IgG anti-gliadin determination with an immunological microfluidic system applied to the automated diagnostic of the celiac disease

Abstract

In the present article, a novel microfluidic immunosensor coupled with electrochemical detection for anti-gliadin IgG antibody quantification is proposed. This device represents an important tool for a fast, simple, sensitive, and automated diagnostic for celiac disease, which is carried out through detection of anti-gliadin IgG antibodies present in human serum samples. Celiac disease (CD) is an autoimmune disease generated by gluten protein fractions called prolamins. This pathology affects about one in 250 people around the world, produces intestinal inflammation, villous atrophy, and crypt hyperplasia, which causes a range of symptoms including altered bowel habits, malnutrition and weight loss. Our immunosensor consists of a Plexiglas device coupled to a gold electrode, with a central channel containing 3-aminopropyl-modified controlled pore glass (AP-CPG). The quantification of anti-gliadin IgG antibodies was carried out using a heterogeneous, non-competitive enzyme-linked immunosorbent assay (ELISA) in which IgG antibodies bound to gliadin protein, immobilized on AP-CPG, were determined by alkaline phosphatase (AP) enzyme-labeled second antibodies specific to human IgG. The p-aminophenyl phosphate (p-APP) was converted to p-aminophenol (p-AP) by AP, and the electroactive product was quantified on a gold electrode at 0.250 V. The calculated detection limits for electrochemical detection and the ELISA procedure were 0.52 and 2.72 UR mL(-1), respectively, and the within- and between-assay coefficients of variation were below 5.8%. The optimized procedure was applied to the determination of anti-gliadin IgG antibodies in human serum samples.