As nanopartículas de semicondutores são de grande interesse científico e tecnológico devido ao fato das suas propriedades eletrônicas e ópticas dependerem do tamanho das partículas. Os nanocristais de semicondutores têm sido intensamente investigados, por exemplo, como nanocargas em diversas matrizes poliméricas. Neste trabalho é apresentada a síntese de nanocompósitos obtidos pela incorporação de nanocristais (NCs) de ZnO no copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty} (sty = estireno e vpy = 4-vinilpiridina). Numa primeira etapa, o copolímero foi preparado por meio da reação entre os monômeros trans- [RuCl 2 (vpy) 4 ] e estireno. Em seguida, NCs de ZnO passivados organicamente foram misturados com o copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty}, em CH 2 Cl 2 , para produzir filmes poliméricos do nanocompósito após evaporação do solvente (método ex situ). As propriedades destes materiais foram comparadas com as de nanocompósitos análogos obtidos a partir da polimerização in situ na presença de NCs de ZnO.Nanosized semiconductor particles are of great scientific and technological interest because of their size-dependent electronic and optical properties. Semiconductor nanocrystals have been investigated, for example, as nano-fillers for diverse polymer matrices in order to produce new optically active materials. Here we report, for the first time, results concerning the preparation of nanocomposites made of ZnO nanocrystals (NCs) incorporated in the co-polymer poly-{trans-[RuCl 2 (vpy) 4 ]/sty (sty = styrene and vpy = 4-vinylpyridine). In a first step, the co-polymer was prepared by reaction of trans-[RuCl 2 (vpy) 4 ] with styrene. Then, organically capped ZnO NCs and poly-{trans-[RuCl 2 (vpy) 4 ]/sty} were mixed in CH 2 Cl 2 to produce cast films of the nanocomposites after evaporation of the solvent (ex situ method). The properties of these materials were compared to those of nanocomposites obtained by in situ polymerization in the presence of ZnO NCs. Keywords: ruthenium(II) complexes, nanocomposites, ZnO nanocrystals IntroductionSemiconductor nanocrystals (NCs) show size-dependent optical properties and have been investigated as new optical materials in the field of nanotechnology.1 For example, these nanosized particles have been used together with polymers to produce new optically active inorganic/ polymer nanocomposites. This approach takes advantage not only of the intrinsic properties of the starting materials but might also result in new properties due to synergistic effects arising from the combination of the inorganic and organic components.2 Depending on the nanoparticles' characteristics and the synthesis/processing of the polymer matrices, there are several synthetic strategies to prepare polymer nanocomposites. Available approaches include solgel methods, 3 melt-processing 4,5 and in situ polymerization.6,7The homogeneous distribution of inorganic nanoparticles within the polymer matrix and the strong interface adhesion between the matrix and nano-fillers are important aspects to be conside...

This study examines the antimicrobial activity of silver nanoparticles incorporated into nanostructured membranes made of cellulose acetate (CA) and blends of chitosan/poly-(ethylene oxide, CTS/PEO) and prepared by electrospinning. The formation of chemically synthesized Ag nanoparticles (AgNPs) was monitored by UV-visible spectroscopy (UV-Vis) and characterized by transmission electron microscopy (TEM). The size distribution of the AgNPs was measured by dynamic light scattering (DLS), with an average size of approximately 20 nm. The presence of AgNPs on the surface of electrospun nanofibers was observed by field emission electron microscopy (FEG) and confirmed by TEM. The antimicrobial activity of AgNPs incorporated into nanostructured membranes made of CA and CTS/PEO electrospun nanofibers was evaluated in the presence of both Gram-positive bacteria, such as Staphylococcus aureus ATCC 29213 and Propionibacterium acnes ATCC 6919, and Gram-negative bacteria, such as Escherichia coli ATCC 25992 and Pseudomonas aeruginosa ATCC 17933. Microbiological results showed that the presence of AgNPs in CA and CTS/PEO nanostructured membranes has significant antimicrobial activity for the Gram-positive bacteria Escherichia coli and Propionibacterium acnes. Uniterms:Electrospinning. Silver nanoparticles/antibacterial activity. Cellulose acetate. Chitosan.Neste trabalho avaliou-se a atividade antimicrobiana das nanopartículas de prata (AgNPs) incorporadas em membranas de acetato celulose (AC) e blendas de quitosana/poli-óxido de etileno (CTS/PEO) preparadas pelo método de eletrofiação. A formação das AgNPs previamente sintetizadas foi monitorada por UV-Vis e caracterizada por microscopia eletrônica de transmissão (MET). A distribuição de tamanho das AgNPs foi mensurada por espalhamento de luz dinâmico, com tamanho médio em torno de 20 nm. A presença das NPs na superfície das nanofibras eletrofiadas foi observada por microscopia eletrônica com emissão de campo (FEG) e confirmada por MET. A atividade antimicrobiana das membranas nanoestruturadas de AC e CTS/PEO foi avaliada pelo uso de bactérias Gram-positivas, tais como Staphylococcus aureus ATCC 29213 e Propionibacterium acnes ATCC 6919, e Gram-negativas, como Escherichia coli ATCC 25992 e Pseudomonas aeruginosa ATCC 17933. Os resultados microbiológicos mostraram a presença das AgNPs nas membranas de AC e CTS/PEO com significativa atividade antimicrobiana para Escherichia coli e Propionibacterium acnes, respectivamente.Unitermos: Eletrofiação. Nanopartículas de prata/atividade antimicrobiana. Acetato de celulose. Quitosana. 912 INTRODUCTIONThe use of metal nanoparticles in various medical and biotechnological applications is one of the most investigated areas in materials science. These applications require appropriate chemical functionalization of the nanoparticles with organic molecules or their incorporation into polymer matrices (Dallas, Sharma, Zboril, 2011). Among the numerous types of nanoparticles that have been used to decorate polymers, silver nanoparticles (AgNPs) ...

A nanopartícula de prata (AgN) é um dos mais proeminentes nanoprodutos, uma vez que a prata exibe propriedades físicas, químicas e biológicas notavelmente incomuns. Creatina quinase (CK) desempenha um papel central no metabolismo de tecidos que consomem muita energia, tais como o cérebro, músculo esquelético e coração, funcionando como um efetivo sistema tampão dos níveis de ATP celular. Uma diminuição na atividade da CK pode alterar a homeostase energética, contribuindo para a morte celular. No presente trabalho nós estudamos o efeito in vitro de AgN na atividade da CK de cérebro, coração e músculo esquelético de ratos. Nossos resultados demonstraram que AgN (10, 25 e 50 mg L -1 ) in vitro inibiram a atividade da CK em cérebro e músculo esquelético, porém não em coração. Vários trabalhos mostraram que os efeitos citotóxicos da AgN provavelmente envolvem a interação entre íons prata e grupos sulfidrila de proteínas. Nós sugerimos que a AgN inibiu a atividade da CK por meio da interação com grupos tiol da enzima.One of the most prominent nanoproducts is the silver nanoparticle (AgN), since silver ions exhibit remarkably unusual physical, chemical and biological properties. Creatine kinase (CK) plays a central role in metabolism of high-energy consuming tissues such as brain, skeletal muscle and heart, where it functions as an effective buffering system of cellular ATP levels. A decrease of CK activity may impair energy homeostasis, contributing to cell death. In the present work we studied the in vitro effect of AgN on the activity of CK from rat brain, heart and skeletal muscle. Our results demonstrated that AgN (10, ) in vitro inhibited CK from brain and skeletal muscle, but not from heart. Several works showed that AgN cytotoxic effects probably involve interaction between silver ions and sulphydryl groups of proteins. We suggest that AgN inhibited CK activity through interactions with thiol groups of the enzyme.Keywords: silver nanoparticles, creatine kinase, brain, heart, skeletal muscle IntroductionMedicinal inorganic chemistry is a discipline of growing significance in both therapeutic and diagnostic medicine. Inorganic compounds have been used in medicine in an empirical way with little attempt to design the compounds to be used. The design of new biologically active compounds involves the control of toxicity and the target of the metal to specific tissues, organs, or cells.1 The current array of successful metallopharmaceuticals includes platinum anticancer drugs, radio diagnostic agents and others.2 Thus, biomedical inorganic chemistry offers the potential for the design of novel therapeutic and diagnostic agents and for the treatment and understanding of diseases. 3Nanotechnology involves the creation and manipulation of materials at nanoscale levels and is a promising field for generating new applications in medicine. [4][5][6][7][8] One of the most prominent nanoproducts are silver nanoparticles Paula et al. 1557 Vol. 20, No. 8, 2009 (AgN), since silver exhibits remarkably unusual physical, chemic...

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Silver nanoparticles (AgNPs) are nanoforms that express higher antimicrobial potential due to their shape and reduced size. The use of fungi to mediate the synthesis of AgNPs has increased the interest of scientists because of their rapid growth, large-scale cultivation and secretion of non-toxic molecules. The aim of this study was to synthesize AgNPs mediated by Aspergillus oryzae DPUA 1624 and evaluate the antimicrobial activity of these molecules incorporated in cellulose acetate nanomembranes (NanoMAC). The synthesis of AgNPs was confirmed by UV-visible spectroscopy and the characterization was performed by dynamic light scattering, transmission electron microscopy, X-ray diffraction, X-ray dispersive energy and advanced spectroscopy and spectroscopy methods. The synthesis of the membrane was done by electro-spinning and its thickness was analyzed in scanning electron microscope. The AgNPs were added to NanoMAC and the antimicrobial effect was evaluated by agar diffusion method against Staphylococcus aureus, Escherichia coli and Candida albicans. The aqueous extract of A. oryzae mediated the synthesis of AgNPs with rounded and some triangular shapes. The diameter and zeta potential of these particles were 61.15±11.45 nm and-28.7 mv, respectively. The NanoMAC with AgNPs showed an increase in antifungal activity of 24.22% when tested against C. albicans. This study demonstrated that A. oryzae is able to mediate AgNP synthesis with anti-yeast action and the impregnation of AgNPs in acetate cellulose nanomembranes resulted in the development of a more efficient antimicrobial nanocomposite.