The Construction Of Biomimetic MPS/Ag Composite Microspheres And Its Research On Anti-bacterial Adhesion Super-wetting Surface

Bacterial attachment on various surfaces of materials often leads to unexpected bacterial colonization,the formation of biofilm,or even severe biofouling,and has become an extremely severe problem existing in industry,daily life,and the marine and medical fields.What deserves our great attention is that bacterial attachment poses a potentially significant risk of infection to people,subsequent bacterial contamination,and even the acceleration of the corrosion of material surfaces resulting in adverse effects on their specific functions,such as those found in textiles,petroleum pipelines and aquatic flow systems,medical devices or implants,and marine vessels,etc.Hence,designing a bacterially anti-adhesive surface over arbitrary surfaces of materials so as to prevent and inhibit the formation of biofilm has attracted widespread concern both in academia and industry.In order to solve this major scientific problem of microbial pollution,researchers at home and abroad have developed various anti-biofilm methods,such as constructing antibacterial and super-wetting surface.However,there are still existing considerable challenges such as inadequate durability,simple application,and unclear mechanism of anti-biofilm,especially some existing restriction on profiled equipment and specific wettability requirements.Herein,to break through the limitations of the material itself and single wettability,a durable composite microspheres surface aimed to be developed on the surface of arbitrary materials and devices to achieve excellent antibacterial and bacterial anti-adhesion.The main research contents of this paper are as following:?1?Design and preparation of micro/nano structural PS/Ag microspheres with antibacterial and bacterial anti-adhesion:The dispersed polymerization method was employed to obtain hydroxylation polystyrene microspheres with precise dimension of 2?m;By adopting free radical polymerization to regulate the molecular chain distribution and content of multifunctional monomers grafted on the surface of the microspheres,a series of hydrophilic modified polystyrene microspheres with different amount of PEGMA were prepared;Nanosilver particles was in situ growed on the MPS by reduction of PVP to obtain micro/nano structured MPS/Ag composite microspheres,by regulating the contents of silver resources?0.1M,0.3M,0.6M and 0.9M?.ICP-AES was utilized to measure the content of silver of microspheres from 0.2 wt%to 2.98 wt%,and the dimension of nanosilver particles was 40 nm.?2?The antibacterial performance and mechanism of the composite microspheres was investigated,this experimental results showed that antibacterial performance of the composite microspheres gradually increased with increase of the nano-silver content,and the antibacterial rate against E.coli was better than that of S.aureus;MPS/Ag_0.9 achieves the best antibacterial performance with a concentration of 0.02 mg/m L,the antibacterial rate exceeded 99%.Furthermore,the minimum bactericidal concentration?MBC?of MPS/Ag microspheres was explored,and the MBC value was 0.08 mg/mL;Finally,the durably antibacterial properties of the composite microspheres were studied,that is,after the completely releasing silver ions,and performing five repeated antibacterial tests,the antibacterial rate could still be maintained above 84%.Consequently,the synergistic antibacterial mechanism of the release-type inorganic nanosilver and the contact-type quaternary ammonium salt was proposed.?3?Hydrophilic-type antibacterial and bacterial anti-adhesion surface was studied,a facile spraying-coating method was employed to construct hydrophilic-type antibacterial and bacterial anti-adhesion surface.It was shown that the surface exhibited superb antibacterial properties,the antibacterial rate reached above 99.99%;Moreover,with the increase of PEGMA grafted on the microspheres,water contact angle of the hydrophilic surface decreased sharply to 9.6?,and the oil contact angle underwater increased to 121.1?,the bacterial anti-adhesion was significantly improved.The bacterial adhesion rate reached above 94.9%,which was ascribed to the excellent superhydrophilic and underwater oleophobic properties.Furthermore,MD simulation revealed that the hydrophilic surface interacted with water molecules to form a hydration layer to repel the bacteria.Therefore,the bacterial anti-adhesion mechanism of hydrophilic surface in wenzel state was proposed,and bacterial anti-adhesion model based on Wenzel wetting state was established.?4?Hydrophobic-type antibacterial and bacterial anti-adhesion surface was studied,a facile fabrication method was employed to easily transform the hydrophilic-type antibacterial and bacterial anti-adhesion surface to the superhydrophobic one.It was demonstrated that with the increase of fluorosilane,the hydrophobicity and underwater oleophobicity properties of surface was significantly enhanced,the surface energy sharply decreased,and the bacterial anti-adhesion rate was drastically improved.when the content of spraying microspheres on surface was 0.5 mg/cm²,superhydrophobicity?WCA=154.1??and underwater oleophobicity?UWOCA:132.71??were achieved.Furthermore,both antibacterial rate and bacterial anti-adhesion rate were above 98.15%.The superhydrophobic property was achieved by combination of low surface energy fluorine?atomic percentage=46.81%?and roughness?0.568?m?,which was carried out by EDX and AFM characterizations.Moreover,the composite surface exhibited incredible self-cleaning property that bacterial droplets can quickly roll off the surface at a slope angle of 9?in 70 ms?v=0.143m/s?.Finally,the Cassie-Baxter wetting state model was proposed to reveal that resisting effect of the air layer formed by the superhydrophobic surface capturing air and underwater oleophobicity were the inherent mechanism for bacterial anti-adhesion.?5?Furthermore,bacterial anti-adhesive technology was applied in ten typical substrates?stainless steels,aluminium,polypropylene plastic?pp?,PDMS,titanium sheets,glass plates,filter paper,wood,PVDF membrane and textiles?by spraying microsphere modification,bacterial droplets of water,milk,coffee,green tea,cola and animal blood were tested.Amazingly,all modified surface exhibited excellent superhydrophobic and self-cleaning capabilities,reflecting the universality of this strategy.In order to investigate the durability of the constructed superhydrophobic surface,tests of friction,impact,and chemical corrosion were carried out,after friction and impact test,WCA of the composite surface has small vibration?WCA:157-150??and the micro/nano structure of the composite surface are almost unchanged before and after tests.For performing chemical corrosion tests,composite surface was immersed in high concentration of acidic?pH=1?,alkaline?pH=14?,and salt?c=1mol/L?,all WCA values are in the range of 150.5-157.9?.These experimental results indicated that the superhydrophobic,antibacterial and bacterial anti-adhesion properties of composite surface were not changed,which showed excellent durability.