A photoelectrochemical immunoassay for tumor necrosis factor-α using a GO-PTCNH2 nanohybrid as a probe

A simple photoelectrochemical (PEC) immunoassay based on an amino-terminated perylene derivative (PTCNH2) was developed for highly sensitive and specific detection of tumor necrosis factor-alpha (TNF-α). Simple grinding and sonication afforded a π-π stacked graphene oxide (GO)/PTCNH2 assembly exhibiting fast electron transfer kinetics and excellent photoelectric performance, and this assembly was applied as a PEC probe. The GO-PTCNH2 assembly provided not only a large surface area, fast electron transfer kinetics and abundant active sites for further biomolecule conjugation but also high PEC activity. A “signal-off” PEC immunoassay for TNF-α was developed by assembling GO-PTCNH2 on the electrode, followed by conjugation of anti-TNF-α with GO-PTCNH2 and subsequent capture of the target protein TNF-α. The linear detection range was from 10 pg/mL–100 ng/mL with a limit of detection (LOD) of 3.33 pg/mL. This method was also successfully applied for detecting TNF-α in human serum with recoveries ranging from 92.5% to 96.6% and a relative standard deviation of less than 9.99%. For the first time, this work reports a simple PEC immunoassay achieved by using PTC-NH2 as a photoelectrochemically active probe for the detection of a tumor biomarker. This assay could be applicable to the detection of other biomarkers for clinical diagnosis.