Navegando por Palavras-chave "Nanomedicine"
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- ItemSomente MetadadadosCombined bactericidal activity of silver nanoparticles and hexadecylpyridinium salicylate ionic liquid(Springer, 2015-03-10) Silveira, Leonardo T. [UNIFESP]; Liberatore, Ana Maria A. [UNIFESP]; Koh, Ivan H. J. [UNIFESP]; Bizeto, Marcos A. [UNIFESP]; Camilo, Fernanda F. [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Recently, ionic liquids have been used as dispersing agents for silver nanoparticle (AgNP) preparation. in this paper, we have shown a simple method to prepare AgNP in aqueous media using an ionic liquid called hexadecylpyridinium salicylate (HDPSal) as dispersing agent. the dispersions were produced by the chemical reduction of silver ions in aqueous media with different concentrations of HDPSal and tetrabutylammonium borohydride as reducing agent. the UV-Visible electronic spectra showed the characteristic plasmonic resonance band around 420 nm, confirming the formation of AgNPs. the TEM images confirmed the formation of spherical particles with diameters lower than 10 nm. the charge of these particles was determined by Zeta potential and they were around +50 mV, indicating that the HDP cations are surrounding the AgNPs, avoiding their agglomeration. Most of the dispersions remained stable for at least 1 month. Microbiological assays showed that the combination of AgNP with HDPSal results in wider range of antimicrobial effect.
- ItemSomente MetadadadosEstudo Das Biointerações De Nanopartículas De Ouro Ultrapequenas: Influência Do Tamanho E Revestimento De Superfície Dissertação(Universidade Federal de São Paulo (UNIFESP), 2017-03-31) Knittel, Luiza Leite [UNIFESP]; Sousa, Alioscka Augusto Caldeira Araujo [UNIFESP]; Universidade Federal de São Paulo (UNIFESP)Thus, it is possible to control the size, shape and surface chemistry of nanomaterials, aiming stable and inert structures, or even aiming to regulate the interactions of nanomaterials with proteins and cells. For example, studies showed that ultrasmall gold nanoparticles (NPs) «3 nm) coated with glutathione are excreted by the kidneys at the same time that it has a good retention in the tumor environment. Thus, this work presents an in vitro study of ultrasmall gold NPs behavior in biological fluid and the conditioning of this behavior to the physicochemical characteristics of the particles. In a first step, we studied the relation between the size of ultrasmall NPs coated with glutathione and its colloidal stability. ;~ In a second step, we seek to improve the surface chemistry of the preceding NPs, to produce new nanostructures with improved colloidal stability and greater resistance capacity to interaction with serum proteins. Therefore, we use zwitterionic surface molecules. In the third and final stage of this work, we modulated the surface chemistry with new synthetic tripeptide aiming the formulation of ultrasmall NPs that had a purposeful interaction with serum proteins. In order to establish a relation between the surface chemistry of NPs and the identity of proteins adsorbed therein, we will seek to identify via mass spectrometry, in a next step, the serum proteins that have a preferential interaction by the different NPs. In general, this work aims a better understanding of the relation between the physicochemical properties of ultrasmall gold NPs and their biointeraction in vitro, in order to predict and possibly control its bioresponses in vivo.
- ItemSomente MetadadadosNanobiotechnology of Carbon Dots: A Review(Amer Scientific Publishers, 2016) Duran, Nelson; Simoes, Mateus B.; de Moraes, Ana C. M.; Favaro, Wagner J.; Seabra, Amedea B. [UNIFESP]In recent years, carbon dots (CDs) have gained increasing attention owing to their unique properties and enormous potential for several biomedical and technological applications. CDs are biocompatible, have a small size with a relatively large surface area, are photostable, and have customizable photoluminescence properties. This review is divided into the following discussions of CDs: general definitions
- ItemSomente MetadadadosSynthesis 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.