Bovine Serum Albumin Protein Adsorption Research Articles

Response of Osteoblasts on Amine-Based Nanocoatings Correlates with the Amino Group Density.

Increased life expectancy in industrialized countries is causing an increased incidence of osteoporosis and the need for bioactive bone implants. The integration of implants can be improved physically, but mainly by chemical modifications of the material surface. It was recognized that amino-group-containing coatings improved cell attachment and intracellular signaling. The aim of this study was to determine the role of the amino group density in this positive cell behavior by developing controlled amino-rich nanolayers. This work used covalent grafting of polymer-based nanocoatings with different amino group densities. Titanium coated with the positively-charged trimethoxysilylpropyl modified poly(ethyleneimine) (Ti-TMS-PEI), which mostly improved cell area after 30 min, possessed the highest amino group density with an N/C of 32%. Interestingly, changes in adhesion-related genes on Ti-TMS-PEI could be seen after 4 h. The mRNA microarray data showed a premature transition of the MG-63 cells into the beginning differentiation phase after 24 h indicating Ti-TMS-PEI as a supportive factor for osseointegration. This amino-rich nanolayer also induced higher bovine serum albumin protein adsorption and caused the cells to migrate slower on the surface after a more extended period of cell settlement as an indication of a better surface anchorage. In conclusion, the cell spreading on amine-based nanocoatings correlated well with the amino group density (N/C).

PCL/Si-Doped Multi-Phase Calcium Phosphate Scaffolds Derived from Cuttlefish Bone.

Increasing attention is focused on developing biomaterials as temporary scaffolds that provide a specific environment and microstructure for bone tissue regeneration. The aim of the present work was to synthesize silicon-doped biomimetic multi-phase composite scaffolds based on bioactive inorganic phases and biocompatible polymers (poly(ε-caprolactone), PCL) using simple and inexpensive methods. Porous multi-phase composite scaffolds from cuttlefish bone were synthesized using a hydrothermal method and were further impregnated with (3-aminopropyl)triethoxysilane 1–4 times, heat-treated (1000 °C) and coated with PCL. The effect of silicon doping and the PCL coating on the microstructure and mechanical and biological properties of the scaffolds has been investigated. Multi-phase scaffolds based on calcium phosphate (hydroxyapatite, α-tricalcium phosphate, β-tricalcium phosphate) and calcium silicate (wollastonite, larnite, dicalcium silicate) phases were obtained. Elemental mapping revealed homogeneously dispersed silicon throughout the scaffolds, whereas silicon doping increased bovine serum albumin protein adsorption. The highly porous structure of cuttlefish bone was preserved with a composite scaffold porosity of ~78%. A compressive strength of ~1.4 MPa makes the obtained composite scaffolds appropriate for non-load-bearing applications. Cytocompatibility assessment by an MTT assay of human mesenchymal stem cells revealed the non-cytotoxicity of the obtained scaffolds.

Albumin Protein Adsorption on CoCrMo Implant Alloy: Impact on the Corrosion Behaviour at Localized Scale

The protein adsorption and both its conformational arrangements and electrochemical interactions on the surface of metallic biomaterials has an immense impact on corrosion/biodegradation and biocompatibility of implantable metals. In this study, we used scanning Kelvin probe force microscopy (SKPFM) to reveal the synergistic effect of various bovine serum albumin (BSA) concentrations and overpotential conditions on BSA protein adsorption mechanisms and its influence on the corrosion behaviour of the CoCrMo alloy in phosphate-buffered saline solution. Electrochemical measurements showed that CoCrMo alloy was more resistant to corrosion in the 2 g l−1 BSA protein medium than in the 0.5 g l−1 one. The SKPFM analysis revealed a lower surface potential on the regions where BSA was adsorbed forming clusters, than on the un-covered CoCrMo substrate. When the surface overpotential and the protein concentration were increased from the OCP to +300 mV vs Ag/AgCl and from 0.5 to 2 g l−1, respectively, on both protein covering and surface potential were increased. Field emission scanning electron microscopy indicated that localized corrosion eventually occurred at the BSA protein/substrate interface owing to the adsorption of counterions and the difference between the surface potential values.

Multifarious anti-biofouling bioprosthetic heart valve materials with the formation of interpenetrating polymer network structures

The bioprosthetic heart valve (BHV) has attracted considerable attention in clinical practice. However, complications of the BHV such as thrombosis, calcification, and early deterioration after implantation have limited further applications. In the present study, we provide a strategy to fabricate an anti-biofouling BHV by constructing interpenetrating polymer network structures on both inner and outer valve materials. We systematically investigated the morphologies, wetting properties, elemental compositions, stability of the extracellular matrix, transparency, mechanical properties, and anti-biofouling properties (e.g., anti-cell adhesion, resistance to bovine serum albumin protein adsorption, anticoagulant properties, and anti-calcification properties) of the modified BHV via both in vitro and in vivo experiments. Compared to the BHV without coating treatment, treated with heparin, or treated with a hydrophobic polydimethylsiloxane coating, the BHV treated with a hydrophilic coating containing both polyacrylic acid and polydimethylsiloxane exhibited better multifarious anti-biofouling properties. Our findings provide a method for the preparation of multi-antifouling medical materials with better synergistic hemocompatibility and anti-calcification.

Unraveling How Ethanol-Induced Conformational Changes Affect BSA Protein Adsorption onto Silica Surfaces.

Protein adsorption at solid-liquid interfaces is highly relevant to a wide range of applications such as biosensors, drug delivery, and pharmaceuticals. Understanding how protein conformation in bulk solution impacts adsorption behavior is fundamentally important and could also lead to the development of improved protein-based coatings. To date, relevant studies have been conducted in aqueous solutions, while it remains largely unknown how organic solvents and more specifically solvent-induced conformational changes might influence protein adsorption. Herein, using the quartz crystal microbalance-dissipation (QCM-D) and localized surface plasmon resonance (LSPR) techniques, we systematically investigated the real-time adsorption behavior of bovine serum albumin (BSA) protein onto silica surfaces in different water-ethanol mixtures ranging from 0 to 60% (v/v) ethanol. The results showed that there was greater protein adsorption at higher ethanol fractions in the 10-30% range, while more complex adsorption profiles were observed in the 40-60% range. The combination of QCM-D and LSPR measurements led us to further identify specific cases in water-ethanol mixtures where washing steps caused densification of the adsorbed protein layer as opposed to typical desorption of weakly adsorbed molecules in aqueous conditions. We discuss mechanistic factors that drive these overall adsorption trends by taking into account how ethanol fraction affects BSA conformation in bulk solution. Together, our findings demonstrate that BSA proteins can adsorb onto silica surfaces across a wide range of water-ethanol mixture conditions, while specific adsorption profiles depended on the ethanol fraction in a manner closely linked to solution-phase conformational properties.

Synthesis of Magnetic Fe3O4 Nanorings for BSA Protein Adsorption

AbstractThe adsorption of bovine serum albumin (BSA) protein is important for protein research but remains a great challenge. Here, the hydrothermal method and calcination in a hydrogen-argon mixed atmosphere were used to obtain ordered mono-crystalline magnetic Fe3O4 nanorings with controllable size and uniform structure, which were applied to the adsorption of BSA protein. The results showed that the magnetic Fe3O4 nanorings prepared have the advantages of good crystallinity, controllable morphology, and excellent magnetic response. The Fe3O4 nanorings had an outer diameter of ~160–180 nm, inner diameter of ~80–110 nm, and height of 70 to ~110 nm. The amount of BSA adsorbed by magnetic Fe3O4 nanorings increased with increasing protein concentration; when the concentration of BSA was ~2.75 mg·mL-1 the adsorption amount approached saturation. When the pH value of the solution was ~5, the Fe3O4 nanorings absorption of BSA was greatest. With increasing adsorption time, the amount adsorbed increased gradually. Adsorption equilibrium was reached after 3 h. According to the formula, the saturated adsorption capacity of BSA per gram of magnetic Fe3O4 nanorings was 325.2 mg.Graphical Abstract

Short fluorocarbon chains containing hydrophobic nanofibrous membranes with improved hemocompatibility, anticoagulation and anti-fouling performance

Thromboembolic diseases have become one of the most hazardous and mortal diseases to human life. In this paper, a highly hydrophobic nanofibrous membrane was prepared via electrospinning of PCL-b-PHFBA (polycaprolactone -b- poly (heptafluoro butyl acrylate)) block copolymers. The nanofibrous membranes showed high hydrophobicity with a water contact angle of ˜136° due to their rough nanofibrous surface morphology and contained small portion of short fluorocarbon chain polymer PHFBA. According to the results of whole blood clotting time (CT), prothrombin time (PT), activated partial thromboplastin time (APTT), plasma re-calcification time test (PRT), platelets adhesion and the ultra-low hemolysis rate of 1.13% to red blood cells (RBCs), the membranes exhibited interesting anticoagulant and decreased-platelet adhesion performance. PCL-b-PHFBA nanofibrous membranes showed mild anti-fouling activity, reduced Bovine Serum albumin (BSA) protein absorption and bacterial adhesion compared with PCL nanofibrous membranes. The introduction of PHFBA component did not lead to any obvious cytotoxicity according to the cytocompatibility and cell adhesion study, suggesting that the PCL-b-PHFBA nanofibrous membranes are promising for blood related applications by minimizing the coagulation, hemolysis, BSA protein adsorption, bacterial attachment and platelet adhesion.

One pot preparation of polysulfone-amino functionalized SiO2 nanoparticle ultrafiltration membranes for water purification

Highly hydrophilic and fouling resistant polysulfone (PSF) membranes were prepared via one pot methodology by simultaneous phase inversion and nanoparticle formation. Membrane morphology, hydrophilicity, and surface charge behavior were thoroughly characterized by scanning electron microscopy, atomic force microscopy, contact angle, and zeta potential measurements. The SiO2-NH2 nanoparticle distribution in membrane matrix was also investigated by energy dispersive X-ray spectroscopy and transmission electron microscopy. The water purification performances, some of the membranes flux, rejection, and flux recovery, were evaluated by ultrafiltration of bovine serum albumin protein, Congo red, and methylene blue dyes under dead end mode. The fouling tendency of the membrane was evaluated by bovine serum albumin protein adsorption and ultrafiltration. The properties of the prepared membranes could be tuned by varying the SiO2-NH2 concentration. The nanocomposite membranes exhibited superior water permeation, rejection, and antifouling performance as compared to neat PSF membranes. Hydrophilicity was increased due to amino functionalized SiO2 particles, leading to up to 7-fold increase in water flux and more than 93% protein rejection efficiency with PSF-APTEOS-20 and -10 membranes, respectively. Overall, this work proves an easy and straightforward method for nanocomposite ultrafiltration membrane preparation with good separation and filtration efficiency.

Morphology-Variable Aggregates Prepared from Cholesterol-Containing Amphiphilic Glycopolymers: Their Protein Recognition/Adsorption and Drug Delivery Applications.

In this study, a series of diblock glycopolymers, poly(6-O-methacryloyl-d-galactopyranose)-b-poly(6-cholesteryloxyhexyl methacrylate) (PMAgala-b-PMAChols), with cholesterol/galactose grafts were prepared through a sequential reversible addition-fragmentation chain transfer (RAFT) polymerization and deprotection process. The glycopolymers could self-assemble into aggregates with various morphologies depending on cholesterol/galactose-containing block weight ratios, as determined by transmission electronic microscopy (TEM) and dynamic laser light scattering (DLS). In addition, the lectin (Ricinus communis agglutinin II, RCA120) recognition and bovine serum albumin (BSA) adsorption of the PMAgala-b-PMAChol aggregates were evaluated. The SK-Hep-1 tumor cell inhibition properties of the PMAgala-b-PMAChol/doxorubicin (DOX) complex aggregates were further examined in vitro. Results indicate that the PMAgala-b-PMAChol aggregates with various morphologies showed different interaction/recognition features with RCA120 and BSA. Spherical aggregates (d ≈ 92 nm) possessed the highest RCA120 recognition ability and lowest BSA protein adsorption. In addition, the DOX-loaded spherical complex aggregates exhibited a better tumor cell inhibition property than those of nanofibrous complex aggregates. The morphology-variable aggregates derived from the amphiphilic glycopolymers may serve as multifunctional biomaterials with biomolecular recognition and drug delivery features.

Tethering of hyperbranched polyols using PEI as a building block to synthesize antifouling PVDF membranes

Antifouling PVDF membranes were prepared by grafting hyperbranched polyols on the membrane surface via a three-step modification method. The membrane was first prepared by alkaline treatment to introduce alkenyl groups, then chemically immobilizing hyperbranched poly(ethyleneimine) (HPEI) on membrane surface through Michael reaction followed by ring opening reaction of the glycidol with amine groups. Chemical compositions, surface morphology and physicochemical properties of the original and modified membranes were characterized via attenuated total refection-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), water contact angle (WCA) and zeta potential measurements. The antifouling property of the modified membrane was assessed by the static bovine serum albumin (BSA) and lysozyme (LZM) adsorption as well as cross-flow filtration of BSA aqueous solution. The results explicate that surface modification using hyperbranched polymers can alter membrane chemistry and morphology significantly. In contrast to the original PVDF membrane, the modified membrane shows superhydrophilic property and relatively high capability to resist nonspecific protein adsorption. Three HPEIs were used for modification and the obtained PVDFA-g-PG60,000 membrane has a static BSA protein adsorption of 45μg/cm2 and shows the highest protein resistance. However, the PVDF-g-PG membrane is positively charged due to the unreacted amine groups. As a result, the PVDF-g-PG membranes also show high flux decline during the filtration of BSA aqueous solution due to the electrostatic interaction. In spite of that, the PVDF-g-PG membranes still maintain high flux recovery ratio and good washing properties.

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4′-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37°C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86±1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87±3.16°). The ultimate tensile strength and elastic modulus of PEU (27±1MPa and 14±2MPa) and PEU-PDMS (8±1MPa and 26±1MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial cells from proliferating and migrating into the defect space by facing the soft tissue flaps. This study demonstrates the potential of a dual natured PEU barrier membrane for use in periodontal tissue engineering applications and further investigations are required.

Exploring Nonspecific Protein Adsorption on Lignocellulosic Amphiphilic Bicomponent Films

In this contribution, we explore the interaction of lignocellulosics and proteins aiming at a better understanding of their synergistic role in natural systems. In particular, the manufacturing and characterization of amphiphilic bicomponent thin films composed of hydrophilic cellulose and a hydrophobic lignin ester in different ratios is presented which may act as a very simplified model for real systems. Besides detailed characterizations of the films and mechanisms to explain their formation, nonspecific protein adsorption using bovine serum albumin (BSA) onto the films was studied using a quartz crystal microbalance with dissipation (QCM-D). As it turns out, the rather low nonspecific protein adsorption of BSA on cellulose is further reduced when these hydrophobic lignins are incorporated into the films. The lignin ester acts in these blend films as sacrificial component, probably via an emulsification mechanism. Additionally, the amphiphilicity of the films may prevent the adsorption of BSA as well. Although there are some indications, it remains unclear whether any kind of protein interactions in such systems are of specific nature.

Physicochemical and biochemical properties of iron-loaded silicon substituted hydroxyapatite (FeSiHAp)

We have synthesized scaffolding materials based on iron-loaded silicon substituted hydroxyapatite (SiHAp) (FeSiHAp). The compounds, Ca10−x(Fex)(PO4)5-(SiO4)(OH)2−δ (x = 0.1, 0.3, 0.5), were synthesized using the stoichiometric amounts of the chemical constituents. Both physicochemical properties (structure, surface charge and hardness) and in vitro biochemical properties (Bovine serum albumin (BSA) adsorption and rat osteoblast-like UMR-106 cells response) of the products were measured. The synthesized powders still exhibited the apatite structure for iron contents up to x = 0.5. The surface charge became less negative, from −21.3 to −13.5 mV as the iron loading was increased. Compounds of FeSiHAp whisker showed a micro hardness in rang of 80–84 MPa for x = 0.1–0.5. BSA protein adsorption by FeSiHAp particles was able to fit to the energetically homogeneous behaviors in the Freundlich and Langmuir models. The release of BSA from the iron-loaded SiHAp particles was slow when compared to the release from the non iron loaded particles. Mineralization study showed the formation of apatite crystals on the FeSiHAp surface after modified simulated body fluid (m-SBF) incubation. In vitro cell growth on the FeSiHAp surface, the density of cells, the spread and production of calcium nodules on the substrate were seen to be higher for iron content x = 0.1 (FeSiHAp01). MTT tests on the FeSiHAp indicated that the UMR-106 cells were viable and there was a confluence of cells on the substrate.

Plasma surface modification effects on biodegradability and protein adsorption properties of chitosan films

This study investigates how plasma surface modification influences chitosan film biodegradability and protein adsorption properties. Plasma-modified chitosan films exhibit significantly more hydroxyl and carboxylic acid absorption bands in infrared spectra, and therefore exhibit superior hydrophilicity to that of unmodified chitosan films. The plasma-modified chitosan films exhibit rougher surface morphologies and higher swelling ratios in comparison to unmodified chitosan films. The plasma-modified chitosan films possess enhanced biodegradability in comparison to unmodified chitosan films, because more hydroxyl and carboxylic acid groups are metabolized during biodegradation. The plasma-modified chitosan films exhibit less bovine serum albumin (BSA) adsorption in bicinchoninic acid protein assays because the carboxylic acid group in bovine serum albumin is charge-charge repulsed from the abundant carboxylic acid group on the film surface. The 120s plasma-modified chitosan film possesses optimal hydrophilicity, swelling property, biodegradability, and the lowest BSA protein adsorption, because prolonged plasma treatment time may cause films surface damage.

Plasma Proteins Adsorption Mechanism on Polyethylene-Grafted Poly(ethylene glycol) Surface by Quartz Crystal Microbalance with Dissipation

Protein adsorption has a vital role in biomaterial surface science because it is directly related to the hemocompatibility of blood-contacting materials. In this study, monomethoxy poly(ethylene glycol) (mPEG) with two different molecular weights was grafted on polyethylene as a model to elucidate the adsorption mechanisms of plasma protein through quartz crystal microbalance with dissipation (QCM-D). Combined with data from platelet adhesion, whole blood clotting time, and hemolysis rate, the blood compatibility of PE-g-mPEG film was found to have significantly improved. Two adsorption schemes were developed for real-time monitoring of protein adsorption. Results showed that the preadsorbed bovine serum albumin (BSA) on the surfaces of PE-g-mPEG films could effectively inhibit subsequent adsorption of fibrinogen (Fib). Nonspecific protein adsorption of BSA was determined by surface coverage, not by the chain length of PEG. Dense PEG brush could release more trapped water molecules to resist BSA adsorption. Moreover, the preadsorbed Fib could be gradually displaced by high-concentration BSA. However, the adsorption and displacement of Fib was determined by surface hydrophilicity.

Enhanced Bioactivity of Calcium Phosphate Coatings Obtained by a Direct Electrodeposition from Hanks’ Solution on Ti Surface / Zwiekszona Bioaktywnosc Powłok Fosforanowo-Wapniowych Otrzymanych Metoda Bezposredniego Elektroosadzania Na Powierzchni Ti Z Roztworu Hanka

The main requirements for titanium biomaterials are: (a) biocompatibility, (b) resistance to biological corrosion and (c) antisepticity. These requirements may be met by a new generation of titanium biomaterials with a specific surface layer of strictly defined microstructure, chemical and phase composition. Recently, various surface modifications have been applied to form a bioactive layer on Ti surface, which is known to accelerate osseointegration. The purpose of this study was to investigate bioactivity of porous calcium phosphate coatings prepared by a direct electrodeposition on Ti surface from a modified Hanks’ solution. The thick 200 nm coatings, were prepared via cathodic polarization at constant voltage -1.5 V vs. OCP in a Hanks’ solution. In order to evaluate the potential use of the coatings for biomedical applications, the adsorption of bovine serum albumin (BSA), the most abundant protein in blood, and living cells attachment (osteoblasts, U2OS) were studied. The observed differences in living cells attachment suggest a more promising initial cellular response of Ca-P coatings with a pre-adsorbed albumin. The topography and a cross-section view of the Ca-P coatings were characterized using SEM and STEM techniques. The surface analytical techniques (AES, XPS, and FTIR) were used to characterize their chemical composition before and after protein BSA adsorption.

Cryogenically cured hydroxyapatite–gelatin nanobiocomposite for bovine serum albumin protein adsorption and release

This research paper presents the first results on the protein adsorption and release kinetics and in vitro biodegradability of cryogenically cured hydroxyapatite–gelatin based micro/macroporous scaffolds (CHAMPS). While the adsorption and release of bovine serum albumin (BSA) protein exhibits steady state behavior over an incubation period of up to 10 days, Fourier transform infrared (FT-IR) analysis importantly confirms the absence of any change in the secondary structure of BSA proteins due to interaction with the CHAMPS scaffold. The compression properties of the CHAMPS scaffold with interconnected porosity (pore size ∼50–200 μm) is characterized by a non-linear stress–strain response with a strength close to 5 MPa and a maximum strain of up to 24%. The slow but systematic increase in weight loss over a period of 7 days as well as apatite layer formation indicates its good bioactivity. The extensive micro-computed tomography (micro-CT) analysis establishes cancellous bone-like highly interconnected and complex porous architecture of the CHAMPS scaffold. Importantly, the excellent adsorption (up to 50%) and release (up to 60% of adsorbed protein) of BSA has been uniquely attributed to the inherent porous microstructure of the CHAMPS scaffold. Overall, the present study provides an assessment of the interaction of protein with the gelatin–hydroxyapatite macroporous scaffold in vitro, as well as reporting for the first time the efficacy of such scaffolds to release 60% of BSA loaded onto the scaffold in vitro, which is significantly higher than earlier literature reports.

Surface-functionalization of PDMS for potential micro-bioreactor and embryonic stem cell culture applications.

This study presents a novel and inexpensive method to prepare a disposable micro-bioreactor for stem cell expansion. The micro-bioreactor was fabricated in the form of a fixed bed bioreactor with a microchannel reactor bed. The micro-bioreactor was constructed from polydimethylsiloxane (PDMS), and the microchannel was functionalized to enable cell adhesion and resistance to bovine serum albumin protein adsorption. The PDMS reactor bed surface was activated by oxygen plasma, then aminized with trimethoxysilylpropyl(polyethyleneimine), followed by grafting with carboxylmethyl cellulose (CMC) and gelatin in sequence. The functionalized PDMS surface demonstrated improved hydrophilicity and antifouling properties. The grafting of gelatin promoted cell adhesion. The functionalized surface was found to be biocompatible with MDA-MB-231 and Oct4b2 cells and was demonstrated to facilitate cell proliferation. The expanded Oct4b2 cells retained their proliferation potential, undifferentiated phenotype and pluripotency.

Fluorescence From Metallic Silver and Iron Nanoparticles Prepared by Exploding Wire Technique

The observation of intense visible fluorescence from silver and iron nanoparticles in different solution phases and surface capping is reported here. Metallic silver and iron nanoparticles were obtained by exploding pure silver and iron wires in pure water. Bovine serum albumin protein adsorption on the silver nanoparticles showed an enhanced fluorescence. The presence of poly-vinyl pyrrolidone polymer in the exploding medium resulted in a stabilized growth of iron nanoparticles with enhanced fluorescence intensity. The fluorescence was found to be surface /interface dependant. The fluorescence is attributed to electronic transitions among characteristic interface energy bands. The magnetic nature of iron nanoparticles was confirmed from the hysteresis measurements.

Adsorption of bovine serum albumin protein onto amino‐containing thermosensitive core‐shell latexes

AbstractAdsorption of bovine serum albumin (BSA) onto positively charged core‐shell latex particles with a polystyrene core and a rich poly(N‐isopropylacrylamide) (NIPAM)) shell layer was investigated as a function of pH, ionic strength and temperature. Adsorption of BSA protein onto such cationic and thermosensitive particles was found negligible below the LCST of poly(NIPAM), whereas it was much higher above it. In addition, the pH and the salinity dependence of the adsorbed amount at the plateau reflected the role of electrostatic interactions. Protein adsorption behaviour was discussed by taking into account the changes in the interfacial properties of polymer particles (structure of the shell, hydrophilic–hydrophobic balance, charge density) versus temperature, suggesting that coulombic forces are mostly operating in this process. A desorption study showed that the BSA release efficiency was dependent upon the incubation time of the preliminary adsorbed step, and the effect of pH and ionic strength confirmed the contribution of electrostatic interactions. Copyright © 2004 Society of Chemical Industry