Acid-substituted polyaniline-grafted hydrogel copolymer and use thereof

A method of treating a bacterial infection comprising sequentially performing following steps:

• a) injecting a photo-thermal agent having the general formula shown as below at an infection site that is caused by bacteria, the photo-thermal agent is formed from a chitosan group, a polyaniline group, and a proton acid group by a polymerization process:
• wherein A is a proton acid group, m and n are same or different integers greater than 0, x is an integer equal to or greater than 0, and y is an integer equal to or greater than 1, provided that x and y are the same or different at each occurrence, and at least an x is not 0;
• wherein the proton acid group is selected from the group consisting of:
• 3-mercapto-1-propanesulfonic acid sodium salt (MPS-Na), 3-mercaropropinoic acid, and thioglycolic acid;
• and
• b) exposing the infection site to Near-Infrared light for generating a heat energy to kill the bacteria inside the infection site.