A multichannel biosensor integrated with a controller board for standard addition voltammetric signal analysis of...

Conventional miniaturized immunosensors featuring a single working electrode are often time-consuming due to the lengthy immunoassay procedures they require. Additionally, they necessitate background correction of the voltammetric signal. To overcome these challenges, a multichannel electrochemical immunosensor with six working electrodes has been developed. This innovative design enables the simultaneous analysis of six antigen solutions using the standard addition calibration protocol for precise background correction. This multichannel sensor has been used for cardiac troponin I (cTnI) determination in human serum using multiwall carbon nanotubes/carboxylate-functionalized polyaniline/gold nanoparticles working electrodes to ensure efficient electron transfer and immobilize cTnI antibodies. The immunoassay was optimized to employ a low concentration of cTnI antibody on a preactivated immunosensor, enabling a rapid assay completed within 45 min. The current signals in differential pulse voltammetry mode have been measured from the six electrodes at two different times. This enabled the plot of standard addition calibration for background correction with high reproducibility (RSD% = 2.64 %) in a dynamic range of 0.05-0.5 ng/mL cTnI antigen and detection limit of 0.02 ng/mL. Reliable quantification of cTnI in spiked and retained serum samples was obtained by the proposed electrode and compared favourably to chemiluminescent immunoassay. The proposed multi-electrode chip is not only inexpensive and simple to fabricate using photoresist etching but also allows efficient electrode switching through a homemade printed-circuit-board controller for practicality. This chip has been compared favourably to other reported electrochemical sensors, and it shows a feasible and reproducible approach for point-of-care diagnostics.