Bacteria-Assisted Selective Photothermal Therapy for Precise Tumor Inhibition

Photothermal therapy (PTT) has drawn extensive research attention as a promising approach for tumor treatment. In this study, a bacteria-assisted strategy relying on the selective reduction of perylene diimide derivative based supramolecular complex (CPPDI) to radical anions (RAs) by Escherichia coli in hypoxic tumors is developed to realize highly precise PTT of tumors. Noninvasive E. coli are first injected intravenously for selectively accumulating and replicating in the tumor due to the hypoxia tropism. Then, CPPDI is loaded in a peptide-hybrid matrix metalloproteinase-2 (MMP-2) responsive liposome (MRL) and injected intravenously. After accumulated and released from MRL in the tumor where MMP-2 is overexpressed, CPPDI is reduced by E. coli in the hypoxic tumor environment to produce CPPDI RAs (CRAs), which serve as effective photothermal agents for tumor cells thermal ablation under near-infrared light irradiation. Since E. coli accumulate and grow in tumor sites selectively, this strategy accurately limits the production of CRAs in tumors for highly selective PTT, which will find great potential for precise tumor inhibition.