Excellent Protein Resistance Research Articles

Tough and anisotropic Janus hydrogel for tendon injury repair with controlled release of bFGF in tendon microenvironment

To address the high complexity and challenging nature of large-scale tendon injury repair, an innovative Janus structured hydrogel patch (JAHP@bFGF) was designed in this study. The patch combines microenvironmental responsiveness with efficient repair function, aiming to optimise and accelerate the tendon healing process. The outer layer is a PVA/SA/Na3Cit hydrogel with excellent mechanical properties, protein resistance, and low friction, which provides firm support to the tendon and reduces adhesions to ensure the recovery of gliding function. The inner layer of TCSB@bFGF microgel responds intelligently to changes in the microenvironment, precisely regulates the release of bFGF, promotes cell proliferation and migration, accelerates tissue regeneration, and has high adhesion strength and antimicrobial properties, which significantly reduces the risk of postoperative infection. Experimental results show that JAHP@bFGF significantly optimises the healing process, accelerates the repair speed and improves the repair quality under simulated large-scale tendon injury conditions. The unique Janus surface design and the intelligent drug release function, in synergy, not only bring new hope to patients with large-scale tendon injuries, but also provide an important reference for the application of biomedical materials in the repair of complex tissues, which heralds the arrival of the era of more efficient and personalised tendon repair.

Strong yet tough cross-linked oligosiloxane elastomer with impact-resistant and antifouling properties

Polyurea with strong hydrogen bond interactions has excellent mechanical strength, toughness, and strain-rate-dependent behavior. However, the too fast polymerization and lack of functions limit its applications. In this study, a high-strength polyurea elastomer with impact resistance and antifouling function was prepared with secondary amine–oligosiloxane nanoclusters and a diisocyanate-terminated polytetrahydrofuran (PTMG)-based prepolymer, where the nanoclusters provide mechanical strength and antifouling ability while the urea segments give elasticity and toughness. Due to the lower reaction activity of secondary amine groups, the polymerization rate decreases, so that the operation time can be extended to more than 60 min without gelation. The polyurea elastomers exhibit excellent tensile strength (7.7–28.2 MPa) and strain rate sensitivity (10.8–16.6 MPa). The dynamic mechanical tests demonstrate that it has good energy dissipation capacity (tan δ ＞ 0.3 at 25–30 ℃). Bioassays show that the polyurea elastomers exhibit excellent protein resistance and can effectively inhibit the adhesion of microorganisms (bacteria S. aureus, E. coli, and Pseudomonas sp., as well as diatom N. incerta). The polyurea elastomers exhibit good versatility and can be combined with Kevlar fabric through a simple dip-coating process to form a composite with puncture resistance force as high as 108.8 N, 10 times higher than that of the one-layer Kevlar fabric. The prepared polyurea elastomers are expected to find applications in flexible wear protection, marine antifouling, and biomedical engineering.

Hemocompatibility of polyzwitterion-modified titanium dioxide nanotubes

Titanium dioxide nanotubes (TNTs) have attracted increasing interest as implantable materials due to their many desirable properties. However, their blood compatibility remains an issue. In this paper, TNTs of different diameters were modified with two types of zwitterionic polymers, poly(sulfobetaine methacrylate) (pSBMA) and poly(carboxybetaine methacrylate) (pCBMA), which were grafted onto the TNTs using ARGET-ATRP (activators regenerated by electron transfer atom transfer radical polymerization) method. Both pSBMA and pCBMA brushes coatings were found to greatly reduce adsorption of bovine serum albumin (BSA) and fibrinogen (Fib) onto the TNTs, showing excellent protein resistance. Moreover, the effects of the surface topography on the amount of protein adsorption were largely suppressed by the polyzwitterion coatings. The conformation of the protein adsorbed to the substrates was analyzed at the molecular level by Fourier-transform infrared reflection spectroscopy (FT-IR), which revealed that the BSA adsorbed on the polyzwitterion-modified TNTs adopted significantly different secondary structures from that on the virgin TNTs, whereas the conformation of the adsorbed Fib remained basically the same. The polyzwitterion-modified TNTs were found to be non-hemolytic, and platelet adhesion and activation was significantly reduced, showing excellent blood compatibility.

Synthesis and characterization of tailor-made zwitterionic lignin for resistance to protein adsorption

Tailor-made zwitterionic lignin with protein resistance was synthesized by a two-step grafting reaction. Lignin was modified using 3-Dimethylamino-1-propyl chloride hydrochloride and 1,3-Propanesultone by a continuous grafting reaction to provide sulfobetaine structures. Structural analyses from Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and proton nuclear magnetic resonance spectroscopy (1H NMR) confirmed the successful introduction of zwitterionic sulfobetaine structures into lignin. A higher dosage of 1,3-Propanesultone resulted in a higher density of zwitterionic sulfobetaine structures in lignin. A negative zeta potential, improved hydrophilicity, and slightly decreased thermal stability were observed after zwitterionication. Additionally, the protein (bovine serum albumin, BSA) adsorption of zwitterionic lignin (ZL2) was 27.0 ± 0.9 μg⋅ cm−2, which represented a significant decrease compared to the 114.3 ± 8.1 μg⋅ cm−2 measured for unmodified lignin. Moreover, ZL2 maintained comparable antioxidant activity to the commercial antioxidant butylated hydroxytoluene (BHT). Therefore, zwitterionic lignin with excellent protein resistance and antioxidant activity presents a promising prospect.

Intelligent nanogels with self-adaptive responsiveness for improved tumor drug delivery and augmented chemotherapy

For cancer nanomedicine, the main goal is to deliver therapeutic agents effectively to solid tumors. Here, we report the unique design of self-adaptive ultrafast charge-reversible chitosan-polypyrrole nanogels (CH-PPy NGs) for enhanced tumor delivery and augmented chemotherapy. CH was first grafted with PPy to form CH-PPy polymers that were used to form CH-PPy NGs through glutaraldehyde cross-linking via a miniemulsion method. The CH-PPy NGs could be finely treated with an alkaline solution to generate ultrafast charge-reversible CH-PPy–OH–4 NGs (R-NGs) with a negative charge at a physiological pH and a positive charge at a slightly acidic pH. The R-NGs display good cytocompatibility, excellent protein resistance, and high doxorubicin (DOX) loading efficiency. Encouragingly, the prepared R-NGs/DOX have prolonged blood circulation time, enhanced tumor accumulation, penetration and tumor cell uptake due to their self-adaptive charge switching to be positively charged, and responsive drug delivery for augmented chemotherapy of ovarian carcinoma in vivo. Notably, the tumor accumulation of R-NGs/DOX (around 4.7%) is much higher than the average tumor accumulation of other nanocarriers (less than 1%) reported elsewhere. The developed self-adaptive PPy-grafted CH NGs represent one of the advanced designs of nanomedicine that could be used for augmented antitumor therapy with low side effects.

Antifouling Antioxidant Zwitterionic Dextran Hydrogels as Wound Dressing Materials with Excellent Healing Activities.

Hydrogels as wound dressings have received great attention in recent years. It is highly important yet challenging to develop hydrogel dressings that are biocompatible and that can promote wound healing by lowering the risk of inflammatory responses. In this work, we designed and prepared zwitterionic dextran-based hydrogels using carboxybetaine dextran (CB-Dex) and sulfobetaine dextran (SB-Dex) as raw materials, respectively. The efficacy of CB-Dex and SB-Dex hydrogels in promoting wound recovery was evaluated using a mouse skin wound model. Results suggested that the zwitterionic dextran wound dressings showed a faster healing rate than natural dextran hydrogel and a commercial wound dressing (Duoderm film) due to their excellent protein resistance and capacity to scavenge free hydroxyl radicals. In addition, both CB-Dex and SB-Dex hydrogel wound dressings showed excellent cytocompatibility with NIH3T3 and L929 cells, as well as antibacterial adhesion against Staphylococcus aureus and Escherichia coli. Furthermore, both zwitterionic hydrogels demonstrated self-healing properties and can be stretched to adapt to irregular full-thickness wound beds. More importantly, they can be removed from the wound site painlessly by washing with normal saline. Overall, this work provided a new pathway to fabricate multifunctional polysaccharide hydrogels for wound treatment and pain relief when changing wound dressings.

Self-Generating and Self-Renewing Zwitterionic Polymer Surfaces for Marine Anti-Biofouling.

Regeneration of antifouling polymer surfaces after contamination or damage is an important issue, especially in complex marine environments. Here, inspired by the self-renewal of silyl acrylate polymers and the protein resistance of zwitterionic polymers, we prepared a novel hydrolysis-induced zwitterionic monomer, tertiary carboxybetaine triisopropylsilyl ester ethyl acrylate (TCBSA), and copolymerized it with methyl methacrylate (MMA). Such a copolymer rapidly self-generates a zwitterionic surface and provides fouling resistance in marine environments. Furthermore, TCBSA was copolymerized with MMA and 2-methylene-1,3-dioxepane (MDO), where MDO causes degradation of the polymers. Our study demonstrates that the degradation of the polymer is controlled, and the degradation rate increases with the external enzyme concentration in the seawater, leading to a self-renewing dynamic surface. Quartz crystal microbalance with dissipation measurements show that the polymeric coating with self-generating zwitterions has excellent protein resistance in seawater. Bioassays demonstrate that the coating can effectively inhibit the adhesion of marine bacteria (Pseudomonas sp.) and diatoms (Navicula incerta). The coating with a self-generating and self-renewing zwitterionic surface is potential to find applications in marine anti-biofouling.

Protein-resistant properties of poly(N-vinylpyrrolidone)-modified gold surfaces: The advantage of bottle-brushes over linear brushes

Poly(N-vinylpyrrolidone) (PVP)-modified surfaces have been shown to possess excellent protein resistance and good biocompatibility. However, PVP-modified surfaces with different molecular architectures have not been prepared, and their protein-resistant properties have not been studied. Herein, gold surfaces modified with linear PVP brush and PVP bottle-brush architectures were prepared by photoinitiated surface grafting polymerization. Ellipsometry, X-ray photoelectron spectroscopy (XPS), water contact angle, Fourier transform infrared (FTIR) spectroscopy and atomic force microscopy (AFM) were utilized to characterize the prepared surfaces. The protein-resistant properties were investigated by a quartz crystal microbalance with dissipation (QCM-D) with bovine serum albumin (BSA), fibrinogen (Fg) and lysozyme (Lyz). Compared with the ungrafted QCM-D chips, the PVP bottle-brush-grafted chips (9.3 nm thickness) showed superior protein resistance over linear PVP brush-grafted chips (9.9 nm thickness). Furthermore, the PVP bottle-brushes reduced the levels of BSA, Fg and Lyz adsorption by 97%, 85% and 69%, respectively. Moreover, to demonstrate potential applications as functional biosensors and in the biomedical field, PVP bottle-brushes containing glycopolymer-grafted gold surfaces were fabricated. Laser scanning confocal microscopy (LSCM) demonstrated that these glycopolymer surfaces showed excellent protein resistance and specific ConA binding ability. Overall, we speculate that the data presented here can provide useful information for the development of excellent antifouling materials and functional biosensors.

Biomimetic antifouling PDMS surface developed via well-defined polymer brushes for cardiovascular applications

Despite the distinct advantages of poly(dimethylsiloxane) (PDMS) for biomedical applications, because of its hydrophobic nature, suffers from non-specific protein adsorption and platelet adhesion and activation when used as a blood-contacting material. To confer hydrophilicity and biomolecules repelling characteristics, well-defined and high-density poly(2-hydroxyethyl methacrylate) (PHEMA) brushes are synthesized via surface-initiated atom transfer radical polymerization (SI-ATRP) on the PDMS substrate. First, PDMS surface is activated using an ultraviolet/ozone (UVO) wet treatment in water media to introduce hydroxy moieties without scarifying the surface property resulting a crack-free SiO2 surface. Then, 3-(2-bromoisobutyramido)propyl(trimethoxy)silane (BrTMOS), the active ATRP initiator, is immobilized on the UVO-treated PDMS surface to prepare a thin layer of hydrophilic PHEMA brush on PDMS substrate exhibiting excellent protein and platelet resistance. PHEMA brushes supply a biomimetic feature by combining antifouling properties due to hydrophilic characteristic with bioactive properties resulted from the presence of a high density hydroxy groups, which are subsequently used for biomolecules conjugation. The results indicate that grafting of PHEMA chains on the PDMS surface enhances the surface wettability which leads to a decrease in non-specific protein adsorption and platelet adhesion compared to the bare PDMS substrate. The adhered platelets on the PHEMA-tethered PDMS substrate maintain their normal round morphology. Furthermore, the conjugated gelatin macromolecules onto the tethered PHEMA chains promote the adherence and growth of human umbilical vein endothelial cells via ligand-receptor interactions.

Surface-Initiated Poly(oligo(2-alkyl-2-oxazoline)methacrylate) Brushes.

Polymer brushes are particularly performant antifouling coatings, owing to their high grafting density that prevents unwanted biomacromolecules to diffuse through the coating and adhere to the underlying substrate. In addition to this structural feature, polymer brushes require a relatively high level of hydrophilicity and a globally neutral structure to display ultrahigh protein resistance. Poly(2-alkyl-2-oxaolines) are attractive building blocks for such coatings as they can display relatively high hydrophilicity, owing to their amide repeat units, but can also be side-chain and end-chain functionalized relatively readily. However, poly(2-alkyl-2-oxazolines) have not yet been introduced through a radical-mediated grafting from polymer brush structure that would confer the high level of grafting density that is the hallmark of highly protein resistant brushes. Here, we present the formation of a series of poly(oligo(2-alkyl-2-oxazoline)methacrylate) brushes generated via a grafting from approach, via atom transfer radical polymerization. We characterize the chemical structure of the resulting coatings via ellipsometry, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. We show that allyl end groups can be introduced as a side chain of these brushes to allow functionalization via thiol-ene chemistry. We demonstrate the excellent protein resistance of these coatings in single protein solutions as well as serum solutions at concentration typically used for cell culture. Finally, we demonstrate the feasibility of using these brushes for the micropatterning of cells and the generation of cell-based assays.

Preparation and evaluation of a self-anticlotting dialyzer via an interface crosslinking approach

It is challenging to improve the hemocompatibility of commercial dialyzers packaging more than 10,000 fibers. Herein, we report the preparation and evaluation of a self-anticlotting Polysulfone dialyzer via an interface crosslinking approach. By modulating the conformation of sulfate, carboxyl groups and pyrrolidone (VP) in heparin-like polymers, the hemocompatibility of the dialyzer was significantly improved. It was found that the sequential structure of functional groups influenced the anticoagulant performances substantially. The hollow fiber modified by the blended polymer (Poly (N-vinyl-2-pyrrolidone-co-triethoxyvinylsilane) and poly (Sodium 4-vinylbenzenssulfonate-co-triethoxyvinylsilane-co-Acrylic acid) (P(VP-VTES)-b-P(SSNa-VTES-AA))) exhibited better hemocompatibility than the contrast membrane modified by poly (Acrylic acid-co-triethoxyvinylsilane-co -N-vinyl-2-pyrrolidone-co- -co-Sodium 4-vinylbenzenssulfonate) (P(AA-VTES-VP-SSNa)). The chemical composition was determined by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectra (FTIR). The morphology of the hollow fiber membranes was observed by a scanning electron microscopy (SEM). The thrombin time (TT), plasma fibrinogen (FIB), activated partial thromboplastin time (APTT), prothrombin time (PT) and protein adsorption were measured to examine the hemocompatibility. The modified hollow fiber showed self-anticlotting properties with excellent protein resistance, remarkably prolonged coagulation time (APTT > 600 s), suppressed complement activation and nontoxicity to osteoblasts. The modified dialyzer showed practicable ultrafiltration coefficient and clearance performance, indicating its great potential application in dialysis treatment.

Synthesis of Well-Defined PVDF-Based Amphiphilic Block Copolymer via Iodine Transfer Polymerization for Antifouling Membrane Application

An innovative strategy is devised to obtain poly(vinylidene fluoride) membranes with splendid fouling resistance using amphiphilic block copolymer containing poly(vinylidene fluoride) (PVDF) segments as modification agent. The PVDF-based block copolymer with poly[2-(N,N-dimethylamino) ethyl methacrylate] as the hydrophilic segment (PVDF-b-PDMAEMA) was successfully fabricated by iodine transfer polymerization. This strategy not only improved the PVDF membrane structure and hydrophilicity but also assisted in fouling resistance properties as an ultrafiltration membrane. The obtained PVDF/PVDF-b-PDMAEMA blend membrane displayed excellent water flux, which was enhanced 3 fold compared with that of the original membrane. The bovine serum albumin (BSA) rejection ratio (≥90%) was maintained at a reasonable level. Meanwhile, by incorporation of the amphiphilic block copolymer, the PVDF-based modified membrane possessed excellent protein resistance and high flux recovery ability. The blend membranes with high BSA ...

Preparation of hydrophilic polymer brushes magnetic microspheres by surface-initiated for magnetic dispersive solid phase extraction of tetracycline antibiotic residues from honey

Activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP) was applied to the continuous grafting of polybasic polymers and poly(ethylene glycol) (PEG) brushes on the surface of the magnetic microspheres (MMs). At first, the MMs were coated with silica gel, modified by amino group, and then 2-bromoisobutyryl bromide was grafted on the surface of MMs. After that, the hydrophilic polymer brushes magnetic microspheres (HMMs) were prepared by polymerization on the surface of the MMs. HMMs were characterized by transmission electron microscope (TEM) and Fourier transform-infrared (FT-IR) spectrometer. The adsorption performance to protein was studied. The results demonstrated that HMMs have the relatively uniform particle size, good dispersity and excellent protein resistance properties. Tetracycline antibiotics (TCs, tetracycline hydrochloride, chlortetracycline hydrochloride and doxycycline hydrochloride) in honey samples were determined by magnetic dispersion solid phase extraction (MDSPE) using the prepared HMMs and high performance liquid chromatography (HPLC). The average recoveries were obtained in the range of 85.8%-94.5%. The limits of detection (LODs) and limits of quantification (LOQs) of the proposed method were in the ranges of 1.92-2.56 μg/kg and 6.40-8.53 μg/kg, respectively. The proposed method was successfully applied to fast clean-up and enrichment of the TCs residues in honey.

Serum Protein-Resistant Behavior of Multisite-Bound Poly(ethylene glycol) Chains on Iron Oxide Surfaces.

Recent surveys have shown that the number of nanoparticle-based formulations actually used at a clinical level is significantly lower than that expected a decade ago. One reason for this is that the physicochemical properties of nanoparticles fall short for handling the complexity of biological environments and preventing nonspecific protein adsorption. In this study, we address the issue of the interactions of plasma proteins with polymer-coated surfaces. With this aim, we use a noncovalent grafting-to method to functionalize iron oxide sub-10 nm nanoparticles and iron oxide flat substrates and compare their protein responses. The functionalized copolymers consist of alternating poly(ethylene glycol) (PEG) chains and phosphonic acid grafted on the same backbone. Quartz crystal microbalance with dissipation was used to monitor polymer adsorption kinetics and evaluate the resistance to protein adsorption. On flat substrates, functionalized PEG copolymers adsorb and form a brush in moderate or highly stretched regimes, with densities between 0.15 and 1.5 nm–2. PEG layers using phosphonic acid as linkers exhibit excellent protein resistance. In contrast, layers prepared with carboxylic acid as the grafting agent exhibit mitigated protein responses and layer destructuration. The present study establishes a correlation between the long-term stability of PEG-coated particles in biofluids and the protein resistance of surfaces coated with the same polymers.

Controlling the Integration of Polyvinylpyrrolidone onto Substrate by Quartz Crystal Microbalance with Dissipation To Achieve Excellent Protein Resistance and Detoxification.

Blood purification systems, in which the adsorbent removes exogenous and endogenous toxins from the blood, are widely used in clinical practice. To improve the protein resistance of and detoxification by the adsorbent, researchers can modify the adsorbent with functional molecules, such as polyvinylpyrrolidone (PVP). However, achieving precise control of the functional molecular density, which is crucial to the activity of the adsorbent, remains a significant challenge. In the present study, we prepared a model system for blood purification adsorbents in which we controlled the integration density of PVP molecules of different molecular weights on an Au substrate by quartz crystal microbalance with dissipation (QCM-D). We characterized the samples with atomic force microscopy, X-ray photoelectron spectroscopy, and QCM-D and found that the molecular density and the chain length of the PVP molecules played important roles in determining the properties of the sample. At the optimal condition, the modified sample demonstrated strong resistance to plasma proteins, decreasing the adsorption of human serum albumin (HSA) and fibrinogen (Fg) by 92.5% and 79.2%, respectively. In addition, the modified sample exhibited excellent detoxification, and the adsorption of bilirubin increased 2.6-fold. Interestingly, subsequent atomistic molecular dynamics simulations indicated that the favorable interactions between PVP and bilirubin were dominated by hydrophobic interactions. An in vitro platelet adhesion assay showed that the adhesion of platelets on the sample decreased and that the platelets were maintained in an inactivated state. The CCK-8 assay indicated that the modified sample exhibited negligible cytotoxicity to L929 cells. These results demonstrated that our method holds great potential for the modification of adsorbents in blood purification systems.

Physical Cross-Linking Starch-Based Zwitterionic Hydrogel Exhibiting Excellent Biocompatibility, Protein Resistance, and Biodegradability

In this work, a novel starch-based zwitterionic copolymer, starch-graft-poly(sulfobetaine methacrylate) (ST-g-PSBMA), was synthesized via Atom Transfer Radical Polymerization. Starch, which formed the main chain, can be degraded completely in vivo, and the pendent segments of PSBMA endowed the copolymer with excellent protein resistance properties. This ST-g-PSBMA copolymer could self-assemble into a physical hydrogel in normal saline, and studies of the formation mechanism indicated that the generation of the physical hydrogel was driven by electrostatic interactions between PSBMA segments. The obtained hydrogels were subjected to detailed analysis by scanning electron microscopy, swelling ratio, protein resistance, and rheology tests. Toxicity and hemolysis analysis demonstrated that the ST-g-PSBMA hydrogels possess excellent biocompatibility and hemocompatibility. Moreover, the cytokine secretion assays (IL-6, TNF-α, and NO) confirmed that ST-g-PSBMA hydrogels had low potential to trigger the activation of macrophages and were suitable for in vivo biomedical applications. On the basis of these in vitro results, the ST-g-PSBMA hydrogels were implanted in SD rats. The tissue responses to hydrogel implantation and the hydrogel degradation in vivo were determined by histological analysis (Hematoxylin and eosin, Van Gieson, and Masson's Trichrome stains). The results presented in this study demonstrate that the physical cross-linking, starch-based zwitterionic hydrogels possess excellent protein resistance, low macrophage-activation properties, and good biocompatibility, and they are a promising candidate for an in vivo biomedical application platform.

Zwitterionic-Modified Starch-Based Stealth Micelles for Prolonging Circulation Time and Reducing Macrophage Response.

Over the last few decades, nanoparticles have been emerging as useful means to improve the therapeutic efficacy of drug delivery and medical diagnoses. However, the heterogeneity and complexity of blood as a medium is a fundamental problem; large amounts of protein can be adsorbed onto the surface of nanoparticles and cause their rapid clearance before reaching their target sites, resulting in the failure of drug delivery. To overcome this challenge, we present a rationally designed starch derivative (SB-ST-OC) with both a superhydrophilic moiety of zwitterionic sulfobetaine (SB) and a hydrophobic segment of octane (OC) as functional groups, which can self-assemble into "stealth" micelles (SSO micelles). The superhydrophilic SB kept the micelles stable against aggregation in complex media and imbued them with "stealth" properties, eventually extending their circulation time in blood. In stability and hemolysis tests the SSO micelles showed excellent protein resistance properties and hemocompatibility. Moreover, a phagocytosis test and cytokine secretion assay confirmed that the SSO micelles had less potential to trigger the activation of macrophages and were more suitable as a drug delivery candidate in vivo. On the basis of these results, doxorubicin (DOX), a hydrophobic drug, was used to investigate the potential application of this novel starch derivative in vivo. The results of the pharmacokinetic study showed that the values of the plasma area under the concentration curve (AUC) and elimination half-life (T1/2) of the SSO micelles were higher than those of micelles without SB modifications. In conclusion, the combination of excellent protein resistance, lower macrophage activation, and longer circulation time in vivo makes this synthesized novel starch derivative a promising candidate as a hydrophobic drug carrier for long-term circulation in vivo.

Preparation and characterization of protein resistant zwitterionic starches: The effect of substitution degrees

Zwitterionic polymers are known to possess excellent protein resistance due to high hydration capacity of their zwitterionic moieties. In this study, polysaccharide‐based zwitterionic polymers 3‐dimethyl(propyl) ammonium propanesulfonate starches (Z‐starches) with different degrees of substitution of the zwitterionic moieties (DSZM) were synthesized successfully. The value of DSZM can be controlled exactly in the range of 0–0.46. The cytotoxicity of Z‐starches with different DSZM was evaluated by an MTT assay, and the Z‐starch with DSZM of 0.26 promoted cell proliferation when the concentration of this polymer solution was 1–25 mg/mL. The protein resistance and cell adhesion of Z‐starch hydrogels were evaluated, and the amount of protein adsorption or cell adhesion on Z‐starch hydrogels was decreased as the DSZM increased. The preliminary protein resistance and cell adhesion tests suggest that the Z‐starches have potential applications in drug delivery carriers and coatings of implanted sensors where protein resistance is needed.

Immobilizing PEO–PPO–PEO triblock copolymers on hydrophobic surfaces and its effect on protein and platelet: A combined study using QCM-D and DPI

Dual polarization interferometry was used to monitor the immobilization dynamics of four Pluronics on hydrophobic surfaces and to elucidate the effect of Pluronic conformation on protein adsorption. The proportion of hydrophobic chain segments and not the length of the hydrophobic chain can influence the chain densities of the Pluronics. The immobilized densities of the Pluronics resulted from competition between the hydration of polyethylene oxide (PEO) in the aqueous solution and the hydrophobic interaction of polypropylene oxide on the substrate. P-123 obtained the largest graft mass (2.89±0.25ng/mm2) because of the dominant effect of hydrophobic interactions. Hydrophobic segments of P-123 were anchored slowly and step-wise on the C18 substrate. P-123 exhibited the largest hydrophobic chain segment proportion (propylene oxide/ethylene oxide=3.63) and formed a brush chain conformation, indicating excellent protein and platelet resistance. The result of quartz crystal microbalance with dissipation further confirmed that the PEO conformation in P-123 on the substrate exhibited a relatively extended brush chain, and that L-35 showed relatively loose and pancake-like structures. The PEO in P-123 regulated the conformation to maintain the native conformation and resist the adsorption of bovine serum albumin (BSA). Thus, the hemocompatibilities of the immobilized Pluronics were influenced by the proportion of hydrophobic chain segments and their PEO conformations.

Investigation of nonfouling polypeptides of poly(glutamic acid) with lysine side chains synthesized by EDC·HCl/HOBt chemistry

Nonfouling polypeptides with homogenous alternating charges draw peoples’ attentions for their potential capability in biodegradation. Homogenous glutamic acid (E) and lysine (K) polypeptides were proposed and synthesized before. In this work, a new polypeptide formed by poly(glutamic acid) with lysine side chains (poly(E)-K) was synthesized by facile EDC·HCl/HOBt chemistry and investigated. Results show that these polypeptides also have good nonspecific protein resistance determined by enzyme-linked immunosorbent assay. The lowest nonspecific adsorption of the model proteins, anti-IgG and fibrinogen (Fg), on the self-assembling monolayers (SAMs) surface of poly(E)-K was only 3.3 ± 1.8 and 4.4 ± 1.6%, respectively, when protein adsorption on tissue culture polystyrene surface was set as 100%. And, the relative nonspecific protein adsorption increases when the polypeptide molecular weight increases due to the repression of low density polymer brushes. Moreover, almost no obvious cytotoxicity and hemolytic activity in vitro were detected. This work suggests that polypeptides with various formats of homogenous balanced charges could achieve excellent nonspecific protein resistance, which might be the intrinsic reason for the coexistence of high concentration serum proteins in blood.