Preparation And Performance Study Of Starch-based Haloamine Antibacterial Materials

Recent literature surveys have demonstrated that due to a lack of safety consciousness and control,numerous emerging and re-emerging pathogens have caused widespread human disease and deaths,raising global fears of pandemics.To prevent and control emerging infection-induced diseases,numerous researchers have been focusing on the development of highly effective antibacterial techniques so that pathogens can be eliminated before they become hazardous.Of the new antibacterial agents that effectively kill a wide spectrum of pathogens,halogen-based antibacterial agents are known to prevent lethal diseases from infectious pathogens and therefore have attracted significant research interest,as they can play an effective role in protecting human health and improving environmental hygiene.Used predominantly as disinfectants,halogen-based antibacterial agents have been adopted throughout the world because of their cost-effectiveness and ability to kill the majority of microorganisms rapidly.N-Halamines have many advantages over other antibacterial agents,including effectiveness against a broad spectrum of microorganisms,long-term physicochemical stability,high structural durability,and the regenerability of their functional groups.In this thesis,on the basis of previous studies,a kind of non-cyclic N-halamine antibacterial starch particles and a non-cyclic N-halamine antibacterial starch film were successfully prepared and their properties were systematically studied.(1)Synthesis and Properties of Porous N-Halamine Antibacterial Starch particlesThe porous antimicrobial starch particles containing N-Halamine functional groups(ST-MBA-Cl particles)were synthesized by a crosslinking polymerization between starch(ST)and N,N’-methylenebisacrylamide(MBA),and then a chlorination of amide groups of MBA.The synthetic process used only water as the solvent and was environmentally friendly.The structure and morphology of the as-synthesized PST-MBA-Cl particles were characterized by means of FTIR,SEM,XPS,and XRD.The results showed that under the optimal preparation conditions,the as-synthesized ST-MBA-Cl particles could have a Cl~+%of 8.60%.Antimicrobial tests showed that ST-MBA-Cl particles had very powerful antimicrobial efficacy against both Staphylococcus aureus and Escherichia coli and could completely kill Staphylococcus aureus with a concentration of 2.1×10~6 CFU/mL and Escherichia coli with a concentration of 5.6×10~6 CFU/mL within a contact time of one minute.Interestingly,swelling test showed that ST-MBA-Cl particles had a 205.4%of swelling degree,possibly enhancing their disinfection ability.Furthermore,the N-Halamine functional groups of ST-MBA-Cl particles also showed excellent stability under storage and reproducibility.(2)Synthesis and Properties of N-Halamine Antibacterial Starch FilmsAn antibacterial film-forming aqueous solution containing N-halamine-modified starch was obtained via a Michael addition between potato starch(PST)and N,N’-methylenebisacrylamide(MBA)and then a chlorination of amide groups of MBA in water.The antibacterial starch film(PST-MBA-Cl)was formed by simply spreading and drying.The as-prepared PST-MBA-Cl film was characterized by SEM,FTIR,XPS,and XRD.The results showed that under the optimal preparation conditions,the Cl~+%of the as-prepared PST-MBA-Cl film could reach up to 0.61%.Antibacterial tests showed that the PST-MBA-Cl film showed high antibacterial activity against Staphylococcus aureus and Escherichia coli and could completely killed S.aureus with a concentration of 2.1×10~6 CFU/mL and E.coli with a concentration of 5.6×10~6CFU/mL within 10 min.In addition,the antibacterial N-halamine functional groups in PST-MBA-Cl film also showed excellent stability under storage.