Nanoparticles conjugated with bacteria targeting tumors for precision imaging and therapy.

The hypoxic region microenvironment reduces the susceptibility of the cancer cells to radiotherapy and anticancer drugs of the solid tumors. However, the reduced oxygen surroundings provide an appreciable habitat for anaerobic bacteria to colonize and proliferate. Herein, we present a biocompatible bacteriabased system that can deliver poly(lactic-co-glycolic acid)(PLGA) nanoparticles(PLGA NPs) specifically targeting into solid tumor to achieve precision imaging and treatment. In our strategy, anaerobic bacterium Bifidobacterium longum (B. longum) that colonizes selectively in hypoxic regions of animal body was successfully used as a vehicle to conjugate with PLGA NPs and transported into solid tumors. To improve the efficacy and specificity of tumor therapy, low-boiling point perfluorohexane (PFH) liquid was wrapped in the core of PLGA NPs (PFH/PLGA NPs), which could increase the deposition of energy by affecting the acoustic environment of the tumor and destroy cells after liquid-gas phase transition during High Intensity Focused Ultrasound (HIFU) irradiation. This strategy shows an effective diagnosis and treatment integration for giving stronger imaging, longer retention period and more effective tumor therapy.