# Deep excitation afterglow luminescent probes for biomedical applications

## TL;DR

This paper discusses afterglow imaging probes that can provide deep tissue imaging without continuous excitation, improving sensitivity and reducing background noise for biomedical applications.

## Contribution

The paper introduces deep excitation afterglow luminescent probes that overcome limitations of conventional imaging techniques.

## Key findings

- Afterglow imaging avoids autofluorescence and improves signal-to-background ratio.
- X-ray-activated afterglow probes allow effective imaging of deep-seated lesions.
- The paper outlines strategies for molecular design and clinical translation of afterglow probes.

## Abstract

In addition to the high sensitivity, excellent spatio-temporal resolution and powerful real-time imaging capabilities, biomedical applications impose high demands on imaging techniques. Unfortunately, conventional imaging relies on the real-time excitation and suffers from limited tissue penetration. In contrast, afterglow imaging can provide continuous and deep luminescence once the probe is excited by NIR-light, X-ray or ultrasound. As such, it can effectively avoid autofluorescence and improve the imaging sensitivity and signal-to-background ratio. Moreover, X-ray-activated afterglow probes benefit from enhanced depth of penetration, thereby allowing more effective imaging of deep-seated lesions. Such advantages have attracted the interest of researchers, which should speed up the translation of biomedical afterglow research for clinical applications. With this perspective, we provided a comparative and analytical summary of the latest advances while highlighting the most promising afterglow probes. This perspective also outlines forward-looking strategies for molecular design, working mechanisms, and clinical prospects. Moreover, future challenges and research directions are discussed. As such this perspective describes how to formulate the most promising chemical strategies through mechanistic understanding, molecular design, and functional integration, thereby maximizing the successful development of clinical probes for visualization in humans.

Afterglow imaging provides continuous deep luminescence when excited by NIR-light, X-ray or ultrasound. Avoiding autofluorescence, improving imaging sensitivity and signal-to-background ratio.