Banca de QUALIFICAÇÃO: MAÍRA CRISTINA MARCOLINO

EVALUATION OF THE ANTIBACTERIAL AND ANTIBIOFILM POTENTIAL OF NANOCOMPOSITES IN SYNTHETIC AND

BIOLOGICAL  SUPPORTS

Bacterial infections, Nanoparticles, Green synthesis, Conductive polymer, Medical devices.

This thesis discusses the development and evaluation of antimicrobial and antibiofilm materials, with a focus on their biomedical applications. The first study analyzed the antibiofilm activity of polypyrrole (PPy), silver nanoparticles (AgNPs), and the PPy/AgNP composite, aiming to simulate catheter-associated urinary tract infections. The results demonstrated that both PPy and AgNPs were effective in preventing biofilm formation, with AgNPs being the most effective agent, particularly against singlespecies and mixed-species biofilms. Spectroscopic characterization confirmed the interactions between the components and their structural features. The low cytotoxicity of the composites, with cell viability exceeding 70%, indicated a promising potential for developing new formulations. However, further investigations are needed to assess biocompatibility and ecotoxicity, include other bacterial strains, and elucidate the mechanisms of action of the nanocomposites. The second study focused on investigating the antibacterial and antibiofilm potential of biocuratives based on tilapia skin functionalized with silver nanoparticles biosynthesized from the aqueous extract of Mimosa tenuiflora. Phytochemical evaluation confirmed the presence of phenolic compounds in the extract, and factorial design identified the optimal parameters for nanoparticle biosynthesis. Physicochemical analyses confirmed the successful synthesis of AgNPs and MtAg-NPs. While the aqueous extract showed limited efficacy against the studied strains, the AgNPs and the MtAg-NPs composite demonstrated strong antibacterial and antibiofilm activity, with reduced MIC, MBC, MPC, and MBEC values. Acute toxicity analysis revealed that AgNPs exhibited intermediate toxicity, whereas MtAg-NPs showed lower toxicity, suggesting that biosynthesis with M. tenuiflora helps mitigate toxic effects. The study highlights the potential of functional biocuratives to combat bacterial infections and biofilms, emphasizing their application in sustainable biomedicine, although additional studies are needed.