Dual-readout immunosensor based on multifunctional MXene probe triggers the signal amplification for detection of autoimmune hepatitis marker.

A dual-readout immunosensor coupled with electrochemical impedance and temperature signal was successfully proposed to detect autoimmune hepatitis markers (ASGPR). Nb2C MXene with excellent conductivity, abundant surface functional groups, and extraordinary photothermal conversion efficiency, was designed to be a multifunctional biological probe, whose specific binding with antigen enhanced steric hindrance to generate electrochemical impedance signal, and at the same time, it had a strong optical response in the near-infrared band to achieve temperature output. In addition, poly(N-isopropyl acrylamide) (PNIPAM) was a temperature-sensitive polymer, which was adopted as the sensing matrix. When the multifunctional probe was specifically bound to the antigen, under 808-nm laser irradiation, the captured Nb2C MXene achieved photothermal conversion to increase the electrode surface temperature, and the conformation of PNIPAM changed from a free spiral to a spherical shape, further realizing double amplification of the EIS signal. Under the optimized experimental conditions, the impedance values and the temperature changes increased proportionally with the increase of the ASGPR concentration from 10-5 to 1 ng/mL, and the detection limit of the immunosensor was 3.3 × 10-6 ng/mL. The established dual-readout immunosensor exhibited good selectivity and acceptable stability and provided an effective detection method for autoimmune hepatitis marker detection.