Novel Theranostic Agents with Functions of Two-Photon Imaging and Therapeutic Treatment

Fluorescent probes are very powerful tools for real-time tracking of various biomolecules, cellular activities and physiological events in living cells. Probes that show the ability to recognize a biomarker or detect a disease are a clinically useful tool for monitoring disease progression and treatment effects. Because of the use of the long- wavelength/low-energy excitation source and the characteristics of the intensity- dependence of the two-photon absorption process, the two-photon excitation offers considerable advantages for biological fluorescence imaging and sensing such as higher spatial resolution, less photobleaching and photodamage as well as deeper tissue penetration as compared to those of one-photon excitation.

Probes with site-targeting specificity such as tumor or brain tissue selectivity and/or subcellular localization property offering direct and efficient delivery to the site of interest are particularly attractive and useful for practical clinical applications. A target-specific probe can also play a key role in carrying and delivering a pro-drug/drug to the target site for disease treatment giving rise to a novel theranostic capability. Such a theranostic agent would allow the investigation and monitoring of the cellular uptake and therapeutic effect at the subcellular/tissue level using the imaging technique. As a result, the development of novel biocompatible and site-targeting selective theranostic agents that show two-photon imaging capability and therapeutic treatment function are of practical significance and have recently drawn tremendous attention.

Thus, we propose herein to design and synthesize novel site-targeting specific theranostic agents that are highly two-photon fluorescence active simultaneously with disease treatment capability or potential. In addition, a systematic investigation of their structure-two-photon absorption properties, exploration of their applications in two- photon bioimaging in vitro and in vivo as well as studying the potential as a pro- drug/drug for disease treatment will be carried out. The findings of this study hold promise for future improved medicine capable of diagnostics and therapeutics providing a more effective and personalized treatment.