Rational Design Of A Novel Type Of Iodine-based Antiseptics And Investigation Of Its Antibacterial Mechanism

Microbial infection and the growing antibiotic-resistance of microbes remain big challenges to modern medicine.Iodine as a type of effective and wide-spectrum antiseptics has been used in the treatment of bacterial infection for more than 160 years.It is noteworthy that there have been few reports of microbial resistance to iodine in the literature.However,some intrinsic physicochemical properties of iodine,such as low water-solubility and easy sublimation at ambient temperature and pressure,limit its antibacterial applications.The reaction between iodine and starch to form deep blue complex is highly specific and sensitive and thus is widely used in analytical chemistry.Nevertheless,the antibacterial properties of the deep blue complex have not been explored so far.Herein,we propose the preparation of a novel type of iodine-based antiseptics,iodine?I₂?-soluble starch?SS?aerogel.By mixing the solution of SS and Lugol's iodine,and then lyophilizing the mixture,we obtained the I2-SS aerogel.After optimization,the as-prepared I2-SS aerogel contains 2 wt%effective iodine and dissolves instantly in water.The I2-SS aerogel solution shows comparable antibacterial efficacy with Lugol's iodine and the commercial-available povidone-iodine solution.Specifically,the I2-SS aerogel solution can reduce>6 Logs of the Gram-positive bacteria Staphylococcus aureus in 2 min and the Gram-negative bacteria Escherichia coli in 5 min at effective iodine concentrations of 0.5?g mL^-1?²?M?and 2?g mL^-1?⁸?M?,respectively.In addition,due to the high iodine affinity of soluble starch,the loss rate of the loaded effective iodine in the I2-SS aerogel solution is significantly reduced compared with that in Lugol's iodine and povidone-iodine.Particularly,the I2-SS aerogel stored in the dark and dry conditions shows no detectable effective iodine loss within 6 months.The outstanding antibacterial activity,capability of accelerating wound healing,and good biocompatibility of I2-SS aerogel are verified through further in vitro and in vivo experiments.Although scientists and doctors have known that iodine is a type of highly effective antiseptics,the specific antibacterial mechanism of iodine is still not clear.In this work,we also explore the molecular mechanism of iodine sterilization from the perspectives of reactive oxygen species generation,the interaction between iodine and amino acids,and so on.In summary,we demonstrate the preparation of a novel type of iodine-based antiseptics,I2-SS aerogel,and explore its physicochemical properties,in vitro and in vivo antibacterial efficacy,and molecular mechanism of iodine-induced bacterial inactivation ability.We hope the as-obtained I2-SS aerogel can be applied in treating mouth ulcer and skin infection.This work is also expected to inspire the preparation of new antiseptics and clarification of the antibacterial mechanism of halogen.