Direct detection of TNF-α by copper benzene tricarboxylate MOFs/gold nanoparticles modified electrochemical label-free immunosensor using FFT admittance voltammetry

•Fabrication of novel label free chemically efficient electrochemical immunosensor for TNF-α direct determination.•Using FFT admittance signal for TNF-α concentration monitoring as advanced modern electroanalytical technique.•Preparing effective imbed for TNF-α antibody immobilizing using HKUST-1/Au NPs.•Reaching lower detection limit and higher sensitivity compared with conventional quantitative electrochemical methods. A new simple label-free electrochemical immunosensor was designed for sensitive and selective determination of tumor necrosis factor-alpha (TNF-α), through gold nanoparticles (GNPs) incorporated copper benzene tricarboxylate metal organic frameworks (HKUST-1) modified gold electrode, where TNF-α specific monoclonal antibody was bonded to the electrode surface through shaped self-assembled monolayer (SAM) of mercapto compounds. The fabrication steps were monitored by field emission scanning electron microscopy (FE-SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Under optimized experimental conditions, fast Fourier transform admittance voltammetry (FFTADV) used for TNF-α measurement. A wide linear range of current response towards the TNF-α concentration from 0.0005 to 50 ng/mL and LOD value of 0.15 pg/mL were achieved using FFTADV. The described immunosensor had adequate sensitivity and selectivity towards direct determination of TNF-α in complex biological matrix.