Preparation Of Novel Antibacterial Materials And Its Antibacterial Properties

Bacterial infection remains to be a growing global health problem,afflicting millions of people annually.Among the pathogenic microorganisms,bacterial infections alone account for one-third of global mortality.Currently,the treatment paradigms are heavily relying on antibiotics,causing rapidly increased multidrug resistance and sharply decreased therapeutic effect.Worldwide,antimicrobial resistance is increasing at an alarming rate,results to one of the greatest threats to human health.It is estimated by 2050,cancer deaths will be outnumbered by deaths from bacterial infections.The overuse and misuse of antibiotics is one of the main factors contributing to the problem of antibiotic resistance.At present,in addition to the development of new antibiotics,how to reduce the use of antibiotics is also one of the ways to solve the current health threat caused by multi-drug resistant bacteria.In this study,four kinds of new antimicrobial materials were prepared and applied to the fruit anticorrosion,crops waterlogging and wound infection treatment with their good antibacterial properties and biocompatibility.（1）A series of coordination polymer nanoparticles were synthesized by stirring3,5-dicarboxyphenylboronic acid as ligand with acetate salts of copper,cobalt,zinc,iron and magnesium at room temperature.The comparative study shows that the prepared copper coordination polymer nanoparticles have good antibacterial performance against Salmonella.By changing the ratio of ligand to metal ions,a series of copper coordination polymer nanoparticles were prepared and their antibacterial properties were investigated.The results showed that when the ratio of ligand to metal ions was 2:3,the prepared coordination polymer nanoparticles had good antibacterial properties against Salmonella.By taking E.coli,S.aureus,Kanamycin-resistant E.coli,MRSA,Salmonella and Listeria monocytogenes as model bacteria,the antibacterial properties of copper acetate,3,5-dicarboxyphenylboric acid,and the prepared polymer nanoparticles were compared.The results showed that 3,5-dicarboxyphenylboric acid had no inhibitory effect on all bacteria,and copper acetate had no inhibitory effect on Kanamycin-resistant E.coli and a certain inhibitory effect on S.aureus,and the prepared copper coordination polymer nanoparticles show a strong inhibitory activity against all bacteria.Finally,taking mung bean,wheat and banana as actual samples,the feasibility of nanomaterials in antibacterial application was investigated.The results showed that simple synthesis process,low raw material cost,and broad-spectrum antibacterial properties made the new antibacterial materials have broad application prospects in food preservation,crop preservation,and waterlogging prevention.（2）Guanosine nucleotide phosphate,as a bacterial stress signal molecule,plays an important role in bacterial repair of damaged DNA.Therefore,molecular imprinted polymer nanoparticles（MIP-NPs）were prepared using guanosine-5’-diphosphate（pp G）as a false template.The morphology of the material was characterized,and its recognition performance,biocompatibility and feasibility as an antibiotic adjuvant were investigated.The results showed that the addition of MIP-NPs as adjuvants（UV irradiation+MIP-NPs or antibiotics+MIP-NPs）in the system had a good inhibitory effect on the tested bacteria compared with single UV irradiation or antibiotic treatment.When the concentration of the material was 0.05 mg mL^-1,the inhibition rate of MIP-NPs+UV radiation on E.coli increased by 80%.In addition,when the bacteriostatic effect is similar,the use of MIP-NPs as adjuvant can reduce the dose of antibiotics by 50%.MIP-NPs have good biocompatibility（no obvious hemolytic and cytotoxic effects）.By using MIP-NPs as an antibiotic adjuvant in the treatment of wound infection in mice,the results showed that the treatment effect was not affected when the amount of antibiotics was reduced by half.All the above results indicate that the MIP-NPs designed have bright prospects in dealing with the growing threat of antibiotic resistance.（3）Based on the good antibacterial effect of copper coordination polymer nanoparticles prepared previously and the positive effect of MIP-NPs as antibiotic adjuvant,molecular imprinted polymer nanomaterials doped with copper coordination polymer nanoparticles were prepared（Cu@MIP-NPs）.The morphology of the material was characterized,and its recognition performance,antibacterial activity and biocompatibility were investigated.The experimental results show that,Cu@MIP-NPs have good inhibition effect on E.coli,S.aureus,Salmonella,Listeria monocytogenes,MRSA and Kanamycin-resistant E.coli,and the inhibition rate on E.coli and S.aureus reaches 80%.Compared with copper acetate and copper coordination polymer nanoparticles,Cu@MIP-NPs shows stronger antibacterial ability（inhibition rate increased to 80%）and the lowest copper content（decreased by 3/4）,which improves the antibacterial a ctivity and greatly reduces the toxicity of materials.Cu@MIP-NPs with good biocompatibility（no obvious hemolysis）and antibacterial activity,as well as good therapeutic effect in the process of wound treatment in mice,it has great strength in dealing with the increasingly serious threat of bacterial infection and antibiotic resistance.（4）A natural biomass raw material（Chicory crown hair fiber）with wide sources and low cost,was treated by simple heating and extracted with ethanol.The effects of treatment temperature,extraction time and extract concentration on the antibacterial properties were investigated.The results showed that the antibacterial effect of extracted components was better when the extraction time was 10 h after heating at 200°C.The antibacterial efficiency of the extract reached 99%when the mass concentration of Chicory crown hair fiber was 1.0 mg mL^-1.