Fluorescent Nanodiamonds

9Cell Tracking and Deep Tissue Imaging

Cell labeling, both specific and nonspecific, discussed in the previous chapter belongs in part to the field of cell therapy, defined as “administration of live whole cells or maturation of a specific cell population in a patient for the treatment of a disease” [1]. Cell therapy is an emerging field in the medical research as a promising treatment option for human injuries and diseases [2]. While the first use of cells for therapeutic purposes can be traced to the nineteenth century [3], much is still lacking in our knowledge of the therapy, including the biodistribution, pharmacokinetics, and pharmacodynamics of transplanted human cells in vivo [4]. Such knowledge is essential for detailed understanding of the cells’ development, fate, and contribution to regenerating tissues prior to clinical trials.

The advent of nanotechnology in the 1980s (Section 1.1) makes it possible to produce innovative fluorescent markers to solve this long‐standing cell tracking issue. High expectation has been raised for using functional nanomaterials to overcome limitations inherited in conventional therapeutic and diagnostic approaches [5]. However, in this type of application, it is critical to ensure that the cell labeling technique is robust and safe to use. Inorganic fluorescent nanoparticles such as quantum dots have been considered as a potential candidate owing to their superior optical properties [6]. But there is always a concern about the inherent ...