| For medical implants and devices,bacterial attachment adversely affects the functionality and limits the lifetime of devices,and bacterial infections represent a common and substantial complication in the clinic,sometimes even leading to death.Therefore,it is very necessary to develop materials that can resist the attachment of bacteria or kill bacteria attached to the surface.In recent decades,various antibacterial can be divided into three categories based on the their operating mechanisms: bactericidal surfaces?bacteria-resistant surfaces and bacteria-release surfaces,but each methodology has inherent advantages and disadvantages.The bactericidal components in traditional bactericidal surfaces are mainly chemical bactericides,including quaternary ammonium compounds(QAC),silver nanoparticles(Ag NPs),cationic polymers and various antibiotics,which will contribute to the emergence of resistant strains.And poly(N-isopropylacrylamide)(PNIPAAm)is commonly used and best studied thermo-responsive polymer in bacteria-resistant surfaces.To prepare an ideal antibacterial surface,the antibacterial component and the environmental response component can be combined to prepare a dual-function antibacterial surface with "killrelease".In recent years,some researchers have discovered that some animals and plants in nature have special nanostructures on their surfaces.These special structures make them have miraculous resistance to external risks under harsh natural conditions.When studying the interaction between cicada wings with nanocone structured surfaces in nature and the bacteria,it was found that the killing of the bacteria on the surface is a purely physical killing process.This reveals a whole new field of antibacterial surface research.In this paper,a dual-functional antibacterial surface with killing and releasing bacteria is prepared by combining surface nanocone structure and temperature-responsive polymer.The nanocones structure was prepared on the polymethyl methacrylate(PMMA)surface via template-assisted nanoimprinting and template removal.Then the temperature-responsive polymer poly-N-(isopropylacrylamide)(PNIPAAm)was grafted on the surface by aqueousbased atom transfer radical polymerization.The composition of functional groups and the chemical composition on the surface of the nanocones structure were detected by FTIR and XPS,respectively.SEM was used to observe the surface morphology of the grafted nanocones structure.And the static contact angles on the surfaces with different PNIPAAm grafting concentrations were detected at 20 ? and 37 ? by surface contact angle analyzer.The results showed that PNIPAAm was successfully grafted on the surface of the nanocones structure.When the grafting concentration was less than 1.0 M,the nanocones structure was normal;when it was larger than 1.0 M,the surface nanocones aggregated and clustered.Next,this paper studied the adhesion and desorption of bacteria on the antibacterial surface of the nanocone structure with different PNIPAAm grafting concentrations.The bactericidal situation and desorption capacity of the surface were observed by SEM and fluorescence electron microscope.The results show that these surfaces all have the ability of sterilization and desorption,and as the grafting concentration increases,the amount of bacterial adhesion on the surface shows a trend of increasing first and then decreasing,which is consistent with the change trend of bacteria detachment after cooling to 4 ?.When the grafting concentration is 0.5 M,the surface has good bactericidal and desorption performance,and the killing efficiency is 98.63 ± 1.14%;The bacteria detachment at 4 ? is 90.20 ± 2.0%;the dead bacteria detachment is 90.17 ± 2.8%.And this surface can be used repeatedly. |
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