A highly sensitive and selective aptasensor based on fluorescence polarization for the rapid determination of oncoprotein vascular endothelial growth factor (VEGF)

Abstract

Vascular endothelial growth factor (VEGF) discrimination in blood is useful for the early diagnosis, staging, and monitoring of cancers. However, effective and efficient methods are needed to improve the diagnosis and assessment of cancer. Here, we report a DNA aptasensor based on fluorescence polarization for the detection of vascular endothelial growth factor (VEGF), a predominant biomarker of cancer angiogenesis. An anti-VEGF DNA aptamer, labeled by a single fluorescent dye at its extremity, was employed as a model functional nucleic acid probe. The DNA conformational change generated by the VEGF binding was able to induce a significant increase in the fluorescence polarization signal. In the absence of VEGF, fluorescently labeled aptamer is in a flexible single strand state, and will have a low P value of the system. Upon the addition of VEGF, it binds with its aptamer, forming a G-quadruplex aptamer–VEGF complex upon its association with the protein. This leads to a significant increase of P value, which provides the quantitative basis of the detection of VEGF. The sensor is prepared in aqueous solution, without separation and washing, and essentially reagentless. We envision that our developed aptasensor holds utilities for point-of-care cancer prognostics by incorporating simplicity in detection, low-cost for test, and required small sample volumes.