De Martino, Selene (2018) Azobenzene-based Biomaterials as Dynamic Cell Culture Systems. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Azobenzene-based Biomaterials as Dynamic Cell Culture Systems
De Martino,
Date: 11 December 2018
Number of Pages: 123
Institution: Università degli Studi di Napoli Federico II
Department: Ingegneria Chimica, dei Materiali e della Produzione Industriale
Dottorato: Ingegneria dei prodotti e dei processi industriali
Ciclo di dottorato: 31
Coordinatore del Corso di dottorato:
Netti, Paolo AntonioUNSPECIFIED
Date: 11 December 2018
Number of Pages: 123
Keywords: azopolymers, dynamic CIMs, azobenzene, stem cell, dynamic topographic switch
Settori scientifico-disciplinari del MIUR: Area 09 - Ingegneria industriale e dell'informazione > ING-IND/22 - Scienza e tecnologia dei materiali
Area 09 - Ingegneria industriale e dell'informazione > ING-IND/34 - Bioingegneria industriale
Date Deposited: 07 Jan 2019 23:47
Last Modified: 17 Jun 2020 08:19

Collection description

The aim of this Thesis is to fabricate dynamic light-switchable biomaterials as scaffolds to study cell behavior in a more complex environment than the one generated by the use of static systems. We take advantage of compelling properties of azobenzenes to engineer photoresponsive 2D and semi-3D platforms to investigate different biological processes from adhesion up to differentiation. In vivo, in addition to the chemical and mechanical properties, the topographic cues play a main role to guide cell response. The ECM is filled with nano- to micro-meter scale landscapes (e.g., ridges, pores and fibers) in continuous remodeling. However, the topography of the most widely implemented in vitro platforms is static and difficulty mimics the dynamicity of ECM. Thus, we propose platforms, which can dynamically tune on demand their topographic properties upon external stimulation. In particular, azobenzene-containing systems can tune their properties under light illumination, recapitulating the spatial-temporal changes of the physiological cell environment. In Chapter 1, we will discuss about important properties of azobenzene molecules and present different applications of a variety of materials containing azobenzenes from amorphous materials to highly organize liquid crystal polymers. In particular, we will focus on the recent use of azopolymers as dynamic cell instructive materials. As of now, there is a lack of knowledge on the role of dynamic topography and, even more on its effect on stem cell differentiation. In the light of this, in Chapter 2 we will present a technique to photo patterning azopolymer thin films in situ by means of a laser-based confocal microscopy. Further, we will analyze the human mesenchymal stem cell (hMSC) response after the spatial-temporal dynamic topographic changes. In more details, a mass migration phenomenon of azopolymers elicited under light irradiation allows to emboss a variety of patterns on cell-populated azopolymer films. We will investigate the stem cell response on a switchable topography from a linear pattern to a grid both in term of cell cytoskeletal re-organization and cell differentiation. Our aim is to investigate the impact of dynamic remodeling of cell environment on hMSCs gene expression profile, in comparison to static surfaces. In order to achieve our goal, we will investigate the cell behavior over time, changing the topographic aspects of the substrate and analyzing the effect of dynamic cues in modulating cell morphology and osteogenic gene expression profile. In particular, we will investigate whether epigenetic effect induced by changes in the biophysical properties of the substrate over time would redirect the expression of lineage specific markers. In Chapter 3, we will discuss about an athermal photofluidization process that can directly reshape an azopolymer pillar array in the presence of cells to investigate the dynamic reassemble of F-Actin on deformed pillars. We will show that pillar arrays can be reshaped along the direction of laser polarization, resulting in elongated structures with controllable eccentricity. This light-driven phenomenon, permits to usesuch type of systems as platforms to analyze cell membrane curvature remodeling in respond to dynamic pillar reshaping. The plasma membrane wraps around the pillars, which generate local curvatures on cell membrane and trigger the F-actin accumulation. Human bone osteosarcoma epithelial cells (U2OS) will be used to investigate the reorganization of F-Actin during the platform transition from pillar to ellipsoidal-shape structures over time. In Chapter 4, we will focus on designing semi-3D hydrogel platforms containing azobenzene to engineer and manipulate culture systems in order to develop photoactuable cell confining systems. Acrylamide-modified gelatin containing azobenzene-based cross linkers will be used to microfabricate well-defined semi-3D photo-responsive structures by means of two-photon lithography (2PP). As proof of concept, we will show an example of an array of squared structures, where cells are physically confined between the adjacent gelatin blocks, which can be remotely stimulated. The light irradiation can be converted in a local mechanical stimulation able to deform the nucleus at a single-cell level. In Conclusion and Future Perspectives, a summary of the main results achieved in this thesis is presented and future applications are proposed.


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