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Growth arrest‐specific 6 (GAS6) protein plays a key role in processes related to proliferation, inflammation, angiogenesis, and atherosclerotic plaque formation. In addition, it has been reported that plasma levels of GAS6 are related to cancer prognosis and other relevant pathologies, such as heart failure or sepsis. We report here the first electrochemical immunoplatform for the determination of GAS6, which has demonstrated to be competitive with other available methodologies in terms of cost, simplicity, and decentralized application. The developed immunoplatform involves a sandwich immunoassay using magnetic microparticles (MBs) and uses amperometric detection at disposable screen‐printed carbon electrodes (SPCEs). The MBs were modified with an antibody specific to GAS6 for its selective capture, which is further recognized by a biotinylated secondary antibody subsequently labeled with a streptavidin‐horseradish peroxidase (Strep‐HRP) conjugate. The electrochemical detection was carried out using the hydroquinone (HQ)/H2O2 system. The developed bioplatform exhibits a great selectivity and low limit of detection (27 pg/mL) that allowed the determination of the GAS6 circulating level in plasma samples from patients suffering heart failure (HF) and diagnosed with pancreatic ductal adenocarcinoma (PDAC), as well as the determination of the target protein in raw secretomes of human colorectal cancer cell lines. [ABSTRACT FROM AUTHOR]

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related death worldwide. Alterations in proteins of the p53-family are a common event in CRC. ΔNp73, a p53-family member, shows oncogenic properties and its effectors are largely unknown. We performed an in-depth proteomics characterization of transcriptional control by ΔNp73 of the secretome of human colon cancer cells and validated its clinical potential. The secretome was analyzed using high-density antibody microarrays and stable isotopic metabolic labeling. Validation was performed by semiquantitative PCR, ELISA, dot-blot and western blot analysis. Evaluation of selected effectors was carried out using 60 plasma samples from CRC patients, individuals carrying premalignant colorectal lesions and colonoscopy-negative controls. In total, 51 dysregulated proteins were observed showing at least 1.5-foldchange in expression. We found an important association between the overexpression of ΔNp73 and effectors related to lymphangiogenesis, vasculogenesis and metastasis, such as brain-derived neurotrophic factor (BDNF) and the putative aminoacyl tRNA synthase complex-interacting multifunctional protein 1 (EMAP-II)- vascular endothelial growth factor C-vascular endothelial growth factor receptor 3 axis. We further demonstrated the usefulness of BDNF as a potential CRC biomarker able to discriminate between CRC patients and premalignant individuals from controls with high sensitivity and specificity. [ABSTRACT FROM AUTHOR]

The development of versatile and sensitive biotools to quantify specific SARS‐CoV‐2 immunoglobulins in SARS‐CoV‐2 infected and non‐infected individuals, built on the surface of magnetic microbeads functionalized with nucleocapsid (N) and in‐house expressed recombinant spike (S) proteins is reported. Amperometric interrogation of captured N‐ and S‐specific circulating total or individual immunoglobulin (Ig) isotypes (IgG, IgM, and IgA), subsequently labelled with HRP‐conjugated secondary antibodies, was performed at disposable single or multiplexed (8×) screen‐printed electrodes using the HQ/HRP/H2O2 system. The obtained results using N and in‐house expressed S ectodomains of five SARS‐CoV‐2 variants of concern (including the latest Delta and Omicron) allow identification of vulnerable populations from those with natural or acquired immunity, monitoring of infection, evaluation of vaccine efficiency, and even identification of the variant responsible for the infection. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD), the most common neurodegenerative disorder, demands new cost‐effective and easy‐to‐use strategies for its reliable detection, mainly in the preclinical stages. Here, we report the first immunoplatform for the electrochemical multidetermination of four candidate protein biomarkers in blood, neurofilament light chain (NfL), Tau, phosphorylated Tau (p‐Tau) and TAR DNA‐Binding Protein 43 (TDP‐43). It involves implementation of sandwich‐type immunoassays and enzymatic labelling with horseradish peroxidase (HRP) on the surface of magnetic microbeads (MBs). Amperometric detection is performed after depositing the magnetic immunoconjugates on disposable quadruple transduction platforms by monitoring the enzymatic reduction of H2O2 mediated by hydroquinone (HQ). The immunoplatform achieved LOD values smaller than the content of target biomarkers in plasma of healthy subjects, with RSD values<5 %, and lower cost and shorter assay time (60–90 min) than other available methodologies and was applied to the analysis of plasma from healthy controls and AD patients. [ABSTRACT FROM AUTHOR]

An electrochemical biosensing platform for serum autoantibodies (AAbs) detection is reported in this work, exploiting for the first time six Alzheimer's disease (AD)‐specific phage‐derived and frameshift aberrant HaloTag peptides as receptors, immobilized on magnetic microbeads (MBs) surface and captured on disposable electrodes to perform amperometric detection. Operational analytical characteristics and clinical diagnostic ability of the bioplatform were probed in optimized key experimental conditions by analysing serum AAbs of AD patients and healthy subjects. The value of 100 % obtained for AUC, sensitivity, and selectivity from the all peptides combined ROC curve, indicate full AD‐diagnostic capability of the methodology, which was further implemented, as proof of concept, in a POC multiplexing platform to detect the signature in a single test over clinically actionable times (1 h 15 min), opening great promise for the type of diagnosis and AD patients' monitoring follow‐up currently pursued. [ABSTRACT FROM AUTHOR]

This work reports the development of the first integrated electrochemical immunosensor for the determination of the ligand receptor activator nuclear factor‐κB (RANKL), a biomarker that plays an important role in the regulation of bone resorption process and, as reported recently, in oncology by modulating the immune system response facilitating the tumor growth and metastatic process during cancer development. The developed platform involves a sandwich‐type immunoassay with covalent immobilization of biotinylated capture antibodies onto streptavidin/4‐aminobenzoic acid (p‐ABA) grafted screen‐printed carbon electrodes (bCAb‐Strep/p‐ABA‐SPCE) and the use of an hybrid nanomaterial composed of gold nanoparticles (AuNPs) and multi‐walled carbon nanotubes (MWCNTs) as nanocarrier of multiple detector antibody and HRP molecules. Amperometric detection with the H2O2/hydroquinone (HQ) system allowed the construction of a linear calibration plot for RANKL standards between 10.4 and 1,000 pg mL−1 with a LOD of 3.1 pg mL−1. The determination implied simple handling protocols and short assay times. The developed immunosensor was applied to the determination of RANKL in human serum of patients diagnosed with colorectal cancer (CRC) or rheumatoid arthritis (RA). Each determination required only 5 μL of undiluted serum and took less than 2 h counting since the preparation of blocked‐bCAb‐Strep/p‐ABA‐SPCE. [ABSTRACT FROM AUTHOR]

Alzheimer's disease, Candidate biomarkers, Electrochemical multiplexing immunoplatform, Magnetic microbeads Plasma Keywords: Alzheimer's disease; Candidate biomarkers; Electrochemical multiplexing immunoplatform; Magnetic microbeads Plasma EN Alzheimer's disease Candidate biomarkers Electrochemical multiplexing immunoplatform Magnetic microbeads Plasma 1 1 1 05/17/22 20220513 NES 220513 B The Cover Feature b illustrates a quadruple immunoplatform for the amperometric determination of blood protein candidate biomarkers (NfL, Tau, p-Tau and TDP-43) to assist in the reliable and minimally invasive Alzheimer's disease diagnosis. [Extracted from the article]