Furthermore, the effect of adding glycerol to the compositesof chitosan and WS2 NTs on the antimicrobial efficacy of bothcomponents was evaluated. Upon inclusion of glycerol and atlower WS2 NT loadings, antibacterial activity against E. coli and S.aureus was obtained; however, with increasing WS2 NT loading,an increase in bacterial viability was observed (Figure 10b-i,ii),Table 6). In comparison to the composites without glycerol, addition of glycerol reduces the level of intramolecular hydrogenbonding in chitosan altering the intrinsic antibacterial activityof chitosan and WS2 NTs.[82] The bacterial-growth-favoring properties of CG films with increasing WS2 NTs concentration mayalso be due to the ability of E. coli and S. aureus to utilize glycerol as a carbon source via dehydrogenation and/or phosphorylation pathways.[83] Since the antibacterial assay is performed ina multi-well plate, bacteria can grow both in a planktonic stateand by producing biofilms. As biofilms typically form a surfacebarrier, bacteria may not be in direct contact with the active sitesof the NTs, thereby protecting bacteria from the antibacterial activity of chitosan and/or the WS2 NTs. However, in the absenceof WS2 NTs, CG exhibited a notable decrease in E. coli and S.aureus viability (Figure 10b-i,ii), Table 6). In contrast, CG with increasing WS2 NTs loading decreased the viability of P. fluorescens(Figure 10b-iii, Table 6). As P. fluorescens is a non-lactose/lacticacid fermenter, it is unable to use glycerol as a carbon source forsurvival, and therefore it is sensitive to the antibacterial actionof chitosan and/or chitosan-WS2 NTs. Comparative antibacterialperformance of the composites of chitosan and WS2 NTs withand without glycerol across bacteria is shown in Figure S10 (Supporting Information).

感谢Constantinidou 沃里克大学沃里克医学院，英国Coventry CV4 7AL；A. Zak 科学学院霍隆理工学院引用文献