A novel type of carbon dots for discriminating yeast cell viability and nuclear labeling

As a new type of nanomaterial, carbon dots (CDs) have demonstrated potential in the field of biological imaging. Currently, research utilizing them for labeling microorganisms is confined to simple imaging, with limited studies exploring their application in detecting cell viability and organelle targeting. Yeast, serving as both a fermenting agent and a model cell, constitutes an ideal research subject This study synthesized ascorbic acid-based CDs (A-CDs) using citric acid, ascorbic acid, and ethylenediamine as raw materials via hydrothermal method. A-CDs were uniformly dispersed, with an average particle size of 3.28 nm. The surface functional groups, such as NH 2 and -OH, endowed them with hydrophilicity. Additionally, A-CDs exhibited concentration-dependence, good photostability, and biocompatibility. By labeling yeast with A-CDs, it was observed that cells in dead, alive, and intermediate states exhibited different imaging effects, which were highly correlated with the concentration of A-CDs entering the cell due to variations in cell membrane permeability. Through co-localization experiments with A-CDs and DAPI, it was confirmed that A-CDs could target and label cell nucleus. Preliminary endocytosis experiments indicated that A-CDs primarily entered cells via clathrin-mediated and lipid raft-mediated endocytosis. The ability of A-CDs to discriminate between cell viability and label nuclei offers new perspectives on the application of CDs in the field of biological imaging.