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      Silver nanoparticles biosynthesized using Opuntia ficus aqueous extract

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          Abstract

          Silver nanoparticles were synthesized using a green chemistry method. Stable silver nanoparticles in a colloidal aqueous solution were prepared successfully by the chemical reaction of silver nitrate (AgNO3) and Opuntia ficus indica aqueous extract, used as both, reducing and stabilizing agent. Nanoparticle size, morphology and optical properties were analyzed by using transmission electron microscopy (TEM) and UV-Vis spectroscopy, respectively. TEM images revealed a nanoparticle average size of 23 nm. An absorption band centered around 398 nm was observed, this absorption corresponds to the surface plasmon resonance (SPR) of the silver nanoparticles.

          Translated abstract

          A partir de una nueva ruta de síntesis empleando la química verde, se obtuvieron nanopartículas de plata. Una solución coloidal de nanopartículas de plata se obtuvo a través de la reacción química entre el nitrato de plata (AgNO3) y una solución acuosa de extracto de nopal (Opuntia ficus indica), el cual juega el papel de agente reductor y estabilizador. El tamaño, morfología y propiedades ópticas de las nanopartículas fueron analizadas mediante microscopia electrónica de transmisión (TEM) y espectroscopia de absorción óptica UV-Vis, respectivamente. Imágenes de TEM mostraron que el tamaño promedio de las nanopartículas obtenidas fue de 23 nm. En los espectros absorción se observó una banda centrada en 398 nm, la cual corresponde a la resonancia del plasmón superficial de las nanopartículas de plata.

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          Most cited references21

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          Optimization of an AMBER Force Field for the Artificial Nucleic Acid, LNA, and Benchmarking with NMR of L(CAAU)

          Locked Nucleic Acids (LNAs) are RNA analogues with an O2′-C4′ methylene bridge which locks the sugar into a C3′-endo conformation. This enhances hybridization to DNA and RNA, making LNAs useful in microarrays and potential therapeutics. Here, the LNA, L(CAAU), provides a simplified benchmark for testing the ability of molecular dynamics (MD) to approximate nucleic acid properties. LNA χ torsions and partial charges were parametrized to create AMBER parm99_LNA. The revisions were tested by comparing MD predictions with AMBER parm99 and parm99_LNA against a 200 ms NOESY NMR spectrum of L(CAAU). NMR indicates an A-Form equilibrium ensemble. In 3000 ns simulations starting with an A-form structure, parm99_LNA and parm99 provide 66% and 35% agreement, respectively, with NMR NOE volumes and 3 J-couplings. In simulations of L(CAAU) starting with all χ torsions in a syn conformation, only parm99_LNA is able to repair the structure. This implies methods for parametrizing force fields for nucleic acid mimics can reasonably approximate key interactions and that parm99_LNA will improve reliability of MD studies for systems with LNA. A method for approximating χ population distribution on the basis of base to sugar NOEs is also introduced.
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            Detailed Characterization of a Nanosecond-Lived Excited State: X-ray and Theoretical Investigation of the Quintet State in Photoexcited [Fe(terpy)2]2+

            Theoretical predictions show that depending on the populations of the Fe 3d xy , 3d xz , and 3d yz orbitals two possible quintet states can exist for the high-spin state of the photoswitchable model system [Fe(terpy)2]2+. The differences in the structure and molecular properties of these 5B2 and 5E quintets are very small and pose a substantial challenge for experiments to resolve them. Yet for a better understanding of the physics of this system, which can lead to the design of novel molecules with enhanced photoswitching performance, it is vital to determine which high-spin state is reached in the transitions that follow the light excitation. The quintet state can be prepared with a short laser pulse and can be studied with cutting-edge time-resolved X-ray techniques. Here we report on the application of an extended set of X-ray spectroscopy and scattering techniques applied to investigate the quintet state of [Fe(terpy)2]2+ 80 ps after light excitation. High-quality X-ray absorption, nonresonant emission, and resonant emission spectra as well as X-ray diffuse scattering data clearly reflect the formation of the high-spin state of the [Fe(terpy)2]2+ molecule; moreover, extended X-ray absorption fine structure spectroscopy resolves the Fe–ligand bond-length variations with unprecedented bond-length accuracy in time-resolved experiments. With ab initio calculations we determine why, in contrast to most related systems, one configurational mode is insufficient for the description of the low-spin (LS)–high-spin (HS) transition. We identify the electronic structure origin of the differences between the two possible quintet modes, and finally, we unambiguously identify the formed quintet state as 5E, in agreement with our theoretical expectations.
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              Interaction between carbon nanotubes and mammalian cells: characterization by flow cytometry and application.

              We show herein that CNT-cell complexes are formed in the presence of a magnetic field. The complexes were analyzed by flow cytometry as a quantitative method for monitoring the physical interactions between CNTs and cells. We observed an increase in side scattering signals, where the amplitude was proportional to the amount of CNTs that are associated with cells. Even after the formation of CNT-cell complexes, cell viability was not significantly decreased. The association between CNTs and cells was strong enough to be used for manipulating the complexes and thereby conducting cell separation with magnetic force. In addition, the CNT-cell complexes were also utilized to facilitate electroporation. We observed a time constant from CNT-cell complexes but not from cells alone, indicating a high level of pore formation in cell membranes. Experimentally, we achieved the expression of enhanced green fluorescence protein by using a low electroporation voltage after the formation of CNT-cell complexes. These results suggest that higher transfection efficiency, lower electroporation voltage, and miniaturized setup dimension of electroporation may be accomplished through the CNT strategy outlined herein.
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                Author and article information

                Journal
                sv
                Superficies y vacío
                Superf. vacío
                Sociedad Mexicana de Ciencia y Tecnología de Superficies y Materiales A.C. (Ciudad de México, Ciudad de México, Mexico )
                1665-3521
                March 2012
                : 25
                : 1
                : 31-35
                Affiliations
                [03] Ensenada B.C. orgnameUniversidad Nacional Autónoma de México. orgdiv1Centro de Nanociencias y Nanotecnología. México
                [02] Toluca Edo. de México orgnameUniversidad Autónoma del Estado de México. orgdiv1Facultad de Medicina. orgdiv2Laboratorio de Fotomedicina, Biofotonica y Espectroscopia Láser de Pulsos Ultracortos. México macamachol@ 123456uaemex.mx
                [01] Toluca Estado de México orgnameUniversidad Autónoma del Estado de México. orgdiv1Facultad de Química. orgdiv2Centro de Investigación en Química Sustentable. México
                Article
                S1665-35212012000100006 S1665-3521(12)02500100006
                2d561d70-f990-42b8-8e2c-5a20dd7d5749

                This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.

                History
                : 04 January 2012
                : 28 July 2011
                Page count
                Figures: 0, Tables: 0, Equations: 0, References: 35, Pages: 5
                Product

                SciELO Mexico


                Síntesis biogénica,Silver nanoparticles,bioreduction,green nanochemistry,Opuntia ficus indica,biogenic synthesis,optical properties,Nanopartículas de plata,Biorreducción,Nanoquimica verde,Propiedades ópticas

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