Preliminary Study of a Low-Cost Point-of-Care Testing System Using Screen-Printed Biosensors for Early Biomarkers Detection Related to Alzheimer Disease

Among neurodegenerative diseases, Alzheimer Disease (AD) represents one of the most widespread pathologies, for which an early diagnosis is still missing. A peculiar expression of an altered conformational isoform of p53 protein was reported to be a potential biomarker able to distinguish AD subjects from healthy population, quantifiable using a blood-based enzyme-linked immunosorbent assay (ELISA). In order to overcome ELISA limitations, related to reliability and to improve sensitivity, this study aimed to realize a low cost highly sensitive portable point-of-care (PoC) testing system based on screen printed electrochemical sensors (SPES). The development of the platform specifically included both the design of the sensing probe and of the electronic circuit devoted to the conditioning and acquisition of the transduced electric signal. Preliminary testing of the circuit were performed recording changes in the conductivity of NaCl solution and quantifying electrodes coating with antibodies using Electrochemical Impedance Spectroscopy (EIS) principle. Results obtained with saline solution, showed the ability of the circuit to give the best response corresponding to low changes in NaCl concentration (sensitivity 0.2 mA/(mg/ml)), suggesting a good sensitivity of the platform. Findings obtained from EIS showed the ability of the circuit to discriminate between different concentrations of antibodies coatings (sensitivity 80 mu A/mu g). Preliminary calibration of the sensor using interleukin IL-8 showed an increase in the maximum peak of current proportional to the increase of protein concentration, achieving a sensitivity of 35 mu A/ng and reporting also a good value of reproducibility, really promising in the perspective of lower values of proteins concentrations.