Recent advances in the targeted fluorescent probes for the detection of metastatic bone cancer

Tumors of the breast, prostate, and lung are most likely to metastasize to the bone and typically indicates a poor cure and survival rate in cancer patients. Detection of metastatic bone cancer in early stage would save many lives and greatly improve patients' quality of life. Clinically, bone scintigraphy is often utilized to visualize bone metastases due to its relatively low cost and high sensitivity. Recently, a growth number of analytical researches aimed at developing targeted fluorescent probes to noninvasively image bone metastases with improved spatial resolution and specificity has been reported. In this review, we will summarize and discuss the recent published fluorescent probes on the accurate detection of metastatic bone cancer. First, the design principles of various targeted probes for imaging bone metastases will be presented, highlighting the signal moieties, targeting ligands, and physicochemical properties of the bone-specific probes. Next, the up-to-date bone-targeting fluorescent probes will be summarized and overviewed. Finally, future perspectives and challenges confronting the researchers in this field will be discussed. We believe this review will encourage novel ideas to develop smart targeted molecular probes for bone metastasis imaging, image-guided surgery, and therapeutic imaging materials.