Enzyme-powered nanomotors navigating in complex viscoelastic media

One of the most promising scientific goals that could change the medical field is to find an accurate drug delivery system on the human body, especially for cancer treatment. In the last years, researchers in fields like bioengineering and nanotechnology have designed biocompatible nanomotors for biomedical applications. After the demonstration of the possibility to adopt the self-propulsion by enzyme catalysis, the dynamics of nanoscale swimmers have been studied in simple fluids like water. The motion of micro- and nano-motors in complex fluids has not been extensively addressed. This thesis aims to understand the motion of enzyme-based nanoparticles, developed in a chemical laboratory, that navigate in a complex fluid: Hylauronic Acid (HA). To characterize the motors in HA was necessary to do different steps starts from the chemical experiments. This part is represented by the synthesis of the particles of silica, the ammine functionalization, the addition of PEG and at the end the urease enzyme, which allows that motors propel because of the decomposition of Urea. The entire project lasted approximately 6 months and was supported by Smart-Nano-Bio Devices Group from IBEC. The output of this study starts from Dynamic Light Scattering (DLS) measurements, where MSD is extracted, by a Phyton program, to find out if the enzymatic reaction alters the environment and thus the motion of the nanomotors. In this way it was possible to see microscopical changes while the macroscopic ones are studied with Rheometer, to understand the fluid properties, and are seen with the optical microscope: SEM. The results of all the experiments led to different conclusions. First, that the synthesis was successfully supported by z-potential and readings DLS. these last underlined also that adding PEG avoided extreme aggregation of particles and that the motors with urease and urea move in water as proved by the diffusion of the MSD. For the HA it has been possible to see an increase in the motion parameters which indicates that there is an enhancement of it. There are also some indications of electrostatic interactions between the particles and the HA depending on the charge, as supported by the DLS motion experiments. Now, the work will continue with the experiments to make focus on these results and to correlate them to a real possible motion in a complex fluid. In this way, it will be possible to get close to a possible way to work on a system every time more like human tissue. d nanomotors navigating in complex viscoelastic media