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

This study presents a novel electrochemical aptasensor utilizing polydopamine-graphene (PDA-G) nanocomposite for VEGF₁₆₅detection. 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 VEGF₁₆₅binding). 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 VEGF₁₆₅levels in healthy donor serum were determined to be 28.4 ± 3.2 pg ml^-1. The method's practicality was validated through comprehensive interference studies, with common serum proteins generating relative responses below 5.2% compared to the target.