Development of a polydopamine-graphene nanocomposite electrochemical aptasensor for sensitive detection of lung cancer biomarker VEGF.

This study presents a novel electrochemical aptasensor utilizing polydopamine-graphene (PDA-G) nanocomposite for VEGFdetection. The PDA-G nanocomposite was synthesized through a one-step self-polymerization process and characterized by SEM, XPS, and FTIR, confirming successful PDA coating on graphene sheets with 22.3% C-N bond incorporation. Electrochemical characterization confirmed stepwise increases in charge transfer resistance (Rct), and quantitative detection was based on ΔRct (the change in Rct before vs. after VEGFbinding). Under optimized conditions (pH 7.4, 37 °C, 30 min incubation), the sensor demonstrated dual-linear response regions with high sensitivity. Analysis of clinical samples showed minimal matrix effects with a 1:4 dilution ratio, and endogenous VEGFlevels in healthy donor serum were determined to be 28.4 ± 3.2 pg ml. The method's practicality was validated through comprehensive interference studies, with common serum proteins generating relative responses below 5.2% compared to the target.