Non-Covalent Functionalization of Graphene Oxide with Porphyrazine Macrocycles

Abstract

Graphene Oxide (GO) possesses a large and rigid π-conjugated planar structure, coupled with oxygen-containing groups on the edges and in the basal plane, which provides the material with several amazing physicochemical properties, such as excellent water dispersibility, surface modifiability, biological compatibility, and so on. For these reasons, it is considered among the most promising nanomaterials for biological imaging or sensing, drug delivery, composite materials, and luminescent devices. This report presents a comprehensive study on the non-covalent functionalization of graphene oxide (GO) with a pentanuclear porphyrazine macrocycle (Pz), exactly [(PtCl2)4LZn] where L = tetrakis-2,3-[5,6-di(2-pyridyl)-pyrazino]porphyrazinato dianion, an active photosensitizer for 1O2 production, with the aim of obtaining a stable hybrid nanostructure with unique physico-chemical properties. The primary objective was to achieve the binding of porphyrazine molecules to GO sheets, resulting in the synthesis of a novel porphyrazine-graphene oxide hybrid material (Pz@GO). This system was characterized by UV-Visible, infrared (IR) and Raman spectroscopy and photoluminescence measurements. The hybrid Pz@GO shows better water solubility characteristics than pure porphyrazine, which is of great interest for potential biomedical applications in the field of Photodynamic Therapy and in other multimodal therapies. However, the problematic aspect of water solubility needs to be further optimised. A preliminary investigation on the photosensitizing efficiency of Pz@GO in the production of the 1O2 was carried out, which highlighted the need to select a suitable method to conduct this type of analysis on this nanostructured material. All the results obtained in this Thesis Work lay the foundation for future investigations and potential biomedical applications, with the aim of further advancing the understanding and utilization of porphyrazine-graphene oxide hybrids in various fields, including Photodynamic Therapy.