A ratiometric fluorescent probe based on molecularly imprinted carbon dots for specific detection and quantification of Mn2+ in living cells

Manganese (Mn), an essential trace element in the human body, can independently activate the cGAS-STING pathway, thereby significantly enhancing the therapeutic efficacy of immunotherapy. However, precise quantification of Mn 2+ in living cells remains technically challenging, hindering mechanistic studies of Mn-mediated cGAS-STING pathway activation. To address this limitation, a novel Mn 2+ -specific fluorescent probe, Mn 2+ -CDs-MIPs, was developed by integrating molecular imprinting techniques with carbon dots (CDs). Upon excitation at 290 nm, two distinct emission peaks were observed at 365 nm and 520 nm. In the presence of Mn 2+ , the emission intensity at 365 nm was significantly enhanced, while the peak at 520 nm remained constant. By using the signals at 365 nm and 520 nm as responsive and reference signals, respectively, a novel ratiometric sensor for Mn 2+ quantification was developed. Under optimal conditions, a strong linear correlation between Mn 2+ concentration and the ΔF 365 /F 520 ratio was observed over the range of 0.8–80 μM, with a detection limit as low as 0.3 μM. Leveraging the precisely tailored cavities and Mn 2+ -induced modulation of fluorescence properties, this method exhibits high specificity and salinity tolerance, facilitating its application in Mn 2+ quantification within complex biological systems and living cells.