An AIEgen-Peptide Conjugate as a Phototheranostic Agent for Phagosome-Entrapped Bacteria

The detection and elimination of intracellular bacteria remain a major challenge. In this work, we report an aggregation-induced emission (AIE) bioprobe that can detect bacterial infection and kill bacteria surviving inside macrophages through a dynamic process, notably specific molecular tailoring of the probe by caspase-1 activation in infected macrophages and accumulation of the residue on phagosomes containing bacteria, leading to light-up fluorescent signals. Moreover, the AIEgen can serve as a photosensitizer for generation of reactive oxygen species (ROS); and the average ROS indicator fluorescent signal intensity per unit area in the bacterial phagosomes is approximately 2.7-fold higher than that in the cytoplasm. This, in turn, induces bacteria killing with high efficiency and minimal cytotoxicity towards macrophages. We envision that this specific light-up bioprobe may provide a new approach for selective and sensitive detection and eradication of intracellular bacterial infections.