Persistent luminescence materials for imaging and therapeutic applications

Persistent luminescence materials (PLMs) are unique as their afterglow emission. The distinctive non-in-situ excitation mechanism could eliminate interference from autofluorescence and scattered light, enabling high sensitivity for optical imaging applications. Additionally, PLMs can be integrated with metal ions, photothermal species, photosensitizers, therapeutic drugs, nucleic acid, or immunological adjuvants to realize imaging-guided therapy. In this review, we summarized the advancements in the synthesis and emission mechanisms of inorganic, organic, and hybrid PLMs. We also discussed their applications in optical imaging in terms of excitation sources, such as X-ray, UV, light-emitting diodes, NIR lasers, thermal, radiopharmaceuticals, and ultrasound. Further, the theranostic applications of PLMs were summarized, including imaging-guided chemotherapy, photothermal therapy, photodynamic therapy, gene therapy, immunotherapy, and multi-modality therapy. The bioapplications of PLMs in tumour ablation, bacterial infection, inflammation, rheumatoid arthritis, atherosclerosis, and osteoporosis are also introduced. Besides, persistent luminescence imaging-guided surgical navigation without the need of real-time excitation could simplify the instrumentation and provide high precision for tumour elimination, and we introduce several examples of surgical navigation. Finally, the toxicity concerns associated with PLMs are discussed. The challenges, potential problems, and prospects regarding the translational medicine applications of PLMs are outlooked.