Fabrication And Application Of Antibacterial Nanomaterials With Special Surface Structures

Bacterial infections seriously affect human health.At present,the commonly used treatment is still antibiotic therapy.However,the abuse of antibiotics has led to the emergence of drug-resistant bacteria,thus failing to achieve the desirable therapeutic effect.Therefore,it is necessary to prepare highly-effective,safe antimicrobial materials to combat bacterial infections.Photothermal therapy(PTT),chemodynamic therapy(CDT)and metal ions antibacterial approach for anti-infection have attracted much attention due to the advantages of high efficiency,resistance to drug-resistant bacteria and no drug resistance.Studies have shown that nanomaterials with special surface structures can enhance the interactions with bacteria,and then improve the antibacterial effect.In addition,some nanomaterials with special surface structures can physically kill bacteria.Based on the enhanced interaction of special surface structures with bacteria,in this thesis,we constructed nanoparticles with rough surfaces as a new type of antibacterial material for PTT/CDT synergistic anti-drug-resistant bacteria infection treatment.We also introduced the array structure with rough surface into the dental implant to build a dental implant material with both antibacterial and osteogenic effect.The main research contents are as follows.1.In order to solve the problem that the weak interaction between the material and the bacteria prevents the PTT/CDT from fully exerting the treatment effect,in this thesis,carbon shell/iron tetroxide hybrid nanoparticles(RCF)with rough surface structure were prepared in combination with rough surface nanoparticles to enhance bacterial adhesion for near infrared region ?(NIR-?)light-responsive PTT/CDT synergistic anti-infection therapy.Herein,rough carbon shells(RC)with near-infrared ?(NIR-?)photothermal effect were prepared by sacrificing silicon oxide templates method,and RCF were obtained by assembling peroxidase-active Fe3O4 NPs with rough carbon nanoshells using a simple assembly strategy.NIR-? light-induced PTT enhanced the production of ·OH induced by Fe3O4 NPs,while CDT increased the permeability of the bacterial membrane making the bacteria more sensitive to heat.Therefore,the collaboration between PTT and CDT results in a synergistic antibacterial effect.The experimental results showed that RCF(256 ?g/mL)was 99.9%effective against Escherichia coli(E.coli)and Staphylococcus aureus(S.aureus)and methicillin-resistant Staphylococcus aureus(MRSA)at 1064 nm,0.5 W/cm2 of NIR-? light and in the presence of hydrogen peroxide.Synergistic effect between PTT and CDT was also obtained.Compared with smooth surfaces,RCF with rough surfaces enhanced the interaction with bacteria by adhering to them,and the synergistic antibacterial effect was increased by 43%for E.coli and 21%for MRSA compared with SCF.In vivo experiments demonstrated that the RCF with rough surfaces showed excellent PTT/CDT synergistic anti-drug-resistant bacterial infection in a wound infection model in rats.The results demonstrate that the designed and synthesized rough structured carbon/iron oxide nanohybrids have the potential to deal with drug-resistant bacterial infections and provide a practical strategy for the construction of efficient antibacterial nanoplatforms with special surface structures to achieve synergistic antibacterial activity.2.In order to solve the problem that the implant lacks antibacterial function and easily causes infection Based on the characteriastics of the array structure with rough surfaces to physically kill bacteria,zinc oxide nanoarrays with rough surfaces were prepared on the surface of the titanium sheet by easy and mild seed growth method,which were then modified with polydopamine(PDA)and hyaluronic acid(HA).A titanium-based dental implants(Ti-ZnOPDA-HA)with dual functions of antibacterial and bone-promoting effects were obtained.The rough surface of ZnO nanoarrays can cause physical damage to bacteria,while the released Zn2+has a bactericidal effect.In addition,Zn2+ has the ability to promote osteoblast differentiation.The introduction of PDA and HA was used to chelate Zn2+ and reduce cytotoxicity to meet the osteogenic requirement.The experimental results showed that TiZnO had 86%inhibition effect on E.coli and 91%inhibition effect on S.aureus,modification of PDA and HA reduced the cytotoxicity of Ti-ZnO and maintained 80%inhibition effect on E.coli and S.aureus,we also demonstrated the inhibition effect was mainly from Zn2+released by ZnO nanoarrays.More importantly,Ti-ZnO-PDA-HA did not affect the cellular activity of alveolar bone marrow mesenchymal stem cells(ABSMCs),and the arrays could promote osteogenic differentiation of ABSMCs and promote osteopontin expression.The arrays on the surface of implants designed and fabricated in this work with both antimicrobial and osteogenic functions are useful for the construction of new multi-functional clinical implants.