Study On Antimicrobial Activity Of Chitosan-bornoel Composites

Chitosan has a wide application in our daily life and occupies a high status, especially in the field of antibacterial due to it"s broad spectrum of antibacterial, high bacteriostatic, well biocompatible and so on. However,chitosan has many drawbacks such as poor water-solubility and attenuate antibacterial activity in solid form. In order to minimize the disadvantages of chitosan, scientists have done a lot of related works. For example, water-soluble chitosan derivatives were designed to increase its bactericidal effect in aqueous solution. Besides, quaternary ammonium salt, antimicrobial small molecules, and other fungicides were grafted in chitosan main chain to enhance the antibacterial performance.Herein, we prepare a glycol-chitosan/borneol (GCB) composite by a facile Schiff Base reaction. The specific stereochemical configuration of the GCB impacts the microbial perception system to achieve the purpose of antibacterial.First, the GCB was synthetized by the imidization reaction between water-soluble glycol chitosan (GC) and formylbenzoic acid-L-borneol(FAB), which was prepared though the esterification reaction. Then, the molecular structure of the FAB and the GCB were confirmed by IR and NMR, respectively. The layer-by-layer (LBL) self-assembly was used to coat the GCB on quartz wafer with different layers. UV spectra and atomic force microscope were used to test the coating amount and the morphology, respectively. The stability of the GCB quartz tablets were test in physiological saline, bacteria susppension and weak acid. After that, antibacterial and antifungal effects of the GCB were evaluated.According to the antibacterial properties of the GCB, we designed anti-bacterial "prison break" experimental model and anti-fungal "barrier landing" experimental model. In the "prison break" experiment, the breaking time of bacteria was recorded to evaluate bacterial growth restriction of the materials. Through the anti-fungal "barrier landing"experimental model, the anti-adhesion effect of GCB was evaluated by the number of fungi adhered to the GCB filter paper. At the same time,the cytotoxicity and biocompatibility were evaluated to verify biosafety of the GCB.Based on the above experimental study, we developed a facile strategy to improve the antibacterial properties of chitosan nonwovens,which are the common used commercial products. First, the effect of chitosan's concentration and molecular weight on the antifungal adhesion properties was evaluated. The results showed that chitosan has poor antifungal properties. Conversely, chitosan non-woven fabrics modified by borneol exhibits outstanding anti-fungal adhesion performance and effectively prevents the proliferation of fungi. Furthermore, the effect of this borneol/chitosan nonwoven composite on skin sensitization and skin's own-flora interference were investigated. The results showed that this composite does not cause allergies and own-flora's interference on the skin of guinea pig, suggesting its good biocompatibility.