One-step electrochemical magneto assays for the development of point-of-care (poc) diagnostic devices

Resumen

One of the greatest challenges for monitoring and improving the health of the population at a global level is the lack of appropriate diagnostic tests for early detection of diseases, selection of appropriate treatments and patient follow-up over time. The availability of sufficiently fast, sensitive and robust diagnostic tools will be crucial to achieving patients’ well-being worldwide. In this context, nanotechnology and biosensor development are rapidly evolving fields that have generated great expectations, producing tests faster and easier to carry out than most classical methods. Biosensors have been described based on the use of a wide variety of biotechnology elements and types of signal transduction. Among them, electrochemical biosensors are the most common type in use today thanks to the portability and low cost of the measuring equipment, fast, robust and quantitative measures provided, and easiness of miniaturization of the whole detection system. The recent incorporation of paper and paper-like materials for the production of paper printed electrodes and lateral flow electrochemical assays is fostering the development of extremely inexpensive devices that, thanks to the fluidic properties of paper, allow reducing assay complexity and level of manipulation for the end user. This favors the development of "Point-of-Care" diagnostic devices (POC), which can be used directly by the patient or at primary health care centers. On the other hand, magnetic beads (MB) have been used with great success in the optimization of magneto-biosensors. MB are attractive for this purpose because, once modified with an appropriate bioreceptor, they grant simple, rapid and specific preconcentration of the targeted analyte. MB offer also relatively large 3D active surfaces, which mixed under constant agitation with the sample supply efficient and fast analyte binding as well. Nevertheless, MB display limitations too, requiring tedious and time-consuming handling that is only at reach of highly trained users. The main objective of this PhD Thesis project was the production of rapid, easy to perform, robust and sensitive electrochemical magneto-biosensors for the detection of diagnostic biomarkers in serum, plasma and blood samples. As it will be shown, this has been achieved at two levels. First, by developing an extremely fast and simple magneto-immunoassay format. Second, by fabricating simple and inexpensive microfluidic paper electrodes, which were exploited to carry out on-chip most of the steps of the simplified magneto-immunoassay with minimal user intervention.