Synthesis of “Offensive and Defensive Integrated” Cyclodextrin-Grafted N+-borneol Esters Antibacterial Polymer via RAFT

Bacterial infection of surface-damaged fruit is one of the troubling issues in daily life. To address this issue, the β-cyclodextrin (CD) grafting N+-borneol ester antibacterial polymer (CD-NBOx), containing borneol with active groups and quaternary ammonium compounds (QACs) positive charges, was successfully synthesized using RAFT and characterized by NMR, Fourier-transform infrared, and gel permeation chromatography. Its antibacterial activity and biofilm inhibition were evaluated against Escherichia coli and Staphylococcus aureus, and the adhesion resistance was measured by crystal violet (CV) staining experiments. It indicated that the antibacterial rate of CD-NBOx reached 99.9 and 87.3% and the biofilm inhibition rates were up to 97.5% against E. coli. Interesting, there was no spoilage of the fruit and only 20% weight loss in the 15-day fruit preservation experiment. CD-NBOx possesses excellent antibacterial and adhesion resistance due to the synergy between cyclodextrin for biocompatibility and N cation for antibacterial and borneol stereochemistry. In summary, CD-NBOx as a constructing “offensive and defensive integrated” is validated as a viable antibacterial material while also expanding potential life applications of N+-borneol ester polymers in fruit preservation in the future.