Film Using Pendant Bubble Tensiometry: From a Clean Interface to Saturation

Two open issues on the measurement of the dilational modulus (E) for an adsorbed protein film during the adsorption process have been unacknowledged: how E varies during the adsorption and the length of time needed to attain a stable E value. A new approach for detecting the E variation from a clean air–water interface to saturated film and estimating the time needed to reach a saturated state was proposed. A pendant bubble tensiometer was utilized for measuring the relaxations of surface tension (ST) and surface area (SA), and the E was evaluated from the relaxation data of minute distinct perturbances. The data showed a clear variation in E during the BSA adsorption: E sharply decreased to a minimum at the early stage of BSA adsorption; then, it rose from this minimum and oscillated for a while before reaching an E corresponding to a saturated BSA film after a significant duration. The adsorbed BSA film took ~35 h to reach its saturated state, which was much longer than the reported lifetime of the adsorbed film in the literature. A rapid surface perturbation (forced bubble expansion/compression) could change the E, causing a significant drop in E followed by a slow increase to the original stable value.

Study on electrical and structural properties of PVA doped BSA and dyes composite films

Bio composites have been synthesized by mixing BSA and organic dyes like Coomassie Bromophenol and Phloroglucinol to solution blend by casting method. Study of structural, Morphological, composition of elements, UV–Vis and di-electrical properties for polymer blend and with different dyes have been investigated. The UV–Vis spectra resulted at the ranges of wavelength (300–800 nm). For AC conductivity the di-electrical properties were measured which revealed increase by adding BSA-PVA-organic dyes and its unique structured, optical and electrical characters results in many applications that are characterized by interesting analysis with EDAX, XRD, UV &SEM which are further characterized to find whether binding among PVA, BSA and organic dyes.

Self-adhesive protein/polypyrrole hybrid film for flexible electronic sensors in physiological signal monitoring

Flexible electronic sensors composed of conductive material and flexible film have attracted increasing attention in decades due to its commercial, medical and scientific value. However, the poor interfacial bonding robustness between conductive materials and flexible film influences widely practical application of sensors. It is still a great challenge to fabricate a self-adhesive conductive film. Herein, we report a freestanding and self-adhesive bovine serum albumin/polypyrrole (BSA/PPy) hybrid film at the air/water interface. It is discovered that the PPy nanoparticles aggregate uniformly on the BSA film that is formed by amyloid-like BSA aggregation. The BSA/PPy film was integrated with polydimethylsiloxane (PDMS) film to fabricate flexible electronic sensors. The test indicates that the BSA/PPy film-based sensor could tolerate 500 cycles of bending without the resistance performance variation. The BSA/PPy film functions as a key mediator to dynamically tune the PPy conductance in response to external pressures and strains. The sensors exhibit ability for detecting tiny acoustic vibration, real-time human motion, physiological behavior and for differentiating various breathing pattern. Our strategy may open a pathway to readily construct flexible electronic sensors toward practical applications.

In-situ and one-step preparation of protein film in capillary column for open tubular capillary electrochromatography enantioseparation

In this work, the phase-transitioned BSA (PTB) film using the mild and fast fabrication process adhered to the capillary inner wall uniformly, and the fabricated PTB film-coated capillary column was applied to realize open tubular capillary electrochromatography (OT-CEC) enantioseparation. The enantioseparation ability of PTB film-coated capillary was evaluated with eight pairs of chiral analytes including drugs and neurotransmitters, all achieving good resolution and symmetrical peak shape. For three consecutive runs, the relative standard deviations (RSD) of migration time for intra-day, inter-day, and column-to-column repeatability were in the range of 0.3%–3.5%, 0.2%–4.9% and 2.1%–7.7%, respectively. Moreover, the PTB film-coated capillary column ran continuously over 300 times with high separation efficiency. Therefore, the coating method based on BSA self-assembly supramolecular film can be extended to the preparation of other proteinaceous capillary columns.

Compact protein (bovine serum albumin/human serum albumin) layer under Langmuir-Blodgett deposition on hydrophilic Si (001) surface

Langmuir monolayers of globular proteins (bovine serum albumin, i.e., BSA and human serum albumin, i.e., HSA) are formed on the water surface at pH ≈ 7.0, and compact protein layers are deposited on hydrophilic Si (001) surface using the Langmuir-Blodgett deposition method. Stability of these protein monolayers are studied from the normalized molecular area-time (A/A0-t) curves, which confirms that deposition over a long period of time is possible from both the protein monolayers. Compact bimolecular layered structure of the protein films are deposited on Si surface at higher surface pressure (17 mN/m) of the BSA and HSA monolayers, which is confirmed from the electron density profiles (EDPs) obtained from the analysis of the X-ray reflectivity data. Mostly the thickness of the molecular layers increases as the molecular tilting takes place and new molecules are deposited inside the vacant positions of the layer and as a result the electrons per unit area increases. EDPs obtained from the deposited BSA and HSA films also confirm that the increment in molecular tilting and electrons per unit area is protein specific. EDPs and surface morphology obtained from the atomic force microscopy images of the deposited films confirm that interrupted layer-by-layer or Frank-van der Merwe growth mode is followed in such protein multilayer deposition.

BSA films as sensitive coatings for gas sensors: adsorption properties, application perspectives

The possibility of application of BSA-based sensitive films for the development of gas sensors is investigated. BSA was deposited on three types of surfaces: fullerenes C60, NiTAA organic film and the silver electrode of a QCM sensor. Two of the resulting films, namely Ag-BSA and C60-BSA, have demonstrated big response values to a range of analytes, good repeatability, reversibility and long-term stability. The adsorption properties of the films strongly depend on the nature of the bottom layer. This opens a possibility to develop protein-based sensitive layers for multisensor arrays with predefined adsorption properties.

Molecular Assembly of a Durable HRP-AuNPs/PEDOT:BSA/Pt Biosensor with Detailed Characterizations.

In this study, we provided the detailed characterizations of our recent HRP-AuNPs/PEDOT:BSA/Pt biosensor, constructed through a simple fabrication procedure with improved stability and good sensitivity. Raman and Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy not only confirmed the synthesis of conductive PEDOT where BSA was the template for the polymerization, but also provided further insights into the stable immobilization of AuNP on the PEDOT:BSA film. Scanning electron microscopy revealed that the attachment of AuNPs were stable under a high salt environment. The current technology demonstrates a feasible procedure to form a functional AuNPs/PEDOT:BSA film that has potential applications in the fabrication of various biosensors and electric devices.

Time dependent gold nanoclusters and nanocrystals formation on BSA at solid-water and air-solid interfaces

A straight forward process of growing nanoclusters and in later stage from nanoclusters to nanocrystals growth is explored on BSA protein thin films using UV–Vis and photoluminescence spectroscopy, X-ray diffraction (XRD), atomic force microscopy (AFM) and dynamic light scattering (DLS) techniques. It is observed that if different interaction times are provided between BSA thin films and HAuCl4 aqueous solutions of mM concentration, then initially formed tiny gold nanoclusters transform into nanocrystals of different shapes and sizes. From UV–Vis experiments growth of gold nanoclusters from AuCl4− ions at solid-air interface and in later stage from nanoclusters to nanocrystals growth at solid-air interface is confirmed by the presence of peaks at 320nm and 525nm respectively. If the nanoclusters embedded films are kept undisturbed in air and also in dark condition nearly for 30days then nanoclusters convert into nanocrystals. XRD analysis shows the formation of both gold nanoclusters and nanocrystals of faced-centered cubic lattice along (111) crystalline direction and AFM studies confirm the presence of triangular and spherical nanostructures. DLS technique is used to have the average sizes of the nanocrystals. Langmuir-like growth behavior is identified for BSA films induced gold nanoclusters and nanocrystals formation and it is found that both have nearly the same growth dynamics.

Stabilization of viruses by encapsulation in silk proteins.

Viruses are important for a range of modern day applications. However, their utility is limited by their susceptibility to temperature degradation. In this study, we report a simple system to compare the ability of different dried protein films to stabilize viruses against exposure to elevated temperatures. Films from each of three different silks, silkworm, honeybee silk and hornet silk, stabilized entrapped viruses at 37 °C better than films of albumin from bovine serum (BSA) and all four proteins provided substantially more stabilization than no protein controls. A comparison of the molecular structure of the silks and BSA films showed no correlation between the ability of the proteins to stabilize the virus and the secondary structure of the protein in the films. The mechanism of stabilization is discussed and a hypothesis is suggested to explain the superior performance of the silk proteins.

Drainage and critical thickness of foam films from mixed solutions of bovine serum albumin and n-dodecyl-β-D-maltoside

Data for the kinetic stability of foam films from ``bovine serum albumin'' (BSA) solution, or from its mixed solutions with non-ionic surfactant ``n-dodecyl-β-D-maltoside'' (C12G2) are presented and discussed based on the specificity of interactions between the components analyzed by tensiometry and fluorescence spectroscopy.The thickness as a function of time in different areas of BSA or BSA/ C12G2 films formed at different experimental conditions (different molar ratios between protein and surfactant, film radius) is measured interferometrically from a video recording of the film evolution. The thinning velocity presented via drainage coefficient, α, in the areas where first, or other black spots appear, or in other film areas was determined from the lnh (t) dependences up to the critical state (first black spot formation in the film). It is found that BSA film has the slowest thinning and the most regular thickness. The thinning velocity of the both BSA and BSA/surfactant films in the area where first spot appears decreases considerably with increasing of the film radius. The thinning velocity values in other film areas are close to those obtained in areas with spots, but only in the initial period of film drainage. The thinning in these places almost stops around the critical state. In above mentioned different film areas the thicknesses, corresponding to the critical state are measured and compared. It is found that the values of critical thickness in areas with spots are noticeably smaller, than critical thickness in other areas, irrespectively of the film radius and molar ratio of the stabilizers. It means that the value of critical thickness for a protein film can not be obtained as an average value of the thickness values determined in different film areas just before the first black spot formation.

A novel low-cost and easy to develop functionalization platform. Case study: Aptamer-based detection of thrombin by surface plasmon resonance

A novel low-cost platform to assess biomolecular interactions was investigated using surface plasmon resonance and an aptamer-based assay for thrombin detection. Gold SPR surface functionalized with a carboxylated cross-linked BSA film (cBSA) and commercially available carboxymethylated dextran chip (CM5) were used as immobilization platforms for the thrombin binding aptamer. The high end commercial instrument Biacore 3000 and a custom made FIA set-up involving TI Spreeta sensor (TSPR2K23) were used to assess different concentrations of thrombin within the range 0.1-150 nM both in buffer and in a complex matrix (plasma) using the obtained aptasensors. Based on data derived from both CM5 and cBSA platforms, the cBSA aptasensor exhibited good selectivity, stability and regeneration ability, both in buffer and in complex matrices (plasma), comparable with CM5.

The Fluorescence Enhancement of the Protein Adsorbed on the Surface of Ag Nanoparticle

The fluorescence enhancement of the BSA adsorbed on the surface of Ag nanoparticles is reported, where non-fluorescent collagen is used as the separator between the BSA and Ag nanoparticles. The study indicates that Ag nanoparticles can enhance the fluorescence of the BSA, especially the fluorescence of the tyrosine residues with lower quantum. Three types of Ag nanoparticles are evaluated including Ag island film, Ag colloids and fractal Ag electrode. Of them Ag island film is the best. The investigation suggests that the fluorescence enhancement of the BSA is related to the adsorption of the BSA on the surface of Ag island film through the hydrophobic interaction, while the collagen can promote the adsorption of the BSA on the surface of Ag island film and change its conformation, resulting in the interaction between BSA and Ag island film.

A New Enzyme Immobilization Technique Based on Thionine‐Bovine Serum Albumin Conjugate and Gold Colloidal Nanoparticles for Reagentless Amperometric Biosensor Applications

AbstractA novel enzyme immobilization technique based on thionine‐bovine serum albumin conjugate (Th‐BSA) and gold colloidal nanoparticles (nano‐Au) was developed. Thionine was covalently bound onto the BSA film with glutaraldehyde(GA) as cross‐linker to achieve Th‐BSA conjugate. The free amino groups of thionine were then used to attach nano‐Au for the immobilization of horseradish peroxidase (HRP). Such nano‐Au/Th‐BSA matrix shows a favorable microenvironment for retaining the native activity of the immobilized HRP and thionine immobilized in this way can effectively shuttle electrons between the electrode and the enzyme. The proposed biosensor displays excellent catalytic activity and rapid response for H2O2. The linear range for the determination of H2O2 is from 4.9×10−7 to 1.6×10−3 M with a detection limit of 2.1×10−7 M at 3σ and a Michaelies‐Menten constant K$\rm{ {_{M}^{app}}}$ value of 0.023 mM.

Giant Domain Formation in a Thin Film of Bisstyrylanthracene Derivatives by a Simple Melt Process

Bisstyrylanthracene derivatives with long alkyl side chains(BSA), which were prepared into the thin films composed of giant anisotropic domains by simple melt process, showed interesting property. The derivatives that changed the chains length and chains form were synthesized. We introduced the film preparation and investigated thermal properties of the films using differential scanning calorimetry(DSC), polarization micrograph, and fourier transform infrared spectroscopy(FT-IR). The phenomena of the giant domain formation and phase transition in BSA films are discussed.

Comparison of Device Performance in Two Thin-Film Electroluminescent Devices Made of Vacuum-Sublimed Dye Film and Spin-Coated Polymer Film

Electroluminescent (EL) characteristics in EL devices made of vacuum-sublimed dye films and spin-coated polymer films were compared. Low-molar-mass dye, 9,10-bis[4-(N,N-diphenylamino)styryl]anthracene (dye-BSA), for the preparation of vacuum-sublimed films, and polymer with 9,10-bis[4-(N,N-diphenylamino)-styryl]anthracene chromophore linked with alkylether groups (polymer-BSA) were employed. Single-layer devices, indium-tin oxide (ITO)/dye-BSA/MgAg and ITO/polymer-BSA/MgAg were prepared, and EL performances were compared. Double-layer devices which have an oxadiazole derivative (OXD-7) electron transport layer, ITO/dye-BSA/OXD-7/MgAg and ITO/polymer-BSA/OXD-7/MgAg, were also prepared. The current density-voltage relationships between dye-BSA devices and polymer-BSA devices were considerably different mainly due to the poor film quality of polymer-BSA. The comparisons of the luminance-current density relationships of the devices with two classes of BSA films showed that the polymer-BSA devices exhibited similar EL characteristics as the dye-BSA devices in the region of current density higher than 10 mA/cm2. The possibility of the use of common material design concept for low-molar-mass materials and polymers was discussed.