Amperometric magnetoimmunoassay for the direct detection of tumor necrosis factor alpha biomarker in human serum

• Electrochemical magnetoimmunosensor for tumor necrosis factor alpha (TNFα) biomarker.
• Sensitive and selective detection of TNFα in undiluted serum.
• LOD achieved lower than the cut-off value established for relevant illnesses.
• Useful and affordable alternative to ELISAs for TNFα determination in serum.

An amperometric immunoassay for the determination of tumor necrosis factor alpha (TNFα) protein biomarker in human serum based on the use of magnetic microbeads (MBs) and disposable screen-printed carbon electrodes (SPCEs) has been developed. The specifically modified microbeads were magnetically captured on the working electrode surface and the amperometric responses were measured at −0.20 V (vs. Ag pseudo-reference electrode), upon addition of hydroquinone (HQ) as electron transfer mediator and H2O2 as the enzyme substrate. After a thorough optimization of the assay, extremely low limits of detection were achieved: 2.0 pg mL−1 (36 fM) and 5.8 pg mL−1 (105 fM) for standard solutions and spiked human serum, respectively. The simplicity, robustness and this clinically interesting LOD proved the developed TNFα immunoassay as a good contender for real clinical application.

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