**3. Bio-imaging**

Bioimaging is an emerging field of biomedical science that comprises of the development and application of various materials for imaging technologies [51, 52]. The bioimaging techniques principles are mainly based on optics, magnetic resonance, nuclear medicine, radiation, ultrasonics, photonics and spectroscopy. The anatomical and physiological quantification of clinical parameters is measured with the image processing and analysis. With the recent development of biomedical science and emerging newer technologies, the *in vivo* or *ex viv*o biological tissue characterization of imaging properties aids in discerning its structure and function through visualization at several resolutions, extending from organ and cellular to molecular level. FL, near IR CT, PET, MRI and ultrasound images are commonly used for clinical diagnosis and research (**Figure 3**). The characteristic 'energy-matter' interaction is utilized by most bioimaging techniques to provide precise particulars of the biological processes. The imaging modality's uniqueness defines in terms of anatomical and molecular details, spatial and temporal resolution, depth of imaging and properties of contrast agents of augmented imaging. In many clinical

**Figure 3.** *Applications of carbon dots.*

scenarios, the application of multimodal imaging techniques is advantageous for a simultaneous, faster and more accurate diagnosis. Exogenous contrast agents which are used in many imaging modalities enhances the signal to noise ratio. So, the development of multimodal contrast agents is essential to achieve better efficacy and accuracy in diagnosis and therapeutics.
