Non-delaminating Polymer Hydrogel Coatings via C,H-Insertion Crosslinking (CHic) - A Case Study of Poly(oxanorbornenes)

Antibacterial-Based Hydrogel Coatings and Their Application in the Biomedical Field-A Review

Hydrogels exhibit excellent moldability, biodegradability, biocompatibility, and extracellular matrix-like properties, which make them widely used in biomedical fields. Because of their unique three-dimensional crosslinked hydrophilic networks, hydrogels can encapsulate various materials, such as small molecules, polymers, and particles; this has become a hot research topic in the antibacterial field. The surface modification of biomaterials by using antibacterial hydrogels as coatings contributes to the biomaterial activity and offers wide prospects for development. A variety of surface chemical strategies have been developed to bind hydrogels to the substrate surface stably. We first introduce the preparation method for antibacterial coatings in this review, which includes surface-initiated graft crosslinking polymerization, anchoring the hydrogel coating to the substrate surface, and the LbL self-assembly technique to coat crosslinked hydrogels. Then, we summarize the applications of hydrogel coating in the biomedical antibacterial field. Hydrogel itself has certain antibacterial properties, but the antibacterial effect is not sufficient. In recent research, in order to optimize its antibacterial performance, the following three antibacterial strategies are mainly adopted: bacterial repellent and inhibition, contact surface killing of bacteria, and release of antibacterial agents. We systematically introduce the antibacterial mechanism of each strategy. The review aims to provide reference for the further development and application of hydrogel coatings.

Antibacterial hydrogel coating: Strategies in surface chemistry

Hydrogels have emerged as promising antimicrobial materials due to their unique three-dimensional structure, which provides sufficient capacity to accommodate various materials, including small molecules, polymers and particles. Coating substrates with antibacterial hydrogel layers has been recognized as an effective strategy to combat bacterial colonization. To prevent possible delamination of hydrogel coatings from substrates, it is crucial to attach hydrogel layers via stronger links, such as covalent bonds. To date, various surface chemical strategies have been developed to introduce hydrogel coatings on different substrates. In this review, we first give a brief introduction of the major strategies for designing antibacterial coatings. Then, we summarize the chemical methods used to fix the antibacterial hydrogel layer on the substrate, which include surface-initiated graft crosslinking polymerization, anchoring the hydrogel layer on the surface during crosslinking, and chemical crosslinking of layer-by-layer coating. The reaction mechanisms of each method and matched pretreatment strategies are systemically documented with the aim of introducing available protocols to researchers in related fields for designing hydrogel-coated antibacterial surfaces.

Self-Regenerating Antimicrobial Polymer Surfaces via Multilayer-Design - Sequential and Triggered Layer Shedding under Physiological Conditions

Regeneration of materials properties through surface regeneration could extend the lifetime of devices and is still an emerging field of research. (Self-)regenerating antimicrobial polymer surfaces could help to fight biofilm formation and related bacterial infections. In this paper, four different polymer multilayer designs for the regeneration of antimicrobial surfaces by layer shedding are presented. The multilayer architectures consist of 100-200 nm thick, discrete polymer layers. They are made from poly(guanidinium oxanorbornene) networks as the antimicrobial component, and different interlayers made from degradable poly(adipic anhydrides), depolymerizable poly(ethyl glyoxylate), or water-soluble poly(acrylamide). Layer shedding is designed to occur after hydrolysis, dissolution or depolymerization under simulated physiological conditions. The multilayer fabrication and disassembly is monitored by fluorescence microscopy, ellipsometry FT-IR spectroscopy and atomic force microscopy. By testing the antimicrobial activity of the restored surfaces, their functional integrity after layer shedding is confirmed.