Non-Specific Interactions Between Cationic Nanoparticle-Polymer Composites and Biomolecules

This dissertation describes the consequences of non-specific binding between cationic nanoparticles (NPs) and biological materials ranging from persistence length reduction of single actin filaments, to modified kinetics of myosin V motility, and culminating with correlating THP-1 cell metabolic stress to viscoelastic changes. The bulk of the thesis (chapters 3-5), utilizes optically transparent polymer-NP composites with controllable hierarchical roughness to tune the interaction strength between actin filaments and the surface and impact myosin V kinetics. To generate hierarchical roughness, precise control over the thermodynamics and dynamics of NH2-functionalized NPs in polystyrene-ran-acrylic acid (SAA) is demonstrated in chapter 3. In particular, an interplay between aggregation and dispersion of NPs occurs by varying SAA composition, leading to roughness ranging from a few nms to hundreds of nms and tunable wettability with water contact angles ranging from 70° to 170°. Chapter 4 describes the relationship between roughness and actin binding with a model based on the worm-like chain model that weighs the bending energy associated with actin binding to surface features based on their size and density against the electrostatic potential of the surface. The model predicts the experimentally observed weakening of f-actin surface binding with increasing roughness, from immobilized, to side-on wobbly, and eventually end-on. Chapter 5 quantifies how perturbations in actin structure by electrostatic surface attachment effects myosin V kinetics. Myosin V velocity is slowed by backward stepping on NP-decorated surfaces. The Michaelis-Menten relationship of myosin velocity versus [ATP] exhibits a reduction in KM and VMAX explained by a reduced coordination between myosin and f-actin which causes backwards stepping and an increased ADP affinity. Chapter 7 outlines the method of variable indentation-rate rheometric analysis by Laplace transform (VIRRAL) which is developed to utilize basic Hertzian fitting of force curves to measure the viscoelasticity of THP-1 cells. Dextran-lysozyme nanogels loaded with Ag nanoparticles cause mitochondrial damage which metabolically stresses cells decreasing the ATP/ADP. Reduced [ATP] increases f-actin concentration and slows intracellular transport making the cytoplasm stiffer by increasing both low and high-frequency elasticity and the viscosity. Thus, metabolic stress in THP-1 cells is correlated with proportional increases in viscosity and elasticity, while the relaxation time of the cell, τ, remains unchanged

Reconstructing the historical shoreline evolution of the Northern Bay of Cádiz (SW Spain) from geomorphological and geoarchaeological data

During the last 3 ka, different human communities occupied the Bay of Cádiz (SW Spain), including Phoenician, Carthaginian, Roman, Medieval and Modern settlements. Traces of such historical occupations have been recognized along the bay from a geoarchaeological point of view. Some of them bear a palaeogeographical interest related to the historical location of the shoreline. At the same time, Holocene sedimentary units and geomorphological elements identified along the bay can be interpreted as evidences of its morphological evolution. The objective of the present paper is to represent all the available data about archaeological sites and geomorphology in the northern Bay of Cádiz, with the aim of combining both sources of data for elaborating a simple proposal of landscape evolution during the last 3 millennia. The base for mapping was multiple, from historical aerial photographs to satellite imagery and a digital terrain model with a maximum resolution of 0.35 m.12 página

Intracellular Nanoparticle Dynamics Affected by Cytoskeletal Integrity

The cell interior is a crowded chemical space, which limits the diffusion of molecules and organelles within the cytoplasm, affecting the rates of chemical reactions. We provide insight into the relationship between non-specific intracellular diffusion and cytoskeletal integrity. Quantum dots entered the cell through microinjection and their spatial coordinates were captured by tracking their fluorescence signature as they diffused within the cell cytoplasm. Particle tracking revealed significant enhancement in the mobility of biocompatible quantum dots within fibrosarcoma cells versus their healthy counterparts, fibroblasts, as well as in actin destabilized fibroblasts versus untreated fibroblasts. Analyzing the displacement distributions provided insight into how the heterogeneity of the cell cytoskeleton influences intracellular particle diffusion. We demonstrate that intracellular diffusion of non-specific nanoparticles is enhanced by disrupting the actin network, which has implications for drug delivery efficacy and trafficking

Vaccini anti Covid-19: analisi comparata della comunicazione politica dalle pagine Facebook di cinque Presidenti di Regione

Nella situazione di emergenza scaturita dalla pandemia Covid-19, che ha visto l’Italia tra i paesi più colpiti, la comunicazione da parte degli esponenti delle istituzioni ha avuto da subito un ruolo chiave. Il seguente elaborato si pone come obiettivo principale l’analisi della comunicazione politica sulla questione vaccini anti Covid-19 effettuata tendendo in considerazione le pagine Facebook di cinque Presidenti di Regione (Cirio A.- Piemonte; Marsilio M.- Abruzzo; Fedriga M.-Friuli-Venezia Giulia; Bonaccini S.- Emilia-Romagna; De Luca V. - Campania). Facebook ha avuto un ruolo importante per la diffusione delle notizie, per questo motivo si è scelto di esaminare le pagine dei Presidenti su questo social. Il punto di partenza è una trattazione teorica sul fenomeno della comunicazione politica e dei cambiamenti che si sono verificati nel modo di interagire tra i suoi attori principali: sistema dei media, sistema politico e cittadini-elettori. Si procede poi inquadrando il contesto generale della situazione coronavirus in Italia, si guarda con attenzione al rapporto tra Stato e Regioni e al ruolo dei mezzi di informazioni durante gli ultimi due anni. I dati utilizzati per la ricerca sono stati forniti dal Laboratorio Multidisciplinare MediaLaB del dipartimento di Scienze Politiche dell’Università di Pisa che li ha ricavati e identificati tramite lo strumento CrowdTangle. Dopo un’analisi qualitativa delle singole pagine, per studiare quanto e in che modalità i Governatori si sono espressi sulla tematica vaccini-anti Covid-19, si è cercato di delineare una conclusione che metta a confronto la loro comunicazione rispondendo così all’obiettivo centrale dell’elaborato