Binary MoS2 nanostructures as nanocarriers for amplification in multiplexed electrochemical immunosensing: simultaneous determination of B cell activation factor and proliferation-induced signal immunity-related cytokines.

A dual immunosensor is reported for the simultaneous determination of two important immunity-related cytokines: BAFF (B cell activation factor) and APRIL (a proliferation-induced signal). Sandwich-type immunoassays with specific antibodies (cAbs) and a strategy for signal amplification based on labelling the detection antibodies (dAbs) with binary MoS2/MWCNTs nanostructures and using horseradish peroxidase (HRP) were implemented. Amperometric detection was carried out at screen-printed dual carbon electrodes (SPdCEs) through the hydroquinone HQ/H2O2 system. The developed dual immunosensor provided limit of detection (LOD) of 0.08 and 0.06 ng mL-1 for BAFF and APRIL, respectively, and proved to be useful for the determination of both cytokines in cancer cell lysates and serum samples from patients diagnosed with autoimmune diseases and cancer. The obtained results agreed with those found using ELISA methodologies.

Electrochemical bioplatform to manage alpha-gal syndrome by tracking the carbohydrate allergen in meat.

This work presents the first bioplatform described to date for the determination of galactose-α-1,3-galactose (α-Gal), a non-primate mammalian oligosaccharide responsible for almost all cases of red meat allergy. The bioplatform is based on the implementation of an indirect competitive immunoassay and enzymatic labeling with the enzyme horseradish peroxidase (HRP) built on the surface of magnetic microparticles (MBs) and amperometric transduction on screen-printed carbon electrodes (SPCEs) using the H2O2/hydroquinone (HQ) system. The target α-Gal competed with biotinylated α-Gal immobilized on the surface of neutravidin-modified MBs for the limited immunorecognition sites of a detection antibody enzymatically labeled with an HRP-conjugated secondary antibody. The resulting magnetic immunoconjugates were trapped on the surface of the SPCE working electrode and amperometric transduction was performed, providing a cathodic current variation inversely proportional to the concentration of α-Gal in the analyzed sample. The developed biotool was optimized, characterized and applied with satisfactory results to the determination of the target allergen in different samples of raw and processed meats.

Electrochemical biotool for the dual determination of epithelial mucins associated to prognosis and minimal residual disease in colorectal cancer.

This work reports a dual immunoplatform for the simultaneous detection of two epithelial glycoproteins of the mucin family, mucin 1 (MUC1) and mucin 16 (MUC16), whose expression is related to adverse prognosis and minimal residual disease (MRD) in colorectal cancer (CRC). The developed immunoplatform involves functionalised magnetic microparticles (MBs), a set of specific antibody pairs (a capture antibody, cAb, and a biotinylated detector antibody b-dAb labelled with a streptavidin-horseradish peroxidase, Strep-HRP, polymer) for each target protein and amperometric detection at dual screen-printed carbon electrodes (SPdCEs) using the hydroquinone (HQ)/horseradish peroxidase (HRP)/H2O2 system. This dual immunoplatform allows, under the optimised experimental conditions, to achieve LOD values of 50 and 1.81 pg mL-1 (or mU mL-1) for MUC1 and MUC16, respectively, and adequate selectivity for the determination of the two targets in the clinic. The developed immunoplatform was employed to analyse CRC cell protein extracts (1.0 µg/determination) with different metastatic potential providing results in agreement with those obtained by blotting technologies but using affordable and applicable point-of-care instruments. This new biotool also emerges competitive in state-of-the-art electrochemical immunoplatforms seeking a compromise among simplicity, reduction of test time and analytical characteristics.

Ultrasensitive detection of soy traces by immunosensing of glycinin and ß-conglycinin at disposable electrochemical platforms.

This work reports the first electrochemical bioplatform for the determination of soy traces in food. The bioplatform involves sandwich-type immunoassays using specific antibodies for ß-conglycinin and glycinin, which are the main allergenic soy proteins, and carboxylic acid-modified magnetic microbeads. Amperometric detection at -0.20 V (vs. an Ag pseudo-reference electrode) was performed using single or dual screen-printed carbon electrodes and the H2O2/hydroquinone (HQ) system. The measured variation in the cathodic current was directly proportional to the concentration of target allergenic proteins. The developed bioplatforms exhibit a good selectivity and sensitivity providing limits of detection (LOD) values of 0.03 and 0.02 ng mL-1 for ß-conglycinin and glycinin, respectively. The determination of both proteins can be carried out in only 1.5 h. The electrochemical bioplatforms allow their accurate determinations (with results statistically comparable to those provided by ELISA methodologies) in raw cookie dough and baked cookies enriched with soy flour. The results obtained confirm, in a pioneering way with electrochemical biosensors, the possibility of discriminating samples incurred with as little as 0.0005 ppm of a food allergen in model cookie extracts.