The choice of antimicrobial polymers:Hydrophilic or hydrophobic?

Owing to the spread of COVID-19,it is difficult to ignore the existence and importance of antimicrobial polymers(AMPs)because most protective appliances are made of polymers.Generally,bacteria prefer hydrophilic compounds,while fungi prefer hydrophobic ones.In recent decades,AMPs have made significant strides due to the versatile design of the functional groups or units for hydrophilic,hydrophobic,or amphiphilic performances.This review summarizes the advances of AMPs itself from the perspective of their wettability.Moreover,this study aims to clarify how the functional groups determine the interaction between the polymer and microorganisms directly affects the antimicrobial efficacy of the designed polymers.Based on the advances,the challenges and outlooks of AMPs from the perspective of wettability are systematically discussed to build a bridge between the structural design of AMPs and the requirements of practical applications.

Facially amphiphilic polyionene biocidal polymers derived from lithocholic acid

Bacterial infections have become a global issue that requires urgent attention,particularly regarding to emergence of multidrug resistant bacteria.We developed quaternary amine-containing antimicrobial poly(bile acid)s that contain a hydrophobic core of lithocholic acid in the main-chain.Interestingly,by choosing appropriate monomers,these cationic polymers can form core-shell micelles.These polymers exhibited biocidal activity against both Gram-positive and Gram-negative bacterial species.It is demonstrated that the micelles can deliver hydrophobic antibiotics that functionally have dual antimicrobial activities.Cytotoxicity assays against HeLa cells showed dosage-dependent toxicity for polymers with longer linkers.

Synergistic Combination of Biodegradable Peptide Polymer and Curcumin as Promising Antibiotic Substitution in Aquaculture to Alleviate the Global Challenge of Antimicrobial Resistance

The massive use of antibiotics in aquaculture and resulted antibacterial resistance problem urgently need antibiotic substitutions. Herein, we report a promising substitution of aquaculture antibiotics using a synergistic combination of biodegradable peptide polymers and curcumin, a natural compound from plant. The synergistic combination shows strong antibacterial activity against V. fluvialis and some other common bacteria in aquaculture. The membrane-damaging antibacterial mechanism echoes our finding that the synergistic combination will not induce bacteria to develop resistance after continuous use. The synergistic combination also displays effective cure on V. fluvialis-infected zebrafish. The biodegradability of the peptide polymer enables the combination to lose antibacterial activity and will not cause selective pressure on bacterial in the environment. Our study indicates potential application of synergistic composition, biodegradable peptide polymer and curcumin, as promising antibiotic substitution in aquaculture, which represents a promising strategy to address the global challenge of antimicrobial resistance.

Rapid inactivation of multidrug-resistant bacteria and enhancement of osteoinduction via titania nanotubes grafted with polyguanidines

The rapid in situ inhibition of bacterial contamination and subsequent infection without inducing drug resistance is highly vital for the successful implantation and long-term service of titanium(Ti)-based orthopedic implants.However,the instability and potential cytotoxicity of current coatings have deterred their clinical practice.In this study,anodic oxidized titania nanotubes(TNT)were modified with antibacterial polyhexamethylene guanidine(PG)with the assistance of 3,4-dihydroxyphenylacetic acid.Interestingly,the prepared TNT-PG coating exhibited superior in vitro antibacterial activity than flat Ti-PG coating and effectively killed typical pathogens such as Escherichia coli and superbug methicillinresistant Staphylococcus aureus with above 4-log reduction(>99.99%killed)in only 5 min.TNT-PG coating also exerted excellent hemocompatibility with red blood cells and nontoxicity toward mouse pre-osteoblasts(MC3 T3-E1)in 1 week of coculture.In addition,the efficient in vivo anti-infective property of this coating was observed in a rat subcutaneous infection model.More importantly,TNT-PG coating improved the expression of alkaline phosphatase and enhanced the extracellular matrix mineralization of pre-osteoblasts,denoting its osteoinductive capacity.This versatile TNT-PG coating with excellent antibacterial activity and biocompatibility could be a promising candidate for advanced orthopedic implant applications.