Nanostructured Au-Pt hybrid disk electrodes for enhanced parathyroid hormone detection in human serum

Most clinical tests for biomarker detection require the support of a laboratory, and the results are usually slow, less sensitive, and lack the possibility for Point-of-Care (PoC) testing. Further, with the increasing demand for sensitive, portable, rapid, and low-cost devices for clinical PoC applications, innovative methods are crucial. Thus, we report on utilizing nanostructured gold-platinum (Au-Pt) hybrid electrodes as a PoC device for highly sensitive and selective PTH detection in human serum samples. The method employs the immobilization of 3-mercaptopropionic acid to Au and subsequent activation of the carboxyl groups to enable anti-PTH antibody immobilization. Serum PTH was detected by monitoring the changes in electrochemical properties (ΔR_ct and Δi) of the sensor using electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV) against a standard hexacyanoferrate (II/III) probe. Changes in relative response percentage (RR%) in electrochemical properties due to increased PTH concentrations in serum were observed with EIS and DPV. The biosensor exhibited a low detection limit of 0.36 pg.mL^-1 (EIS) and 0.59 pg.mL^-1 (DPV) in serum with a linear range of 1 to 100,000 pg.mL^-1. Further, to validate the accuracy of the proposed method, clinical samples (n = 20) were examined using the EIS method and compared to an established commercial test.