Bioimaging is a technology to visualize biological processes in a real-time and non-invasive manner, which plays an important role in the development of medicine by monitoring the physiological processes in the human body. Many imaging modalities have been developed and applied clinically, such as X-ray computed tomography (CT), nuclear magnetic resonance imaging (MRI), and positron emission tomography (PET). However, the present technologies are still suffering from limitations like radioactivity and low sensitivity and resolution. Compared with these traditional imaging modalities, fluorescence imaging is a potential technology for dynamic visualization with advantages of great sensitivity, high resolution, and low cost. Although the fluorescence imaging has now been widely used in many in vitro applications, such as immunofluorescence assays and super-resolution imaging, the poor penetration depth of most fluorescent materials largely impeded their applications in vivo.