Abstract

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.

摘要

据报道，一种基于镀金磁性纳米颗粒 (MNPs@Au) 的无标记电化学阻抗谱 (EIS) 传感器可用于测定细胞培养基中的血管内皮生长因子 (VEGF)。在 MNPs@Au 上修饰 VEGF 抗体 (Ab) 以构建磁性固定在磁性玻璃碳电极 (mGCE) 上的 Ab 结合磁性复合物 (MNPs@Au-Ab)。VEGF 被 MNPs@Au-Ab/mGCE 捕获，导致用于测定 VEGF 的电子转移电阻（ R _{et ）增加。}将抗体高效固定在磁性纳米复合材料上与电化学阻抗谱的高灵敏度相结合，VEGF 浓度的出色动态范围为 1.0 × 10 ^-2至 1.0 × 10 ⁴ ng mL ^-1的检测限为 2.43 pg mL ^-1。还进行了各种细胞分泌VEGF的定量测定和研究。癌细胞（MDA-MB-231 细胞和 HCT116 细胞）释放的 VEGF 显着高于正常细胞（L02 细胞），这与酶联免疫吸附试验 (ELISA) 非常匹配。这些结果表明，VEGF的分泌与细胞的转移水平有关。报道的传感器有望应用于癌症和肿瘤转移的研究。