Triple-negative breast cancer (TNBC) does not respond to many targeted drugs due to the lack of three receptors (i.e.,
estrogen receptor,
progesterone receptor, and
human epidermal growth factor receptor-2), which makes it difficult for TNBC detection and treatment. As compared to traditional
breast cancer treatments such as surgery and
chemotherapy,
photodynamic therapy (
PDT) has emerged as a promising approach for treating TNBC due to its precise controllability, high spatiotemporal accuracy, and minimal invasive nature. However, traditional
photosensitizers used in
PDT are associated with limitations of aggregation-caused quenching (ACQ), and the ACQ induced a significant decrease in
reactive oxygen species (ROS) generation. To address these, we synthesized a cyclic
arginine-glycine-aspartic acid (
cRGD) peptide-decorated conjugated
polymer (CP) nanoparticles with poly[2-methoxy-5-(2-ethyl-hexyloxy)-1,4-phenylenevinylene] (
MEH-PPV) as the
photosensitizer for the
theranostics of TNBC. The synthesized CP nanoparticles show bright fluorescence with high stability and could effectively produce ROS under light irradiation. Cell viability studies showed that the CP nanoparticles have negligible dark cytotoxicity and could efficiently kill the αvβ3
integrin-overexpressed MDA-MB-231 cells (one subtype of TNBC cells) in a selective way. With the use of cRGD-modified
MEH-PPV nanoparticles as the
theranostic agent, it permits targeted imaging and
PDT of TNBC both in the in vitro 3D
tumor model and in living mice. The application of CP nanoparticles in the successful
theranostics of TNBC could pave the way for future development of CP-based
photosensitizers for clinical applications.