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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - LACTOPOC (A Low-cost disposAble eleCTrochemical biOsensor for Point Of Care (POC) hypolactasia diagnostic testing)

Teaser

Summary

Point of Care (PoC) systems are miniaturized portable devices containing all the functions of centralized laboratory without the need for trained staff. PoC testing is better tolerated by patients since the sample extraction is less invasive and also preferred by the clinical industry due to their cost and practicality. LACTOPOC project aimed the development of a low-cost disposable electrochemical PoC biosensor for hypolactasia diagnosis. Hypolactasia affects over half of the world population and is related to lactase deficiency, preventing digestion of ingested lactose. Common symptoms (bloating, abdominal pain, flatulence and osmotic diarrhea after ingestion of dairy products) are usually nonspecific and susceptible to false diagnosis. The reference method for diagnosis is the direct determination of lactase activity following an intestinal biopsy, but it results very invasive and it is not commonly used. Other clinical tests for hypolactasia diagnosis are based on the intake and digestion of D-xylose-related compounds. The amount of D-xylose in the body is then proportional to lactase activity and it might be used as an indicative of hypolactasia. Current methods for D-xylose determination rely on traditional analytical techniques or expensive lab-based automatic analysers, requiring trained staff in both cases. LACTOPOC project sought to develop a more accessible, inexpensive and user-friendly diagnostic tool for D-xylose determination. To fulfil the overall objective, the following technological goals were approached: design of a paper-based printed microfluidic platform for electrochemical biosensors; development of a D-xylose biosensor to assist hypolactasia diagnosis in urine and blood based on plastic and paper; testing of the robustness of the D-xylose biosensor to fulfil CE marking requirements, towards clinical validation and commercialization. The global objective of the project was achieved and an IVD product (Osaxyl) was placed in the market. Actions to properly disseminate and exploit the project results were additionally undertaken.

Work performed

During the first part of the project, the ER worked on the fabrication of a paper-based printed platform for electrochemical biosensors. Paper-based devices are emerging as an alternative for Point of Care (PoC) manufacturing as they are amenable to mass production at low cost using wax and screen printing. Several paper substrates and printing conditions were evaluated, according to their feasibility for electrochemical applications. Since D-xylose biosensor was to be employed primarily with blood samples, the effect of haematocrit on the electrochemical detection of analytes was assessed. The use of human blood was authorised by ethical approval from the corresponding regional ethical committee. While waiting for ethical approval, the ER was focused on the optimization of a D-xylose biosensor for urine samples. A flexible approach that may be applied to the analysis of other molecules of high interest in diagnosis and to other biological fluids was then developed. Due to the innovation and commercial possibilities of such strategy, a patent application was filed to protect the invention and to ensure further exploitation.
The new strategy was subsequently applied for the determination of D-xylose in plasma samples. The plastic-based D-xylose biosensor prototype was tried with spiked plasma samples, showing very promising results: 80% of the tested samples exhibited %recoveries within 85-115% range. This showed the high accuracy and reproducibility of the new system. Further adjustments to test whole blood samples were also tried. Regarding paper substrate, a fully operative D-xylose biosensor was achieved by combining previous advances in plastic-based biosensors and paper-based electrodes. Preliminary analytical data in buffer were shown to be very promising, although further optimization for biological sample testing was required. At the final stage of the project, the analytical and clinical correlation of Osaxyl device (system for D-xylose determination in urea) was performed. The ER participated in the planning and design of the validation protocols. Also, she collaborated in the procedure to achieve CE marking and ISO 13485 certification.

Final results

LACTOPOC project generated new opportunities for innovative research and commercialization to OSASEN, which was key for a young health-biotech SME. At the end of the project, a novel diagnostic device (Osaxyl) for hypolactasia diagnosis in urine samples was introduced into the market. Regarding societal impact, Osaxyl will facilitate lactose intolerance diagnosis and patient experience by bringing the analytical tools closer to the general public and decreasing waiting time. Osaxyl was already presented during the National Week of the Digestive Disease (SED 2018, Valencia) where a high interest was shown by medical specilists and patients. Moreover, the development of the innovative strategy for analyte determination in biological fluids opens the door to a range of possible applications in the healthcare sector and in other scientific areas (food quality and environmenta monitoring).
Regarding the biosensor platforms, LACTOPOC project supported the development of a paper-based electrochemical biosensor capable of the quantitative determination of analytes at low concentrations. Although this area is still at an early stage, the advances and optimization work showed in the project represent a thrust toward the consolidation of paper substrate as an alternative to plastic in the market of healthcare biosensors.