Inhibition Of Protein Adsorption Research Articles

A novel acid-responsive polymer coating with antibacterial and antifouling properties for the prevention of biofilm-associated infections

Chronic infections caused by the pathogenic biofilms on implantable medical devices pose an increasing challenge. To combat long-term biofilm-associated infections, we developed a novel dual-functional polymer coating with antibacterial and antifouling properties. The coating consists of N-vinylpyrrolidone (NVP) and 3-(acrylamido)phenylboronic acid (APBA) copolymer brushes, which bind to curcumin (Cur) as antibacterial molecules through acid-responsive boronate ester bonds. In this surface design, the hydrophilic poly (N-vinylpyrrolidone) (PVP) component improved antifouling performance and effectively prevented bacterial adhesion and aggregation during the initial phases. The poly (3-(acrylamido) phenylboronic acid) (PAPBA, abbreviated PB) component provided binding sites for Cur by forming acid-responsive boronate ester bonds. When fewer bacteria overcame the anti-adhesion barrier and colonized, the surface responded to the decreased microenvironmental pH by breaking the boronate ester bonds and releasing curcumin. This responsive mechanism enabled Cur to interfere with biofilm formation and provide a multilayer anti-biofilm protection system. The coating showed excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, preventing biofilm formation for up to 7 days. The coating also inhibited protein adsorption and platelet adhesion significantly. This coating also exhibited high biocompatibility with animal erythrocytes and pre-osteoblasts. This research offers a promising approach for developing novel smart anti-biofilm coating materials.

Dynamic surfaces of latex films and their antifouling applications

Latex polymer particles have been widely used in industry and everyday life. For decades the fabrication of “smart” latex film from latex particles has been a great challenge due to the difficulty in the synthesis of the functional latex particles by traditional emulsion polymerization using small molecular surfactants. In this manuscript, a simple and environmentally-friendly approach to the fabrication of “smart” latex films with dynamic surfaces is reported. Latex particles with poly(n-butyl methacrylate) (PnBMA) in the cores and zwitterionic poly-3-[dimethyl-[2-(2-methylprop-2-enoyloxy) ethyl]azaniumyl]propane-1-sulfonate (PDMAPS) in the shells are synthesized by reversible addition-fragmentation chain transfer (RAFT) mediated surfactant-free emulsion polymerization. The kinetics for the emulsion polymerization is studied, and the latex particles are analyzed by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dynamic light scattering (DLS). Latex films are prepared by casting aqueous solutions of the latex particles at temperatures above the glass transition temperature (Tg) of PnBMA. On the dried latex film, the hydrophobic PnBMA blocks occupy the top surface; after water treatment, the hydrophilic PDMAPS blocks migrate to the surface. A change in the surface hydrophilicity results in a change in the water contact angle of the latex film. A mechanism for the formation of the dynamic surface structure is proposed in this research. Antifouling applications of the latex films are investigated. Experimental results indicate that the water-treated latex film is able to efficiently inhibit protein adsorption and resist bacterial adhesion.

CARD29: Sodium Bicarbonate as an Adjunctive Local Anti-Thrombotic Agent for Cardiovascular Therapeutic Devices

Purpose: Despite clinical efficacy, mechanical circulatory support (MCS) systems remain challenged in maintaining physiologic hemostatic balance. The Impella heart pump is a micro-axial percutaneous MCS device that utilizes a purge flow for maintaining bearing lubrication, purge patency, and anti-thrombosis purposes, forming a purge gap micro-environment wherein purge fluid and blood may mix. During operation, a continuous 5% dextrose in water (D5W) + heparin purge solution flows through the Impella catheter to inhibit protein adsorption and thrombosis in internal purge gaps. This exogenous heparin can increase bleeding risk and complicate systemic heparin and anticoagulation management. Recent FDA approval has made available sodium bicarbonate (SB) as an alternative to purge heparin. Despite promising early clinical results, the influence of SB on blood platelets, central mediators of thrombosis and bleeding, remains unclear. Here, we investigated the effect of SB on human platelet function (adhesion, aggregation, activation) in vitro following incubation with relevant concentrations of heparin or SB. Methods: Human gel-filtered platelets (20,000/µL) or platelet rich plasma (100,000/µL) were obtained from ACD-A anticoagulated whole blood. Platelets were incubated (6:4 platelets: purge) at 37°C for 15 min with purge solutions (D5W; 50U/mL heparin + D5W; 25mEq/L SB + D5W; 50mEq/L SB + D5W; 100mEq/L SB + D5W). Platelet activation was measured as thrombin generation rate utilizing a previously-described modified prothrombinase assay. Platelet adhesion was measured via imaging (Nikon DS-Qi2; 100X) of fluorescent-labelled platelets (BioTracker490) adhered to glass. Platelet aggregation was quantified from agonist-mediated aggregation using a light-transmission aggregometer (PAP8E). All experiments were performed in duplicate with N≥3 donors. Results: SB altered overall platelet function in a concentration-dependent manner. 100mEq/L SB led to a significant decrease in platelet adhesion (0.11% decrease; Fig 1A), whereas only 25mEq/L SB led to a significant reduction in thrombin generation rate (14.0% decrease; Fig 1B). Collagen-mediated aggregation was significantly reduced after addition of 100mEq/L SB (42.2% decrease; Fig 1C). Traditional D5W+heparin solution significantly reduced platelet function, in all categories, to a greater degree than 25mEq/L SB, but had a similar effect to 50 or 100mEq/L SB when comparing platelet adhesion and activation metrics. Conclusion: SB in the concentrations tested led to altered platelet function, modulating surface adhesion, activation, and collagen-mediated aggregation –useful effects to limit device fouling and purge gap thrombosis. Use of SB as a localized anti-thrombotic agent, where its concentration and effect are not rapidly diluted, is promising for MCS such as the Impella system. SB use offers the potential for locally limiting thrombogenicity at the purge gap, while avoiding the need for exogenous heparin.

Electrothermally excited plasma droplet evolution on the laser-patterned surface

Droplet behavior involving electrothermal coupling fields has gradually attracted the attention of researchers, one of which includes electrosurgical scalpels that often contact biofluids. However, the evolution of bio-droplets exposed to the surface of electrosurgical scalpels is not yet well understood. Here, we experimentally studied the effect of different heating temperatures on plasma droplets on the laser-patterned surface (LPS) and the original surface (OS) under defined direct-current (DC) or alternating-current (AC) electric fields. The results show that at a lower heating temperature, the evolution of plasma droplets was dominated by electrolysis. Oxygen bubbles generated on the papillae on the LPS in the DC field inhibited the targeted adsorption of plasma proteins on this surface. In contrast, in the AC field, only a small number of bubbles was generated, which is not sufficient to inhibit protein adsorption, leading to the formation of coagulation on the papillae after heating. At higher heating temperatures, the rapid formation of coagulation resulted in the suppression of electrolysis. The plasma proteins were then transported by the Marangoni flow causing coagulation to reach a thickness of stress mutation. Stress release over the entire coagulation caused its edges to bend and then detach from the papillae. Thus, the LPS exhibited excellent anti-adhesive properties to plasma droplets under electrothermal excitations compared to the OS. This study provides valuable information for understanding the mechanisms of contact behavior between biofluids and electrosurgical scalpels and demonstrates great promise for their anti-adhesive performance.

Modification of a PES microfiltration membrane to enhance sterile filtration by inhibiting protein adsorption

Microfiltration membranes are increasingly used in sterilization processes in the pharmaceutical industry. However, in the pharmaceutical industry, product loss caused by the adsorption of high value-added proteins to membranes during the sterilization process is a critical problem. Hence, it is necessary to reduce protein adsorption and fouling through the hydrophilic modification of the entire membrane, not just the surface. We developed a method for fabricating a porous poly(ethersulfone) (PES) microfiltration membrane using vapor-induced phase separation (VIPS) and then conducting hydrophilic modification of the membrane. Two types of symmetric membranes with 0.2 μm pores were prepared using two different additives, one of which was an amphiphilic copolymer (Pluronic® PE6400) that is known to increase the hydrophilicity of PES membranes. Both membranes had high water permeability and suitable mechanical strength. However, protein filtration testing, including an adsorption study, revealed that the hydrophilicity imparted by Pluronic was not sufficient to effectively inhibit protein adhesion. In contrast, the modification via the atom transfer radical polymerization of a hydrophilic oligomer (poly(ethyleneglycol) methacrylate) significantly increased the hydrophilicity of the entire membrane while reducing the surface roughness. These properties reduced protein adsorption and membrane fouling, to the benefit of sterile filtration and protein filtration processes.

Impact of spontaneous liposome modification with phospholipid polymer-lipid conjugates on protein interactions

ABSTRACT Liposome surface coating has been studied to avoid the immunological responses caused by the complement system, and alternative materials to poly(ethylene glycol) (PEG) have been explored recently since the production of anti-PEG IgM antibodies has been found in humans. We previously reported a liposome coating with poly(2-methacryloyloxyethyl phosphorylcholine) (poly(MPC))-conjugated lipids (PMPC-lipids) and demonstrated its protective effect on blood protein interactions. Here, we attempted to modify the liposome surface by exogenously adding PMPC-lipids, which were spontaneously incorporated into the outer membrane via hydrophobic interactions. The polymerization degree of the PMPC segment was regulated from 10 to 100. The incorporated ratio of PMPC-lipid increased with a decrease in the degree of PMPC polymerization. Due to surface modification with PMPC-lipids, increase in the length of the PMPC-chain increased the size of the liposomes. The modified liposomes were kept stable for 14 d in terms of their size, polydispersity, and surface properties, where approximately 70% of PMPC-lipids were incorporated into the liposome surface. We demonstrated that liposome surface modification with PMPC-lipids can inhibit protein adsorption when exposed to serum, regardless of the degree of polymerization of PMPC. In addition, the PMPC-lipid modified surface was not recognized by the anti-PEG IgM antibody, whereas PEG-lipid was recognized by the antibody. Thus, we successfully fabricated an inert liposome surface via spontaneous modification with PMPC-lipids, where only the outer bilayer surface was modified. This technique can be available for full loading of water-soluble active pharmaceutical ingredient inside the modified liposome.

Iodination of PEGylated Polymers Counteracts the Inhibition of Fibrinogen Adsorption by PEG.

Poly(ethylene glycol), PEG, known to inhibit protein adsorption, is widely used on the surfaces of biomedical devices when biofilm formation is undesirable. Poly(desaminotyrosyl-tyrosine ethyl ester carbonate), PDTEC, PC for short, has been a promising coating polymer for insertion devices, and it has been anticipated that PEG plays a similar role if it is copolymerized with PC. Earlier studies show that no fibrinogen (Fg) is adsorbed onto PC polymers with PEG beyond the threshold weight percentage. This is attributed to the phase separation of PEG. Further, iodination of the PC units in the PC polymer, (I2PC), has been found to counteract this Fg-repulsive effect by PEG. In this study, we employ surface-sensitive X-ray techniques to demonstrate the surface affinity of Fg toward the air-water interface, particularly in the presence of self-assembled PC-based film, in which its constituent polymer units are assumed to be much more mobile as a free-standing film. Fg is found to form a Gibbs monolayer with its long axis parallel to the aqueous surface, thus maximizing its interactions with hydrophobic interfaces. It influences the amount of insoluble, surface-bound I2PC likely due to the desorption of the formed Fg-I2PC complex and/or the penetration of Fg onto the I2PC film. The results show that the phase behavior at the liquid-polymer interface shall be taken into account for the surface behavior of bulk polymers surrounded by tissue. The ability of PEG units rearranging into a protein-blocking layer, rather than its mere presence in the polymer, is the key to antifouling characteristics desired for polymeric coating on insertion devices.

Reduced restenosis and enhanced re-endothelialization of functional biodegradable vascular scaffolds by everolimus and magnesium hydroxide

BackgroundCoronary artery disease is a cardiovascular disease with a high mortality and mortality rate in modern society. Vascular stent insertion to restore blood flow is essential to treat this disease. A fully biodegradable vascular scaffold (BVS) is a vascular poly (L-lactic acid) (PLLA) stent that is receiving growing interest as this is biodegradable in the body and does not require secondary removal surgery. However, acidic byproducts composed of PLLA produced during the biodegradation of the BVS can induce an inflammatory response. Magnesium hydroxide, a basic inorganic particle, neutralizes the acidic byproducts of PLLA. MethodsIn this study, we investigated using a BVS coated with everolimus and surface-modified magnesium hydroxide that suppresses smooth muscle cell proliferation and protects endothelial cells, respectively. The various characteristics of the functional stent were evaluated using in vitro and in vivo analyses. ResultsThe BVS was successfully prepared with evenly coated everolimus and surface-modified magnesium hydroxide. A neutral pH value was maintained by magnesium hydroxide during degradation, and everolimus was released for one month. The coated BVS effectively inhibited protein adsorption and platelet adhesion, demonstrating excellent blood compatibility. In vitro analysis showed that BVS protects endothelial cells with magnesium hydroxide and selectively inhibits smooth muscle cell proliferation via everolimus treatment. The functional BVS was inserted into porcine coronary arteries for 28 days, and the results demonstrated that the restenosis and inflammation greatly decreased and re-endothelialization was enhanced as compared to others.ConclusionsThis study provides new insights into the design of drug-incorporated BVS stent for coronary artery disease.Graphical

Differential Surface Adsorption Phenomena for Conventional and Novel Surfactants Correlates with Changes in Interfacial mAb Stabilization.

Protein adsorption on surfaces can result in loss of drug product stability and efficacy during the production, storage, and administration of protein-based therapeutics. Surface-active agents (excipients) are typically added in protein formulations to prevent undesired interactions of proteins on surfaces and protein particle formation/aggregation in solution. The objective of this work is to understand the molecular-level competitive adsorption mechanism between the monoclonal antibody (mAb) and a commercially used excipient, polysorbate 80 (PS80), and a novel excipient, N-myristoyl phenylalanine-N-polyetheramine diamide (FM1000). The relative rate of adsorption of PS80 and FM1000 was studied by pendant bubble tensiometry. We find that FM1000 saturates the interface faster than PS80. Additionally, the surface-adsorbed amounts from X-ray reflectivity (XRR) measurements show that FM1000 blocks a larger percentage of interfacial area than PS80, indicating that a lower bulk FM1000 surface concentration is sufficient to prevent protein adsorption onto the air/water interface. XRR models reveal that with an increase in mAb concentration (0.5-2.5 mg/mL: IV based formulations), an increased amount of PS80 concentration (below critical micelle concentration, CMC) is required, whereas a fixed value of FM1000 concentration (above its relatively lower CMC) is sufficient to inhibit mAb adsorption, preventing mAb from co-existing with surfactants on the surface layer. With this observation, we show that the CMC of the surfactant is not the critical factor to indicate its ability to inhibit protein adsorption, especially for chemically different surfactants, PS80 and FM1000. Additionally, interface-induced aggregation studies indicate that at minimum surfactant concentration levels in protein formulations, fewer protein particles form in the presence of FM1000. Our results provide a mechanistic link between the adsorption of mAbs at the air/water interface and the aggregation induced by agitation in the presence of surfactants.

Catching Speedy Gonzales: Driving forces for Protein Film Formation on Silicone Rubber Tubing During Pumping

Interfacial adsorption is a major concern in the processing of biopharmaceutics as it not only leads to a loss of protein, but also to particle formation. Protein particle formation during peristaltic pumping is linked to interfacial adsorption to the tubing and subsequent tearing of the formed protein film. In the current study, driving forces and rate of the adsorption of a monoclonal antibody to the silicone rubber surface during pumping, as well as particle formation, were studied in different formulations. Particle concentration and size distribution were influenced by the formulation parameters; specifically high ionic strength led to more particles and the build-up of particles larger than 25 µm. Formulation pH and ionic strength had an effect on the total amount of adsorbed protein. Adsorbed protein amounts increased when the Debye length of the protein was decreased, leading to a higher packing density. Atomic force microscopy and streaming potential determination revealed that the irreversible protein film formation on the hydrophobic tubing surface occurs in less than a second. Electrostatic interactions are the dominating factor for the initial adsorption speed. In intimate contact to the silicone rubber surface, hydrophobic interactions govern the protein adsorption. PS20 quickly coats the tubing surface which leads to an increase in hydrophilicity and shielding of electrostatic interactions, thereby efficiently inhibiting protein adsorption. Overall, atomic force microscopy and streaming potential determination possess great potential for the characterization of adsorbed protein films and the adsorption kinetic evaluation in high-speed mode. Protein adsorption to silicone tubing is driven by a combination of electrostatic and hydrophobic interactions which is effectively shielded by PS20.

Injectable polydimethylsiloxane microfiller coated with zwitterionic polymer for enhanced biocompatibility

Silicone-based fillers have been applied in several branches of medicine, such as soft tissue augmentation, because of their stability and durability. However, the inherently hydrophobic surfaces of silicone occasionally cause excessive deposition of the fibrous matrix in vivo, leading to severe fibrosis. In this study, we evaluated the use of a zwitterionic copolymer to offer a facile surface treatment method for silicone-based fillers and performed a preclinical trial of the formulation as-prepared. The copolymer has amphiphilic moieties, which act as macromolecular surfactants that can functionalize and stabilize the silicone particles during fabrication. The effectiveness and safety of the particle filler were evaluated histologically by scoring the peri-implant tissues into previously defined categories. Our results suggest that zwitterion-coated silicone fillers can inhibit protein adsorption, and thus, help attenuate foreign body reactions in a rat model. This demonstrates their potential for wide application in different fields within the discipline of medicine.

Influence of Protein Adsorption on Aggregation in Prefilled Syringes.

Protein aggregate formation in prefilled syringes (PFSs) can be influenced by protein adsorption and desorption at the solid-liquid interface. Although inhibition of protein adsorption on the PFS surface can lead to a decrease in the amount of aggregation, the mechanism underlying protein adsorption-mediated aggregation in PFSs is unclear. This study investigated protein aggregation caused by protein adsorption on silicone oil-free PFS surfaces [borosilicate glass (GLS) and cycloolefin polymer (COP)] and the factors affecting the protein adsorption on the PFS surfaces. The adsorbed proteins formed multilayered structures that consisted of two distinct types of layers: proteins adsorbed on the surface of the material and proteins adsorbed on top of the proteins on the surface. A pH-dependent electrostatic interaction was the dominant force for protein adsorption on the GLS surface, while hydrophobic effects were dominant for protein adsorption on the COP surface. When the repulsion force between proteins was weak, protein adsorption on the adsorbed protein layer was increased for both materials and as a result, protein aggregation increased. Therefore, a formulation with high colloidal stability can minimize protein adsorption on the COP surface, leading to reduced protein aggregation.

Facile method for covalent-bonding coating of crosslinked silicone layer onto poly(ester-urethane) surface to improve tensile properties and hemocompatibility

In this paper, a facile method was provided to prepare covalent-bonding coating of crosslinked silicone (CLS) layer onto the poly(ester-urethane) (PEU) surface for improving its properties. The PEU containing well-ordered hard segments was prepared by the direct chain extension of poly(ε-caprolactone) with diurethane diisocyanate (HBH), and the PEU films were acquired via solvent evaporation. The CLS layer was covalently coated onto the film surface by a three-step chemical treatment: the -NCO groups were first introduced onto the PEU film surface by chemical treatment of the film with hexamethylene diisocyanate; the free NCO groups were subsequently coupled with the NH2 groups of γ-aminopropyltriethoxysilane to fix the active alkoxysilane groups on the surface; finally, the alkoxysilane groups self-crosslinked to produce a CLS coating on the PEU surface (PEU-Si). FT-IR, XPS and SEM were used to characterize the modified surface. The studies on physicochemical properties of the films manifested that the PEU-Si film exhibited higher thermal stability, excellent tensile properties (broken elongation: 1389 %; ultimate strength: 41.6 MPa), and slower in vitro hydrolytic degradation (only 16.0 % weight loss after 18 months of degradation) than PEU film. The hemocompatibility evaluation of film surface was performed by protein adsorption and platelet adhesion measurements, and the results showed that the CLS-coated surface strongly inhibited protein adsorption (2.92 μg/cm2) and platelet adhesion (2,129 platelets/mm2). The PEU-Si exhibited excellent tensile properties, slow degradability, and superior surface hemocompatibility, indicating promise as a long-term implant.

Multi-functional zwitterionic coating for silicone-based biomedical devices

Bacteria associated infection, blood coagulation, inflammation, tissue adhesion and weak surface lubrication are major issues challenging the biomedical application (especially long-term indwelling) of silicone rubber (SR) based catheters. Here, we report a new strategy to simultaneously address these issues by fabricating a simple zwitterionic/active ester copolymer coating via a facile two-step process. Take advantage of well-controlled reversible addition–fragmentation chain transfer polymerization (RAFT), well designed zwitterionic sulfobetaine/active ester block copolymers (pSBMA-b-pNHSMA) with different zwitterionic segment lengths (repeat units of 20 and 90) were prepared. Stable polymeric coatings were constructed on SR substrates upon covalent bonding between the active ester pendant from the copolymer and the amino residues on the activated SR surface. Robust relationship between the composition of block polymers and the ability to combat biofilm formation, blood coagulation, inflammation, cell/tissue adhesion, as well as to improve the lubricating properties of SR substrates, has been systematically established. Results showed that the polymer containing a zwitterionic sulfobetaine segment of 20 repeat units can significantly inhibit protein adsorption, platelet adhesion, bacterial adhesion, and cell adhesion for short-term (within 24 h), while the longer zwitterionic sulfobetaine segment (90 repeat units) can endow long-term antibacterial (no biofilm formation at day 21), anti-cell/tissue-adhesion (no cell adhesion at day 7), anti-inflammation (7 days) properties, as well as significantly improved surface lubrication to SR substrates. In the meantime, the surface modification didn’t compromise the mechanical property of SR substrates. The facile yet efficient surface modification process can be easily applied to SR based urinary catheters. This strategy may inspire diverse surface functionalization of SR based biomedical devices for a wide range of biomedical applications.

A novel diazoresin/polystyrene-poly(ethylene oxide) covalent capillary coating for the analysis of proteins by capillary electrophoresis

A novel method for the preparation of covalently linked capillary coatings of polystyrene-poly (ethylene oxide) (PS-PEO) was demonstrated by using photosensitive diazoresin (DR) as coupling agents. Layer by layer (LBL) self-assembly membrane of DR and PS-PEO based on hydrogen bonding firstly was fabricated on the inner wall of capillary, then with the treatment of UV light through the unique photochemistry reaction of DR, the hydrogen bonding was converted into covalent bonding. The covalently bonded coatings have the ability of inhibiting protein adsorption on the inner surface of capillary, and thus a baseline separation of Lysozyme (Lys), cytochrome c (Cyt-c), bovine serum albumin (BSA), ribonuclease A (RNase A) and myoglobin (Mb) was achieved by using capillary electrophoresis (CE). Compared with bare capillary or non-covalently bonded DR/PS-PEO coatings, the covalently linked DR/PS-PEO capillary coatings improved the CE separation performance for proteins; what’s more, it exhibited good stability and repeatability. This method can provide a green and easy way to make the covalently coated capillaries for CE, replacing of the old way which using highly toxic and moisture sensitive silane coupling agent by DR in the covalent coating preparation.

Constructing a Dual-Function Surface by Microcasting and Nanospraying for Efficient Drag Reduction and Potential Antifouling Capabilities.

To improve the drag-reducing and antifouling performance of marine equipment, it is indispensable to learn from structures and materials that are found in nature. This is due to their excellent properties, such as intelligence, microminiaturization, hierarchical assembly, and adaptability. Considerable interest has arisen in fabricating surfaces with various types of biomimetic structures, which exhibit promising and synergistic performances similar to living organisms. In this study, a dual bio-inspired shark-skin and lotus-structure (BSLS) surface was developed for fabrication on commercial polyurethane (PU) polymer. Firstly, the shark-skin pattern was transferred on the PU by microcasting. Secondly, hierarchical micro- and nanostructures were introduced by spraying mesoporous silica nanospheres (MSNs). The dual biomimetic substrates were characterized by scanning electron microscopy, water contact angle characterization, antifouling, self-cleaning, and water flow impacting experiments. The results revealed that the BSLS surface exhibited dual biomimetic features. The micro- and nano-lotus-like structures were localized on a replicated shark dermal denticle. A contact angle of 147° was observed on the dual-treated surface and the contact angle hysteresis was decreased by 20% compared with that of the nontreated surface. Fluid drag was determined with shear stress measurements and a drag reduction of 36.7% was found for the biomimetic surface. With continuous impacting of high-speed water for up to 10 h, the biomimetic surface stayed superhydrophobic. Material properties such as inhibition of protein adsorption, mechanical robustness, and self-cleaning performances were evaluated, and the data indicated these behaviors were significantly improved. The mechanisms of drag reduction and self-cleaning are discussed. Our results indicate that this method is a potential strategy for efficient drag reduction and antifouling capabilities.

Preparation of diazoresin/graphene oxide covalent coated capillary for separation of proteins by capillary electrophoresis

Protein adsorption on the inner surface of capillary is the main reason for the poor separation performance of capillary electrophoresis. Currently, many ways have been reported to inhibit protein adsorption, while they have numerous disadvantages, such as complicated, toxic and unstable. Here, by using photosensitive diazoresin (DR) as coupling agents and graphene oxide (GO) as coating, we found a simple, economic and environmental friendly approach to inhibit protein adsorption. Through layer by layer (LBL) self-assembly technique and unique photochemistry reaction of DR, a stable and efficient capillary coating could be obtained. The bare capillary, non-covalently GO coated capillary and covalently GO coated capillary were all characterized. Results indicated that the DR/GO covalently linked capillary coatings showed great separation performance of proteins with excellent stability and repeatability. Compared with bare capillary and non-covalent, better separation efficiency was achieved by covalent GO capillary column.

Protein corona formation and its constitutional changes on magnetic nanoparticles in serum featuring a polydehydroalanine coating: effects of charge and incubation conditions

The inevitable formation of a protein corona upon contact of nanoparticles with different biological fluids is of great interest in the context of biomedical applications. It is well established that the surface chemistry of the respective nanomaterial has tremendous impact on protein adsorption, both in terms of the actual amount as well as the type of proteins adsorbed. In that regard, especially polyzwitterions are discussed as coating materials as they are known to partially inhibit protein adsorption. We herein present comparative incubation studies on iron oxide nanoparticles (either single core (SPION) or multicore nanoparticles (MCNP)) after coating with either polyanionic or polyzwitterionic polymeric shells based on polydehydroalanine (PDha). Apart from varying surface charge and chemistry, also the influence of incubation time and temperature on the formation and composition of a protein corona upon exposure to fetal calf serum was investigated. The amounts of adsorbed biomolecules were determined using thermogravimetric analysis. SDS-PAGE experiments revealed information on protein composition as major components of the biomolecule corona. Our results show that distinctly lower amounts of proteins are adsorbed onto polyzwitterionic hybrid nanoparticles in general, but also the corona composition varies as indicated by elevated relative ratios of medium molecular weight proteins (i.e. proteins 25–100 kDa) estimated by non-specific silver protein staining. In addition, increasing relative amounts of albumin (67 kDa) via specific Western blot assays on PDha-coated MCNP are detected.

Design of a star-like hyperbranched polymer having hydrophilic arms for anti-biofouling coating.

A star-like hyperbranched polymer having hydrophilic poly(ethyleneoxide acrylate) arms (HB-PEO9A) was prepared by a core-first method based on atom transfer radical polymerization. The PEO9A layer coated on a solid substrate was dissolved by water, and effectively inhibited protein adsorption and cell adhesion.

Comparison of Surface Modification Techniques on Polydimethylsiloxane to Prevent Protein Adsorption

Polydimethylsiloxane (PDMS) is commonly used in microchip fabrication due to its biocompatibility, which is essential for biological applications, as well as other properties, including transparency to visible light, controllable gas permeability, mechanical and heat stability, and elasticity. Despite these properties, adsorption of biomolecules remains a major limitation of PDMS in biochips. Methods to prevent sample adsorption have been reported, and herein we compare several surface engineering methods that do not incorporate plasma pretreatment. Three methods - Teflon coating, water-repellent spraying, and perfluorodecyltrichlorosilane (FDTS) blending - were compared by evaluating the amount of fluorescein-isothiocyanate- conjugated bovine serum albumin (FITC-BSA) adsorbed onto the biochips. FDTS-blended PDMS significantly inhibited protein adsorption and showed good oleophobicity, but provided the lowest visible light transmittance of all materials tested.