Northiosquaraine-Based Nanoparticles for Red-Light-Induced Photodynamic Therapy via Singlet Oxygen Generation

Phototheranostics have captured growing attention for their undenying superiority over traditional cancer therapy treatments. The integration of all phototheranostics modalities from ensuring near-infrared absorption-emission properties to an efficient photodynamic therapy (PDT) behavior in a single molecule is a challenging task. Herein, we have achieved this by self-assembled northiosquaraine nanoparticles (TSQ-NPs) that exhibit high water dispersion ability, good biocompatibility, good optical behaviors, and a metal-free design. The synthesized TSQ-NPs have been found to exhibit one of the highest values of singlet oxygen quantum yield and appreciable photostability among the reported organic nanoparticles. The in vitro studies of TSQ-NPs on KB and HeLa cells suggest efficient cell uptake within an hour, a structure inherent mitochondrion targeting property, and ability to yield intracellular reactive oxygen species (ROS) under illumination of light that can be used for cell therapy applications. The excellent PDT effect induced by red light by nanoparticles originating from a single organic compound is promising for the future of cancer diagnostics, therapy, and molecular imaging.