RESUMO
Nature provides remarkable examples of mass-produced microscale particles with structures and chemistries optimized by evolution for particular functions. Synthetic chemical tailoring of such sustainable biogenic particles may be used to generate new multifunctional materials. Herein, we report a facile method for the synthesis of hybrid nano/microstructures Ag-Fe3O4 based on Dimorphotheca ecklonis pollen grains as bio-template. Silver nanoparticles was biosynthesized using pollen grains as a reduction and stabilization agent as well as a bio-template promoting the adhesion of silver nanoparticles to pollen surface. Fe3O4 nanoparticles were synthesized by co-precipitation method from FeSO4. Hybrid nano/microstructures Ag-Fe3O4 based on Dimorphotheca ecklonis pollen grains as bio-template were obtained and characterized using Scanning Electron Microscopy and Transmission Electron Microscopy to study the morphology and structure; Energy-Dispersive X-ray Spectroscopy to determine the chemical composition distribution; and Confocal Fluorescence Microscopy to demonstrate the fluorescence properties of hybrid nano-microstructures. Furthermore, these hybrid nano-microstructures have been studied by Surface-Enhanced Raman Scattering (SERS), using methylene blue as a target molecule; the hybrid nano-microstructures have shown 14 times signal amplification.
Assuntos
Asteraceae , Vias Biossintéticas , Compostos Férricos/química , Nanopartículas Metálicas/química , Pólen/química , Prata/química , Análise Espectral Raman , Azul de Metileno , Microscopia Eletroquímica de Varredura , Microscopia Eletrônica de Transmissão , Pólen/ultraestrutura , Espectrometria por Raios XRESUMO
Resumen: La señal de la amplitud en análisis de Potenciales Evocados Visuales (PEVs) es una variable que depende del tipo y posición de los electrodos, de la fuente, del estímulo y por consecuente, de la intensidad luminosa por lo que es fundamental reportarla para cada diseño experimental y así, garantizar su reproducibilidad. El objetivo de este trabajo es caracterizar una lámpara con 96 LEDs para la adquisición de PEVs en ratas. Se midió la iluminancia y la intensidad luminosa promedio en un sistema espacial XYZ de 8 cm3 aplicable a un sistema estereotáxico para la fijación de ratas. Se realizaron desplazamientos cada 2 cm en cada plano. Se observó que debido a la distribución geométrica de los LEDs la distribución de la iluminancia no sigue la ley del inverso cuadrado, ya que aumenta conforme la lámpara se aleja. Finalmente, se seleccionó una coordenada para la colocación del ojo de la rata empleando una intensidad luminosa promedio para la adquisición del PEV de 1.043 cd e iluminancia de 128.77 luxes a una distancia ojo-lámpara de 9 cm. Una vez caracterizada la intensidad luminosa y de acuerdo con los PEVs obtenidos, esta lámpara puede utilizarse para estudios PEV en ratas en investigaciones posteriores.
Abstract: Signal amplitude for recordings of Visual Evoked Potentials (VEPs) is a variable dependent on the type and position of the electrodes, the source, the stimulus and consequently the luminous intensity; therefore, it is relevant to report it to assure experimental reproducibility. The objective of this work is to characterize flash lamp with 96 LEDs in order to perform the acquisition of VEPs in rats. We measure the illuminance and mean light intensity on space system XYZ of 8 cm3 corresponding to a stereotaxic frame for rodents. Displacements were performed every 2 cm in each plane. Because of the geometric distribution of the LEDs in the EBNeuro lamp the spatial distribution of illuminance does not follow the law of the inverse square, because the illuminance increases as the lamp goes away. Finally a spatial coordinate was selected for the rat eye positioning were the mean luminous intensity was 1.043 cd and 128.77 luxes of illuminance at an eye-lamp distance of 9 cm. According to the obtained VEPs and spatial characterization this lamp can be used for acquire of recordings PEV in rats for further investigations.
RESUMO
Resumen: Objetivo: Analizar los espectros de absorción neta de las películas radiocrómicas EBT2 y EBT3 para describir su influencia en el comportamiento de las curvas de dosis-respuesta. Metodología: Las películas se irradiaron en un acelerador lineal de 6 MV. La obtención de los espectros de absorción neta se realizó con espectrofotómetro UV/VIS. Las curvas de dosis-respuesta se obtuvieron con un escáner, un láser He-Ne y un espectrofotómetro. Resultados: El espectro de absorción de las EBT2 muestra tres bandas de absorción centradas que conservan la posición y aumentan su intensidad en función de la dosis, sin embargo, este comportamiento no se observa en las películas EBT3. La curva dosis-respuesta muestra la máxima sensibilidad utilizando el espectrofotómetro, pero no muestra un comportamiento definido. Implicaciones: Generación de nuevos conocimientos para la creación de nuevos sistemas ópticos capaces de amplificar la sensibilidad de la respuesta de las películas. Originalidad: Mostrar la correlación entre los espectros de absorción neta y su influencia en las curvas dosis-respuesta en tres diferentes sistemas ópticos. Conclusiones: El comportamiento de los espectros de absorción aunado al comportamiento de las curvas dosis-respuesta nos ayuda a descartar el uso de sistemas ópticos que no garanticen un uso clínico confiable.
Abstract: Objective: To analyze the net absorption spectra of EBT2 and EBT3 radiochromic films to describe their influence on the behavior of dose-response curves. Methodology: The films were irradiated in a linear accelerator of 6 MV. The net absorption spectra were obtained with a UV / VIS spectrophotometer. Dose-response curves were obtained with a scanner, a He-Ne laser and a spectrophotometer. Results: The absorption spectrum of the EBT2 shows three focused absorption bands that retain position and increase their intensity as a function of dose, however, this behavior is not observed in EBT3 films. The dose-response curve shows maximum sensitivity using the spectrophotometer, but does not show a defined behavior. Implications: Generation of new knowledge for the creation of new optical systems capable of amplifying the responsiveness of the films. Originality: Show the correlation between net absorption spectra and their influence on dose-response curves in three different optical systems. Conclusions: The behavior of absorption spectra combined with the behavior of the dose-response curves helps to discard the use of optical systems that do not guarantee a reliable clinical use.
RESUMO
A multifunctional system of gold nanoparticles (AuNP) capped by the [Tyr(3)]Octreotide (TOC) peptide was prepared and characterized by transmission electron microscopy (TEM) and UV-Vis, infrared and fluorescence spectroscopy. AuNP and AuNP-TOC fluorescence emission spectra were obtained both in solution and in murine AR42J-tumor tissues. Results suggest that AuNP were functionalized with TOC through interactions with the N-terminal amine of the phenylalanine, the amide groups and possibly with the indole group of the tryptophan residue. The fluorescence analyses in tissue revealed a recognition of the AuNP-TOC conjugate for the neuroendocrine tumor because of the lower energy position of the fluorescence resonance (692 nm) with respect to that of the AuNP in the same tumoral tissue (684 nm). The emission band observed in the near-infrared region (692 nm) opens the possibility for AuNP-TOC use in bioimaging.