Highly efficient phototheranostics of macrophage-engulfed Gram-positive bacteria using a NIR luminogen with aggregation-induced emission characteristics

Although phagocytosis serves as the front line to attack invading pathogens, its low bacterial encounter and killing rates leads to an ineffective bactericidal output. In view of this, developing multifunctional theranostic probe to effectively discriminate and ablate intracellular bacteria is highly desirable. However, the shielding effect of the host macrophages put the detection and elimination of macrophage-engulfed bacteria into a challenging task. Herein, we utilize a luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, as a simple and effective probe for simultaneous tracing and photodynamic killing of intracellular Gram-positive bacteria. With the help of the AIE property, excellent water solubility, near-infrared (NIR) emission and strong reactive oxygen species (ROS) generating ability, TTVP performed ideally to be a targeting agent to intracellular Gram-positive bacteria with high signal contrast, as well as to be a photosensitizer to effectively ablate intracellular bacteria without attacking host macrophages. This work thus provides insights for the next generation antibiosis theranostic application for potential clinical trials.