The Study Of Ionic Nitric Oxide Donor And Controlled Reslease Of Nitric Oxide For Antibacterial

In recent years,as antibiotics have been abused and the resistance of bacteria has increased,so it is necessary to develop new products to kill or inhibit bacteria.Nitric oxide(NO)plays a role as an important signal molecule in the pathological processes of the organism.In addition,NO is also an effective antibacterial and antiviral agent.However,there are still problems for NO donors,such as poor biocompatibility,low NO loading,poor controlled release and slow elease effects.Chitosan based hydrogel has captured more interests due to its good biocompatibility,biodegradability,antibacterial activity,and has shown excellent functional properties in both tissue repair and drug release,as a very promising biomedical material.3D printing is a technology that builds a target model by stacking materials layer by layer through computer-aided design models and computer-controlled software.The use of 3D printing technology can quickly,accurately,and efficiently control the size and internal structure of the model to achieve the purpose of controlled drug release.In recent years,the combination of 3D printing technology and antibacterial materials has become a hot spot for researchers.Therefore,in this thesis,the study of ion donors and 3D printing technology in achieving the purpose of NO sustained release and controlled release,includes two parts as followed:1.CPCS crosslinked bPEI used as NO sustained release Carrier and its antibacterial effectIn order to prolong NO release and enhance the antibacterial effect,in this study,N-carboxy propionyl chitosan sodium(CPCS)was cross-linked to branched polyethylenimine(bPEI)(CPCS-bPEI)and used as a NO donor.The CPCS-bPEI has been followed with the reaction with NO gas under a parr high-pressure reactor to yield CPCS-bPEI-NO.Successful preparation of CPCS-bPEI and CPCS-bPEI-NO were confirmed by FITR,SEM and BET.The molar ratio actually involved in the reaction was determined by elemental analysis.The effective release of NO was determined by in vitro release.The antibacterial effect of CPCS-bPEI-NO on Gram-negative Escherichia coli(E.coli)and Gram-positive Staphylococcus aureus(S.aureus)was investigated by antibacterial experiments.The results showed that sufficient amount of NO released from CPCS-bPEI-NO can effectively inhibit E.coli and S.aureus,the NO loading amount and antibacterial effect can be adjusted by the molar ratio of CPCS to bPEI,and there was no significant toxicity of CPCS-bPEI-NO,suggesting that it may serve as an ideal antimicrobial agent.2.3D printing NO donor/PCL/AuNPs used as NO controlled release and its antibacterial effectIn order to achieve NO controlled release,in this system,we used 3D printing technology to control the release amount and rate of NO by controlling the internal structure of the sample.Firstly,three generations of PAMAM were synthesized,and three generations of PAMAM with the reaction with NO gas under a parr high-pressure reactor to yield PAMAM-NO,and PAMAM-NO was coated with PCL and AuNPs.Finally,the internal structure of the sample PAMAM-NO/PCL/AuNPs was controlled by 3D printing technology.The chemical structures of PAMAM and PAMAM-NO were characterized by ~1H NMR,UV and FI-TR.The release of NO was confirmed by NO loading amount and NO releasing experiment.CCK-8 method was used to evaluate its toxic effects on 3T3 cells.The viability of the bacteria was observed by antibacterial and confocal microscopy,and the antibacterial effect of PAMAM-NO/PCL/AuNPs was confirmed.The results showed that NO release was controlled by AuNPs,and the NO loading amount and release rate of PAMAM-NO/PCL/AuNPs were related to the internal structure of the 3D printing product.The sufficient amount of NO released from PAMAM-NO/PCL/AuNPs can effectively inhibit E.coli and S.aureus.This work provides sufficient basis for targeted NO delivery in the biomedical field.