Synthesis and surface modification of silver and gold nanoparticles. Nanomedicine applications against Glioblastoma Multiforme.

In the last decades noble metal nanoparticles (NPs) arose as one of the most powerful tools for applications in nanomedicine field and cancer treatment. Glioblastoma multiforme (GBM), in particular, is one of the most aggressive malignant brain tumors that nowadays still presents a dramatic scenario concerning median survival. Gold nanorods (GNRs) and silver nanoparticles (AgNPs) could find applications such as diagnostic imaging, hyperthermia and glioblastoma therapy. During these three years, both GNRs and AgNPs were synthesized with the “salt reduction” method and, through a novel double phase transfer process, using specifically designed thiol-based ligands, lipophilic GNRs and AgNPs were obtained and separately entrapped into biocompatible and biodegradable PEG-based polymeric nanoparticles (PNPs) suitable for drug delivery within the body. Moreover, a synergistic effect of AgNPs with the Alisertib drug, were investigated thanks to the simultaneous entrapment of these two moieties into PNPs. In addition, Chlorotoxin (Cltx), a peptide that specifically recognize brain cancer cells, was conjugated onto the external surface of PNPs. The so-obtained novel nanosystems were evaluated for in vitro and in vivo applications against glioblastoma multiforme. In particular, for GNRs-PNPs, their safety, their suitability as optoacoustic contrast agents, their selective laser-induced cells death and finally, a high tumor retention were all demonstrated. Concerning AgNPs-PNPs, promising tumor toxicity and a strong synergistic effect with Alisertib was observed (IC50 10 nM), as well as good in vivo biodistribution, high tumor uptake and significative tumor reduction in tumor bearing mice. Finally, the two nanostructures were linked together, through an organic framework, exploiting the click chemistry azido-alkyne Huisgen cycloaddition, between two ligands previously attached to the NPs surface; this multifunctional complex nanosystem was successfully entrapped into PNPs with nanoparticles’ properties maintenance, obtaining in this way a powerful and promising tool for cancer fight and defeat.

Electrochemical surface modification of Single walled carbon nanotubes and graphene-based electrodes for (bio)sensing applications

Sensors are devices that have shown widespread use, from the detection of gas molecules to the tracking of chemical signals in biological cells. Single walled carbon nanotube (SWCNT) and graphene based electrodes have demonstrated to be an excellent material for the development of electrochemical biosensors as they display remarkable electronic properties and the ability to act as individual nanoelectrodes, display an excellent low-dimensional charge carrier transport, and promote surface electrocatalysis. The present work aims at the preparation and investigation of electrochemically modified SWCNT and graphene-based electrodes for applications in the field of biosensors. We initially studied SWCNT films and focused on their topography and surface composition, electrical and optical properties. Parallel to SWCNTs, graphene films were investigated. Higher resistance values were obtained in comparison with nanotubes films. The electrochemical surface modification of both electrodes was investigated following two routes (i) the electrografting of aryl diazonium salts, and (ii) the electrophylic addition of 1, 3-benzodithiolylium tetrafluoroborate (BDYT). Both the qualitative and quantitative characteristics of the modified electrode surfaces were studied such as the degree of functionalization and their surface composition. The combination of Raman, X-ray photoelectron spectroscopy, atomic force microscopy, electrochemistry and other techniques, has demonstrated that selected precursors could be covalently anchored to the nanotubes and graphene-based electrode surfaces through novel carbon-carbon formation.

Studio di biomateriali usati come scaffold per Tissue Engineering e loro caratterizzazione con tecniche spettroscopiche vibrazionali e di analisi termica

This research investigated someone of the main problems connected to the application of Tissue Engineering in the prosthetic field, in particular about the characterization of the scaffolding materials and biomimetic strategies adopted in order to promote the implant integration. The spectroscopic and thermal analysis techniques were usefully applied to characterize the chemico-physical properties of the materials such as – crystallinity; – relative composition in case of composite materials; – Structure and conformation of polymeric and peptidic chains; – mechanism and degradation rate; – Intramolecular and intermolecular interactions (hydrogen bonds, aliphatic interactions). This kind of information are of great importance in the comprehension of the interactions that scaffold undergoes when it is in contact with biological tissues; this information are fundamental to predict biodegradation mechanisms and to understand how chemico-physical properties change during the degradation process. In order to fully characterize biomaterials, this findings must be integrated by information relative to mechanical aspects and in vitro and in vivo behavior thanks to collaborations with biomedical engineers and biologists. This study was focussed on three different systems that correspond to three different strategies adopted in Tissue Engineering: biomimetic replica of fibrous 3-D structure of extracellular matrix (PCL-PLLA), incorporation of an apatitic phase similar to bone inorganic phase to promote biomineralization (PCL-HA), surface modification with synthetic oligopeptides that elicit the interaction with osteoblasts. The characterization of the PCL-PLLA composite underlined that the degradation started along PLLA fibres, which are more hydrophylic, and they serve as a guide for tissue regeneration. Moreover it was found that some cellular lines are more active in the colonization of the scaffold. In the PCL-HA composite, the weight ratio between the polymeric and the inorganic phase plays an essential role both in the degradation process and in the biomineralization of the material. The study of self-assembling peptides allowed to clarify the influence of primary structure on intermolecular and intermolecular interactions, that lead to the formation of the secondary structure and it was possible to find a new class of oligopeptides useful to functionalize materials surface. Among the analytical techniques used in this study, Raman vibrational spectroscopy played a major role, being non-destructive and non-invasive, two properties that make it suitable to degradation studies and to morphological characterization. Also micro-IR spectroscopy was useful in the comprehension of peptide structure on oxidized titanium: up to date this study was one of the first to employ this relatively new technique in the biomedical field.

Comportamento tribologico di materiali per componenti di interesse industriale: Failure analysis e prove tribologiche in laboratorio

L’attività di ricerca della presente tesi di dottorato ha riguardato sistemi tribologici complessi di interesse industriale per i quali sono stati individuati, mediante failure analysis, i meccanismi di usura dominanti. Per ciascuno di essi sono state studiate soluzioni migliorative sulla base di prove tribologiche di laboratorio. Nella realizzazione di maglie per macchine movimentazione terra sono ampiamente utilizzati i tradizionali acciai da bonifica. La possibilità di utilizzare i nuovi microlegati a medio tenore di carbonio, consentirebbe una notevole semplificazione del ciclo produttivo e benefici in termini di costi. Una parte della tesi ha riguardato lo studio del comportamento tribologico di tali acciai. E’ stato anche affrontato lo studio tribologico di motori idraulici, con l’obiettivo di riuscire a migliorarne la resistenza ad usura e quindi la vita utile. Sono state eseguite prove a banco, per valutare i principali meccanismi di usura, e prove di laboratorio atte a riprodurre le reali condizioni di utilizzo, valutando tecniche di modificazione superficiale che fossero in grado di ridurre l’usura dei componenti. Sono state analizzate diverse tipologie di rivestimenti Thermal Spray in termini di modalità di deposizione (AFS-APS) e di leghe metalliche depositate (Ni,Mo,Cu/Al). Si sono infine caratterizzati contatti tribologici nel settore del packaging, dove l’utilizzo di acciai inox austenitici è in alcuni casi obbligatorio. L’acciaio inossidabile AISI 316L è ampiamente utilizzato in applicazioni in cui siano richieste elevate resistenze alla corrosione, tuttavia la bassa resistenza all’usura, ne limitano l’impiego in campo tribologico. In tale ambito, è stata analizzata una problematica tribologica relativa a macchine automatiche per il dosaggio di polveri farmaceutiche. Sono state studiate soluzioni alternative che hanno previsto sia la completa sostituzione dei materiali della coppia tribologica, sia l’individuazione di tecniche di modificazione superficiale innovative quali la cementazione a bassa temperatura anche seguita dalla deposizione di un rivestimento di carbonio amorfo idrogenato a-C:H