| Summary: | Biopolymeric nanobeads stand out as being biocompatible, biodegradable, and chemically versatile nanomaterials for several biomedical applications. In this context, cellulose has shown an increasing potential in this field due to its abundance of hydroxyl groups and consequent ability to be functionalized. Therefore, the objective of the present dissertation consists in the preparation and characterization of multifunctional cellulose-based nanobeads for potential application in cancer diagnosis and treatment. Spherical cellulose-based nanobeads were produced by nanoprecipitation and functionalized with gold nanoparticles (AuNPs) that will play the dual role of cell imaging and therapeutic agent. The cellulose nanobeads were prepared using cellulose acetate (CA) as the starting raw material instead of directly using cellulose because of its high insolubility in most common solvents. So, CA nanobeads were obtained by nanoprecipitation through CA dissolution and regeneration, followed by alkaline hydrolysis to obtain the cellulose nanobeads. Subsequently, cellulose nanobeads/AuNPs hybrid systems were developed by two distinct methodologies, namely by CA regeneration in the presence of AuNPs and subsequent alkaline hydrolysis, or by the in situ reduction of the gold salt in the presence of the cellulose nanobeads. The cellulose nanobeads/AuNPs hybrids were then characterized by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy, and ultraviolet-visible spectroscopy (UV-vis). Overall, the production of the cellulose nanobeads was achieved by dissolving CA in acetone and subsequent regeneration using water as the non-solvent, followed by alkaline hydrolysis. The success of the hydrolysis was confirmed by ATR-FTIR spectroscopy and SEM, while the synthesis of AuNPs was corroborated by UV-vis spectroscopy and STEM. The morphology and size of the hybrid systems were evaluated by SEM and STEM, which confirmed the production of the cellulose nanobeads/AuNPs hybrids with an average size of 415±187 nm for the cellulose nanobeads and 15±3 nm for the AuNPs. Moreover, the in vitro cytotoxicity of the cellulose nanobeads/AuNPs hybrids towards the pigmented human melanoma (MNT-1) cell line was evaluated for 24 h. The resultant data showed that the hybrid system exhibits a dose dependent cellular toxicity, reaching 81.6±4.5% of cell viability for 39.0 μg mL–1 of hybrid system. Thus, a higher dose will most definitely translate into a higher cytotoxic effect towards the tumor cells. All the obtained results revealed that the cellulose nanobeads/AuNPs hybrids have potential for application in the diagnosis and therapy of cancer.
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