A Second Near-Infrared Ru(II) Polypyridyl Complex for Synergistic Chemo-Photothermal Therapy

The clinical success of cisplatin
ushered in a new era of the application
of metallodrugs. When it comes to practice, however, drug resistance,
tumor recurrence, and drug systemic toxicity make it implausible to
completely heal the patients. Herein, we successfully transform an
electron acceptor [1, 2, 5]­thiadiazolo­[3,4-g]­quinoxaline
into a novel second near-infrared (NIR-II) fluorophore H7. After PEGylation and chelation, HL-PEG2k exhibits a wavelength bathochromic shift, enhanced photothermal
conversion efficiency (41.77%), and an antineoplastic effect against
glioma. Its potential for in vivo tumor tracking and image-guided
chemo-photothermal therapy is explored. High levels of uptake and
high-resolution NIR-II imaging results are thereafter obtained. The
hyperthermia effect could disrupt the lysosomal membranes, which in
turn aggravate the mitochondria dysfunction, arrest the cell cycle
in the G2 phase, and finally lead to cancer cell apoptosis. HL-PEG2k displays a superior biocompatibility and
thus can be a potential theranostic platform to combat the growth
and recurrence of tumors.