Highly sensitive electrochemical immunosensor for the detection of Beta-2-microglobulin based on ternary composite polyaniline/poly-L-cysteine/molybdenum disulfide

Beta-2-Microglobulin (β2M) is a critical biomarker for diseases such as kidney disorders and cancer. However, electrochemical detection methods for β2M remain scarce. Therefore, a novel electrochemical immunosensor for the ultrasensitive detection of β2M was developed in this study. It is based on a ternary composite of polyaniline (PANI), poly- l -cysteine (PL-Cys), and molybdenum disulfide (MoS₂) functionalized onto screen-printed carbon electrodes (SPCE). Through the specific recognition between Beta2-microglobulin antibody (anti-β2M) and its target antigen, and utilizing bovine serum albumin (BSA) to block non-specific binding sites, a BSA/anti-β2M/PANI/PL-Cys/MoS₂/SPCE immunosensor was constructed. Experimental results demonstrate that the sensor exhibits excellent linearity within the 0.001–500 ng/mL (R²=0.9924), with a detection limit as low as 0.33 pg/mL. It shows outstanding selectivity (RSD=2.69%), repeatability (RSD=0.74%), and long-term stability (30-day RSD=2.64%). Recovery rates in serum samples range from 100.40% to 103.76%, confirming its reliability in complex biological matrices. The sensor combines the signal amplification effect of the conductive substrate (PANI/L-Cys/MoS₂) with the impedance effect of the insulating biological layer (antibody-antigen complex), utilizing the quantitative relationship between target analyte concentration and signal attenuation to achieve detection. This approach provides an efficient and low-cost new strategy for on-site rapid screening.