Design And Synthesis Of Antibacterial System Based On The Cationic COF_TGTp

Due to porosity,high specific surface area,high chemical stability and designability,covalent organic framework materials?COF?have attracted much attention.In this work,triaminoguanidinium chloride?TG?and 1,3,5-triformylphloroglucinol?Tp?were used to synthesize a guanidinium-based ionic covalent organic framework(COF_TGTp)by solvothermal method.The XRD,FTIR spectra and ¹³C CP MAS revealed that COF_TGTp was successfully synthesized by schiff base with low crystallinity.Furthermore,the Zeta potential of COF_TGTp was+29 mV.Characterized by N₂ adsorption isotherms of the activated samples at 77 K,COF_TGTp was followed Type-II reversible adsorption isotherm,and the Brunauer-Emmett-Teller?BET?surface area was 291.7 m²g^-1 and the pore diameter was 3.8 nm,which has the potential for drug loading.Two drug loading systems were designed based on COF_TGTp as antibiosis material to inhibit E.coli and S.aureus.They are Ag/COF_TGTp and TAPP/COF_TGTp,respectively.In system of Ag/COF_TGTp,AgNPs on COF_TGTpGTp with good dispersibility avoided aggregation and retaining the antibacterial activity.XRD and high-resolution XPS spectra of Ag 3d indicated the presence of Ag⁰ and strong binding of the Ag⁰ site with N and O on the COF_TGTp.Considering the potential heavy metal toxicity of Ag,porphyrin was selected as an antibacterial drug to load on COF_TGTp by?-?interactions for photodynamic antibacterial therapy.The drug load of TAPP/COF_TGTp can reach to 27%.And under white light,the system can produce singlet oxygen?¹O₂?.The system not only solved the problem of hydrophobic and aggregation of TAPP,but also made full use of the positive electricity of cationic guanidyl COF_TGTp to close the distance between bacteria and ROS produced by porphyrin to perform the inhibition of Gram-negative and Gram-positive bacterial in the same time.MTT and hemolysis experiments showed that both Ag/COF_TGTp and TAPP/COF_TGTpGTp systems had good biocompatibility and could be used in subsequent antibacterial experiments.And the two systems proved to have good bacteriostatic ability by agar plate counting method;the SEM photographs of bacteria after treatments was revealed the system mainly kills bacteria by destroying the cell wall;live and dead bacterial staining visually verified the antibacterial effect of the materials.The two systems studied in this paper are expected to replace traditional antibiotics for efficient antibacterial,and have certain practical significance for solving antibiotic resistance and the emergence of super bacteria.