Antibacterial Property of Cationic Hydrogels

【Introduction】 Physical and mechanical properties of a hydrogel, which is soft and has high water content, are similar to those of living tissues. Thus, a hydrogel attracts much interest as material for regenerative medicine and alternatives for human body. These properties of a hydrogel, however, also gives suitable environment for bacteria and mold. Therefore, hydrogel is easily contaminated by bacteria, which becomes a severe problem in their widespread applications. One possible way to solve this problem is use of antibacterial chemical agents. Hydrogels immersed in antibacterial agent aqueous solution can get antibacterial property temporally. However, such agent will gradually flow out and hydrogel lost antibacterial property as time goes on. To overcome this problem, our strategy is to fix the antibacterial agents into the gel networks. It is known that cationic agent has good antibacterial property. In this time we synthesized a cationic hydrogel from (3-acrylamidopropyl)trimethyl-ammonium chloride and investigate antibacterial property of this hydrogel. 【Experiment】We prepared cationic hydrogel from (3-acrylamidopropyl)trimethyl-ammonium chloride, anionic hydrogel from sodium 2-acrylamido-2-methylpropanesulfonate, and neutral hydrogel from N,N-dimethylacrylamide. We also used agar gels as negative control. The prepared gels were soaked in saline to remove residual monomers for 1 week, and then put in saline including SYTO9 and propidium iodide for 1 day to perform live-dead imaging. E.coli was seeded on these samples, and the samples were put in an incubator(37°C) for 12 hour. After that, E.coli on samples were observed with a fluorescence microscope to calculate fraction of dead E.coli. 【Result】After 12 hours culturing, 86.3 % of E.coli on cationic hydrogel was dead whereas fraction of dead E.coli on the other gels was significantly smaller than that (Figure 1). This result suggests that cationic hydrogel has antibacterial property at least for E.coli. Figure 1