Three new metal organic frameworks (MOFs) with chemical formulae [(CH3)2NH2] [Sm3(L1)2(HCOO)2(DMF)2(H2O)]·2DMF·18H2O (1), [Cu2(L2)(H2O)2]·2.22DMA (2) and [Zn2(L1)(DMA)]·1.75DMA were synthesized and structurally characterized. 1 and 2 show a classical NbO-like topology and have two types of interconnected cages. 3 exhibits an uncommon zzz topology and has two types of interconnected cages. These MOFs can adsorb large amounts of the drug 5-fluorouracil (5-FU) and release it in a progressive way. 5-FU was incorporated into desolvated 1, 2 and 3 with loadings of 0.40, 0.42, and 0.45 g g(-1), respectively. The drug release rates were 72%, 96% and 79% of the drug after 96 hours in 1, 120 hours in 2 and 96 hours in 3, respectively. Grand Canonical Monte Carlo (GCMC) simulations were performed to investigate the molecular interactions during 5-FU adsorption to the three novel materials. The GCMC simulations reproduced the experimental trend with respect to the drug loading capacity of each material. They also provided a structural description of drug packing within the frameworks, helping to explain the load capacity and controlled release characteristics of the materials. 5-FU binding preferences to 1, 2 and 3 reflect the diversity in pore types, chemistry and sizes. The calculated drug load is more related to the molecular properties of accessible volume Vacc than to the pore size.
Este trabalho reporta a obtenção de nanopartículas de aluminato de zinco dopado com Eu3+, por meio do método de síntese por reação de combustão. Foram preparadas quatro amostras com diferentes concentrações de dopante, para avaliar o efeito do teor de Eu3+ na luminescência dos pós obtidos. Os resultados de difração de raios X confirmaram a formação da fase espinélio ZnAl2O4 e também traços de fases secundárias identificadas como EuAlO3 e ZnO, em quantidade diretamente proporcional ao teor de dopante das amostras. O espectro de emissão foi excitado em 265 nm (lambdamax), o qual apresentou picos característicos do íon Eu3+ localizados em torno de 578, 591 613, 653 e 703 nm. Os resultados obtidos por microscopia eletrônica de varredura apresentam aglomerados em forma de placas irregulares formadas por nanopartículas com pontos dispersos de fase secundaria na superfície. Baseado nos resultados verificou-se a dependência da intensidade de luminescência com o teor e também com a forma de incorporação do íon Eu3+, inserido na rede hospedeira, adsorvido na superfície de nanopartículas ou formando uma segunda fase.
com o grupo éster do criptato de térbio. A formação do produto foi acompanhada por cromatografia líquida de alta eficiência (CLAE) em 238 nm e 310 nm. A presença de microcistina-LR na molécula marcada foi confirmada através de ensaio com enzima ligada a imunoabsorvente (ELISA) e por reação protéica com ácido bicincônico. O espectro de luminescência do criptato e da molécula conjugada também foram confirmados.A new fluorescent labeled compound of microcystin-LR with terbium cryptate was obtained by initial conjugation of microcystins-LR with aminoethanethiol followed by the reaction with the ester group of terbium cryptate. The product formation was followed by high performance liquid chromatography (HPLC) at 238 nm and 310 nm. The presence of microcystin-LR in the labeled molecule was confirmed by enzyme linked immunosorbent assay ELISA and by protein reaction with bicinhonic acid. Luminescence spectra of cryptate and the conjugated molecule were carried through as well.
Keywords: terbium cryptate, microcystin-LR, cyanobacteria
IntroductionMicrocystins are a group of stable heptapeptide hepatotoxins produced by freshwater cyanobacteria genera that lower the water quality leading to an increase in the risk of intoxication for animals and humans. Species of genera Microcystis, Anabaena, Aphanizomenon, Planktothrix (Oscillatoria), and Nostoc are frequently described as producers of microcystins. 1 The eutrophication of ponds, rivers and other freshwater ecosystems allows cyanobacteria to flourish, leading to contamination of the water. Microcystins are potent inhibitors of protein phosphatases 1 (PP 1 ) and 2A (PP 2A ), which are regulatory enzymes present in the cytosol of mammalian cells. 3 The general structure of microcystins is composed of cyclo-(D-Ala-X-D-MeAsp-ZAdda-D-Glu-Mdha), where X and Z could be various kinds of L-amino acids; D-MeAsp is D-erythro-β-methylaspartic acid; Mdha is N-methyldehydroalanine; and Adda is the unusual amino acid 2S,3S,8S,9S-3-amino-9-methoxy-2,6,8-trimethyl-10-phenyldeca-4E,6E-dienoic acid. 4 The most extensively studied form is microcystin-LR that contains L-leucine and L-arginine in the two main variant positions. In the search for more sensitive markers, some chelates of lanthanides had already been obtained and tested in various biological assay models. [25][26][27] Time-resolved fluoroimmunometric assay (TR-FIA) is a method based on the luminescence emission that is measured after a delay has elapsed from a pulsed excitation, enabling the short-lived background fluorescence to be excluded.
28Soini et. al.29 labeled anti-rabbit IgG with europium chelate as a model to detect rabbit IgG for human smooth muscle myosin in a histological section; Bonin et al. 30 used a complex of europium and samarium for the detection of diphteria antitoxins in serum using the ELISA method and Xu et al.31 labeled anti-β-LH and monoclonal anti-β-FSH antibodies with europium and samarium, respectively. The use of luminescent lanthanide as a substitute for labeled enzyme (e.g. horseradish peroxidas...
Aluminato de zinco dopado com os íons terras raras itérbio e érbio nas proporções 2:1, 3:1, 4:1, e 5:1 mol de Yb:Er foi sintetizado por reação de combustão. O efeito da dopagem simultânea Yb:Er na estrutura e na morfologia do aluminato de zinco foi investigado. Os pós foram sintetizados com base nos conceitos da química dos propelentes e então caracterizados por difração de raios X, análise granulométrica, adsorção de nitrogênio (método BET) e microscopia eletrônica de varredura. Os resultados mostraram a formação da fase cristalina majoritária de ZnAl2O4:Yb:Er e traços das fases secundárias ZnO e Yb2O3 e que o aumento da relação Yb:Er favoreceu o aumento das fases secundárias. Todas as composições apresentaram morfologia formada por aglomerados moles constituídos por partículas finas. A área superficial aumentou em função da elevação da proporção Yb:Er.
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