Gold nanoparticle-modified graphene oxide electrochemical aptasensor for ultrasensitive detection of interferon gamma in kidney transplants

The early and accurate detection of interferon gamma (IFN-γ), a key cytokine in acute cellular rejection following kidney transplantation, is essential for effective immunosuppressive management. Current methods often lack the sensitivity, speed, or simplicity for routine clinical immunomonitoring. Here, we developed a novel electrochemical aptasensor that employs a thiolated reduced graphene oxide/gold nanoparticles (TrGO–AuNPs) nanohybrid interface for IFN-γ detection. The platform integrates an anthraquinone-labeled hairpin aptamer immobilized onto the TrGO/AuNPs-modified glassy carbon electrode, through a binding-induced conformational switching mechanism to enhance signal transduction efficiency. Upon differential pulse voltammetry, the sensor exhibited a wide linear range from 0.28 to 900 pg mL⁻¹ and an ultra-low limit of detection (67 fg mL⁻¹). These analytical values surpass clinically relevant IFN-γ levels observed during acute cellular rejection. The synergistic TrGO/AuNPs combination significantly enhanced aptamer anchoring, surface conductivity, and signal resolution. The sensor demonstrated excellent selectivity in complex matrices and reliable recovery in spiked human serum, with a total analysis time of less than 45 min. To the best of our knowledge, this is the first report to utilize the TrGO–AuNPs nanohybrid architecture for electrochemical quantification of IFN-γ, offering a simplified, rapid, and sensitive strategy for point-of-care transplant immunomonitoring and highlighting the translational utility of the platform.