Photosensitizer of phthalocyanine-conjugated chitosan-doped nano-silver for inactivation against bacteria and promote wound healing

• The photosensitive material of Pc-CS@Ag, phthalocyanine modified chitosan doped silver nanoparticles, could effectively inactivate gram-negative bacteria through photodynamic action antibiotic-resistance bacteria. • The photosensitive material of Pc-CS@Ag had remarkable concentration dependence and light intensity dependence in photodynamic antibacterial mechanism. • The photosensitive material of Pc-CS@Ag could effectively inhibit microbial growth in long terms. Controlling microbial infection should receive more attention and research support against the rapidly growing phenomenon of bacterial resistance to antibiotics caused by the abuse and inappropriate use of antibiotics. Photodynamic antibacterial chemotherapy should be an alternative option to the antibiotic resistance problem. In this study, new photosensitive material of phthalocyanine-modified chitosan (Pc-CS) was synthesized and studied to effectively inactivate Gram-positive and Gram-negative bacteria, including drug-resistant strains, through photodynamic action. The new photosensitive material of Pc-CS@Ag which was synthesized by phthalocyanine-conjugated chitosan and doping nano-silver could photodynamically inactivate the Gram-positive and Gram-negative bacteria with 90 % maximum effect concentration (EC 90 ) of 3.12–6.25 µg/mL, and had the similar eradiation activity against drug-resistant bacteria (EC 90 =6.25 µg/mL). Chitosan conjugation and nano-silver doping had less influence on the singlet oxygen yield of phthalocyanine. The material exhibited significant concentration and light intensity dependence in the photodynamic antibacterial mechanism and had a visible post-antibiotic effect. Moreover, the photosensitive material was effective in healing wounds in BALB/c mice. The healing wounds results suggest that the photosensitive material ameliorate excision wounds, and wound healing could be due to their effective antimicrobial activity and biocompatibility. Therefore, this photosensitive material has good potential for antibacterial applications.