Suppression Of Protein Adsorption Research Articles

Immobilization of carbonic anhydrase on modified PES membranes for artificial lungs.

The introduction of carbonic anhydrase (CA) onto an extracorporeal membrane oxygenation (ECMO) membrane can improve the permeability of carbon dioxide (CO2). However, existing CA-grafting methods have limitations, and the hemocompatibility of current substrate membranes of commercial ECMO is not satisfactory. In this study, a 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxy succinimide (NHS) activation method is adopted to graft CA with CO2-catalyzed conversion activity onto a polyethersulfone (PES) membrane, which is prepared by a phase inversion technique after in situ crosslinking polymerization of 1-vinyl-2-pyrrolidone (VP) and acrylic acid (AA) in PES solution. The characterization results reveal that CA has been grafted onto the modified PES membrane successfully and exhibits catalytic activity. The kinetic parameters of esterase activity verify that the grafted amount of active CA increases with an increase in the concentration of the CA incubation solution. The CA-grafted membrane (CA-M) can accelerate the conversion of bicarbonate to CO2 in water and blood, which demonstrates the special catalytic activity towards bicarbonate of CA. Finally, blood compatibility tests prove that the CA-M does not lead to hemolysis, shows suppressed protein adsorption and increased coagulation time, and is suitable for application in ECMO. This work demonstrates a green and efficient method for preparing bioactive materials and has practical guiding significance for subsequent pulmonary membrane research and ECMO applications.

Surface modification of a PVDF membrane by co‐grafting hydroxyl and zwitterionic polymers to enhance wettability and antifouling property

AbstractPolyvinylidene fluoride (PVDF) membranes have been widely applied in the separation of various organic matters owing to their excellent properties. However, they possess low wettability and undergo fouling because of the hydrophobic nature of PVDF. In this study, poly (2‐hydroxyethyl methacrylate) (PHEMA) and poly (sulfobetaine methacrylate) (PSBMA) were co‐introduced to modify the highly hydrophobic PVDF membrane surface via UV photo‐irradiation. Facile UV photo‐grafting was performed by irradiating the pristine PVDF membrane immersed in a PHEMA/PSBMA mixture solution with UV light for 5 min. The performance of the as‐prepared PHEMA/PSBMA‐grafted membrane was compared with that of membranes modified with solely PHEMA or PSBMA. The hydroxyl and zwitterionic groups of the grafted membranes enhanced wettability and increased flux. A tightly bound water layer was formed because of the enhanced wettability, significantly suppressing protein adsorption. The initial flux of bovine serum albumin (BSA) solution through the PHEMA/PSBMA‐grafted membrane was 2861 LMH, which was 3.1 times higher than that obtained by the pristine PVDF membrane. Furthermore, the flux decline of the modified membrane caused by BSA fouling was 49% lower than that of the pristine PVDF membrane. Finally, the PHEMA/PSBMA‐grafted PVDF membrane showed antifouling properties after three BSA filtration cycles.

Proteins on the Rack: Mechanistic Studies on Protein Particle Formation During Peristaltic Pumping

Peristaltic pumping can cause protein particle formation. The expected causes were unfolding by heat in the pump head, oxidative stress by cavitation generated during roller movement, interfacial adsorption to the tubing wall and mechanical stress by stretching of the tubing itself. The pump head reached 28°C during experiments stayed well below the onset of the melting point of the proteins. Thus, heat may only be a relevant root cause for proteins containing domains with very low unfolding temperature. Analysis by terephthalic acid dosimetry and protein oxidation via RP-HPLC ruled out major induction of reactive hydroxyl radicals by pumping, indicating that cavitation does not play a significant role in particle generation. Addition of surfactants suppresses protein adsorption to the tubing wall and drastically reduced protein particle formation. This indicates that interfacial protein adsorption is a key element. Repeated stretching of tubing filled with protein solution led to the formation of protein particles, demonstrating that expansion and compression of the protein film on the tubing surface is the second key component for particle formation. Thus, protein particle generation during peristaltic pumping originates from the formation of a protein film on the tubing surface which gets stretched and compressed, leading to film fragments entering the bulk solution. This interplay of protein film formation and its rupture has been also observed at liquid/liquid or liquid/air interfaces.

Development of low-fouling PVDF membranes blended with poly(2-methoxyethyl acrylate) via NIPS process

PVDF-based membranes with low-fouling and high permeability properties were developed by blending poly(vinylidene fluoride) (PVDF) with poly(2-methoxyethyl acrylate) (PMEA), a low-fouling polymer, via non-solvent induced phase separation (NIPS). Since PMEA suppresses protein adsorption and is insoluble in water, the PMEA homopolymer was used as an additive. Consequently, transparent dope solutions containing 15 wt% PVDF and 0–7 wt% PMEA were prepared using N-methyl-2-pyrrolidone as the solvent. The macrovoids in the blended membranes were larger than those in the pristine PVDF membrane and were probably attributed to the PMEA-promoted solvent exchange during the NIPS process. As a result, the pure water permeabilities of the blended membranes were 5–10 times higher than those of the pristine PVDF membrane. The ATR FT-IR characterization revealed that the PMEA composition of the membrane surfaces increased as the PMEA blend ratio in the dope solution increased. This resulted in the improvement of their low-fouling properties when used in 1000 ppm of bovine serum albumin (BSA) and lysozyme aqueous solutions. Additionally, the PMEA-blended PVDF membrane with the highest PMEA ratio showed the best low-fouling properties.

Protein Removal from Hydrogels through Repetitive Surface Degradation.

Suppression of protein adsorption is a necessary property for materials used in the living body. In this study, thermoresponsive and degradable hydrogels were prepared by the radical polymerization of 2-methylene-1,3-dioxepane, 2-hydroxyethyl acrylate (HEA), and poly(ethylene glycol) monomethacrylate (PEGMA). The prepared hydrogels re-exposed PEG-grafted chains to the interface through surface degradation, which was confirmed by the maintenance of the chemical composition of the hydrogel surfaces after hydrolysis. Notably, adsorbed proteins can be removed from the hydrogel surfaces through hydrogel surface degradation at least thrice.

Dual stimulus-responsive chitosan-based nanoparticles co-delivering doxorubicin and quercetin for cancer therapy

With limited steps of chemical modification and a simple sonication-drived drug loading approach, the dually sensitive chitosan-based nanoparticles (NPs) co-delivering doxorubicin (DOX) and quercetin (QUE) (DTPQ NPs) were prepared for the treatment of liver cancer. DTPQ NPs had average particle sizes <200 nm and zeta potentials of around 28 mV. Suppressed protein adsorption at neutral conditions and in vitro release in response to glutathione (GSH) concentration were achieved. Owing to their pH and redox responsiveness and synergy of DOX and QUE, DTPQ NPs exhibited the enhanced tumor inhibition efficacy. The results demonstrated that combinational therapy based on dual stimulus-responsive NPs could offer a promising choice to cancer therapy.

Development of tamoxifen-loaded surface-modified nanostructured lipid carrier using experimental design: in vitro and ex vivo characterisation.

The present study aimed to develop a surface-modified biocompatible nanostructured lipid carrier (NLCs) system using polyoxyethylene (40) stearate (POE-40-S) to improve the oral bioavailability of poorly water-soluble Biopharmaceutics Classification System class-II drug like tamoxifen (TMX). Also aimed to screen the most influential factors affecting the particle size (PS) using Taguchi (L12 (211)) orthogonal array design (TgL12OA). Then, to optimize the TMX loaded POE-40-S (P) surface-modified NLCs (TMX-loaded-PEG-40-S coated NLC (PNLCs) or PNLCs) by central composite design (CCD) using a four-factor, five-level model. The most influential factors affecting the PS was screened and optimized. The in-vitro study showed that increased drug-loading (DL) and encapsulation efficiency (EE), decreased PS and charge, sustained drug release for the prolonged period of the time with good stability and suppressed protein adsorption. The Ex-vivo study showed that decreased mucous binding with five-fold enhanced permeability of PNLC formulation after surface modification with POE-40-S. The in-vitro cytotoxicity study showed that the blank carrier is biocompatible and cytotoxicity of the formulation was dependent on the concentration of the drug. Finally, it can be concluded that the surface-modified PNLCs formulation was an effective, biocompatible, stable formulation in the enhancement of dissolution rate, solubility, stability with reduced mucus adhesion and increased permeability thereby which indicates its enhanced oral bioavailability.

Surface functionalization of carbon-based sensors with biocompatible polymer to enable electrochemical measurement in protein-rich environment

Electrochemical biosensors have been widely applied to elucidate various information on pharmaceutically important neurotransmitters such as dopamine (DA). However, the biofouling of electrodes has been a critical issue for electrochemical measurements performed in physiological environments. In this study, highly biocompatible polymer brush made of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was employed to modify carbon-based sensors to prevent biofouling. The PMPC brushes with thicknesses ranging from 15 to 30 nm on top of glassy carbon surfaces successfully suppressed protein adsorption in serum environments, and the polymer modification remained stable for at least 8 h in such conditions. The PMPC-modified glassy carbon electrode (GCE) achieved a limit of detection (LOD) as low as 1.8 μM for DA, as determined from cyclic voltammetry (CV), which exhibited better performance than the bovine serum albumin (BSA)-coated GCE with a LOD of 3.9 μM. The results from this study open new avenues for drug discovery and pharmacokinetics by enabling carbon-based biosensors to accurately and sensitively detect pharmaceuticals in protein-rich environments for an extensive period of time.

Zwitterionic polymer ligands: an ideal surface coating to totally suppress protein-nanoparticle corona formation?

In the last few years, zwitterionic polymers have been developed as antifouling surface coatings. However, their ability to completely suppress protein adsorption at the surface of nanoparticles in complex biological media remains undemonstrated. Here we investigate the formation of hard (irreversible) and soft (reversible) protein corona around model nanoparticles (NPs) coated with sulfobetaine (SB), phosphorylcholine (PC) and carboxybetaine (CB) polymer ligands in model albumin solutions and in whole serum. We show for the first time a complete absence of protein corona around SB-coated NPs, while PC- and CB-coated NPs undergo reversible adsorption or partial aggregation. These dramatic differences cannot be described by naïve hard/soft acid/base electrostatic interactions. Single NP tracking in the cytoplasm of live cells corroborate these in vitro observations. Finally, while modification of SB polymers with additional charged groups lead to consequent protein adsorption, addition of small neutral targeting moieties preserves antifouling and enable efficient intracellular targeting.

In situ surface modification on dental composite resin using 2-methacryloyloxyethyl phosphorylcholine polymer for controlling plaque formation.

Composite resins (CRs) are widely used as dental restorative materials for caries treatment. They cause problems of secondary caries since Streptococcus mutans stays in the dental plaque, which the surface exists and produces acidic compounds during metabolism. The dental plaque depositions are induced by the protein adsorption on the surface. Therefore, suppression of protein adsorption on the surface of the CRs is important for inhibiting the formation of plaque and secondary caries. In this study we developed a surface treatment to provide an antibiofouling nature to the CRs by chemical reaction with 2-methacryloyloxyethyl phosphorylcholine (MPC) polymers in the oral cavity during dental treatment. To carry out the photochemical reaction on the remaining polymerizable groups of CRs, we synthesized the MPC polymer with a polymerizable group in the side chain. The MPC polymer could bind on the surfaces of the CRs chemically under dental treatment procedures. The treated surface showed significant resistance to oral protein adsorption and bacterial adhesion even when the surface was brushed with a toothbrush. Thus, we concluded that the photochemical reaction of the MPC polymer with the CRs in the oral cavity was good for making an antibiofouling surface and preventing secondary caries.

Robust solvent‐free fabrication and characterization of (polydimethylsiloxane‐co‐2‐hydroxyethylmethacrylate)/poly (ethylene glycol) methacrylate (PDMS‐HEMA)/PEGMA hydrogels

Combining hydrophobic materials such as polydimethylsiloxane (PDMS), a natural hydrophobic material with typical hydrophilic monomers without using organic solvent remains a big challenge due to their extreme different properties; hence, fabricating a class of silicone hydrogels with two extremes without use of organic solvents could bring us a novel class of silicone hydrogels. Herein, a range of PDMS‐HEMA‐PEGMA hydrogels was prepared from hydroxyl‐terminated PDMS, 2‐hydroxyethylmethacrylate (HEMA), poly (ethylene glycol) methacrylate (PEGMA), and isophorone diisocyanate via condensation and radical copolymerization reactions. The infrared results confirmed the PDMS‐HEMA‐PEGMA network formation, while the hydrophilicity of the as‐prepared block copolymer was dependent on (PDMS‐HEMA)/PEGMA ratio. Increasing the PEGMA content resulted in increased equilibrium water content, phase separation, surface roughness, and tensile strength, while the tensile modulus, elongation at break, optical transmittance, water contact angle, and oxygen permeability (Dk) were decreasing. At PEGMA content of 28.3%, the relative protein adsorption ratio decreased to 20% and 36% for bovine serum albumin and lysozyme, respectively, compared with that of the control (PDMS‐HEMA), suggesting antiprotein adsorption ability. In overall, the results showed that the PDMS‐HEMA‐PEGMA hydrogels not only exhibited remarkable hydrophilicity and suppressed protein adsorption but also maintained higher optical transparency and oxygen permeability (Dk).

Suppression of protein adsorption on a graphene surface by phosphorylcholine functionalization

In this study, we examined phosphorylcholine (ChoP)-modified epitaxial graphene film based devices for the suppression of non-specific protein adsorptions onto a graphene surface. ChoP-pyrene derivatives were synthesized and immobilized on epitaxial graphene by the π–π stacking effect. The shifts in the transfer curve by protein adsorption were suppressed for the ChoP-modified graphene device, and this effect was independent of the charge and type of protein. In addition, the suppression effect was stable after 15 min of treatment with ultra-pure water owing to strong interactions of π electrons on the graphene surface. Consequently, our results indicate a stable blocking for protein adsorptions is achieved with an epochal ChoP derivative using robust bonding of a pyrene and a graphene film.

Intermediate Water on Calcium Phosphate Minerals: Its Origin and Role in Crystal Growth.

Water molecules are known to play crucial roles both in the formation and biological function of materials. Herein, we show the presence of "intermediate water" on an inorganic solidmaterial, hydroxyapatite. In vitro experiments revealed that Mg substitution of apatite significantly enriched the amount of intermediate water, possibly due to the proton transfer toa hydrogen-bonded network of water around HPO42- on divalent-cation-deficient apatite surfaces. The intermediate water formation related to a markedly suppressed protein adsorption on apatite. Analysis of bone apatites suggested that the intermediate water on minerals could play crucial roles in regulating crystal growth.

Revolutionary advances in 2-methacryloyloxyethyl phosphorylcholine polymers as biomaterials.

In the last 40 years, many strategies to fabricate biocompatible and antithrombogenic polymers have been proposed, especially in Japan. The development of one such polymers composed of 2-methacryloyloxyethyl phosphorylcholine unit, is described in this review, with specific examples of use in biomedical devices. These polymers are typically incorporated into other materials to effectively prevent unfavorable biological responses and reactions. For example, the polymers suppress protein adsorption and cell adhesion to materials in contact with plasma or whole blood, even in the absence of anticoagulant. These properties are due to the extreme hydrophilicity and electrically neutral nature of the polymers, as well as to the ability of phosphorylcholine to induce bulk-like behavior in surrounding waters. Accordingly, these polymers have been used worldwide to modify the surfaces and improve the overall biocompatibility of such medical devices as long-term implantable artificial organs. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 933-943, 2019.

Novel diazoresin/carboxymethyl chitosan capillary coating for the analysis of proteins by capillary electrophoresis

ABSTRACTCapillary electrophoresis has become an effective tool for the separation and analysis of biomolecule macromolecule.In this work, a new method to prepare covalent connection capillary electrophoretic coatings is proposed. Photosensitive diazoresin (DR) as coupling agents and carboxymethyl chitosan as coating was used. Through layer by layer (LBL) self-assembly and unique photochemistry reaction of DR, a stable and efficient capillary coating can be obtained. The covalently bonded coatings have the ability of suppressing protein adsorption on the inner surface of silica capillary, and thus a baseline separation of Lysozyme (Lys), myoglobin (Mb), bovine serum albumin (BSA) and ribonuclease A (RNase A) can be achieved. The covalently linked DR/carboxymethyl chitosan capillary coatings presented good stability and repeatability. This method seems to be an environmental and simple way to prepare the covalently coated capillaries for CE.

Impact of Bioactive Peptide Motifs on Molecular Structure, Charging, and Nonfouling Properties of Poly(ethylene oxide) Brushes

Polymer layers capable of suppressing protein adsorption from biological media while presenting extracellular matrix-derived peptide motifs offer valuable new options for biomimetic surface engineering. Herein, we provide detailed insights into physicochemical changes induced in a nonfouling poly(ethylene oxide) (PEO) brush/polydopamine (PDA) system by incorporation of adhesion ligand (RGD) peptides. Brushes with high surface chain densities (σ ≥ 0.5 chains·nm-2) and pronounced hydrophilicity (water contact angles ≤ 10°) were prepared by end-tethering of heterobifunctional PEOs ( Mn ≈ 20 000 g·mol-1) to PDA-modified surfaces from a reactive melt. Using alkyne distal end group on the PEO chains, azidopentanoic-bearing peptides were coupled through a copper-catalyzed Huisgen azide-alkyne "click" cycloaddition reaction. The surface concentration of RGD was tuned from complete saturation of the PEO surface with peptides (1.7 × 105 fmol·cm-2) to values which may induce distinct differences in cell adhesion (<6.0 × 102 fmol·cm-2). Infrared reflection-absorption and X-ray photoelectron spectroscopies proved the PDA-PEO layers covalent structure and the immobilization of RGD peptides. The complete reconstruction of experimental electrohydrodynamics data utilizing mean-field theory predictions further verified the attained brush structure of the end-tethered PEO chains which provided hydrodynamic screening of the PDA anchor. Increasing the surface concentration of immobilized RGD peptides led to increased interfacial charging. Supported by simulations, this observation was attributed to the ionization of functional groups in the amino acid sequence and to the pH-dependent adsorption of water ions (OH- > H3O+) from the electrolyte. Despite the distinct differences observed in the electrokinetic analysis of the surfaces bearing different amounts of RGD, it was found that the peptide presence on PEO(20 000)-PDA layers does not have a significant effect on the nonfouling properties of the system. Notably, the presented PEO(20 000)-PDA layers bearing RGD peptides in the surface concentration range 5.9 to 1.7 × 105 fmol·cm-2 reduced the protein adsorption from fetal bovine serum to less than 30 ng·cm-2, that is, values comparable to the ones obtained for pristine PEO(20 000)-PDA layers.

A novel diazoresin/rapamycin covalent capillary coating for the separation of biomacromolecules by capillary electrophoresis

ABSTRACTCovalent capillary coatings of diazoresin (DR) and rapamycin (RAPA) were prepared by a layer-by-layer self-assembly. DR worked as the coupling agent. Under ultraviolet light, the corsslinking was carried out by covalent bonds between DR and RAPA. The covalent capillary coatings could suppress protein adsorption. The baseline separation of lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA) and myoglobin (Mb) could be achieved within 17 minutes by using capillary electrophoresis (CE). The covalent capillary coatings exhibited good chemical stability and repeatability. In the synthesis, highly toxic moisture-sensitive silane has been replaced by DR. The method provides an environmentally friendly way to prepare the covalent capillary coating.

Polymer coating glass to improve the protein antifouling effect

Random copolymers (P(M100-m/T m )) composed of 2-methacryloyloxyethyl phosphorylcholine (MPC), which suppresses protein adsorption, and 3-(triethoxysilyl)propyl methacrylate (MTEOS), which can be covalently fixed on a glass surface, were prepared via photoinitiated radical polymerization. When P(M100-m/T m ) was coated on a glass surface, a protein antifouling effect could be observed because of the presence of MPC units on the glass surface. To confirm the coating of the glass surface with P(M100-m/T m ) by fluorescence microscopy, pyrene-labeled P(M100-m/T m ) was also prepared. An ethanol solution of P(M100-m/T m ) was spin-coated on the glass, which was exposed to NH3 vapor to promote the reaction of the pendant triethoxysilyl groups in P(M100-m/T m ) with silanol groups on the glass. The coating of the glass with MPC was confirmed by fluorescence microscopy. The protein antifouling effects of the P(M100-m/T m )-coated glass were confirmed using fluorescence-labeled proteins. It is expected that P(M100-m/T m ) can be applied as a surface-coating agent on glass containers for protein formulations. Random copolymers (P(M100-m/T m )) composed of 2-methacryloyloxyethyl phosphorylcholine, which suppresses protein fouling, and 3-(triethoxysilyl)propyl methacrylate, which can react covalently to the glass surface, were prepared via photoinitiated radical polymerization. Coating of the glass with P(M100-m/T m ) was confirmed by red fluorescence from Rhodamine 6G. The protein antifouling properties of the P(M100-m/T m ) coating on glass were confirmed using fluorescence-labeled proteins.

Sulfobetainized biocomposite mats with improved biocompatibility and antifouling property

Sulfobetaine precursor of poly(BMA-co-DMAEMA) copolymer was first prepared by free radical polymerization of butyl methacrylate (BMA) and N,N-dimethylamino-2-ethyl methacrylate (DMAEMA) monomers. Then, the copolymer was coelectrospun with polyurethane to afford polyurethane/poly(BMA-co-DMAEMA) composite mats. The resultant mats were subsequently sulfobetainized to form zwitterions. The structure and morphology of mats were evaluated by ATR-FTIR, XPS, and SEM. The hemocompatibility and antifouling property of mats were preliminarily investigated by protein adsorption, platelet adhesion, and bacterial adhesion. The results indicated that the zwitterionic biocomposite mats could suppress protein adsorption, platelet adhesion, antibacterial adhesion as well as non-cytotoxicity.

Poly(ε-caprolactone) modification via surface initiated atom transfer radical polymerization with bio-inspired phosphorylcholine

Bio-inspired phosphorylcholine modification on material surface has shown great promise in constructing biocompatible materials. In this study, poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) was grown on poly(ε-caprolactone) (PCL) surface in order to suppress protein adsorption and cells adhesion and to improve blood compatibility. The initiator for surface initiated atom transfer radical polymerization (SI-ATRP) was covalently tethered on PCL surface and then PMPC brushes with diverse graft amounts were grafted to PCL film. X-ray photoelectron spectroscopy (XPS) and water contact angle measurement were used to characterize the modified sheets. The PMPC-grafted PCL sheets showed lower protein adsorption, maintained secondary structure of detached protein, and suppressed adhesion and pseudopodium formation of the platelets, along with keeping longer activated partial thromboplastin time (APTT) in comparison with PCL membranes. At the same time, PMPC-grafted PCL sheets suppressed the LO2 cells adhesion. These results showed that phosphorylcholine SI-ATRP modification on PCL surface may provide PCL more biocompatible in biomaterial applications.