A new label-free impedimetric aptasensor for gluten detection

- An impedimetric label free aptasensor for gluten detection was developed.
- Gli1 aptamer was used to detect gliadin and its peptide fraction.
- The detection limit (5 ppm) was suitable for evaluation of gluten-free products.
- The sensor was successfully applied to the analysis of gluten in raw and processed gluten-free foods.

Celiac disease is a serious autoimmune disorder caused by the ingestion of gluten. Gliadin is the gluten fraction responsible for the triggering of disease. The only cure for the celiac patients, known until now, is a diet with gluten-free foods, classified by the European regulation doesn't exceed 20 ppm in gluten. With the aim to guarantee the food safety for celiac patients in this study the developing and optimization of a fast and reliable label free impedimetric aptasensor for gliadin detection is reported. The aptamer (Gli1) at 0.5 μmol and poly (amidoamine) dendrimer of fourth generation (PAMAM G4) at 2 mg/ml were chosen during the developing steps of the sensing platform because the best ones for the detection of low gluten concentrations with the highest sensitivity. The aptasensor showed linearity in the range of 5-50 μg/l and 50-1000 μg/l in gliadin, a limit of detection of 5 μg/l corresponding to 5 ppm of gluten, a reproducibility lower than 5% and a storage stability at 4 °C of two months. Finally the aptasensor was used to measure gluten, in gluten and gluten-free food products, showing a good agreement with the results obtained with official R5 ELISA method.