Polymer-based activatable optical probes for tumor fluorescence and photoacoustic imaging.

Optical imaging including fluorescence imaging and photoacoustic imaging have been widely employed in early and accurate diagnosis of cancer. Compared to the "always on" optical probes, the molecular probes that could emit their signal in response to the tumor microenvironment exhibit the low background noise and high signal-to-background ratio, allowing sensitive and accurate cancer diagnosis. Polymer-based activatable optical probes display the advantages of improved water solubility, good photostability, extended blood circulation time, and easy functionalization, which enable them to accumulate in tumor for early and accurate diagnosis. This review focuses on recent advances in the development of polymer-based activatable optical probes for tumor fluorescence and PA imaging. The designs of polymer-based optical probes are first discussed. Then the applications for tumor fluorescence and PA imaging using pH, hypoxia, reactive oxygen and nitrogen species, and enzymes responsive polymer-based optical probes are discussed in details. At last, the present challenges and perspectives of polymer-based activatable optical probes to further advance them into the clinical application are also suggested. This article is categorized under: Diagnostic Tools > In vivo Nanodiagnostics and Imaging Diagnostic Tools > Biosensing.