The aim of the PhD work is to create a new microfluidic approach to finely tune applied in-flow forces in order to explore controlled single-cell deformation. In fact, we propose a microfluidic device based on compression forces arising from a viscoelastic fluid solution that firstly align cells and then deform them. By simply changing the rheological properties and the imposed fluid-flow conditions, our approach represents an easy-to-use and versatile tool to collect a comprehensive mapping of single-cell properties, investigating both biophysical and biomechanical characteristics. In a wide-range of applied compression, we observe how different degrees of deformation lead to cell-specific deformation-dependent in-flow dynamics, which correlate the classical deformation parameters (e.g. cell aspect-ratio), with dynamic quantities (e.g. revolution time of rotation during in-flow motion). Thus, a precise in-flow label-free cell phenotyping is achieved allowing the distinction of different cell classes. The observation of different degrees of deformation corresponding to variable compression, lead us to interrogate the inner cell structures possibly involved into the mechanical responses. We demonstrate that re-organization phenomena of actin cortex and microtubules as well as of nuclear envelope and chromatin content, occur. Also in this case, cell-specific responses are collected, allowing us to distinguish healthy from pathological cells depending on the structural mechanical reaction. Furthermore, by playing with the high levels of compression, we show preliminary results about the possibility to induce a nanoparticle intracellular delivery process by escaping physiological endocytosis. In fact, cells result to be able to incorporate nanoparticles into the cytoplasm, without involving a vesicle formation for the entry. These outcome open up new interesting scenarios about the possibility to use the microfluidic device as a platform for cell phenotyping and intracellular delivery, properly engineered for both diagnostic and therapeutic purposes
