As Carbon-Dots are biocompatible and readily functionalized nanoparticles, they have attracted significant interest as conduits for biologically oriented applications. The remarkable fluorescence properties of Carbon-Dots have naturally been primary targets for biological research, particularly focusing on bio-imaging applications (discussed in more detail in Chap. 5). Carbon-Dots have been employed, however, in biological applications other than imaging, mostly related to their nanoscale dimensionalities and the functional units displayed upon their surface. Several examples of such applications are discussed below. It should be emphasized that biological applications of Carbon-Dots still contain many “mechanistic unknowns,” somewhat related to the fact that Carbon-Dot research is still a young scientific discipline.