Synthesis Of Natural L-Borneol-based Polymer And Their Antibacterial Properties

Diseases caused by microbial infections pose a serious threat to human survival.The emergence of drug resistance problems caused by the abuse of antibiotics and the serious consequences that followed have led to an urgent need for new antibiotics to curb the spread of diseases and prevent new bacterial infections.At the same time,in-depth study of the relationship between the structure-property-activity of antibacterial substances is the key to accelerating the development of new antibacterial materials.In view of the fact that essential oils can help plants build a complex defense system to deal with the threats posed by pathogenic bacteria,essential oils and their main active ingredients derived from nature are considered to be one of the strategies that can effectively prevent bacterial infections,However,The defects of being volatile and insoluble in water hinder the more efficient use of essential oils and their active extracts.This study mainly used the method of combining esterification reaction and atom transfer radical living polymerization(ATRP)to introduce the(L)-borneol structure into the main and side chains of the polymer,respectively,and systematically studied the antibacterial activity and influencing factors of polymers containing(L)-borneol groups.The main research contents are as follows:1.The bromo-(L)-borneol initiator was synthesized by the esterification reaction between acyl bromide and the hydroxyl group in(L)-borneol,and then the structure of(L)-borneol was introduced into the end of the main chain of poly(N,N-Dimethylaminoethyl Methacrylate)by using atom transfer radical polymerization(ATRP),a series of(L)-bornyl cationic polymers with different molecular weight were prepared.The structure information of this polymer are obtained through proton nuclear magnetic resonance spectroscopy and gel permeation chromatography tests.Based on the minimum inhibitory concentration(MIC),minimum bactericidal concentration(MBC),bacterial growth curve,time-killing curve,and live/dead cell staining experiments,the synergistic antibacterial effect and influencing factors between the natural active extract(L)-borneol and the cationic polymer were explored.2.In order to further explore the influence of the hydrophilic and hydrophobic part of the amphiphilic(L)Borneol-based polymer on its antibacterial ability,we introduced(L)borneol into a poly(ethylene glycol)acrylate monomer containing a short hydrophilic PEG chain,the(L)borneol structural unit was introduced into the side chain of the polymer through the ATRP copolymerization reaction with cationic DMAEMA monomer,a series of copolymers with different monomer unit ratios were synthesized.The molecular weight and molecular weight distribution of the copolymer were characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography.Based on the minimum inhibitory concentration(MIC),minimum bactericidal concentration(MBC),bacterial growth curve,time-killing curve and live/dead cell staining experiments,the antibacterial properties and its influencing factors of the copolymer were explored.We found that the antibacterial ability of the copolymer is negatively correlated with the molar ratio of the(L)borneol-based acrylate monomer unit containing the hydrophilic PEG chain.The introduction of the hydrophilic(L)borneol-based monomer generally weakens the antibacterial effect.When the proportion of the two types of monomers unit is roughly the same,the MIC value of the smaller molecular weight is low,and the antibacterial effect is better,the hemolytic effect test shows that the introduction of hydrophilic PEG units reduces the hemolytic effect of the cationic copolymer on mammalian red blood cells and improves the biocompatibility of the system.