Smartphone-assisted portable immunosensor toward on-site detection of tumor necrosis factor-α inhibitor adalimumab...

A decentralized electrochemical immunosensor was developed using a smartphone and a portable electrochemical workstation. The system employs a gold nanoflower-modified screen-printed carbon electrode (AuNFs/SPCE) for the sensitive measurement of adalimumab (ADL) in human serum via antigen‒antibody recognition. Scanning electron microscopy, X-ray photoelectron spectroscopy, and atomic force microscopy were used to investigate the AuNFs/SPCE. Compared with the bare SPCE, the AuNFs/SPCE has a 1.47-fold larger specific surface area, which enhances the capture efficiency of ADL for signal amplification. Electrode modification and antigen‒antibody assembly processes are characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The immunosensor achieves excellent electrochemical properties by optimizing experimental conditions, which improves the signal-to-noise ratio and thus the analytical performance. Under the best experimental conditions, the immunosensor has a quantitative range of 0.05‒4 μg/mL in diluted human serum with a detection limit of 9.1 ng/mL, which is consistent with the effective therapeutic window of ADL in clinical settings. The prepared electrodes maintain 10-day stability, while with high reproducibility at different ADL concentrations. High recoveries in the range 94.08‒108.6% are obtained in human serum samples. Furthermore, ADL in the serum samples was measured by both ELISA and the developed sensor. Pearson and Bland‒Altman analyses revealed a consistent trend between the two methods. Therefore, this immunosensor is a promising tool for the point-of-care (POC) measurement of ADL in clinical samples, providing valuable insights for personalizing ADL dosing regimens in clinical practice.