Ultrasensitive interferon-gamma sensor with a bifunctionalized conducting polymer nanobioconjugate for therapy-progress monitoring of cancer patients

Abstract

An ultrasensitive electrochemical aptasensor was designed with a bifunctionalized conducting polymer nanobioconjugate to monitor patients’ progress in cancer immunotherapy by detecting IFN-γ. The sensing probe was fabricated by covalently immobilizing aptamer on a polyterthiophene benzoic acid composited with multi-walled carbon nanotube/Au nanoparticles. The nanobioconjugate was prepared through the self-assembly of bifunctionalized terthiophene aminobenzoic acid (TABA) onto AuNPs then covalently attached with a redox indicator and an antibody on the amine and carboxyl groups of TABA, respectively. At the optimized condition, the sensor detected IFN-γ in the concentration range of 0.5 fM-100 pM with a detection limit of 0.46 ± 0.006 fM (RSD ≤5.1%). The sensor was applied to monitor the extracellular release of IFN-γ by peripheral blood mononuclear cells and the IFN-γ levels in patients’ serum before and after immunotherapy. We observed a low concentration of 0.07 ± 0.004 pM (RSD ≤5.6%) before therapy, which increased significantly to 0.43 ± 0.02 pM (RSD ≤5.1%) after immunotherapy. Meanwhile, a high IFN-γ level of 0.67 ± 0.04 pM (RSD ≤6.2%) was detected in healthy controls. In addition, our study showed IFN-γ is a more effective biomarker for predicting patients’ response to blockade therapy as compared to granzyme B.