Investigating Label-Free markers at Nanoscale for Liquid Biopsy Using Multimodal Microscopy

Liquid biopsy emerges as a noninvasive, easily repeatable, and potentially low-cost approach alternative to standard tissue biopsy. In most cases, it can be used to investigate the cause of symptoms or to help diagnose a number of different health conditions. Although originally used to designate analysis of non-solid tissues to screen for cancer cells, liquid biopsy also refers to the investigation of other general body fluids including its constituents characterization and not necessarily related to cancer. In this thesis, three new applications for the usage of label-free markers in the analysis of body fluid cellular constituents will be presented. Digital holographic microscopy and optical tweezers are applied to the characterization of ex-vivo generated and native red blood cells. In a second application, neutrophils precursors are characterized and classified according to its cellular and nuclear morphology during granulocytic differ- entiation. In a third proposed application, morphological markers retrieved by digital holographic microscopy are used to perform fast screening urinalysis, including leukocyturia and bacteriuria. Lastly, although not label-free, fluorescence superresolution microscopy is used to bring insights into why nuclear morphology can be used as a trustful label-free marker and shows the structural arrangement of lamin in the nucleus of neutrophil precursors with unprecedented resolution. Fast screening label-free liquid biopsies integrates the group of emerging approaches that will revolutionize the future of early disease diagnosis and therapeutic choice with disruptive impact on the society. All the investigations described in this Thesis were aimed to contribute to this promising and intriguing new scenario.