Porphyrin-based covalent organic framework as bioplatfrom for detection of vascular endothelial growth factor 165 through fluorescence resonance energy transfer

Abstract A fluorescent aptasensor based on porphyrin-based covalent organic framework (p-COF) and carbon dots (CDs) was constructed for detecting vascular endothelial growth factor 165 (VEGF165) and imaging of the breast cancer cell line Michigan cancer foundation-7 (MCF-7). The p-COF nanostructure comprises rich functional groups of C=N on the surface, possessed π-stacking planar nanostructure, providing abundant recognition sites with high affinity and specificity, to achieve high capacity for VEGF165 aptamer (AptVEGF) and CDs (CDs acted as the carrier of the VEGF165 aptamer). The FRET effect between p-COF and CDs results in the quenching of the fluorescence feature of CDs. In the presence of VEGF165, the specific recognition between aptamer and VEGF165 leads to the disaggregation of CDs from the p-COF platform. This resulting in the substantial recovery of the fluorescence of CDs. The proposed AptVEGF/CDs/p-COF fluorescence biosensor offered excellent analytical performance for the VEGF165 detection, displayed a detection limit of 21 fg mL-1 within a wide linear range of the VEGF165 concentration of 1.0 pg mL-1–200 ng mL-1. The VEGF165-overexpressed Michigan cancer foundation-7 (MCF-7) cancer cells were determined by the proposed fluorescence aptasensor since the excellent biocompatibility of p-COF and CDs. These results widen the use of COFs in the aptasensor develop and cancer cell detection.