Activatable Second Near-Infrared Fluorescent Probes: A New Accurate Diagnosis Strategy for Diseases

Recently, second near-infrared (NIR-II) fluorescent imaging has been widely applied in biomedical diagnosis, due to its high spatiotemporal resolution and deep tissue penetration. In contrast to the always on NIR-II fluorescent probes, the activatable NIR-II fluorescent probes have specific targeting to biological tissues, showing a higher imaging signal-to-background ratio and a lower detection limit. Therefore, it is of great significance to utilize disease-associated endogenous stimuli (such as pH values, enzyme existence, hypoxia condition and so on) to activate the NIR-II probes and achieve switchable fluorescent signals for specific deep bioimaging. This review introduces recent strategies and mechanisms for activatable NIR-II fluorescent probes and their applications in biosensing and bioimaging. Moreover, the potential challenges and perspectives of activatable NIR-II fluorescent probes are also discussed.

Automated summary

Recently, activatable NIR-II fluorescent probes have shown to have specific targeting to biological tissues, providing higher imaging signal-to-background ratio and lower detection limit. Utilizing disease-associated endogenous stimuli to activate NIR-II probes is significant for achieving switchable fluorescent signals for specific deep bioimaging applications. Challenges and perspectives of activatable NIR-II fluorescent probes are also discussed in this review.