Low Protein Adsorption Research Articles

Blood compatibility of polyethersulfone membrane by blending a sulfated derivative of chitosan

In this study, a novel sulfated derivative of chitosan, which could be dissolved in many common organic solvents, is conveniently synthesized for the modification of polyethersulfone (PES) membrane. Elemental analysis, FTIR, 1H NMR and X-ray diffraction diagrams (XRD) are used to demonstrate the introduction of functional groups. Owing to the solubility in organic solvents, the sulfated derivative of chitosan could be directly blended with PES in organic solvent to prepare membrane by means of a liquid–liquid phase separation technique. The modified membrane showed lower protein (bovine serum albumin (BSA) and bovine serum fibrinogen (BFG)) adsorption and suppressed platelet adhesion. Moreover, the activated partial thromboplastin time (APTT) for the modified membrane was enhanced as high as 60% compared to pure PES membrane. The lower protein adsorption, suppressed platelet adhesion and increased APTT confirmed that the blood compatibility of the modified PES membrane by the sulfated derivative of chitosan was significantly improved.

Conjugation with Betaine: A Facile and Effective Approach to Significant Improvement of Gene Delivery Properties of PEI

Herein, we developed a new gene delivery vector by grafting a betaine monomer (N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate, DMAAPS) onto 25 KDa polyethylenimine (PEI 25K) via the Michael addition reaction. The graft ratio for betaine on PEI polymer could be readily controlled, and in this study three PEI-betaine conjugates PEI-DMAAPS23%, PEI-DMAAPS55%, and PEI-DMAAPS95% were prepared with their graft ratios of 23, 55, and 95%, respectively. The PEI-betaine conjugates exhibited much lower protein adsorption and cytotoxicities compared with PEI 25K, and they also showed little or no hemolytic effect. Moreover, the PEI-betaine conjugates display satisfactory DNA condensation capability; and in the absence and presence of serum, PEI-DMAAPS23%/pEGFP and PEI-DMAAPS55%/pEGFP complexes exhibited remarkable gene transfection efficiencies determined by flow cytometry, which are in general several times higher than that of PEI 25K. With these favorable properties, the PEI-betaine conjugates hold great potential for use as efficient gene delivery vectors. This study suggests that the betaine monomer may serve as a biocompatible modifying agent and this facile strategy may provide a facile and effective way for constructing some other biocompatible materials.

Grafting zwitterionic polymer chains onto PEI as a convenient strategy to enhance gene delivery performance

Herein, we demonstrated a one-step method for preparing a new gene delivery vector by grafting poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) onto the 25 kDa polyethylenimine (PEI 25k) via a TBHP-initiated polymerization. The graft ratio of PMPC on the PEI polymer can be readily controlled, and in this study three PEI-PMPC polymers (PEI-PMPC6%, PEI-PMPC11% and PEI-DMAAPS24%) have been prepared with their graft ratios of 6 wt%, 11 wt% and 24 wt%, respectively. The PEI-PMPC polymers exhibit lower protein adsorption and cytotoxicity compared to PEI 25k. Moreover, the PEI-PMPC polymers display satisfactory DNA condensation capability. In the absence and presence of serum, PEI-PMPC6%/pEGFP and PEI-PMPC11%/pEGFP complexes work well and exhibit satisfactory gene transfection efficiencies, which are in general higher than that of PEI 25k/pEGFP, especially in the presence of 10% serum. With these improved gene delivery properties, the PEI-PMPC polymers hold great potential for being used as efficient gene delivery vectors. This strategy may provide a facile and effective way for constructing some other biocompatible materials.

Poly(acrylic acid) brushes pattern as a 3D functional biosensor surface for microchips

Poly(acrylic acid) (PAA) brushes, a novel three dimensional (3D) precursor layer of biosensor or protein microarrays, possess high protein loading level and low non-specific protein adsorption. In this article, we describe a simple and convenient way to fabricate 3D PAA brushes pattern by microcontact printing (μCP) and characterize it with FT-IR and optical microscopy. The carboxyl groups of PAA brushes can be applied to covalently immobilize protein for immunoassay. Thriving 3D space made by patterning PAA brushes thin film is available to enhance protein immobilization, which is confirmed by measuring model protein interaction between human immunoglobulin G (H-IgG) and goat anti-H-IgG (G-H-IgG) with fluorescence microscopy and surface plasmon resonance imaging (SPRi). As expected, the SPRi signals of H-IgG coating on 3D PAA brushes pattern and further measuring specific binding with G-H-IgG are all larger than that of 3D PAA brushes without pattern and 2D bare gold surface. We further revealed that this surface can be used for high-throughput screening and clinical diagnosis by label-free assaying of Hepatitis-B-Virus surface antibody (HBsAb) with Hepatitis-B-Virus surface antigen (HBsAg) concentration array chip. The linearity range for HBsAb assay is wider than that of conventional ELISA method.

The role of biocompatible coatings of biomaterials for creation of direct and appropriate chemical bounding between bioimplant and bone tissue.

Background and Objective: Nowadays, the surface modification of biomaterials to increase biocompatibility and improve other aspects of environmental performance is widely prevalent and is developing. Biological host response depends on the primary interactions of biological and biomaterials systems at the molecular surfaces. Therefore, the surface properties at the atomic scale influence on compatibility and optimal performance of the material in body. The present study aims to survey the most common surface modification techniques of biomaterials focusing on the surface coating techniques and their applications in bone tissue engineering and tissue repairing field. Furthermore, the process and features of biomaterial surface coating in complex superficial modification of biomaterials as a representation of biomaterials interfaces with the biological environment are discussed. Finally, the potential applications and advantages of these techniques in repairing damaged tissues in neurosurgery and orthopedic surgery are presented. Methods: In this review article, the most common and important methods of surface modification of biomaterials (thermal spray, electrophoresis, pulsed laser deposition, electrochemical, biomimetic, sputtering, Chemical Vapor Deposition (CVD), and, Sol–Gel techniques) which the reputable manufacture companies of biomaterial are applying and many published articles in the biomaterial field (since 2004 up to now). Furthermore, the potential applications and current positions of these methods in bone tissue engineering and effective factors for an optimal tissue repairing using biomaterial surface coating are presented. Results indicated: The Sol-gel method is suitable for obtaining nanoscale structures. Plasma spraying method has a high-speed balance and is the only commercially available method. The pulsed laser coating method can be used in multilayer coatings and structures with a fixed Stoichiometric. The electrophoresis coating methods are able to coat relatively complex shapes with precise control over coating thickness. In recent years, several coating methods such as electrochemical, biomimetic, sputtering, and CVD have been proposed and used by researchers some of them with good satisfactory results. Conclusions: Findings of our survey show that surface modification of biomaterials can keep the crucial physical properties of the biomaterials unchanged which is an important feature in biological reactions. The main advantages of biomaterial surface modification including surface coating can be presented as follows: Reducing protein adsorption: Biomaterials sometimes need to have the lowest protein adsorption, otherwise, will cause uncontrolled immune responses. Lack of cellular coherency Cellular absorption: Biomaterials that are used as replacement tissue cells must have high capability for cell absorption and also should facilitate their growth process. Reducing Clot formation: Biomaterials that are used as blood implants should have the lowest capacity of clot formation. High coherency to bacteria Reducing friction and grinding

Small and Stable Phosphorylcholine Zwitterionic Quantum Dots for Weak Nonspecific Phagocytosis and Effective Tat Peptide Functionalization

Facile surface modification of quantum dots (QDs) to make them water-soluble, small, stable, antibiofouling, and functional is crucial for their biological applications. This study demonstrates a simple ligand-exchange reaction to convert hydrophobic CdSe/ZnS QDs into water-soluble QDs using amphiphilic, zwitterionic 11-mercaptoundecylphosphorylcholine (HS-PC). The phosphorylcholine (PC)-modified QDs (QD-PC) possess several advantages, such as small hydrodynamic diameter, good resistance to pH variations and high salinity, excellent stability in 100% human plasma, and low protein adsorption. Importantly, the PC modification endows the QDs with very low, nonspecific interaction with cells, and strongly minimizes nonspecific phagocytosis of QDs by macrophages. In addition, cell penetrating Tat peptide functionalized QDs can be easily produced by mixing Tat with HS-PC with various ratios, which is proved to effectively enhance QD ability to enter cells and accumulate around perinuclear region. Compared to traditional mercaptoundecanoic acid (MUA) modification, PC modification not only makes the cell penetrating QDs more stable and brighter, but also provides the Tat- and PC-conjugated QDs with much lower nonspecific phagocytic uptake than the Tat- and MUA-conjugated ones. This research will provide insights into designing suitable ligands for surface modification of QDs and improving biofunctional QD performance in biological applications.

A novel antithrombotic coronary stent: lysine-poly(HEMA)-modified cobalt–chromium stent with fibrinolytic activity

Prevention of coagulation appears not to be possible when a foreign surface is in contact with blood; the alternative concept of a clot lysing surface has therefore been suggested. In this work, a mimic of the fibrinolytic system was constructed on L605 cobalt–chromium coronary stents. Lysine which, immobilized on a surface, has been shown previously to adsorb plasminogen in contact with blood was attached to the stent using poly(2-hydroxyethyl methacrylate) (poly(HEMA)) as a spacer. The lysine-poly(HEMA) modified stent was shown to have low nonspecific protein adsorption and to bind plasminogen in high quantity from plasma. Following exposure to plasma and treatment with tissue plasminogen activator, the lysine-modified stents showed clot-lysing properties in vitro while the unmodified L605 stents did not. It was shown that the modified stents retained their clot lysing properties after 24 h exposure to plasma.

Fabricating pH‐Stable and Swellable Very Thin Hyperbranched Poly(ethylene imine)–Oligosaccharide Films Fabricated Without Precoating: First View on Protein Adsorption

For using successful (ultra)thin dendritic macromolecule films in (bio)sensing and microfluidic devices and for obtaining reproducible film properties, alteration effects arising from precoatings have to be avoided. Here, oligosaccharide-modified hyperbranched poly(ethylene imine)s (PEI-OS) were used to fabricate very thin PEI-OS films (15-20 nm in dry state), cross-linked with citric acid under condensation, and vacuum condition. However, no reactive precoating is necessary to obtain stable films, which allows very simple film preparation and avoids alteration of the PEIS-OS film properties arising from precoating. Several methods [(in situ) ellipsometry, AFM, XPS, (in situ) ATR-IR, streaming potential measurements] were applied to characterize homogeneity, surface morphology, and stability of these PEI-OS films between pH 2 and pH 10, but also the low protein adsorption behavior.

Tailored Poly(2‐oxazoline) Polymer Brushes to Control Protein Adsorption and Cell Adhesion

POx bottle-brush brushes (BBBs) are synthesized by SIPGP of 2-isopropenyl-2-oxazoline and consecutive LCROP of 2-oxazolines on 3-aminopropyltrimethoxysilane-modified silicon substrates. The side chain hydrophilicity and polarity are varied. The impact of the chemical composition and architecture of the BBB upon protein (fibronectin) adsorption and endothelial cell adhesion are investigated and prove extremely low protein adsorption and cell adhesion on BBBs with hydrophilic side chains such as poly(2-methyl-2-oxazoline) and poly(2-ethyl-2-oxazoline). The influence of the POx side chain terminal function upon adsorption and adhesion is minor but the side chain length has a significant effect on bioadsorption.

A review of polyvinyl alcohol and its uses in cartilage and orthopedic applications

Polyvinyl alcohol (PVA) is a synthetic polymer derived from polyvinyl acetate through partial or full hydroxylation. PVA is commonly used in medical devices due to its low protein adsorption characteristics, biocompatibility, high water solubility, and chemical resistance. Some of the most common medical uses of PVA are in soft contact lenses, eye drops, embolization particles, tissue adhesion barriers, and as artificial cartilage and meniscus. The purpose of this review is to evaluate the available published information on PVA with respect to its safety as a medical device implant material for cartilage replacement. The review includes historical clinical use of PVA in orthopedics, and in vitro and in vivo biocompatibility studies. Finally, the safety recommendation involving the further development of PVA cryogels for cartilage replacement is addressed.

Polyurethane-based microfluidic devices for blood contacting applications

Protein adsorption on PDMS surfaces poses a significant challenge in microfluidic devices that come into contact with biofluids such as blood. Polyurethane (PU) is often used for the construction of medical devices, but despite having several attractive properties for biointerfacing, it has not been widely used in microfluidic devices. In this work we developed two new fabrication processes for making thin, transparent and flexible PU-based microfluidic devices. Methods for the fabrication and bonding of microchannels, the integration of fluidic interconnections and surface modification with hydrophilic polyethylene oxide (PEO) to reduce protein adsorption are detailed. Using these processes, microchannels were produced having high transparency (96% that of glass in visible light), high bond strength (326.4 kPa) and low protein adsorption (80% reduction in fibrinogen adsorption vs. unmodified PDMS), which is critical for prevention of fouling. Our findings indicate that PEO modified PU could serve as an effective alternative to PDMS in blood contacting microfluidic applications.

Amino-functionalized monolithic spin-type columns for high-throughput lectin affinity chromatography of glycoproteins

Hydrophilic poly(ethylene glycol)-based monoliths were synthesized in the spin-tip format for high-throughput applications via pulsed electron beam irradiation. Monoliths with a homogeneous porous structure and a total porosity of 69% were obtained. The cross-linked polymeric structure was further mechanically stabilized via the incorporation of silica nanoparticles. Amino-functionalization of the monoliths was accomplished by a straightforward, water-based, one-step approach that entailed the electron-beam irradiation-induced grafting of poly(allylamine). The amine functionalized spin columns showed very low unspecific protein adsorption and were successfully applied as adsorbents in lectin affinity chromatography for the purification of ovalbumin. The novel columns also outperformed a commercially available system.

Quantifying Protein Adsorption to Physically Crosslinked Gelatin-Based Networks

ABSTRACTPhysically crosslinked hydrogels based on gelatin functionalized with desaminotyrosine (DAT) (giving Gel-DAT) or desaminotyrosyl tyrosine (DATT) (resulting in Gel-DATT) have shown high potential as biomaterials. Here, protein adsorption to the functionalized gelatins in comparison to gelatin was quantified to see if the functionalization and chain organization of gelatins has an influence on the amount of proteins being adsorbed. For this purpose, gelatin, Gel-DAT, and Gel-DATT were incubated with water or aq. solutions of bovine serum albumin (BSA), fibrinogen, or fibronectin, respectively, at physiological concentrations. Protein concentrations in the supernatant were determined with the bicinchoninic acid (BCA) assay before and after the contact. BSA adsorption to the materials was influenced as well by the hydrophobicity of the material as the degree of swelling, with the observation that higher protein concentrations led to lower protein adsorption. The highest amount of fibronectin was adsorbed to Gel-DAT, followed by gelatin and Gel-DATT, with only small differences for different initial protein concentrations. Fibrinogen adsorption increased with increasing concentration. In the future, adsorption studies based on specific antibody-based techniques might enable quantification of the proteins also in competition assays and direct quantification of adsorbed material.

Development of a Stable Dual Functional Coating with Low Non-specific Protein Adsorption and High Sensitivity for New Superparamagnetic Nanospheres

To overcome major challenges of non-specific protein adsorption on nanoparticles for nanosensing and nanodiagnosis, an efficient method for robust chemical modification was developed to achieve excellent specific biorecognition and long-term stability in complex biomedia. This method is demonstrated by a highly specific and sensitive immunoassay (IA), using superparamagnetic nanospheres (NSs) with high magnetite content. The non-specific protein adsorption on the NSs was suppressed dramatically when modified with dual functional poly(carboxybetaine methacrylate) (polyCBMA) via surface-initiated atom transfer radical polymerization (SI-ATRP) and chemically grafted with antibodies of the β subunit of human chorionic gonadotrop (anti-β-hCG). The response to hCG of IA NSs with polyCBMA coatings was highly consistent in either phosphate-buffered saline (PBS) or 50% fetal bovine serum (FBS), which is far less variable than the response of the IA NSs without polyCBMA coatings. After all, a very robust platform for IA NSs with excellent specific biorecognition was obtained. It is expected that this method for nanoparticle modification could be widely used in ultrasensitive nanosensing and nanodiagnosis in the future.

Poly(ethylene oxide) Layers Grafted to Dopamine-melanin Anchoring Layer: Stability and Resistance to Protein Adsorption

In this study, we propose substrate-independent modification for creating a protein-repellent surface based on dopamine-melanin anchoring layer used for subsequent binding of poly(ethylene oxide) (PEO) from melt. We verified that the dopamine-melanin layer can be formed on literally any substrate and could serve as the anchoring layer for subsequent grafting of PEO chains. Grafting of PEO from melt in a temperature range 70-110 °C produces densely packed PEO layers showing exceptionally low protein adsorption when exposed to the whole blood serum or plasma. The PEO layers prepared from melt at 110 °C retained the protein repellent properties for as long as 10 days after their exposure to physiological-like conditions. The PEO-dopamine-melanin modification represents a simple and universal surface modification method for the preparation of protein repellent surfaces that could serve as a nonfouling background in various applications, such as optical biosensors and tissue engineering.

Thermoresponsive oligo(ethylene glycol) methacrylate colloids with antifouling surface properties

AbstractThermoresponsive polymeric colloids attract great attention in several biotechnological applications owing to their ability to manipulate drug release characteristics in a controlled manner. Majority of these applications utilized N‐isopropylacrylamide (NIPAM)‐based particles for controlled drug release. Despite its advantages, such as easy chemical modification and well‐documented literature, a potentially important bottleneck for NIPAM in biological applications is its tendency for nonspecific protein adsorption. Herein, we report a simple way to prepare novel thermoresponsive colloids composed of oligo(ethylene glycol) side chains via precipitation polymerization technique. In addition to displaying highly reversible thermal response, these particles also have considerably low nonspecific protein adsorption when compared with NIPAM counterparts. These crosslinked poly(ethylene glycol) ethyl ether methacrylate particles were characterized using dynamic light scattering and transmission electron microscopy. The effects of co‐monomer, crosslinker and initiator on particle characteristics were investigated. Finally, particle toxicity studies were carried out using 3T3 fibroblast cell lines in MTT cytotoxicity assay. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Green synthesis of gold nanoparticles with Zingiber officinale extract: Characterization and blood compatibility

Biosynthesis of gold nanoparticles with small size and biostability is very important and used in various biomedical applications. There are lot of reports for the synthesis of gold nanoparticles by the addition of reducing agent and stabilizing agent. In the present study we have synthesized gold nanoparticles, with a particle size ranging from 5 to 15nm, using Zingiber officinale extract which acts both as reducing and stabilizing agent. Z. officinale extract is reported to be a more potent anti-platelet agent than aspirin. Therefore, green synthesis of gold nanoparticles with Z. officinale extract, as an alternative to chemical synthesis, is beneficial from its biological and medical applications point of view, because of its good blood biocompatibility and physiological stability. The formation and size distribution of gold nanoparticles were confirmed by dynamic light scattering (DLS), UV–vis spectrophotometer and transmission electron microscopy (TEM). Gold nanoparticles synthesized using citrate and Z. officinale extract demonstrated very low protein adsorption. Both nanoparticles were non platelet activating and non complement activating on contact with whole human blood. They also did not aggregate other blood cells, however, nanoparticles synthesised with Z. officinale extract was highly stable at physiological condition compared to citrate capped nanoparticles, which aggregated. Thus the usage of nanoparticles, synthesized with Z. officinale extract, as vectors for the applications in drug delivery, gene delivery or as biosensors, where a direct contact with blood occurs is justified.

A new approach to immobilize poly(vinyl alcohol) on poly(dimethylsiloxane) resulting in low protein adsorption

The hydrophobic characteristics of PDMS and non-specific protein adsorption are major drawbacks for its application in biosensing. Here we have combined surface oxidation by plasma and chemical binding of polyvinyl alcohol (PVA) to obtain long-term stability of hydrophilic PDMS surfaces. Mercaptopropyltrimethoxisilane and aminopropyltrimethoxisilane were used as adhesives between the plasma-oxidized PDMS surface and the PVA, immobilized at room temperature. This approach has allowed for fast, uniform, and very stable modification of the PDMS surface, which maintained a hydrophilic character for as long as 30 days. In addition, the modified hydrophilic surface presented minimized protein adsorption when compared to pristine PDMS. The results obtained in this work are important contributions to the growing field of integrated microfluidic biosensors.

Convenient grafting through approach for the preparation of stealth polymeric blood pool magnetic resonance imaging contrast agents

AbstractNew hydrosoluble magnetic resonance imaging (MRI) macrocontrast agents are synthesized by reversible addition fragmentation chain transfer (RAFT) copolymerization of poly(ethylene oxide) methyl ether acrylate (PEOMA) with an acrylamide bearing a ligand for gadolinium, followed by the complexation of Gd3+. This convenient and simple grafting through approach leads to macrocontrast agents with a high relaxivity at high frequency that is imparted by the restricted tumbling of the Gd3+ complex caused by its attachment to the polymer backbone. Importantly a very low protein adsorption is also evidenced by the hemolytic CH50 test. It is the result of the poly(ethylene oxide) (PEO) brush that efficiently hides the gadolinium complex and renders it stealth to the proteins of the immune system. Improved contrast and long blood circulating properties are thus expected for these macrocontrast agents. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Surface-hydrophilic and protein-resistant tris(trimethylsiloxy)-3-methacryloxypropylsilane-containing polymer by the introduction of phosphorylcholine groups

Poly 2-hydroxyethyl methacrylate-co-2-methacryloyloxyethyl phosphorylcholine-co-tris(trimethylsiloxy)-3-methacryloxypropylsilane (PHMT) terpolymer was synthesized in order to evaluate the potential of this polymer to be used as contact lens material. The phosphorylcholine unit played an important role in the terpolymer: increasing both the surface hydrophilicity and the anti-biofouling properties of the original material. Water contact angle measurements suggested that the phosphorylcholine head groups could rearrange on the upper surface of the TRIS containing polymer in the water environment, improving the wettability of the surface. Compared with poly 2-hydroxyethyl methacrylate-co-tris(trimethylsiloxy)-3-methacryloxypropylsilane (PHT) membrane, lower protein adsorption was observed on the surface of PHMT polymer. As observed by AFM, smooth surface was formed by spin coating method from the terpolymer solution. And the oxygen transmissibility (Dk/ t) of the terpolymer PHMT was 64 barrer/mm. The equilibrium water content reached 63%, much higher than the polymers without MPC unit, which may offer comfortable wear feeling. Moreover, PHMT films exhibited high transparency in the visible light wave range (relatively constant at approximately 94%).