Recent advances in D-A-D based Pdots with NIR-II fluorescence for deep-tissue imaging

In recent years, semiconducting polymer-based nanoparticles (Pdots) emitting in the second near-infrared window (NIR-II, 1000-1700 nm) have become a promising type of ultrabright fluorescence probe benefitting from numerous advantages in the NIR-II region, including reduced photon scattering, minimal tissue autofluorescence, and deep-tissue penetration. Among the diverse types of NIR-II fluorescent Pdots, donor-acceptor-donor (D-A-D)-based Pdots exhibit superior properties over others, especially for their high fluorescent brightness and excellent photostability. This mini-review article focuses on the recent development of D-A-D based Pdots emitting in the NIR-II window and their diverse applications in deep-tissue in vivo imaging. Finally, an outlook is given for the future designs of bright NIR-II D-A-D Pdots.