Abstract
Fluorescence imaging is one of the most powerful techniques for visualizing the distribution and function of biomolecules in living organisms. Although many small-molecule fluorescent probes have been developed, probes that can be utilized for in vivo imaging are still urgently needed. One of the biggest barriers to in vivo imaging, particularly when using small-molecule probes, is the difficulty of delivering the probes specifically to the target cells or tissues. In addition, the probes require a specific sensing ability to visualize the function of the target cells. To analyze the osteoclast function in vivo, recent studies have proposed the use of bisphosphonates (BPs), a class of drugs that contains effective bone-targeting functional groups. Furthermore, acidification during bone resorption is one of the distinctive features of these cells and could therefore also be targeted to visualize osteoclast-specific activity. In this review, the latest information about designing probes that would allow the visualization of osteoclast functions is summarized, including bone-targeting functional groups, as well as the recent developments in intravital imaging of osteoclast activity and motility.
