A compact SPR biosensor device for the rapid and efficient monitoring of gluten-free diet directly in human urine

Abstract

Celiac disease (CD) is a chronic autoimmune disorder induced in genetically susceptible individuals by the ingestion of gluten from wheat, rye, barley or certain varieties of oats. A careful diet follow-up is necessary to avoid health complications associated with long-term gluten intake by the celiac patients. Small peptides (GIP, gluten immunogenic peptides) derived from the gluten digestion, which are excreted in the urine and feces, have emerged as promising biomarkers to monitor gluten intake.We have implemented a simple and sensitive label-free point-of-care (POC) device based on Surface Plasmon Resonance for the direct detection of these biomarkers in urine. The assay employs specific monoclonal antibodies and has been optimized for the detection of the 33-mer -gliadin, known as the main immunogenic peptide of wheat gluten, and for the detection of GIP. Direct detection in undiluted urine has been accomplished by using biosensing chips containing a robust and stable biorecognition layer, obtained after carefully optimizing the biofunctionalization protocol. Excellent Limits of Detection have been reached (1.6 -4.0 ng mL -1 ), which ensures the detection of gluten peptides even when the gluten intake is around the maximum tolerable amount in the digestive tract (< 50 mg) for celiac individuals. No sample pretreatment, extraction, or dilution is required, and the analysis takes less than 15 min. The assay has been validated with real samples. These features pave the way towards an end-user easy-to-handle biosensor device for the rapid monitoring of gluten free diet (GFD) and the follow-up of the health status in celiac patients.

Challenges of Monitoring the Gluten-Free Diet Adherence in the Management and Follow-Up of Patients with Celiac Disease

“…A simple and highly sensitive point-of-care (POC) device, based on a surface plasmon resonance biosensor and G12 and A1 monoclonal antibodies, enabled the rapid and efficient monitoring of a GFD directly in urine [ 87 , 88 ]. The excellent limits of detection of GIP (1.6–4.0 ng/mL) ensured the detection of gluten intake around the maximum amount tolerable for patients with CD (<50 mg).…”

Label-Free Plasmonic Biosensor for Rapid, Quantitative, and Highly Sensitive COVID-19 Serology: Implementation and Clinical Validation

“…Once properly cleaned, the sensor chips were placed on the SPR instrument for in-situ covalent immobilization of the viral proteins (N protein, RBD peptide or multianalyte (N+RBD. 1:1)) to carboxyl groups on the gold sensor chip through EDC/s-NHS chemistry [33][34][35] . For all the immobilized surfaces, a final blocking step was included to avoid non-specific adsorptions employing PLL-g-PEG 36,37 .…”

“…concentration). Our biosensor device has previously demonstrated its potential for clinical diagnostics in several areas, 35,38 including infectious diseases 34 and also for the direct detection of antibodies in human serum, 33,36 enabling a one-step, label-free, and sensitive and reliable detection. These features are crucial to develop a fast test with response times below 15-20 minutes (thanks to the no-need of secondary reagents or further signal amplification steps), and with the potential of providing quantitative information (i.e., the concentration range of antibodies in serum).…”

Label-Free Plasmonic Biosensor for Rapid, Quantitative, and Highly Sensitive COVID-19 Serology: Implementation and Clinical Validation

“…concentration). Our biosensor device has previously demonstrated its potential for clinical diagnostics in several areas, 35,38 including infectious diseases 34 and also for the direct detection of antibodies in human serum, 33,36 enabling a one-step, label-free, and sensitive and reliable detection. These features are crucial to develop a fast test with response times below 15-20 minutes (thanks to the noneed of secondary reagents or further signal amplification steps), and with the potential of providing quantitative information (i.e., the concentration range of antibodies in serum).…”