Research On Photoresponsive Antibacterial Hydrogel Based On Cu Co-coordination TCPP-Cur

Bacterial infection has always threatened human life and health.With the progress of the medical treatment all over the world,more and more effective treatment methods for bacterial infection have been developed,but many people still die from bacterial infection every year.It has been reported that more than 7 million people die from bacterial infections worldwide each year,of which more than 1 million people die from infections associated with Staphylococcus aureus（S.aureus）,and more than 800,000 die from Escherichia coli（E.coli）.Therefore,it is very important to find new antibacterial materials to combat clinical bacterial infections and improve the survival rate of patients.As the most common clinical drug,antibiotics are often used to treat bacterial infections.However,the long-term use of antibiotics tends to lead to the development of drug-resistant bacteria,which makes treatment more difficult,prolongs the treatment time of patients and increases healthcare costs.In addition,the development of an antibiotic requires a great economic and time cost,but it only takes a short time for bacteria to develop resistance,so it is extremely important to explore new antibacterial methods that do not lead to the generation of drug-resistant bacteria and can achieve efficient sterilization.Phototherapy is a non-invasive treatment that kills bacteria through synergistic photothermal and photodynamic therapy,which does not lead to the development of drug-resistant bacteria.As a common photosensitiser,porphyrin（TCPP）can produce singly linear oxygen（¹O₂）under the irradiation of certain wavelength of light,destroying the structure of cells and killing bacteria.However,the presence of massive TCPP in the organism is harmful to the health of the patient,so we can enhance its photocatalytic properties and improve the bactericidal effect by modifying TCPP.Therefore,an antibacterial hydrogel with good photocatalytic effect is synthesized by co-coordination to achieve a non-resistance and non-invasive photocatalytic therapy for rapid treatment of bacterial infected wounds.In this study,TCPP-Cur with a structure of donor-acceptor（D-A）is first formed by esterification reaction,and then the hydrogel（CTCS）with good photocatalytic effect is formed by co-coordination of Cu with TCPP-Cur and sodium alginate.This paper is divided into the following three parts:1.Preparation and photocatalytic performance study of TCPP-CurThe TCPP-Cur nanoparticles were formed by the esterification reaction of TCPP with curcumin（Cur）.After a series of characterizations and experiments,it was demonstrated that TCPP-Cur was successfully synthesized and that the D-A structure of TCPP-Cur made it easy to generate photogenerated electrons,which led to TCPP-Cur possessing a good photocatalytic ability.2.Preparation and photocatalytic performance study of CTCS hydrogelThe CTCS hydrogel was formed by combining Cu with TCPP-Cur and sodium alginate through co-coordination.After a series of characterizations and experiments,it was demonstrated that the CTCS hydrogel was successfully synthesized and had good photocatalytic ability.Then,through a series of electrochemical tests,the photocatalytic mechanism of CTCS hydrogel was deeply explored.It was found that the good photocatalytic performance of CTCS hydrogel was due to the D-A structure constructed by TCPP and Cur.Under the excitation of 660 nm,photogenerated electrons would spontaneously flow from the electron-rich Cur to the TCPP,promoting the generation of electron-hole pairs.At the same time,the co-coordination of Cu further reduced the band gap of TCPP-Cur and inhibited the complexation of photogenerated electron pairs,which made CTCS hydrogels have good photocatalytic properties.3.Construction and study of antibacterial system of CTCS hydrogelThe CTCS hydrogel could eliminate 99.95%and 99.85%of S.aureus and E.coli within20 min.The results of in vivo tests showed that CTCS hydrogel not only could rapidly eliminate bacteria,but also reduced the expression of TNF-αand enhanced the expression of IL-10 and VEGF,which could promote wound healing and tissue regeneration.The CTCS hydrogel can not only be used to rapidly treat bacterially infected wounds,but also had good biocompatibility and did not cause significant damage to the major organs of mice,which is an effective method for treating wounds with infections.