Self-healing And Switchable Hydrogels As Antibacterial And Antifouling Coatings

With the development of biomedical materials,the widespread use of implantable medical devices such as biomedical catheters have saved lives and improved therapeutic outcomes in the clinic.However,catheter-related infections caused by bacterial colonization are currently the most common nosocomial infections,which endanger the lives of patients and medical staff.In order to alleviate catheter-related infections and effectively reduce other complications,a variety of efforts(such as surface modification strategies of biomedical catheters)have been made to design functional coatings to inhibit bacterial colonization.In this work,4-arm PEG was grafted with adamantane and zwitterionic groups(QA)to the chain ends through acylation and esterification reactions,and polyvinyl alcohol(PVA)is grafted with β-cyclodextrin(β-CD)to the side group by an esterification reaction.Finally,the modified 4-arm PEG(QA-PEG-Ad)and polyvinyl alcohol(PVA-CD)are coated on the surface of the silicone rubber catheter to prepare hydrogel catheter coatings(PVEQ).The PVEQ coating has good self-healing properties due to the host-guest interaction between Ad and β-CD.The switchable QA group exhibits hydrophilicity in the normal physiological environment(p H 7.4),which showing excellent self-lubricating and anti-fouling properties.It can effectively kill bacteria by transforming into a quaternary ammonium salt group in a bacterial infection environment(p H 5.5).The results of in vitro experiments show that the PVEQ coating has good antibacterial activities against S.aureus(98.9%)and P.aeruginosa(99.2%).The cyclic antibacterial experiment proves that the PVEQ coating is resistant to S.aureus and P.aeruginosa after repeated for 5 times.The stability testing shows that the PVEQ coating still has good stability after being soaked in a physiological environment for more than5 weeks.In addition,the PVEQ coating can resist the adhesion of bacteria and blood cells under physiological conditions,and shows a low adsorption rate of bovine serum albumin(3.42%)and fibrinogen(4.95%).In vitro experiments prove that the PVEQ coating has little coagulation and hemolysis and the extract has no obvious cytotoxicity.After subcutaneous implantation and S.aureus,compared with unmodified silicone rubber catheters,PVEQcoated catheters cause no inflammation and significantly reduce the risk of catheter-related infections.Also thus,we estimate that PVEQ coating with antibacterial,antifouling and selfhealing properties can be widely applied to prevent infection in a variety of interventional/implantable devices.