N-doped carbon dots modified with the epithelial cell adhesion molecule antibody as an imaging agent for HepG2 cells using their ultra-sensitive response to Al³⁺

Carbon dots (CDs) are emerging as an ideal multifunctional materials due to their ease of preparation and excellent properties in medical imaging technology, environmental monitoring, chemical analysis and other fields. N-doped CDs modified with the epithelial cell adhesion molecule antibody (anti-EpCAM-NCDs) were synthesized in an ingenious and high-output approach. Due to the fluorescence enhancement effect of the introduced N atoms, the obtained anti-EpCAM-NCDs exhibited a strong green emission with an absolute quantum yield of up to 32.5%. Anti-EpCAM-NCDs have immunofluorescent properties and an active targeting function. The fluorescence effect and fluorescence quenching of anti-EpCAM-NCDs are used to image cells and detect Al³⁺, respectively. Experimental results show that this probe exhibited a wide linear response to Al³⁺ over a concentration range of 0−100 μM with a detection limit and quantification limit of 3 nM and 6 nM, respectively. Significantly, anti-EpCAM-NCDs, which have negligible cytotoxicity, excellent biocompatibility and high photostability, could be used for the intracellular imaging of HepG2 cells and the detection of Al³⁺ in environmental and biological samples. As an efficient multifunctional material, anti-EpCAM-NCDs hold great promise for a number of applications in biological systems. (paper)