Variable Molecular Weight Nanoparticles for Near-Infrared Fluorescence Imaging and Photothermal Ablation

Theranostic nanoplatforms integrating fluorescence imaging and photothermal therapy have shown great potential in cancer research for tumor detection and image-guided treatment. Herein, a unique theranostic nanomaterial was formulated by combining two different molecular weight (MW) segments of poly[4,4-bis(2-ethylhexyl)-cyclopenta[2,1-b;3,4-b′]-dithiophene-2,6-diyl-alt-2,1,3-benzoselenadiazole-4,7-diyl] (PCPDTBSe). Integration of the oligomer and high-MW fragments of PCPDTBSe was achieved through the nanoprecipitation method to form theranostic variable molecular weight nanoparticles (VMWNPs). Oligomer emission in the NIR region was explored for near-infrared fluorescence imaging, and the photothermal response of high-MW PCPDTBSe was employed for breast cancer cell ablation. The oligomer showed a characteristic phenomenon of aggregation-induced red-shifted NIR emission upon nanoparticle formation. VMWNPs exhibited a large Stoke's shift, excellent physiological stability, photostability, and constant heat generation through multiple cycles of laser irradiation. VMWNPs were utilized for the detection and laser-induced ablation of triple negative breast cancer cells. These results indicate that a theranostic nanomaterial can be composed from two different MW fractions of PCPDTBSe.