Construction Of Functional Coatings On The Biomedical Material Surfaces For Antibacterial/Antifouling Applications

Bacterial infection and colonization are of serious public health concerns.The prevalence and emergence of multiple drug resistance（MDR）to existing antibiotics leads to frequent morbidity and mortality.The infection crisis of biomedical implants has aroused keen interests for antibacterial surface modification of biomaterials.Therefore,a solution to this problem is to develop effective antibacterial coatings,which hinder the growth of surface adhered bacteria and prevent biofilm formation.The modified surfaces with immobilized antibacterial entities have become a practical approach to combat bacterial infections on biomedical implants.Titanium and its different alloy combinations are extensively used in dental,orthopedic,and other biomedical areas because of their excellent biocompatibility,appropriate elastic moduli similar to human bones,ideal anticorrosive property,and non-toxicity.However,the surfaces of Ti and its alloys are inert and prone to bacterial contamination and subsequent biofilm formation,which ultimately causes implant-associated infections.Such conditions could cause implant failure and may need revision surgery,resulting in severe pain and healthcare cost for patients.Thus,there is a tremendous demand for introducing appropriate surface functionalities on the Ti substrates to inhibit the surface adhesion and propagation of contaminated substances such as bacteria.In the first work,a simple one-step process for the simultaneous deposition of a polyphenol tannic acid（TA）and four-armed poly（ethylene glycol）(PEG_10k-4-OH)on the Ti substrate（Ti-TA/PEG）surface was described.Additionally,a two-step process has been employed to fabricate the Ti-TA-PEG surface via successive deposition of TA and PEG_10k-4-OH for comparison.The resultant Ti-TA/PEG surface prepared by simultaneous deposition of TA and PEG_10k-4-OH exhibits higher coating thickness and better surface coverage than the Ti-TA-PEG surface.The Ti-TA/PEG and Ti-TA-PEG surfaces could actively inhibit the non-specific adsorption of proteins,suppress the bacterial and platelet adhesion,and prevents biofilm formation.Moreover,the Ti-TA/PEG surface displays a better antifouling performance than the Ti-TA-PEG surface.Thus,the present study demonstrates a simple and convenient approach for constructing polymeric coating with good anti-adhesive properties on the Ti substrate surface.Polydimethylsiloxane（PDMS）has been widely used in contact lens,catheters,pacemaker leads,and other biomedical devices.Unfortunately,like many other hydrophobic materials,the native PDMS surface is always susceptible to uncontrolled bacterial contamination.In the second work,PDMS-TA-Ply surfaces were prepared by the rapid and successive deposition of TA andε-Poly-L-lysine（ε-Ply）on the PDMS surface via the solution immersion method.The surface chemical elements and hydrophilic properties of PDMS-TA-Ply surfaces were evaluated by X-ray photoelectron spectroscopy（XPS）and contact angle measurement.The anti-protein adsorption,antibacterial adhesion,anti-biofilm formation and cytotoxicity of PDMS-TA-Ply surfaces were evaluated.The results showed that PDMS-TA-Ply surfaces exhibited good antifouling/antibacterial properties and low cytotoxicity toward L929 mouse fibroblasts.In addition,the PDMS-TA-Ply surface with higher content of Ply showed better antifouling/antibacterial performance.