Clinical diagnosis and pathogen detection with a novel multiplexed nanophotonic point-of-care biosensor

Abstract

This Doctoral Thesis focuses on a novel point-of-care device based on a nanophotonic microarray biosensor for the direct and label-free quantification of multiple clinical biomarkers for clinical diagnosis and pathogen detection directly on patient’s sample. The recently developed biosensor is a new large-field-of-view interferometric microscope which measures phase shifts upon changes in refractive indexes. Firstly, the optical physics behind the novel device and its feasibility to be used for biomolecules detection and quantification have been evaluated. Then, several analytical assays based on the use antibodies as bioreceptors have been developed and their performance evaluated. Finally, with the aim of using it as a specific biosensor, the immunoassay that showed the best performance has been applied to actual biomarker detection. Specifically, the biomarkers selected are related with the diagnosis of sepsis, a clinical condition characterized for a grave whole-body inflammatory response caused by an infection. There is an urgent need for fast diagnosis of sepsis because this condition is currently the main cause of death in Intensive Care Units and its incidence is increasing worldwide with a mortality rate between 40 to 50% in developed countries. The work in this Thesis combines the wide knowledge of the research group in the design and creation of biofunctionalised surfaces and the implementation of bioanalytical techniques to achieve cheap, fast and robust biosensors that overcome current challenges related to costly and time-consuming clinical analysis.