Progress and challenges: Responsive long-lived organic luminescent probes for biosensing and bioimaging

Organic long-lived luminescent probes featuring thermally activated delayed fluorescence (TADF) or room temperature phosphorescence (RTP) have emerged as highly promising tools for time-resolved luminescence imaging (TRLI) and sensing (TRLS). Their unique advantage lies in their ability to effectively eliminate interference from short-lived background signals. By introducing an appropriate delay time between the short-lived autofluorescence and measure of the long-lived luminescence emitted by the probes, a background-free approach emerges, enabling the accurate detection and imaging of diverse biologically relevant species. This review provides a comprehensive overview of metal-free organic compound-based responsive probes utilizing TADF and RTP for TRLI and TRLS. It offers detailed insights into the design strategies and sensing principles employed by these probes. Furthermore, the review discusses the current challenges faced by researchers in this rapidly expanding field and highlights the future prospects for advancements in this area of study.