Alzheimer's disease diagnosis based on detection of autoantibodies against A beta using A beta 40 peptide in liposomes

Author(s)

Monteiro Jr, Julio Cesar ; Yuri Yokomichi, Anna Laura ; de Carvalho Bovolato, Ana Livia ; Schelp, Arthur Oscar ; Lima Ribeiro, Sidney Jose ; Deffune, Elenice ; de Moraes, Marli Leite

• Document type: Journal article
• Source: Clinica Chimica Acta; v. 531, p. 7-pg., 2022-06-01.

Abstract

Background: Alzheimer's disease (AD) is the most common form of dementia and affect more than 50 million people worldwide. Thus, there is a high demand by non-invasive methods for an early diagnosis. This work explores the AD diagnostic using the amyloid beta 1-40 (A beta 40) peptide encapsulated into dipalmitoyl phos-phatidyl glycerol (DPPG) liposomes and immobilized on polyethylene imine previously deposited on screen-printed carbon electrodes to detect autoantibodies against A beta 40, a potential biomarker found in plasma samples.& nbsp;Methods: The immunosensor assembly was accompanied by atomic force microscopy (AFM) images that showed globular aggregates from 20 to 200 nm corresponding liposomes and by cyclic voltammetry (CV) through in-crease of the voltammogram area each material deposited. After building the immunosensor, when it was exposed to antibody anti-A beta 40, there was an increase in film roughness of approximately 9 nm, indicating the formation of the immunocomplex.& nbsp;Results: In the detection by CV, the presence of specific antibody, in the range of 0.1 to 10 mu g/ml, resulted in an increase in the voltammograms area and current in 0.45 V reaching 3.2 mu A.V and 5.7 mu A, respectively, in comparison with the control system, which remained almost unchanged from 0.1 mu g/ml. In patient samples, both cerebrospinal fluid (CSF) and plasma, was possible separated among positive and negative samples for AD using CV profile and area, with a difference of 0.1 mu A.V from the upper error bar of healthy samples for CSF sample and 0.6 mu A.V for plasma sample.& nbsp;Conclusions: These results showed the feasibility of the method employed for the non-invasive diagnostic of Alzheimer's disease detecting natural autoantibodies that circulate in plasma through a simple and easy-to-interpret method. (AU)

• FAPESP's process: 18/04648-9 - Immunosensor for the Alzheimer's Disease diagnosis in the preclinical stage by the detection of autoantibodies
• Grantee: Marli Leite de Moraes
• Support Opportunities: Regular Research Grants