Navegando por Palavras-chave "Methylene Blue"

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    Processamento e Caracterização de Scaffolds de β-Fosfato Tricálcico pelo Método de Gelcasting com Incorporação de Nanopartículas para Atividade Antimicrobiana
    (Universidade Federal de São Paulo (UNIFESP), 2020-02-14) Barbosa, Lucas [UNIFESP]; Triches, Eliandra De Sousa [UNIFESP]; Universidade Federal de São Paulo
    Tissue engineering and regenerative medicine are highly relevant to the science of biomaterials, promoting advances in the treatment and recovery of patients with problems caused by diseases, injuries and fractures. Recent studies in tissue engineering have sought to develop multifunctional scaffolds that in addition to having regenerative capacity, have antimicrobial properties through the incorporation of antimicrobial agents, providing a better recovery to the patient and avoiding new surgical procedures for treatment or removal of the implant, since inflammations and infections are often caused by microorganisms. For the production of ceramic scaffolds for bone tissue regeneration, tricalcium β-phosphate (β-TCP) stands out due to its chemical stability and more suitable resorption speed for bone implants. Among the antimicrobial agents that have been studied are metallic nanoparticles, such as silver, and chemical compounds, such as methylene blue. Thus, this work aimed to obtain β-TCP scaffolds by the gelcasting method applied to foams with the incorporation of methylene blue and silver nanoparticles in order to confer antimicrobial properties. For this, the obtained β-TCP scaffolds were immersed in the silver nanoparticles solution and stirring by ultrasonic. Methylene blue was incorporated by dripping the solution into the scaffolds. The synthesized ceramic powder presented the crystalline phase of interest, β-TCP, average particle size after grinding 1.56 μm and density 2.99 g/cm³. Regarding antimicrobial agents, silver nanoparticles had an average hydrodynamic diameter of 39 ± 2 nm, with maximum absorption in the UV-visible spectrum at 429 nm and the methylene blue solution had a concentration of 1.044 mM, with maximum absorption in the UV-visible spectrum at 654 nm. In turn, the β-TCP scaffolds had porosity of 81 ± 2 % and mechanical compressive strength of 1.3 ± 0.5 MPa with spherical and interconnected pores. The test to evaluate the antimicrobial activity, in relation to S. aureus bacteria, of the scaffolds incorporated with antimicrobial agents revealed that the studied samples had little inhibitory action. It is understood that it is not enough to just incorporate an agent with a high antimicrobial capacity into the scaffold, but to understand how this agent will be incorporated into the scaffold and whether this incorporation will leave it in contact with the microorganism during the antimicrobial activity test. Therefore, it was possible to obtain β-TCP scaffolds, incorporate them with antimicrobial agents and although they have little inhibitory action, it was possible to observe the relevance of the research and guide the studies for future work.
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    Synthesis and Characterization of Methylene Blue-Containing Silica-Coated Magnetic Nanoparticles for Photodynamic Therapy
    (Amer Scientific Publishers, 2017) Fudimura, Karina Amancio [UNIFESP]; Seabra, Amedea Barozzi [UNIFESP]; Santos, Marconi da Cruz [UNIFESP]; Haddad, Paula Silvia [UNIFESP]
    Superparamagnetic iron oxide nanoparticles (SPIONs), with appropriate surface coating, are commonly used for biomedical applications such as photodynamic therapy (PDT). This work describes the preparation and characterization of methylene blue (MB)-containing silica-coated SPIONs. Upon exposure to light, MB reacts with molecular oxygen and generates singlet oxygen (O-1(2)) which is cytotoxic and causes irreversible damage to tumor tissues. In this work, SPIONs were synthesized by co-precipitation and coated with a single/double silica layer. The photoactive molecule MB was entrapped in the silica layer deposited on the surface of SPIONs, leading to the formation of hybrid nanomaterials composed of a magnetic core and silica layer. The nanocomposite exhibited magnetic behavior at room temperature due to the presence of its Fe3O4 core. Structural and morphological characterizations were performed by X-ray diffraction (XRD), Fourier transformed infrared (FTIR), SQUID magnetic measurements, ultraviolet-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and dynamic light scattering. The results showed the presence of a crystalline Fe3O4 magnetic core and amorphous silica phases. Kinetic measurements revealed O-1(2) generation by the nanoparticles upon irradiation with visible light (lambda = 532 nm or lambda = 633 nm). The results highlight the potential uses of SPIONs coated with MB-entrapped silica for PDT, whereby a sustained and localized generation of O-1(2) was successfully achieved.