Study On The Role And Mechanism Of Cuttlefish Ink Melanin Or Polydopamine Nanoparticles Chelating Copper Ions In Antibacterial And Wound Healing

Post-traumatic bacterial infections especially S.aureus can cause serious tissue damage and cause related diseases.Therefore,the rapid treatment of wounds is particularly important.At present,the most commonly used method for treating bacterial infections is antibiotic treatment,but excessive use and abuse of antibiotics will produce bacterial resistance,which inevitably reduces the treatment effect and even stimulates the development of super bacteria.The ideal antibacterial material should have broad spectrum and effective antibacterial properties,and low toxicity to mammalian cells.With the rapid development of today’s nanotechnology,nanoparticles functionalized on the surface with excellent antibacterial properties can simultaneously achieve the treatment of bacterial infections and the rapid healing of wounds.Melanin is composed of indole-5,6-quinone(DHI)and 2-carboxyindole-5,6-Quinone(DHICA)composition.This special structure gives melanin surface rich functional groups and metal chelation sites,making melanin a new drug-bearing substrate in the field of biomedicine.Polydopamine(PDA)is an analog of melanin,and it is also a nanomaterial with excellent biocompatibility.The surface of synthetic polydopamine carries a large number of functional groups such as amino,hydroxyl,and carboxyl groups,which chelated metal ions through the formation of ionic bonds,and reacted with organic molecules carrying amino or carboxyl functional groups through chemical reactions.Thus,the surface of the polydopamine was chemically modified to obtain the biomaterial of the intended design.In this paper,Melanin@Cu2+ nanoparticles and PDA@Cu2+nanoparticles were obtained by chelating equal amounts of copper ions using the relevant properties of melanin and polydopamine.The effects of four kinds of nanoparticles,Melanin,PDA,Melanin@Cu2+and PDA@Cu2+,on antibacterial and wound healing were studied.All four materials exhibit good hemostatic properties,the reason is that the adhesion of catechol allows the material to be tightly adsorbed to the bleeding site,forming a sealing effect and enhancing the hemostatic effect.In addition,among the four materials tested,PDA@Cu2+ nanoparticles showed the best antibacterial effect.The minimum bactericidal concentration for E.coli could be as low as 16 ug/mL,and the minimum bactericidal concentration for S.aureus was reduced to 4 ug/mL.On the one hand,the functional groups(such as amino groups and hydroxyl groups)on the surface of PDA could combine with the biological macromolecules of bacterial membrane to causes membrane rupture;On the other hand,the toxic effects of the released copper ions;It is the synergy of the two that gives PDA@Cu2+nanoparticles excellent antibacterial properties Taking into account the outstanding properties of PDA@Cu2+nanoparticles in antibacterial and hemostatic properties,they were applied to the back wounds of mice infected with S.aureus to investigate the effect of wound healing.The results showed that PDA@Cu2+ nanoparticles greatly reduced the inflammatory response caused by bacterial infection and significantly accelerated wound healing compared with the control group.In vivo and in vitro experiments have proved that the PDA@Cu2+nanoparticles have good biocompatibility and hardly cause damage to the main organs and tissues of mice.