Polymeric materials with noble metals nanoparticles

The general focus of this PhD project was the combination of gold and/or silver nanoparticles with a polymeric matrix. In particular, PVA films containing pectin-stabilized AgNP and gold nanostars (GNS) coated with HS-PEG or HS-PEG-COOH have been prepared. These materials proved to combine an intrinsic microbicidal activity, due to the release of Ag⁺ ions, with an on-demand action given by the photothermal response of GNS upon laser irradiation in the NIR bio-transparent window. Films containing GNS coated with HS-PEG-COOH, that act directly as cross-linking agents, are most promising for the development of medical devices for wound healing applications. In addition, the study of PEG coating of AuNP has been carried on, particularly by potentiometric titration, in order to investigate the effect of NP-binding on the acid-base properties of PEG thiols. After the determination of the protonation constants of a set of molecules with different mw, an experimental procedure for the titration of PEG-coated AuNP was set up. The first results on AuNP@HS-PEG-COOH show a reduction of the average acidity of the carboxylic groups, attributed to the interaction between the neighboring molecules confined on the NP surface. Eventually, a novel photothermal material has been produced by the inclusion of GNS in a sponge-like PDMS scaffold, obtained via a simple templating method which could also enable control over pore size and porosity. Very elastic, hydrophobic sponges have been obtained, both with and without PEGylated GNS embedded. Preliminary data from natural solar irradiation show a remarkable photothermal response of the PDMS@GNS samples; however, a finer control is required over irradiation parameters as well as new experimental setups to assess their performance as solar water evaporators and/or oil separation platforms.