Multistimulus Responsive Layer-by-Layer Antibacterial Coating For Treament Of Implant-associated Infections

With medical advancement,implants have been increasingly used for the treatment of clinical diseases.However,bacterial adhesion to the implants surface lead to serious hospital-acquired infections(HAI)which poses a potential threat to human public health.Surface modification can endow implants with antibacterial ability,which is an effective strategy to avoid HAI.The methods used in implants antibacterial modification are categorized as changing surface topography and covering with antibacterial coatings.In contrast to the former,antibacterial coating can modify the implants surface in a milder way and loaded antibacterial substrace by a great variety of ways including adsorption,covalent bonding or self-assembly,which is the most effective surface modification method to inhibit the growth and adhesion of microorganisms on the implants surface.Herein,a multistimulus responsive antibacterial coating(MMT-PPPB-CHA)n was fabricated applying the layer-by-layer(LBL)self-assembly technique.The polymer Poly(PCA-PEG1000-BPBAC)(PPPB)containing disulfide bonds and dynamic covalent bonds was synthesized firstly,which poses specific properties of pH,glucose and redox response.Then,(MMT-PPPB-CHA)n coating was fabricated by LBL self-assemblying of montmorillonite(MMT)nanosheets,chlorhexidine acetate(CHA)and polymer PPPB.The results of Scanning electron microscope(SEM)and Ultraviolet-visible absorption spectrum(UV-Vis)indicated that(MMT-PPPB-CHA)n coating can be fabricated on many types of substrate surfaces(e.g.Titanium,CA,PAN,PVC,PU),and could change the number of bilayers to adjust the loading amount of CHA.Under the stimulation of pH,glucose and dithiothreitol(DTT),(MMT-PPPB-CHA)n coating was able to achieve controlled and sustained release of CHA.In vitro antibacterial experiments showed highly efficient bactericidal activity,(MMT-PPPB-CHA)n coating could kill more than 99%of Staphylococcus aureus(S.aureus)and Escherichia coli(E.coli)at a concentration about 4×108 CFU/mL within 4 h.In vivo subcutaneous tests on mices,(MMT-PPPB-CHA)n could completely kill S.aureus and E.coli in wounds and promoted wounds healing within 14 days.To summarise,(MMT-PPPB-CHA)n coating offers excellent abilities such as multistimulus response,controlled drug release,efficient antibacterial properties in vitro/vivo.This coating provides a novel insight for implants surface modification and clinical infection treatment.