Aptamer induced multicoloured Au NCs-MoS "switch on" fluorescence resonance energy transfer biosensor for dual color simultaneous detection of multiple tumor markers by single wavelength excitation.

An aptamer induced "switch on" fluorescence resonance energy transfer (FRET) biosensor for the simultaneous detection of multiple tumor markers (e.g., AFP and CEA) combining molybdenum disulfide (MoS) nanosheets with multicolored Au NCs by a single excitation was developed for the first time. Here, AFP aptamer functionalized green colored Au NCs (510 nm) and CEA aptamer functionalized red colored Au NCs (650 nm) are used as energy donors, while MoS is used as energy receptor. On the basis of recording the change of the recovered fluorescence intensity at 510 nm and 650 nm upon the addition of targets CEA and AFP, these two tumor markers can be simultaneously quantitatively detected, with detection limits of 0.16 and 0.21 ng mL (3σ) for AFP and CEA, respectively. In addition, it is noteworthy that the developed biosensor can not only realize accurate quantitative determination of multiple tumor markers by fluorescent intensity, but also be applied in semi-quantitative determination through photo visualization. More importantly, confocal microscope experiments prove that serums from normal and hepatoma patients can also be visually and qualitatively discriminated by this FRET-based biosensor with a single excitation wavelength, indicating promising potential of this assay for clinical diagnosis.