Competitive electrochemical immunosensor for the detection of unfolded p53 protein in blood as biomarker for Alzheimer’s disease

Abstract

Alzheimer's disease is one of the most common causes of dementia nowadays, and its prevalence increases over time. Because of this, accurate methods for the analysis of specific biomarkers for an early diagnosis of this disease are much needed. Recently, the levels of unfolded isoform of the multifunctional protein p53 in plasma have been proved to increase selectively in Alzheimer's Disease patients in comparison with healthy subjects, thus entering the list of biomarkers that can be used for the diagnosis of this illness. We present here the development of an electrochemical immunosensor based on nanostructured screen-printed carbon electrodes for the quantification of unfolded p53 in plasma samples. The sensor shows a suitable linear range (from 2 to 50 nM) for its application in real blood samples and a very low limit of detection (0.05 nM). The concentration of unfolded p53 has been accurately detected in plasma of elderly people in healthy conditions, subjects with mild cognitive impairment (MCI) and Alzheimer's Disease (AD) subjects, obtaining results with no significant differences to those provided by an ELISA assay. This result supports the possibility of measuring unfolded p53 levels with a cheap, simple and miniaturized device with a promising future for point-of-care applications in the early diagnosis of Alzheimer's dementia.

Melatonin: Regulation of Biomolecular Condensates in Neurodegenerative Disorders

“…Compared to healthy elderly controls, p53 in AD patients exhibited a 100% increase in p53 in the superior temporal gyrus, and induced the phosphorylation of tau in HEK293a cells in vitro [ 728 ]. Dysregulation of p53 such as unfolded p53 caused by oxidative stress [ 780 ] is a reliable biomarker for AD [ 781 , 782 ], whereas overexpression of the truncated p53 isoform p47 (Δ40p53 or p44) [ 783 ] in mice accelerated aging and increased tau fibrillation [ 782 , 784 , 785 ]. Tau was recently reported to have increased wild-type p53 expression post-translationally through the abnormal modification of MDM2, the E3 ubiquitin ligase which negatively regulates p53 [ 786 , 787 , 788 , 789 ].…”

Novel Trends in Electrochemical Biosensors for Early Diagnosis of Alzheimer’s Disease

“…The protein p53 responds to cellular stress, and the relationship between conformationally altered p53 and AD diagnosis in blood has been studied since 2008 when Lanni and coauthors observed unfold p53 in peripheral blood cells of AD patients. Recently, unfolded protein p53 was determined from blood in the work of Amor-Gutiérrez and coauthors (2020) using a competitive electrochemical immunosensor with promising results [ 46 , 47 ].…”

Electrochemical Biosensors Based on Nanomaterials for Early Detection of Alzheimer’s Disease

“…Amor-Gutiérrez et al [ 95 ] developed an immunosensor for the detection of unfolded p53 in blood samples ( Figure 4 A). Using a SPCEs modified with AuNPs for the immobilization of monoclonal antibodies against p53, they developed a competitive biosensor able to detect unfolded p53 by linear sweep voltammetry (LSV), with a LOD of 0.05 nM.…”

“…( A ) Schematic representation of a competitive immunosensor for the detection of p53 peptide using streptavidin labelled alkaline phosphatase (S-AP) as electrochemical signal (left), accompanied by LSV voltammograms of different p53 concentrations and the corresponding calibration curve (right). Reprinted from [ 95 ]. Copyright (2020) with permission from Elsevier.…”