Vascular Endothelial Growth Factor (VEGF) is a signal protein produced by cells to stimulate the formation of new blood vessels. Although VEGF is essential for physiologic vascular homeostasis, it has been demonstrated to be important in pathogenesis of tumor growth and metastasis, and retinopathy associated with several blinding eye diseases. Studies also suggest the upregulation of VEGF due to various viruses. VEGF detection is difficult to achieve because it is present at extremely low levels (pg/mL), and is currently achieved in the clinical setting through Enzyme-Linked Immunosorbent Assay (ELISA). However, this method has disadvantages such as being a tedious process and takes a long time to perform. Here, we propose a method for trace VEGF detection by using a microfluidic chip integrated with a dielectrophoretic function. This chip can either capture or repel particles by utilizing a dielectrophoresis (DEP) force. Silica beads immobilized with an aptamer specific to VEGF is injected into the chip, which is then captured by the microelectrodes in the chip. A solution of VEGF conjugated to a labeled antibody is subsequently injected into the chip. When the VEGF is captured by the beads, a fluorescence signal is produced, which can then be observed with a fluorescence microscope. The amount of VEGF can then be correlated with the area of fluorescence produced from the beads. This method offers the advantage of being able to detect trace amounts of VEGF (<100 pg/mL) while requiring only a small sample volume (15 μL) and a short assay time (15 min).

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