Preparation And Properties Of Antimicrobial Hydrogels Based On Chitosan Quaternary Ammonium Salts

Hydrogels are a class of hydrophilic polymeric materials that respond to stimuli when ion concentration,p H,temperature,mechanical strain,etc.are changed.Hydrogels are widely used in medical,agricultural and industrial applications due to their ease of preparation,biocompatibility and swelling properties.Based on these advantages,hydrogels prepared by adding natural antibacterial components or loaded with antibacterial drugs can be used to inhibit bacteria and protect wounds.Therefore,in this thesis,antimicrobial drug-releasing hydrogels with physical,chemical and non-covalent bonding interactions were prepared,and various properties of the hydrogels were investigated.Firstly,polyvinyl alcohol(PVA)based,polyvinyl alcohol/chitosan quaternary ammonium salt/nano zinc oxide(PVA-HACC-n ZnO)antimicrobial hydrogels were prepared by repeated freeze-thawing method.The IR showed that the HACC was only entangled in the PVA network structure and no chemical reaction occurred during the mixing process.The prepared hydrogels have some mechanical properties.The effects of freeze-thawing times,changes in the PVA/HACC ratio and the amount of n ZnO on the mechanical properties of the hydrogels were investigated.The results showed that the maximum fracture strength of the hydrogels was 159 k Pa and the toughness was 440.6k J/m~3.The water vapour transmission rate was in accordance with the standard for medical wound dressings.It has antibacterial properties and good biocompatibility.The maximum drug release can reach 98.3%.Secondly,polyacrylic acid/chitosan quaternary ammonium salt/nano zinc oxide(PAA-HACC-n ZnO)composite hydrogels were prepared.PAA-HACC-n ZnO hydrogels were prepared chemically and using the cross-linking agent N,N-methylenebisacrylamide(MBA).The effects of the variation of AA/HACC ratio,n ZnO and MBA dosage on the hydrogel properties and swelling properties were investigated.The results showed that the tensile strength and toughness could reach 195 k Pa and 1.17 MJ/m~3,and the maximum swelling of the hydrogel reached 50 g/g.Meanwhile,the composite hydrogel was breathable and could provide a hypoxic environment in trauma treatment,meeting the conditions of a wound dressing.The results of antimicrobial and biocompatibility tests show that the hydrogel has better antimicrobial properties,with an inhibition loop of 30mm for E.coli and 35 mm for S.aureus.this good performance of the antimicrobial drug-carrying hydrogel is expected to be used as a biomaterial in medical applications such as wound anti-inflammation.