Rhomboidal Pt(II) metallacycle-based NIR-II theranostic nanoprobe for tumor diagnosis and image-guided therapy

Significance The biomedical applications of fluorescent anticancer agents in the first near-IR region (NIR-I) have been hampered by problems of photostability, autofluorescence, and limited penetration depth in biological tissues. To shift the fluorescence theranostic region from the NIR-I to the longer-wavelength region for accurate cancer diagnosis and treatment, Pt(II) metallacycle-based fluorescent nanoprobe 1 with fluorescence emission in the NIR-II region is designed. In vitro and in vivo studies demonstrate that 1 has good photostability and the ability to efficiently inhibit the growth of tumor with minimal side effects. It also improves the fluorescent imaging quality and signal-to-noise ratio for cancer theranostics. This study provides an opportunity for further design of NIR-II theranostic anticancer agents for future biomedical applications.