Digital Theses Archive


Tesi etd-07172023-143146

Type of thesis
A new generation of multi-tool biodegradable platform for biomedical applications
Scientific disciplinary sector
Istituto di Biorobotica - PHD IN BIOROBOTICA
relatore Prof. CIOFANI, GIANNI
  • Polydopamine nanoparticles
  • Multitasking tool
  • Antioxidant nanostructures
  • Combination therapy
  • Space medicine
Exam session start date
The aim of this Ph.D. thesis is to explore the potential of polydopamine nanoparticles (PDNPs) in several fields of biomedicine.<br>PDNPs are obtained by the self-polymerization of dopamine, a molecule with unique properties and a chemical structure very similar to that one of melanin, a natural biopolymer. PDNPs are completely biodegradable, highly biocompatible, and exhibit strong antioxidant capacity and high photothermal conversion ability when exposed to specific light wavelengths, such as those in the near-infrared (NIR) region. These nanoparticles are also easily tunable in terms of size, can be loaded with a large variety of different molecules, and can be easily functionalized to enhance stability and promote targeting. Thanks to these properties, PDNPs represent a potentially disruptive tool to address a vast variety of biomedical needs.<br>The first part of the thesis is focused on the fabrication of a library of differently sized PDNPs (from 145 to 957 nm) and an extensive characterization of PDNP physicochemical properties as a function of their size. Afterward, the work of this thesis focused on four specific applications of PDNPs: PDNPs as an antioxidant nanoplatform for the treatment of autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS); PDNPs as hepatoprotective agents for the treatment of hepatic steatosis; drug-loaded PDNPs as chemo-photothermal therapy agents against colorectal cancer; antioxidant PDNPs as a protective agent for neuronal cells exposed to microgravity and space radiation conditions.<br>ARSACS is a neurodegenerative disease associated with mutations in the sacsin gene (SACS). These mutations result in mitochondrial dysfunction, reduced bioenergetic processes, and increased production of reactive oxygen species (ROS) at the cellular level. In the context of ARSACS, we explored the potential of PDNPs, known for their antioxidant properties, as a treatment for oxidative stress-related disorders. We investigated PDNP interactions with fibroblasts derived from both healthy and ARSACS patients, focusing on biocompatibility, ROS reduction, prevention of ROS-induced apoptosis/necrosis, and protection against ROS-induced mitochondrial dysfunction. Additionally, a comprehensive proteomic analysis was conducted to explore the molecular pathways involved in antioxidant-mediated cell protection mechanisms. Our findings suggest that PDNPs can partially mitigate ROS-induced damage in fibroblasts, making them a potential therapeutic candidate to address the oxidative stress associated with ARSACS.<br>For the treatment of non-alcoholic fatty liver disease (NAFLD), or hepatic steatosis, an in vitro model of NAFLD based on oleic acid-treated HepG2 cells was established. After the characterization of the in vitro model, steatotic cells were incubated with PDNPs to investigate potential protection mechanisms. Treatment with PDNPs resulted effective in counteracting the hallmarks characterizing hepatic steatosis, with a significant reduction of lipid accumulation in vitro. Further analyses also showed a significant reduction in triglyceride and cholesterol levels, jointly with reduced levels of oxidative stress. Altogether, collected findings suggest that PDNPs represent a promising nanoformulation for the prevention and treatment of hepatic steatosis.<br>As a potential therapy against colon cancer, PDNPs were first loaded with a chemotherapeutic agent to obtain sorafenib-loaded PDNPs (Sor-PDNPs). Following quantification of the amount of loaded drug, nanoparticles were characterized to evaluate whether the presence of the chemotherapeutic agent altered their properties, in particular their photothermal conversion capacity. The cytotoxic efficacy of Sor-PDNPs was tested on both colon cancer cells (Caco-2) and their healthy counterparts (CCD-18Co), demonstrating precise antitumor activity without damaging healthy cells. Sor-PDNP-incubated cell lines were then subjected to photothermal therapy (PTT) using a NIR laser source (ʎ = 808 nm), revealing a synergistic activity of chemotherapy and PTT with respect to the single Sor and PPT stimuli.<br>In the framework of a project granted by the Italian Space Agency (ASI), the antioxidant properties of PDNPs were tested on board the International Space Station (ISS) on SH-SY5Y-differentiated cells as in vitro model of neurons. Microgravity and space radiations are well-known stressors that induce the over-production of ROS: PDNPs have been thus proposed as efficient nanotechnological ROS scavengers. The cultures have been carried out in automated fluidic bioreactors allowing for medium exchange, rinsing, and fixation for storage purposes. Once in orbit, the bioreactors were placed in an incubator for performing the experiment at 37 °C. Moreover, a centrifuge on the ISS was exploited to mimic terrestrial gravity and thus decuple effects of microgravity and space radiation. Transcriptomic analysis is currently ongoing to elucidate cell responses in space and PDNP effects.<br>In summary, the obtained results demonstrate that PDNPs hold great promise for a wide range of biomedical applications. They have shown potential as an effective hepatoprotective agent, an innovative anticancer nanoplatform, and a therapeutic candidate for oxidative stress-related diseases.