▎ 摘　　要

NOVELTY - Kit comprises 10-30 mg/l sulfonic acid-based graphene quantum dot solution with a particle size of 2-3 nm. USE - The kit is useful for fluorescent labeling of cell nucleus (claimed) and also used for labeling tissue. ADVANTAGE - The kit enables simple and stable fluorescent labeling of cell nucleus with high efficiency, and the labeled cell nucleus is suitable for long-time tracing. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a method for fluorescent labeling of cell nucleus, which involves (a) fixing a biological sample by using 4% paraformaldehyde, (b) co-incubating the quantum dots with the biological sample and covering the surface of quantum dot biological sample, incubating at room temperature for 5 minutes and washing excess quantum dots on the surface of the biological sample by using phosphate buffer saline (PBS), and (c) observing the cell nucleus by irradiating the biological sample with an excitation light having a wavelength of 405 nm.