DPV and EIS-based ultrasensitive aptasensor for VEGF165 detection based on nanoporous gold platform modified with SH-aptamer

The sensitive detection of trace amounts of vascular endothelial growth factor (VEGF₁₆₅) in samples holds significant potential for clinical cancer diagnosis across various cancer types. This work introduces a novel and cost-effective dual strategy for developing an ultrasensitive electrochemical aptasensor based on the self-assembly of SH-aptamer onto a nanoporous gold electrode for VEGF₁₆₅ detection. SEM and electrochemical characterization confirmed the formation of the nanoporous structure and the increase of the surface area of the gold electrode from 0.1199 cm² to 0.1875 cm². The sensing method relied on the interaction between the DNA probe and VEGF₁₆₅, which increased the charge transfer resistance of Fe(CN)₆^3−/4- in the (signal-on) strategy, as determined by EIS. Conversely, it diminished the reduction peak current of the methylene blue probe in the (signal-off) strategy, as assessed by Differential Pulse Voltammetry (DPV). The limit of detection and linear dynamic range of the prepared electrode were found to be 0.25 pM and 2.5 to 140 pM, respectively, using DPV, and 0.18 pM and 5 to 200 pM, respectively, using EIS. The aptasensor demonstrated desirable stability after storing the aptasensor in a buffer solution for one week. Furthermore, analogous proteins did not exhibit significant interference. Also, detecting the VEGF₁₆₅ cancer marker in undiluted human serum samples had excellent recovery with relatively low standard deviation percentages. Therefore, the findings indicate that the proposed aptasensor could potentially be utilized in the future design of a non-invasive cancer diagnostic kit using a blood or interstitial fluid test instead of the painful and aggressive biopsy method.