Development of a fluorescent peptide for the highly sensitive and selective detection of vascular endothelial growth factor

Abstract

A novel vascular endothelial growth factor (VEGF)-targeting fluorescent peptide (compound 1), with a cyanopyranyl group as the fluorophore and a peptide as the binding site of VEGF, was developed. Compound 1 allowed the detection of VEGF by altering its fluorescence quantum yield. When free in solution, compound 1 displayed weak fluorescence emission, in contrast to the strong fluorescence emission signal when associated with VEGF. The increase in fluorescence intensity was concentration-dependent, and a linear relationship was observed by plotting fluorescence intensity as a function of VEGF concentration. The binding and detection of compound 1 with VEGF was not affected by the presence of other substances, thus allowing a highly selective detection. The detection limit of VEGF by compound 1 was 0.05 ng/mL, indicating a 100 times higher sensitivity than that of a previously reported compound. As an application of this fluorescent reagent, compound 1 was immobilized on the surface of magnetic beads via covalent binding, and, after optimization, the highly sensitive and selective detection of VEGF in buffer and in serum was successfully performed (limit of detection was 0.002 ng/mL). This was due to the increase in the protein binding surface promoted by the integration of compound 1 on the surface of magnetic beads, and to the quick and efficient separation of the beads, reducing background and non-specific binding. Overall, results from this work clearly show that compound 1 is a areliable probe for VEGF detection, that can be widely employed in VEGF detection in diverse areas of research.