A highly sensitive aptasensor for vascular endothelial growth factor based on fluorescence resonance energy transfer from upconversion nanoparticles to MoS2 nanosheets.

A novel sensitive aptasensor for vascular endothelial growth factor-165 (VEGF165) was constructed based on fluorescence resonance energy transfer (FRET) by employing upconversion nanoparticles (UCNPs) and MoS2 nanosheet as energy donor and acceptor, respectively. The upconversion fluorescence resonance energy transfer (UC-FRET) was triggered by the physical adsorption interaction between the aptamer and MoS2 nanosheet, leading to remarkable quenching of UCNPs fluorescence up to 95%. Upon addition of VEGF165 to the UCNPs-aptamer system before MoS2 nanosheet was added, the aptamer preferentially bound to VEGF165 with the change of spatial conformation, which weakened the van der Waals' force between MoS2 nanosheet and the aptamer, thus leading to the separation of the donor and the acceptor. Consequently, the FRET phenomenon was inhibited and the luminescence of UCNPs was regained, which was linearly related to the concentration of VEGF165 from the range of 0.1 ng/mL to 16 ng/mL. By taking advantages of the extreme fluorescence quenching ability of MoS2 nanosheet and the optical merits of UCNPs, the aptasensor based on UC-FRET exhibited favorable performance for the homogeneous assay of VEGF165 in human serum, which is of great value for clinical diagnosis of tumors and related biological studies.