Cell Labeling with Fluorescent Nanodiamonds for Visualization and Manipulation

Fluorescent nanodiamonds (FNDs) have emerged as a powerful tool for cellular labeling and imaging due to their excellent biocompatibility, low cytotoxicity, high photostability, and facile bioconjugation. These carbon-based nanoparticles can label living cells via passive uptake through endocytosis and exhibit minimal exocytosis. Additionally, nitrogen-vacancy centers implanted in the particles emit bright red photoluminescence, enabling high-resolution imaging of individual FNDs within cells by confocal microscopy. Rapid quantification of FND-labeled cells is also possible with flow cytometry, further supporting their long-term tracking and monitoring in vitro and in vivo. This chapter provides a detailed description of methods for cellular labeling using protein-functionalized FNDs via passive uptake, followed by fluorescence microscopy and flow cytometry analysis.