Layer-by-layer self-assembly of MoS2/PDDA hybrid film in microfluidic chips for ultrasensitive electrochemical immunosensing of alpha-fetoprotein

Ultrasensitive detection of cancer biomarkers holds great promise for early stage detection and diagnosis of cancer. Microfluidic electrochemical immunochips have been assessed as powerful detection platforms due to their high sensitivity, low cost, portability, and ease of miniaturization. In this work, an ultrasensitive electrochemical immunochip based on MoS 2 /PDDA hybrid film is designed via layer-by-layer self-assembly method. An electrochemical impedance detection platform is developed for the detection of alpha-fetoprotein (AFP) by integrating a three-electrode system in the micro-channel, which introduces MoS 2 /PDDA film modified with antibodies as the working electrode, Ag/AgCl wire as the reference electrode and indium tin oxide (ITO) as the counter electrode. After MoS 2 /PDDA film is modified with AFP antibodies, the immobilization of various concentrations of AFP antigens is carried on which can cause changes in the electrochemical impedance value. This proposed approach exhibits a linear range from 0.1 ng/mL to 10 ng/mL and a low detection limit of 0.033 ng/mL (S/N = 3). The applicability of the MoS 2 /PDDA immunochip is further investigated by detecting human serum samples. This ultrasensitive microfluidic immunochip is proved to be highly selective with small input liquid volume, which could realize trace detection of AFP and be potentially applied in clinical diagnosis of other biomolecules.