Fluorometric nanoprobes for simultaneous aptamer-baseddetection of carcinoembryonic antigen and prostate specific antigen

A turn-on fluorometric assay based on the combined effects of fluorescence resonance energy transfer (FRET) and internal filter effect (IFE) is described for the rapid and ultrasensitive detection of both carcinoembryonic antigen (CEA) and prostate specific antigen (PSA). Their unique porous structures and high specific surface enable mesoporous silica nanoparticles (MSNs) to load a large number of CdTequantum dots (QDs). These amplify the fluorescence signal and provide a platform to fabricate more distinctly fluorescent MSNs (QD-MSNs). Two kinds of QD-MSNs with the maximum emission wavelengths at 590nm (orange)and 731nm (dark red)were fabricated and served as two types of fluorescent probes for the dual detection. Two aptamers were covalently connected to fluorescent MSNs as the recognition unit to warrant the selectivity of assay. The fluorescence of QD-MSNs can be quenched by molybdenum disulfide nanosheets (MoS2) due to FRET mechanism, IFE also contributed to thethe reduction of fluorescence intensity. The fluorescence of QD-MSNs was further recovered in the presence of CEA and PSA attributing to the excellent specificity of aptamers. A turn-on fluorescent two-channel nanoprobe is introduced for simultaneous quantification of CEA and PSA. The respective limits of detection (at S/N=3) are 0.7fg center dot mL(-1) for CEA and 0.9fg center dot mL(-1) for PSA.