Construction And Application Of Rose Bengal-Based Photodynamic Therapy Antibacterial Materials

Objective:We use Rose Bengal（RB）as photosensitizer to construct two photodynamic therapy antibacterial agents Sericin-（NH-RB）n and Pullulan-（NH-RB）n with excellent water dispersity through covalent linkage,and further study their antibacterial activity in vitro and in vivo photodynamic therapy（PDT）,providing new strategies and technical support for the design of a new generation of antibacterial agents.Methods:Sericin was extracted by hot alkali method and purified by dialysis.Then,sericin and pullulan were modified by adipic acid dihydrazide（ADH）method respectively,so that their molecular skeletons were covalently linked with amino（-NH₂）groups,and Sericin-（NH₂）n and Pullulan-（NH₂）n rich in amino groups were obtained respectively.Next,the carboxyl-containing RB was covalently linked to the molecular skeleton of Sericin-（NH₂）n and Pullulan-（NH₂）n through the amidation reaction of amino and carboxyl groups,and obtain two phototherapy antibacterial agents Sericin-（NH-RB）n and Pullulan-（NH-RB）n;Using Escherichia coli（abbreviated as Escherichia coli）as the gram-negative bacterial model,Staphylococcus aureus（abbreviated as Staphylococcus aureus）as the gram-positive bacterial model,and mice infected with Staphylococcus aureus as the animal model,the antibacterial activities of two phototherapy antibacterial agents in vitro and in vivo were studied by plate coating method.Results:The constructed Sericin-（NH-RB）n and Pullulan-（NH-RB）n can self-assemble into nanoions in aqueous solution,with average particle size of 52.3nm（Sericin-（NH-RB）n）and 35.2 nm（Pullulan-（NH-RB）n）,respectively.Both of them have no antibacterial activity under dark conditions,but have significant bactericidal effect under light conditions.The minimum inhibitory concentrations of Sericin-（NH-RB）n against Staphylococcus aureus and Escherichia coli are 10.0and 20.0μg/m L,respectively;The minimum inhibitory concentrations of Pullulan-（NH-RB）n against Staphylococcus aureus and Escherichia coli were15.0 and 10.0μg/m L,respectively;Under the condition of light irradiation,the photodynamic therapy of both of them on the selected two bacteria is positively correlated with their dose,and is superior to RB with the same effective concentration;The results of scanning electron microscopy showed that both of them killed bacterial by destroying the cell wall of bacterial body and making its contents exudate;Both can be used for subcutaneous administration in vivo to implement photodynamic therapy and sterilization.In addition,both have low cytotoxicity and negligible hemolytic activity,good biocompatibility and high biological safety.Conclusion:The constructed Sericin-（NH-RB）n and Pullulan-（NH-RB）n are safe and non-toxic phototherapy antibacterial agents,and have significant antibacterial effects in vitro and in vivo.Both of them destroy the structure of bacterial cell walls by generating singlet oxygen under light conditions,achieving sterilization.