Long-term antibacterial, antioxidative, and bioadhesive hydrogel wound dressing for infected wound healing applications.

Bacterial infection and oxidative stress hinder clinical wound healing. Therefore, wound dressings with antibacterial and antioxidative properties are urgently needed. In this study, a type of quaternized lignin (QL) functionalized poly(hexamethylene biguanide) hydrochloride (PHMB) complex incorporated polyacrylamide (QL-PHMB-PAM) hydrogel was developed as a multifunctional dressing material for the promotion of infected wound repair. Owing to the abundant catechol groups of quaternized lignin, the QL-PHMB-PAM hydrogel exhibited robust repeatable adhesiveness to various substrates with antioxidative properties. Additionally, the antibacterial components of PHMB in the QL-PHMB-PAM composite hydrogel showed high efficiency and long-term antibacterial activity against Staphylococcus aureus (S.aureus), Escherichia coli (E.coli), and methicillin-resistant S. aureus (MRSA; up to 100%). Furthermore, in vivo experiments indicated that this multifunctional hydrogel accelerated the healing of S. aureus-infected wounds by promoting the reconstruction of blood vessels and hair follicles. These results demonstrate that this antioxidative, antibacterial, and bioadhesive hydrogel is a promising alternative wound dressing material for the prevention of bacterial infections and the acceleration of infected wound regeneration.

Layer-by-layer construction of zwitterionic/biguanide polymers on silicone rubber as an antifouling and bactericidal coating.

Biofilm formation on biomedical devices is a major cause of device-associated infection. Traditional antibiotic treatment for biofilm-associated infection increases the risk of multidrug resistance. Thus, there is an urgent need to develop antibiotic-free strategies to prevent biofilm formation on biomedical devices. Herein, we report a layer-by-layer strategy to construct an antifouling and bactericidal dual-functional coating for silicone rubber (SR)-based substrates. Five zwitterionic active ester copolymers, p(SBMA-co-NHSMA), with varied zwitterionic pSBMA components that ranged from 50 to 90% (molar ratio) were precisely prepared. Based on -NH2/NHS chemistry, a zwitterionic pSBMA antifouling coating was successfully constructed on an -NH2-activated SR surface, while a biguanide polymer (PHMB) bactericidal coating was consequently tethered. The relationship between the composition of the polymeric coating and the overall antibacterial property (antifouling and bactericidal) that was endowed to the SR surface was established. The in vitro and in vivo results consistently showed that the optimal p(SBMA-co-NHSMA) copolymer (SBMA/NHSMA with molar percentage of 70/30) synergistically utilized antifouling and bactericidal abilities to endow a highly efficient overall antibacterial property (near 100% antibacterial ratios) to SR70-PHMB substrates without compromising cellular viability. This strategy may be applied to the many SR-based biomedical implants and devices where an antibacterial surface is required.

Zwitterionic/active ester block polymers as multifunctional coatings for polyurethane-based substrates.

Bacterial-associated infection, blood coagulation, and tissue adhesion are severe issues associated with biomedical implants and devices in clinic applications. Here, we report a general strategy to simultaneously tackle these issues on polyurethane (PU)-based substrates. Taking advantage of reversible addition-fragmentation chain transfer (RAFT) polymerization, well-defined zwitterionic/active ester block polymers (pSBMA-b-pNHSMA) with an identical pNHSMA segment (polymerization degree of 15) but varied zwitterionic pSBMA segments (polymerization degrees of 40 and 100) were precisely prepared. The pSBMA-b-pNHSMA block polymers could be easily covalently constructed on PU substrates that were pretreated with a polydopamine coating based on highly efficient anime-active ester chemistry, as evidenced by the water contact angle and XPS tests. The relationship between the length of pSBMA segments in the coating and the antifouling ability of PU substrates was established. The results indicated that block polymers with a pSBMA segment of 40 repeat units could significantly prevent protein adsorption, bacterial/platelet adhesion, and cell attachment on PU substrates within 24 h, while a longer pSBMA segment (repeat units of 100) could endow long-term antibacterial (14 days without biofilm formation) and anti-cell attachment (5 days without cell attachment) properties to the PU substrates. Furthermore, the coating significantly improved the surface lubricating property of PU substrates without compromising on the mechanical property. This strategy may find many applications in PU-based implants and devices.