Sustainable nanostructured materials based on biodegradable polymers and luminescent carbon nanoparticles

Abstract

In recent years, the investigation of nanostructured materials based on polymer nanofibers/nanoparticles has presented an expressive growth, mainly for the development of miniaturized devices. The reduction of fibers' diameters to the sub-micro and nano scales is responsible for increasing the surface area and also responsible for the generation of materials with improved mechanical performance and flexibility of functionalization. More recently, in the nanoparticle field, the so-called carbon quantum dots (C-dots) and graphene quantum dots (GQDs) have emerged as excellent universal fluorophores, as alternatives to the semiconductor QDs, which are toxic and poorly soluble. Both C-dots and GQDs present a unique combination of properties, e.g., excellent photostability, biocompatibility, bactericidal effect, adjustable photoluminescence and easiness of interaction and functionalization with biomolecules. Although the combination of polymer nanofibers with GQDs and C-dots seems attractive to the generation of hybrid nanomaterials, there is still a notable lack of deeper studies in this field. In this context, this project approaches a systematic study focusing on routes of preparation of hybrid nanostructured materials from the electrospinning of polymer/C-dots and polymer/GQDs solutions. Water-soluble polymers, e.g., poly (vinyl alcohol) (PVA), FDA approved polymers, e.g. polycaprolactone (PCL) and biomass-based polymer such as cellulose acetate and chitosan will be considered. The routes of preparation of C-dots and GQDs will be based on the pyrolysis or carbonization of small organic molecules from natural sources, such as citric acid, glucose and coffee grounds. Given the tridimensional and porous structure of the electrospun matrices and their high surface/volume ratio, these nanomaterials may present a high potential of biomedical applications, in fields such as bioimaging, controlled release of drugs/genes, bactericidal membranes and optical sensing. All materials will be further characterized using a wide range of techniques, including UV-vis and fluorescence spectroscopies, FTIR, as well as thermal analysis (DSC e TG), X-ray diffraction and scanning and transmission electronic microscopies. Posteriorly, aiming at further biomedical applications, these nanostructured materials will be evaluated for their bactericidal activity as well as for their potential as optical sensors for the detection of diverse analytes, as for example, glucose and hexavalent chromium [Cr(VI)]. (AU)