Rational design and synthesis of novel NIR photosensitizers and application in antimicrobial photodynamic inactivation

Abstract

Herein we use our previously developed strategy for the synthesis of NIR photosensitizers based on Malachite Green (MG) skeleton. Firstly, we installed bipyridine group into MG to form bpy-MG, as bidentate chelating ligand, which was then bonded with [Ir(ppy)2Cl]2 (ppy = 2-phenylpyridine) and [Ir(dqpx)2Cl]2 (dqpx = 2,3-diphenylquinoxaline) through the N atoms of bipyridine to produce Ir-MG-ppy and Ir-MG-dqpx, respectively. The photosensitizers display NIR absorption with weak fluorescence and singlet oxygen generation ability because of the free rotation of the indoline moieties. Upon binding with deoxyribonucleic acid sodium salt from salmon testes, the fluorescence and singlet oxygen generation ability were greatly boosted due to the restriction of free rotation. The as-prepared photosensitizers demonstrate potential application in light-induced killing Staphylococcus aureus both in vitro and in vivo.