Using concentration-dependent carbon dots as an antibody-free specific fluorochrome for multi-species bacterial...

Our findings demonstrate a close correlation between the aggregation of carbon nanodots (CDs) in bacterial cells and various cellular properties, including the cellular wall/membrane structure, the protoplasts, and the dead/live state. Therefore, when different species or states of bacteria are stained with concentration-dependent CDs, their fluorescence will differ. This enables the specific labelling of bacterial species and the distinction of dead/live bacteria. In this study, we demonstrated the capacity of independently prepared concentration-dependent CDs to distinguish between dead and live bacteria. Furthermore, by combining these CDs with hyperspectral imaging, we achieved the precise identification of five intestinal bacteria with an accuracy of 96.8%. By comparing the immunofluorescence technique, this antibody-free method has no complicated pre-treatment and requires only one step of staining to label multiple species of bacteria and distinguish between their dead and live states. It demonstrates considerable promise for implementation in the study of bacterial communities.