Preparation of a nitric oxide-releasing chitosan-based composite hydrogel and assessment of its antimicrobial properties
To obtain a wound dressing resistant to bacterial infection,protocatechualdehyde(PA)and iron chloride were coordinated to form iron PA/ferric ion chelate(PA/Fe).Then PA/Fe was crosslinked with carboxymethyl chitosan(CMCS)by Schiff base to form a hydrogel,which was subsequently loaded with a nitric oxide(NO)donor N,N'-di-sec-butyl-N,N'-dinitroso-1,4-phenylenediamine(BNN6)to obtain a BNN6@CMCS-PA/Fe composite hydrogel.The structure and properties of the BNN6@CMCS-PA/Fe composite hydrogel were characterized,and its biosafety and in vitro antibacterial performance were analyzed.The results showed that the hydrogel had excellent mechanical properties,a high swelling ratio(1169%),adhesion to various materials,self-healing ability and excellent biocompatibility.Under 405 nm light irradiation,the rate of NO release from BNN6 in the hydrogel reached 7.2 μmol/(L·h),and the hydrogel exhibited photothermal effect under 808 nm light irradiation,with an average temperature increase of 36.5 ℃ in 10 minutes.At the same time,the hydrogel showed significant inhibitory effects on the growth of Staphylococcus aureus and Escherichia coli,with antibacterial rates exceeding 93%for bacteria inhibited by NO and over 99%for bacteria inhibited by photothermal effects.To sum up,this study provides theoretical basis for the application of gas-releasing dressing in promoting the healing of bacterial infected wounds.