Magneto-imunossensor para detecção do biomarcador ADAM10 no diagnóstico precoce da doença de Alzheimer

Alzheimer's disease (AD) is an irreversible progressive brain disorder, being the most common neurodegenerative disease in the elderly[1]. Previous studies reported a change in ADAM10 platelet protein levels in AD patients compared to healthy patients, suggesting ADAM10 as a potential biomarker for AD[2]. The objective of this work was to develop a disposable magneto-immunosensor for the ADAM10 detection in human plasma sample of elderly with AD and healthy. Homemade screen-Printed Electrode (SPE) were constructed by deposition of carbon and Ag/AgCl conductive ink on polyester sheet, based in the use of a cutter printer and a lamination process[3]. Using the SPE and a magnet, ADAM10 was detected using a magnetic immunoassay and gold nanoparticles (AuNPs) as labels. The immunoassay was done by incubating the biomarker with magnetic beads (MBs) decorated with anti-ADAM10 (MB-Ab1) primary antibody. In this step, ADAM10 was captured from the sample and remained conjugated to MB-Ab1, forming the MB-Ab1/ADAM10 conjugate, which was then separated from the sample and pre-concentrated by applying a magnetic field. MB-Ab1/ADAM10 was incubated with AuNPs decorated with anti-ADAM10 (Ab2-AuNP) secondary antibodies, forming the MB-Ab1/ADAM10/Ab2-AuNP immunoconjugate. Biomarker quantification was determined by the electrochemical detection of AuNPs, proportional to the ADAM10 concentration. AuNPs were preconcentrated by a potential of +1.25 V in HCl 0.2 mol L- 1 . Immediately after the electrochemical oxidation, differential pulse voltammetry was performed. The ADAM10 calibration curve was linear in the range of 10.0 to 1000.0 pg mL-1 , with a linear correlation coefficient of 0.998. Detection and quantification limits were 13.9 and 46.3 pg mL-1 , respectively. Plasma samples from elderly with AD, mild cognitive impairment (preclinical symptomatic phase of AD) and healthy were analyzed and compared with the Enzyme-Linked Immunosorbent Assay (ELISA). An increase in ADAM10 levels in elderly with AD was observed when compared to MCI and healthy, for two methods. Statistical analysis, using the receiver operating characteristic (ROC) curve, indicated that the immunosensor discriminates the AD group from the healthy group with 90% specificity and 70% sensitivity. The device can be an auxiliary tool in the early diagnosis and monitoring of AD and can be applied as point-of-care devices.