Preparation And Properties Of Antibacterial Nanoparticles Based On Schiff Base Bonds

Bacterial infections can cause various illnesses and even death.The current preferred treatment is antibiotics,but the increasing bacterial resistance,adverse reactions,waste of drug resources and other problems have brought new challenges to human life safety and health.Nano-drug delivery systems are a promising strategy in the treatment of bacterial infections.However,traditional drug delivery systems are often accompanied by low drug loading rates,complex preparation processes,and biosafety issues.To overcome these problems,carrier-free nanosystems emerge as a new strategy.Currently,research on carrier-free nanosystems for bacterial infection treatment is still in its infancy.As a new research idea,we are based on the research basis of the antibacterial activity of hydrophilic antibiotic teicoplanin(TEI)and hydrophobic antibacterial small molecule4-aldehyde benzoate borneol(BF),through the interfacial Schiff base bond Based on the principle of combination,TEI and BF were directly prepared to obtain bacterial endogenous acidic p H-responsive carrier-free nanoparticles(TEI-BF NPs).DLS showed that the TEI-BF NPs had a relatively uniform particle size of 180 nm on average.SEM and TEM showed that the TEI-BF NPs were spherical solid structures.In vitro drug release studies demonstrated that TEI-BF NPs were able to maintain stable nanostructures at p H 7.4.Once entering the acidic microenvironment(p H 5.5)at the infection site,the Schiff base bonds in the TEI-BF NPs were broken,and TEI and BF were released in situ to achieve synergistic sterilization.The in vitro antibacterial results showed that compared with the free drug group,TEI-BF NPs showed the strongest killing effect against Staphylococcus aureus(S.aureus)and methicillin-resistant Staphylococcus aureus(MRSA).In vitro cytotoxicity and hemolysis evaluations showed that TEI-BF NPs had good biosafety.The results of in vivo anti-drug resistance evaluation showed that after 10 days of tail vein injection,compared with the control group,the skin infection recovery effect of the mice in the TEI-BF NPs treatment group was significantly better,and the wound healing was up to 85%.The results of skin tissue H&E staining and inflammatory marker analysis showed that TEI-BF NPs had better effect on promoting the recovery and healing of infected skin.This work demonstrates that carrier-free nanoparticles(TEI-BF NPs)constructed using Schiff base bonds can effectively deliver drugs to bacterial infection sites,achieve efficient sterilization and promote skin recovery and wound healing from drug-resistant bacterial infections..This study provides a new direction for the development of more carrier-free nanosystems for the treatment of bacterial infections.