Facile surface modification of silicone rubber with zwitterionic polymers for improving blood compatibility

Two-electron oxidized polyphenol chemistry-inspired superhydrophilic drug-carrying coatings for the construction of multifunctional nasolacrimal duct stents

Nasolacrimal duct obstruction due to infection, inflammation, or excessive fibroblast proliferation may result in persistent tearing, intraocular inflammation, or even blindness. In this study, surface engineering techniques are applied to nasolacrimal duct stents for the first time. Based on the functioning of marine mussels, "one-pot" and "stepwise" methods were employed to construct a novel multifunctional superhydrophilic PDA/RAP coating using dopamine and rapamycin. Micron-sized rapamycin crystals combined with nano-sized polydopamine particles form a micro-nano topographical structure. Therefore, acting synergistically with in situ-generated hydrophilic groups (amino, carboxyl, and phenolic hydroxyl), they impart excellent and long-lasting superhydrophilicity to the nasolacrimal duct stent. The PDA/RAP coating effectively maintained the stability of the initial microenvironment during stent implantation by inhibiting the onset of acute inflammation and infection during the early stages of implantation. Meanwhile, the rapamycin crystals, supported by the superhydrophilic platform, exhibited a sustained-release capability that helped them to better exert their anti-inflammatory, antibacterial, and anti-fibroblast proliferative properties, ensuring conducive conditions for the rapid repair of nasolacrimal duct epithelial cells, verified by a series of experiments. In conclusion, the PDA/RAP hydrophilic coating has anti-inflammatory, antifibrotic, antibacterial, and antithrombotic properties, offering a new strategy to address restenosis following clinical nasolacrimal duct stent implantation.

Recent Advances on the Fabrication of Antifouling Phase-Inversion Membranes by Physical Blending Modification Method

Membrane technology is an essential tool for water treatment and biomedical applications. Despite their extensive use in these fields, polymeric-based membranes still face several challenges, including instability, low mechanical strength, and propensity to fouling. The latter point has attracted the attention of numerous teams worldwide developing antifouling materials for membranes and interfaces. A convenient method to prepare antifouling membranes is via physical blending (or simply blending), which is a one-step method that consists of mixing the main matrix polymer and the antifouling material prior to casting and film formation by a phase inversion process. This review focuses on the recent development (past 10 years) of antifouling membranes via this method and uses different phase-inversion processes including liquid-induced phase separation, vapor induced phase separation, and thermally induced phase separation. Antifouling materials used in these recent studies including polymers, metals, ceramics, and carbon-based and porous nanomaterials are also surveyed. Furthermore, the assessment of antifouling properties and performances are extensively summarized. Finally, we conclude this review with a list of technical and scientific challenges that still need to be overcome to improve the functional properties and widen the range of applications of antifouling membranes prepared by blending modification.

Zwitterionic/phosphonate copolymer coatings endow excellent antifouling properties and robust re-mineralization ability of dentine substrates

Inhibition of biofilm formation and induction of the re-mineralization of damaged dental tissues are two major strategies to combat dental hypersensitivity (DH). However, single component synthetic materials normally cannot fulfil these two functions during the repairing of damaged dental tissues. Here, we report zwitterionic phosphorylcholine based polymers to be a new type of dual functional coating for the repairing of DH. Zwitterionic/phosphonate copolymers, p(DEMMP-co-MPC), bearing varied zwitterionic contents (95 and 75 mol%) were prepared through conventional radical copolymerization. ¹H NMR spectroscopy clearly indicated the precise preparation of the copolymers. The copolymers can be easily coated on dentine substrates based on the high affinity between the phosphonate group and the calcium phosphate minerals of the dentine substrates, as evidenced by XPS and water contact angle measurements. Antifouling evaluations indicated that zwitterionic coating can efficiently inhibit protein adsorption (BSA, egg white, and milk, by 85%) and bacterial adhesion (by 97.1%) on dentine substrates. Furthermore, in vitro and in vivo experiments consistently indicated that the zwitterionic coating could not only induce the robust re-mineralization of dentine surfaces, but also template the extensive re-mineralization of dentine tubules to a similar level of pristine dentine. Both the antifouling properties and the re-mineralization potency are positively correlated with the content of zwitterionic pMPC in the coating copolymer. These findings may provide the zwitterionic phosphorylcholine based materials to be a promising candidate to treat dental hypersensitivity and other related dental diseases.

Enabling Antibacterial and Antifouling Coating via Grafting of a Nitric Oxide-Releasing Ionic Liquid on Silicone Rubber

Infections caused by bacteria and biofilms on the surfaces of biomedical devices and implants pose serious threats to public health. Herein, a nitric oxide (NO) gas-releasing quaternary ammonium-type ionic liquid (IL)-based coating on polydimethylsiloxane (PDMS), PDIL-NO, with effective and long-acting antibacterial and antifouling properties was prepared. N-(2-((2, 3-Dimethylbut-3-enoyl)oxy)ethyl)-N, N-dimethyloctan-1-aminium bromide (IL-Br), and 2-methyl-2-propenoic acid 2-(2-methoxyethoxy) ethyl ester were covalently grafted onto the surfaces of PDMS by a thiol-ene click chemical reaction, followed by incorporation of l-proline anions (Pro^-) through anion exchange with Br^- to adsorb NO gas. The prepared PDIL-NO showed a prolonged NO-releasing time (>1440 min) and a relatively high concentration (88 μM). Additionally, PDIL-NO possessed good and long-term antimicrobial activity, and could effectively reduce the adsorption of bovine serum albumin and adhesion of bacteria, as well as inhibit wound infection and reduce inflammation in vivo due to the synergetic effect of IL and the released NO. This study may provide a new approach to combat bacterial infections associated with biomedical devices and implants.

A novel Y-shaped photoiniferter used for the construction of polydimethylsiloxane surfaces with antibacterial and antifouling properties

The simultaneous introduction of two new functionalities into the same polymeric substrate under mild reaction conditions is an interesting and important topic. Herein, dual-functional polydimethylsiloxane (PDMS) surfaces with antibacterial and antifouling properties were conveniently developed via a novel Y-shaped asymmetric dual-functional photoiniferter (Y-iniferter). The Y-iniferter was initially immobilized onto the PDMS surface by radical coupling under visible light irradiation. Afterwards, poly(2-hydroxyethyl methacrylate) (PHEMA) brushes and antibacterial ionic liquid (IL) fragments were simultaneously immobilized on the Y-iniferter-modified PDMS surfaces by combining the sulfur(VI)-fluoride exchange (SuFEx) click reaction and UV-photoinitiated polymerization. Experiments using E. coli as a model bacterium demonstrated that the modified PDMS surfaces had both the expected antibacterial properties of the IL fragments and the excellent antifouling properties of PHEMA brushes. Furthermore, the cytotoxicity of the modified PDMS surfaces to L929 cells was examined in vitro with a CCK-8 assay, which showed that the modified surfaces maintained excellent cytocompatibility. Briefly, this strategy of constructing an antibacterial and antifouling PDMS surface has the advantages of simplicity and convenience and might inspire the construction of diverse dual-functional surfaces by utilizing PDMS more effectively.

Phosphonate/zwitterionic/cationic terpolymers as high-efficiency bactericidal and antifouling coatings for metallic substrates

Bacteria associated infection is a critical challenge for metallic implants and devices in biomedical applications. Here, we report phosphonate/zwitterionic/quaternary amine terpolymers as a new type of antifouling and bactericidal coating for metallic substrates. Through reversible-addition fragmentation chain transfer polymerization (RAFT) and quaternization, well-controlled phosphonate/zwitterionic/cationic terpolymers with identical phosphonate segments (repeat units of 15) and varied zwitterionic and cationic components (nSBMA : nTMAEMA = 64 : 0, 54 : 18, 18 : 32, 9 : 52, and 0 : 70) were precisely prepared. The polymers can be coated on TC4 substrates based on the strong coordination between phosphonate groups and metallic substrates, as evidenced by water contact angle and XPS tests. Bactericidal evaluation revealed that the antibacterial efficiency was enhanced with the increase of cationic content in the coating polymers. TC4 substrates coated with the polymer coating with a cationic segment of 70 repeat units were able to kill 97.5 and 94.0% of S. aureus and E. coli, respectively. By virtue of the antifouling ability of the zwitterionic component and the bactericidal ability of the cationic component, the antibacterial efficiency was increased to 99.5% without significant compromising of the cytocompatibility. Meanwhile, the dual functional terpolymers could be easily applied on other metallic substrates, such as titanium, stainless steel, and Ni/Cr alloy, which were able to kill up to 97.9% of S. aureus and 99.9% of E. coli, respectively, endowing the excellent antibacterial properties to general bio-metals. The high-efficiency antibacterial modification strategy demonstrated here may find many applications on metallic implants and devices to combat bacterial associated infections.

Zwitterionic Polymer-Grafted Polylactic Acid Vascular Patches Based on a Decellularized Scaffold for Tissue Engineering

More than 10 million people suffer from cardiovascular diseases, and diseased blood vessels need to be treated with vascular patches. For a vascular patch, good affinity for endothelial progenitor cells is a key factor in promoting the formation of endothelial tissue-endothelialization. To construct such a vascular patch with good cell affnity, in this work, we first synthesized a reactive zwitterionic organophosphate containing a phosphorylcholine headgroup: 6-(acryloyloxy)hexyl-2-(N-isopropyl-N,N-dimethylammonio)ethyl phosphate (AHEP). We then grafted AHEP onto a polylactic acid (PLA)-coated decellularized scaffold to obtain a vascular patch. Its hydrophilicity and biocompatibility were investigated. Its in vivo performance was also examined in a pig model with B-ultrasonography, Doppler spectra, and computed tomography angiography. The vascular patch demonstrated a nonhemolytic property, noncytotoxicity, long in vitro coagulation times, the strong ability to resist platelet adhesion, and a good affinity for endothelial progenitor cells. The vascular patch was able to maintain the long-term patency (5 months) of surgical arteries. Hence, the zwitterionic polymer-grafted PLA vascular patch may be a promising candidate for vascular tissue engineering.

Rational design of a zwitterionic–phosphonic copolymer for the surface antifouling modification of multiple biomedical metals

The relationship between the composition of the copolymer and the antifouling ability conferred to the metallic substrates has been established.

Zwitterionic copolymers bearing phosphonate or phosphonic motifs as novel metal-anchorable anti-fouling coatings

Developing a facile but efficient anti-fouling surface coating is highly required for metallic implants. Here, we report two kinds of zwitterionic copolymers (both random and block) bearing phosphonic/phosphonate motifs/segments as novel metal anchorable antifouling coatings. Through conventional free radical polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization, three types of zwitterionic-phosphonic random copolymers with varying mol. ratios (9 : 1, 8 : 2, and 6 : 4) and a phosphonate-zwitterionic block copolymer were precisely prepared based on zwitterionic sulfobetaine methacrylate (SBMA) and phosphonate/phosphonic methacrylate. As evidenced by XPS and water contact angle tests, the two kinds of copolymers with distinguished presenting manners of the metal-anchorable phosphonate/phosphonic motifs were all successfully immobilized on the Ti substrates through a facile one-step post-functionalization. The immobilized copolymers equally exhibited strong inhibition of protein adsorption, platelet adhesion, and bacterial adhesion, endowing significantly improved antifouling ability to the metallic substrates. This work not only provides a novel approach to improve the antifouling ability of Ti substrates, the utilization of phosphonic/phosphonate based copolymers as efficient metal-anchorable coatings may offer a new platform for versatile surface functionalization of many metallic substrates.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Biofunctionalization of silicone rubber with microgroove-patterned surface and carbon-ion implantation to enhance biocompatibility and reduce capsule formation

Purpose

Silicone rubber implants have been widely used to repair soft tissue defects and deformities. However, poor biocompatibility can elicit capsule formation, usually resulting in prosthesis contracture and displacement in long-term usage. To overcome this problem, this study investigated the properties of silicone rubber materials with or without a microgroove-patterned surface and with or without carbon (C)-ion implantation.

Materials and methods

Atomic force microscopy, X-ray photoelectron spectroscopy, and a water contact angle test were used to characterize surface morphology and physicochemical properties. Cytocompatibility was investigated by a cell adhesion experiment, immunofluorescence staining, a Cell Counting Kit-8 assay, and scanning electron microscopy in vitro. Histocompatibility was evaluated by studying the inflammatory response and fiber capsule formation that developed after subcutaneous implantation in rats for 7 days, 15 days, and 30 days in vivo.

Results

Parallel microgrooves were found on the surfaces of patterned silicone rubber (P-SR) and patterned C-ion-implanted silicone rubber (PC-SR). Irregular larger peaks and deeper valleys were present on the surface of silicone rubber implanted with C ions (C-SR). The silicone rubber surfaces with microgroove patterns had stable physical and chemical properties and exhibited moderate hydrophobicity. PC-SR exhibited moderately increased dermal fibroblast cell adhesion and growth, and its surface microstructure promoted orderly cell growth. Histocompatibility experiments on animals showed that both the anti-inflammatory and antifibrosis properties of PC-SR were slightly better than those of the other materials, and there was also a lower capsular contracture rate and less collagen deposition around implants made from PC-SR.

Conclusion

Although the surface chemical properties, dermal fibroblast cell growth, and cell adhesion were not changed by microgroove pattern modification, a more orderly cell arrangement was obtained, leading to enhanced biocompatibility and reduced capsule formation. Thus, this approach to the modification of silicone rubber, in combination with C-ion implantation, should be considered for further investigation and application.

Carbon Ion Implantation: A Good Method to Enhance the Biocompatibility of Silicone Rubber

BACKGROUND

Silicone rubber and silicone rubber-based materials have been used as medical tissue implants in the field of plastic surgery for many years, but there are still some reports of adverse reactions to long-term implants. Earlier studies have shown that ion implantation could enhance the biocompatibility of biomaterials. However, whether ion implantation has a good effect on silicone rubber is unknown.

METHODS

Three types of carbon ion silicone rubber were obtained by implanting three doses of carbon ions. Then, the antibacterial adhesion properties and the in vivo host responses were evaluated. The antibacterial adhesion properties were examined by plate colony counting, fluorescence staining, and scanning electron microscopic observation. The host responses were evaluated by surveying inflammation and fiber capsule formation that developed after subcutaneous implantation in Sprague-Dawley rats for 7, 30, 90, and 180 days. In addition, the possible mechanism by which ion implantation enhanced the biocompatibility of the biomaterial was investigated and discussed.

RESULTS

Carbon ion silicone rubber exhibits less bacterial adhesion, less collagen deposition, and thinner and weaker tissue capsules. Immunohistochemical staining results for CD4, tumor necrosis factor-α, α-smooth muscle actin, and elastin showed the possible mechanism enhancing the biocompatibility of silicone rubber. These data indicate that carbon ion silicone rubber exhibits good antibacterial adhesion properties and triggers thinner and weaker tissue capsules. In addition, high surface roughness and high zeta potential may be the main factors that induce the unique biocompatibility of carbon ion silicone rubber.

CONCLUSION

Ion implantation should be considered for further investigation and application, and carbon ion silicone rubber could be a better biomaterial to decrease silicone rubber-initiated complications.

Review: physico-chemical modification as a versatile strategy for the biocompatibility enhancement of biomaterials

Physico-chemical modification induced improvement in biocompatibility of materials.

Surface modification and endothelialization of biomaterials as potential scaffolds for vascular tissue engineering applications

This review highlights the recent developments of surface modification and endothelialization of biomaterials in vascular tissue engineering applications.

Evaluation of the cytocompatibility hemocompatibility in vivo bone tissue regenerating capability of different PCL blends

In this study, the optimized formulations of polycaprolactone (PCL) combined with poly(lactic-co-glycolic acid) (PLGA), gelatin (GEL), and biphasic calcium phosphate (BCP) were analyzed in terms of cytocompatibility with bone-related cells, hemocompatibility, and in vivo bone-regenerating capacity to determine their potentials for bone tissue regeneration. Fiber morphology of PCL/GEL and PCL/BCP electrospun mats considerably differs from that of the PCL membrane. Based on the contact angle analyses, the addition of GEL and PLGA was shown to reduce the hydrophobicity of these membranes. The assessment of in vitro cytocompatibility using MC3T3-E1 cells indicated that all of the membranes were suitable for pre-osteoblast proliferation and adhesion, with PCL/BCP having a significantly higher reading after seven days of incubation. The results of the in vitro hemocompatibility of the different fibrous scaffolds suggest that coagulation and platelet adhesion were higher for hydrophobic membranes (PCL and PCL/PLGA), while hemolysis can be associated with fiber morphology. The potential of the membranes for bone regeneration was determined by analyzing the microCT data and tissue sections of samples implanted in 5 mm sized defects (one and two months). Although all of the membranes were suitable for pre-osteoblast proliferation, in vivo bone regeneration after two months was found to be significantly higher in PCL/BCP (p < 0.001).