A novel immunoprobe composed of reduced graphene oxide-hemin-thionin-Au nanohybrid for ultrasensitive detection of tumor marker

An ultrasensitive electrochemical immunosensor was fabricated by employing reduced graphene oxide-thionin-hemin-Au (H-rGO-Thi-Au) nanohybrid as probe to measure neuron specific enolase (NSE), a lung cancer biomarker. In this work, the reduced graphene oxide (rGO) was used as support material to immobilize hemin and thionin through aromatic π-π interaction. Then Au nanoparticles were reduced by thionin in situ on the probe. The immunoprobe offers several advantages as follows: (1) thionin can be enriched for signal amplification; (2) the catalysis ability of hemin can be enhanced by preventing the molecules aggregation; (3) the reduced graphene oxide-hemin (H-rGO) acts as signal amplifier to accelerate the redox cycling with H2O2; (4) the composite with good conductivity is beneficial to improve response current. Apart from that, polyaniline hydrogel as substrate prepared by electrochemical polymerization on the glassy carbon electrode showed excellent conductivity which can further improve the performance of immunosensor. Thus, the proposed immunosensor showed excellent analytical performance for the detection of NSE with wide linear range from 0.1 pg mL−1 to 100 ng mL−1 and low detection limit of 0.026 pg mL−1. It is also of note that human serum samples were determined with satisfactory results, indicating its value on clinical application.