Molecular substrates for the construction of afterglow imaging probes in disease diagnosis and treatment

Abstract

This tutorial review introduces recent advances in molecular afterglow imaging using organic materials with a focus on afterglow substrates, afterglow mechanisms, design principles of afterglow imaging probes, and their biomedical applications.

Superoxide Anion-Mediated Afterglow Mechanism-Based Water-Soluble Zwitterion Dye Achieving Renal-Failure Mice Detection

“…Considering this, we speculated that more energy (from singlet to triplet state) was utilized for the ROS production, thus generating the afterglow signal. According to previous literature, − ,,,,− organic-based afterglow materials are dependent on a molecular cascade reaction between 1 O 2 and materials to store energy and release afterglow luminescence. Hence, we then tested their 1 O 2 production ability using 9′,10′-anthracenediyl-bis­(methylene)-dimalonic acid (ABDA) as indicator .…”

“…Fluorescence imaging, due to real-time monitoring, superior sensitivity, and noninvasive nature, has been widely utilized in the biomedicine field. − So far, based on fluorescence imaging, scientists around the world have made impressive achievements in the investigation of physiological/pathological processes. − However, currently most fluorescence materials developed for fluorescence imaging have dissatisfactory water solubility, giving them a non-negligible nanoscale size in vivo, which brings about inevitable metabolic-safety problems. − Such bottleneck problems hamper their clinical translation for in vivo imaging. In addition, notably, fluorescence imaging requires an excitation laser, which leads to non-negligible background fluorescence and even false imaging signals, limiting greatly their further bioapplications for in vivo imaging. − Accordingly, in order to achieve high signal-to-background ratio (SBR) imaging in vivo clinically, it is of great significance to explore an alternative imaging strategy as well as develop a water-soluble contrast agent with high metabolic efficiency.…”

“…and organic nanoparticles ,− (for example, poly [2,7-(9,9′-dioctylfluorene)- alt -4,7-bis­(thiophen-2-yl) benzo-2,1,3-thiadiazole], PFODBT). Although impressive, due to their large nanosize and material type, such afterglow materials have non-negligible metabolic toxicity and potential leakage risk of inorganic heavy-metal ions, hampering further clinical translation. − , In order to overcome this barrier, recently scientists have tried to develop afterglow organic small molecules with minimal concerns of toxicity and good biocompatibility. Unfortunately, organic small molecules with afterglow ability are still extremely scarce, in particular with a sufficient renal metabolic capacity , (Figure a).…”

“…Unfortunately, organic small molecules with afterglow ability are still extremely scarce, in particular with a sufficient renal metabolic capacity , (Figure a). In addition, these organic-based afterglow materials have only a few types, which are usually dependent on a molecular cascade reaction between 1 O 2 and the corresponding afterglow molecule − ,,,,− (Figure a). And afterglow molecules based on other mechanisms have been rarely reported.…”

“…Afterglow imaging is a promising technique, which does not need a real-time excitation laser source. − Generally, materials with afterglow properties could store photoenergy and release it slowly. As a result, afterglow imaging could effectively eliminate background autofluorescence, which could achieve high SBR imaging in vivo.…”