Determination of Vascular Endothelial Growth Factor (VEGF) in Cell Culture Medium by Gold-Coated Magnetic Nanoparticle Based Label-Free Electrochemical Impedance Spectroscopy (EIS)

A gold-coated magnetic nanoparticle (MNPs@Au) based label-free electrochemical impedance spectroscopy (EIS) sensor is reported for determining vascular endothelial growth factor (VEGF) in cell culture media. VEGF antibodies (Ab) were modified on MNPs@Au to construct an Ab-bound magnetic complex (MNPs@Au-Ab) that was magnetically immobilized on a magnetic glassy carbon electrode (mGCE). The VEGF is captured on the MNPs@Au-Ab/mGCE, leading to increased electron-transfer resistance (R_et) utilized for the determination of VEGF. Combining the highly efficient immobilization of antibodies on magnetic nanocomposites with the high sensitivity of electrochemical impedance spectroscopy, an excellent dynamic range for the VEGF concentration from 1.0 × 10⁻² to 1.0 × 10⁴ ng mL⁻¹ was obtained with a detection limit of 2.43 pg mL⁻¹. Quantitative determination and the investigation of the secretion of VEGF by various cells were also conducted. VEGF released by cancer cells (MDA-MB-231 cells and HCT116 cells) was significantly higher than for normal cells (L02 cells), which matched well with an enzyme linked immunosorbent assay (ELISA). These results show that the secretion of VEGF is associated with the metastatic level of cells. The reported sensor is expected to be applied in studies of cancer and tumor metastasis.

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