A self-calibrating IoT portable electrochemical immunosensor for serum human epididymis protein 4 as a tumor biomarker for ovarian cancer

Nowadays analytical techniques are moving towards the development of smart biosensing strategies for point-of-care accurate screening of disease biomarkers, such as human epididymis protein 4 (HE4), a recently discovered serum markers for early ovarian cancer diagnosis. In this context, the present work represents the first implementation of a competitive enzyme-labelled magneto-immunoassay exploiting a homemade IoT Wi-Fi cloud-based portable potentiostat for differential pulse voltammetry readout. The electrochemical device was specifically designed capable of autonomous calibration and data processing, switching between calibration and measurement modes: in particular, firstly a baseline estimation algorithm is applied for correct peak computation, then calibration function is built by interpolating data with a four-parameter logistic function. The calibration function parameters are stored on the cloud for inverse prediction to determine the concentration of unknown samples. Interpolation function calibration and concentration evaluation are performed directly on-board, reducing the power consumption. The analytical device was validated in human serum, demonstrating good sensing performance for analysis of HE4 with detection and quantitation limits in human serum of 3.5 and 29.2 pM, respectively, reaching the sensitivity required for diagnostic purposes, with high potential for applications as portable and smart diagnostic tool for point-of-care testing.