Chitosan-Silicon Phthalocyanine Conjugate as Effective Photo-Functional Hydrogel for Tracking and Killing of Bacteria

Hydrogels are attractive materials for many biomedical applications, including drug delivery and wound healing. A light-triggered antibacterial activity can be conferred to the material with the introduction of appropriate photosensitizers (PS). In this study, we have synthesized water-soluble silicon(IV)phthalocyanine derivative (SiPc) that contains four carboxylic groups on the periphery of the macrocycle. Obtained PS serves not only as an active chromophore but also as a cross-linking gelator, enabling simple and easy synthesis of chitosan conjugate (SiPcCh). Although UV/Vis and fluorescence spectroscopic methods showed that both free and conjugated PS are non-aggregated in water media, only SiPcCh possess remarkable antibacterial effect against Gram-positive B. subtilis and Gram-negative E. coli.