Abstract
Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.
Highlights
Vascular endothelial growth factor (VEGF165), a glycolated protein belonging to the platelet-derived growth factor family of the cystine-knot growth factors, is essential for vascular development [1]
The PANI/carbon nanotube (CNT)-modified electrode showed individual fibers, indicating that the PANI covered the surface of the CNTs because the active sites of the CNTs could act as a backbone for PANI [36,39,40]
The P2p spectrum of the PANI/CNT showed no peak, while the PANI/CNT/Apt layer showed a phosphate peak at 132.73 eV due to the aptamer molecules (Figure 4D) [41]. These results demonstrated that the PANI/CNT/Apt nanocomposite was successfully synthesized
Summary
Vascular endothelial growth factor (VEGF165), a glycolated protein belonging to the platelet-derived growth factor family of the cystine-knot growth factors, is essential for vascular development [1]. It is active in angiogenesis, vasculogenesis, and endothelial cell growth, causing endothelial cell proliferation, promoting cell migration, inhibiting apoptosis, and inducing blood vessel permeabilization [2,3,4]. For the patient of VEGF drug treatment, there are a few significant studies on the detection of VEGF165 levels in bio samples [13,14,15,16]; more accurate, reliable, and stable detection methods with higher sensitivity are still required
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