Ru(II)-based aggregation-induced emission (AIE) agents with efficient 1O2 generation, photo-catalytic NADH oxidation and anticancer activity

Photodynamic therapy (PDT) has received much attention in recent years. However, traditional photosensitizers (PSs) applied in PDT usually suffer from aggregation-caused quenching (ACQ) effect in H2O, single and inefficient photochemical mechanism of action (MoA), poor cancer targeting ability and etc. In this work, two novel Ru(II)-based aggregation-induced emission (AIE) agents (Ru1 and Ru2) were developed. Both complexes exhibited long triplet excited lifetimes and nearly 100% singlet oxygen quantum yields in H2O. In addition, Ru1 and Ru2 displayed potent photo-catalytic reduced nicotinamide adenine dinucleotide (NADH) oxidation activity with turnover frequency (TOF) values of about 1779 and 2000 h−1, respectively. Therefore, both Ru1 and Ru2 showed efficient PDT activity towards a series of cancer cells. Moreover, Ru2 was further loaded in bovine serum albumin (BSA) to enhance the tumor targeting ability in vivo, and the obtained Ru2@BSA could selectively accumulate in tumor tissues and effectively inhibit tumor growth on a 4T1 tumor-bearing mouse model. So far as we know, this work represents the first report about Ru(II) AIE agents that possess high singlet oxygen quantum yields and also potent photo-catalytic NADH oxidation activity, and may provide new ideas for rational design of novel PSs with efficient PDT activity.