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 Ti3C2 MXene for quantitative detection of thrombin. The dye labelled thrombin-binding aptamer (TBA) was deposited on the surface of Ti3C2, and the fluorescence of which was efficiently quenched owing to the FRET between the dye and Ti3C2. The fact that thrombin forms quadruplex with TBA on Ti3C2 surface is due to the high electronic affinity between thrombin and Ti3C2. This process will cause the subsequent detachment of dye from the surface of Ti3C2, resulting in the recovery of fluorescence. Because of the special structure and high fluorescence quenching efficiency of Ti3C2 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 Ti3C2 MXene-based FRET aptasensor can detect thrombin in human serum accurately. These results suggest that the Ti3C2 MXene-based FRET aptasensor hold a great prospect in clinical diagnosis in the real-world applications.