3 research outputs found
Sistemas biomimĂ©ticos na sĂntese de nanopartĂculas de ouro para aplicaçÔes biomĂ©dicas e biotecnolĂłgicas
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro TecnolĂłgico, Programa de PĂłs-Graduação em CiĂȘncia e Engenharia de Materiais, FlorianĂłpolis, 2015.Esta tese descreve o desenvolvimento de duas rotas sintĂ©ticas rĂĄpidas e eficazes para produção de nanoestruturas de ouro: nanopartĂculas de ouro estabilizadas com a hesperetina (Ht), um flavonoide de cĂtricos, conhecido por seus efeitos anti-inflamatĂłrio, anti-hipertensivo e antiaterogĂȘnico; e um compĂłsito de nanopartĂculas de Ăłxido de ferro@ouro (?-Fe2O3@Au). As nanoestruturas foram facilmente preparadas sob condiçÔes brandas, seguindo os princĂpios de quĂmica verde. Na primeira parte da tese, apresenta-se o desenvolvimento do mĂ©todo de sĂntese das nanopartĂculas de ouro com Ht (HtAuNP), realizada Ă temperatura ambiente e em uma Ășnica etapa. As HtAuNP foram entĂŁo caracterizadas por Microscopia EletrĂŽnica de TransmissĂŁo de Alta Resolução (HRTEM), Espalhamento de Luz DinĂąmico (DLS), Espectrometria de EmissĂŁo de FotoelĂ©trons Excitados por Raios-X (XPS), Difração de Raios-X e Espectrofotometria UV-Vis. AlĂ©m disso, realizou-se um estudo, usando a Teoria do Funcional de Densidade (DFT) para avaliação da interação Au3+:Ht. Assim, observou-se que a redução do ĂĄcido cloroĂĄurico em condiçÔes alcalinas, e na presença de Ht, gerou suspensĂ”es concentradas (4-7 mmolL-1) e uniformes de HtAuNP de forma esfĂ©rica, medindo aproximadamente 15 nm e com distribuição estreita de tamanho (Abstract : This dissertation reports two synthesis procedures with a reduced use of toxic chemicals and solvents for gold nanoparticles and a composite of ?-Fe2O3@Au nanoparticles, according to the principles of green chemistry, methods that are highly sought after nanoparticles production, particularly for use in biomedical/biotechnological applications. In the first part, a fast single-pot method at room temperature to synthesize AuNP, using hesperetin (Ht), a flavonoid from citrus fruits known for its anti-inflammatory, antihypertensive and antiatherogenic effects is reported. Experimentally, the HtAuNP and ?- Fe2O3@Au were characterized using high-resolution transmission electron microscopy (HRTEM), dynamic light scattering (DLS), X-ray photoelectron spectrometry (XPS) and UV-Vis spectrophotometry. Also, a theoretical study to assess the interaction of hesperetin with Au3+ ions was also performed by quantum chemical calculation using density functional theory (DFT). The reduction of chloroauric acid in alkaline conditions in presence of hesperetin yielded concentrated suspensions of uniform 15 nm spherical HtAuNP with a narrow size distribution (<15%) that remain stable for at least a year at 2-8 ÂșC, without changing their shape over time. Our theoretical calculations suggest the electron transfer from hesperetin to gold as a consequence of complexation, reducing Au3+ ions to Au0. In the second part, iron oxide-gold nanoparticles displaying both magnetic and plasmonic behaviors were synthetized. Here, iron oxide nanoparticles (NPs) prepared by coprecipitation of Fe(II) and Fe(III) chlorides. These bare nanoparticles ~ 9 nm were then dispersed in the presence of HAuCl4 using ultrasonic irradiation to adsorb AuCl4 - ions on their surface. Gold was subsequently reduced in an alkaline environment by adding the flavonoid hesperetin with the further drop-addition of pH modifier within a frame time of 10 minutes. ?-Fe2O3@Au composite synthesized under the aforementioned conditions suggests morphology consistent with bare magnetite decorated with gold nanoparticles along with coreĂ shell magnetite-gold particles, forming discrete aggregates (55 nm by DLS), displaying a strong SPR band around 580 nm. As prepared these nanoparticles could be used for a wide range of applications taking advantage of both magnetic and optical properties
Influence of Surfactant and Lipid Type on the Physicochemical Properties and Biocompatibility of Solid Lipid Nanoparticles
Nine types of solid lipid nanoparticle (SLN) formulations were produced using tripalmitin (TPM), glyceryl monostearate (GM) or stearic acid (SA), stabilized with lecithin S75 and polysorbate 80. Formulations were prepared presenting PI values within 0.25 to 0.30, and the physicochemical properties, stability upon storage and biocompatibility were evaluated. The average particle size ranged from 116 to 306 nm, with a negative surface charge around â11 mV. SLN presented good stability up to 60 days. The SLN manufactured using SA could not be measured by DLS due to the reflective feature of this formulation. However, TEM images revealed that SA nanoparticles presented square/rod shapes with an approximate size of 100 nm. Regarding biocompatibility aspects, SA nanoparticles showed toxicity in fibroblasts, causing cell death, and produced high hemolytic rates, indicating toxicity to red blood cells. This finding might be related to lipid type, as well as, the shape of the nanoparticles. No morphological alterations and hemolytic effects were observed in cells incubated with SLN containing TPM and GM. The SLN containing TPM and GM showed long-term stability, suggesting good shelf-life. The results indicate high toxicity of SLN prepared with SA, and strongly suggest that the components of the formulation should be analyzed in combination rather than separately to avoid misinterpretation of the results
Influence of Surfactant and Lipid Type on the Physicochemical Properties and Biocompatibility of Solid Lipid Nanoparticles
Nine types of solid lipid nanoparticle (SLN) formulations were produced using tripalmitin (TPM), glyceryl monostearate (GM) or stearic acid (SA), stabilized with lecithin S75 and polysorbate 80. Formulations were prepared presenting PI values within 0.25 to 0.30, and the physicochemical properties, stability upon storage and biocompatibility were evaluated. The average particle size ranged from 116 to 306 nm, with a negative surface charge around â11 mV. SLN presented good stability up to 60 days. The SLN manufactured using SA could not be measured by DLS due to the reflective feature of this formulation. However, TEM images revealed that SA nanoparticles presented square/rod shapes with an approximate size of 100 nm. Regarding biocompatibility aspects, SA nanoparticles showed toxicity in fibroblasts, causing cell death, and produced high hemolytic rates, indicating toxicity to red blood cells. This finding might be related to lipid type, as well as, the shape of the nanoparticles. No morphological alterations and hemolytic effects were observed in cells incubated with SLN containing TPM and GM. The SLN containing TPM and GM showed long-term stability, suggesting good shelf-life. The results indicate high toxicity of SLN prepared with SA, and strongly suggest that the components of the formulation should be analyzed in combination rather than separately to avoid misinterpretation of the results