Preparation Of Layer-wise Self-assembled Oxidized Chitosan Microcapsules And Antimicrobial Finishing Of Cotton Fabrics

Cotton fabrics are considered as a potential medium for the reproduction and transmission of pathogenic microorganisms,which leads to the degradation of its taking performance and endangers human health,so it is important to provide antimicrobial finishing to cotton fabrics.In response to the problems of low utilization and poor durability caused by antimicrobial agents for conventional finishing of cotton fabrics,microencapsulation technology can be used to improve the utilization of antimicrobial substances by embedding them in a multilayer membrane structure and releasing them slowly,but there is a problem of weak bonding between microencapsulation and cotton fabrics finishing.Based on the above reasons,in this project,DCS microcapsules with antimicrobial properties were prepared using layer-by-layer self-assembly（LBL）technology with oxidized chitosan（DCS）as the main wall material and loaded with antimicrobial drugs of different properties.The aldehyde group of DCS and the hydroxyl group of cotton fabrics can be used for hemiacetal reaction,thus preparing antibacterial cotton fabric.The details and results are as follows:First,in order to investigate the effect of hydrophilic drug microcapsules on the antimicrobial finishing of cotton fabrics,polyelectrolytes such as DCS were alternately deposited onto Ca CO₃ particles doped with polystyrene sodium sulfonate（PSS）,and after removing the template using ethylenediaminetetraacetic acid（EDTA）,the hydrophilic drug ciprofloxacin hydrochloride（CIP）was encapsulated to form CIP/DCS microcapsules.The antimicrobial cotton fabrics were prepared by impregnation treatment.The adsorption performance of the microcapsules was investigated using rhodamine B（drug model）,and the adsorption process of the microcapsules was more consistent with the quasi-secondary adsorption kinetic model and the Langmuir adsorption isotherm model,and the adsorption capacity of the monolayer reached 252.08 mg/L.The release rate of CIP in acidic environment was higher than that in alkaline environment,and the release mechanism was consistent with Fickian diffusion.The CIP/DCS microencapsulated cotton fabrics were found to be more effective against Staphylococcus aureus was 84.49%and 81.89%against E.coli.Secondly,to explore the effect of hydrophobic drug microcapsules on the antibacterial finishing of cotton fabrics,the hydrophobic drug ibuprofen（IBU）was adsorbed to Ca CO₃particles using the porous structure of Ca CO₃ particles,and then alternately deposited with polyelectrolytes such as DCS to form IBU/DCS microcapsules.the slow release rate of IBU was higher in alkaline environment than in acidic environment,and its release mechanism was Fickian diffusion.The inhibition rate of IBU/DCS microencapsulated cotton fabrics was78.4%for Staphylococcus aureus and 75.93%for Escherichia coli.Finally,to further improve the antibacterial performance of cotton fabrics,the effect of microcapsules co-loaded with hydrophilic and hydrophobic drugs on the antibacterial finishing of cotton fabrics was investigated.Poly（lactic-co-glycolic acid）（PLGA）loaded IBU was selected as the microcapsule wall material,and then CIP was encapsulated to prepare CIP/IBU/DCS microcapsules loaded with hydrophilic and hydrophobic drugs.The adsorption process of microcapsules was more consistent with the quasi-secondary adsorption kinetic model and Langmuir adsorption isotherm model,and the adsorption capacity of monolayer reached 300.40 mg/L.The release of both IBU and CIP followed Fickian diffusion.With the release of IBU and CIP,the inhibition rate of CIP/IBU/DCS microencapsulated cotton fabrics was 92.52%against S.aureus and 90.32%against E.coli.This indicates that the antibacterial microcapsules prepared by LBL technology can impart antibacterial properties to cotton fabrics,which provides a certain reference for antibacterial textiles.