Mauro, Francesca (2023) Photo-switchable bio-interfaces for the dynamic control of cell behaviour. [Tesi di dottorato]

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Abstract

The external cellular environment carries out a crucial role in affecting and dictating cellular functions thus influencing several biological processes such as morphogenesis, tissue regeneration and repair. The bidirectional communication between cells and the extracellular matrix (ECM) occurs through the transmission of biochemical/biophysical signals at sub-micrometric level involving different sub-cellular components such as focal adhesions, cytoskeleton structures and the nucleus, activating then a series of biological events that can eventually affect cellular fate. Indeed, the extracellular matrix has a peculiar 3D organization dictated by the spatial organization of fibres bundles, providing a specific geometry that is involved in shaping tissue architecture and functions. Moreover, the ECM is a dynamic entity and its properties change during time (i.e. tissue growth, disease progression) representing a fundamental aspect that should be taken into account in order to design more reliable bio-interfaces able to impact cell function and fate. Numerous studies have been done in order to investigate cellular response to external stimuli, but the majority includes the presentation of static signals. Thus, the aim of my PhD project is focused on the realization of dynamic bio-interfaces that reliably replicate the native extracellular environment for in-vitro cell culturing. To this purpose, photo-deformable azopolymer material has been chosen to cover glass-bottom petri-dishes and provide dynamic platform for cells. Indeed, azobenzene-based materials have the ability to change the shape of surface topography in response to light, as a consequence of mass movement triggered by the trans-cis photoisomerization of the azo-moiety. Precisely, by illuminating their surface with a linearly polarized light, a linear pattern, in the form of parallel ridges/grooves can be imprinted on the azopolymer surface and easily erased with a non-polarized or circularly polarized light. We investigated the behaviour of human breast epithelial cells (MCF10A) in response to in-situ linear light-induced topography patterning, in terms of cell and nuclear 8 morphology and mechanical properties, in order to spatiotemporally control and guide their functions. Additionally, we found that the transmission of topographic signal can have an impact also on the internal organization of cell nucleus, stating that the propagation of macroscopic deformation can reach the internal nuclear structures up to chromatin level. Then, the photo-switching properties of azopolymer were exploited in order to transmit cyclic topographical signals by finely presenting/removing a linear pattern with the aim to examine the effectiveness of the dynamic platform to reverse cells behaviour.

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