Molecular afterglow imaging for biomedical applications

Afterglow imaging is an emerging optical modality using agents that emit long-lasting luminescence after excitation ceases to eliminate tissue autofluorescence and improve signal-to-background ratios, achieving high imaging sensitivity and deep tissue penetration. Here we review recent advances in molecular afterglow imaging for biomedical applications, highlighting the materials and mechanisms involved in afterglow imaging modalities induced by light, ultrasound and ionizing radiation, termed photoafterglow, sonoafterglow and radioafterglow, respectively. We describe strategies to modulate the lifetime, intensity and wavelength of afterglow materials and principles for designing afterglow imaging probes that feature biomarker-activatable signal readouts and optimal biophysical properties for in vivo applications. We also highlight the applications of afterglow materials in disease diagnosis, imaging-guided therapy and in vitro diagnostics, and discuss the current challenges in the clinical translation of these technologies. This Review discusses recent advances in afterglow materials for biomedical applications, the distinct imaging modalities that these agents enable and strategies to optimize their properties for improved disease diagnosis and therapies.