2D titanium carbide nanosheets based fluorescent aptasensor for sensitive detection of thrombin.

The emerging two-dimensional titanium carbides (MXenes) have a large potential in biomedical sensing owing to their excellent electrical and optical properties. Herein, a fluorescence resonance energy transfer (FRET) aptasensor with high sensitivity and specificity was constructed with single layer TiC MXene for quantitative detection of thrombin. The dye labelled thrombin-binding aptamer (TBA) was deposited on the surface of TiC, and the fluorescence of which was efficiently quenched owing to the FRET between the dye and TiC. The fact that thrombin forms quadruplex with TBA on TiC surface is due to the high electronic affinity between thrombin and TiC. This process will cause the subsequent detachment of dye from the surface of TiC, resulting in the recovery of fluorescence. Because of the special structure and high fluorescence quenching efficiency of TiC MXene, the aptasensor shows a high sensitivity with a low detection limit for thrombin at 5.27 pM. Three different aptamers were compared, and the aptamer HD22 is most sensitive for detection of thrombin originated from its great specificity in the human plasma. Importantly, this TiC MXene-based FRET aptasensor can detect thrombin in human serum accurately. These results suggest that the TiC MXene-based FRET aptasensor hold a great prospect in clinical diagnosis in the real-world applications.