Preparation of biomass-derived red emission carbon dots for real-time and long-term tracking of cells and tumor growth

Effective real-time cell tracking and tumor growth monitoring are important for precise diagnosis and therapy of tumors and can also be used to monitor biological processes. In this study, a facile, green microwave method was developed to synthesize biomass-derived red emission carbon dots (RCDs) using the ethanolic extract of holly leaves. Owing to the advantages of the prepared RCDs, such as near infrared emission, stability, strong fluorescence intensity, excellent biocompatibility, penetration of thick tissues, avoiding background fluorescence interference, and improvement of the signal-to-noise ratio of biological imaging, they were applied to cell imaging, real-time cell tracking and tumor growth monitoring. Experimental results revealed that the RCDs could present strong red fluorescence emission when they entered the cells. The labeled cells still emitted red fluorescence after 13 generations of passage and could monitor tumor growth in real-time for more than 18 days. These results indicated that RCDs could be used as effective long-term near-infrared fluorescent imaging probes for cells and tumors, presenting broad application prospects in image-guided therapy.