A Novel Electrochemical Aptasensors Utilizing AuNW/AuNC/PAA Nanocomposite for Label‐Free Detection of IL‐6 in Human and Mammalian Culture Serum

A versatile and highly sensitive sensing platform has been developed by incorporating a nanocomposite of gold nanowire (AuNW), gold nanocolloid (AuNC), and polyacrylamide (PAA) onto the surface of a screen-printed carbon electrode (SPCE). This innovative approach is designed for the efficient detection of interleukin-6 (IL-6) in human serum and mammalian cell culture. The synthesized gold nanocomposite enhanced the SPCE's electrochemical signal via high conductivity, increased the electroactive surface for efficient electron transfer, and enabled thiolated aptamer immobilization through AuS bonds. In this regard, the AuNW/AuNC/PAA nanocomposite and thiolated IL-6 aptamers were used to construct an IL-6 aptasensor for sensitive and selective detection of IL-6 using differential pulse voltammetry (DPV) in 5 mM [Fe(CN)₆]^3-/4- as a redox probe. The fabricated aptasensor demonstrated sensitive detection of IL-6, with a detection range of 0.1-1000 pg mL^-1 and a limit of detection (LOD) of 0.1 pg mL^-1. Moreover, the developed IL-6 aptasensor exhibited excellent stability, reproducibility, and selectivity. Its applicability was validated by IL-6 detection in human serum, showing 93.9%-104.8% recovery. Additionally, IL-6 levels in cell culture media were tested using both the aptasensor and a commercial ELISA kit, showing only a 1.38% difference, further confirming its reliability.