Efecto de la concentración de L-cisteina sobre la resonancia del plasmón de nanoesferas de oro sintetizadas por química húmeda
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Date
2017
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Universidad Nacional de Trujillo
Abstract
El desarrollo de este trabajo consisti o en obtener nanoesferas de oro funcionalizadas_x000D_
con L-ciste na, para ello, se prepar o nanoesferas de oro por el m etodo de Turkevich_x000D_
modi cado por Frens. En la s ntesis, se us o un volumen jo de 1.7 mL de acido_x000D_
tetracloro aurico trihidratado (HAuCl4.3H2O) (0.005 M) como precursor en todas las_x000D_
preparaciones y se us o diferentes vol umenes de citrato (C6H5Na3O7.2H2O) (0.017 M)_x000D_
desde 13 mL hasta 23 mL con incrementos de 2 ml. Se realizaron estudios de caracterizaci_x000D_
on con UV-Vis, DLS y zeta potencial, as como mediciones de pH; en estos_x000D_
estudios se pudo con rmar lo reportado por Frens y otros autores, esto es, que a mayor_x000D_
concentraci on de citrato, se obtuvo nanoesferas de di ametros menores, con una resonancia_x000D_
de plasm on super cial a menor longitud de onda y mayor pH. Los valores de_x000D_
zeta potencial se hicieron m as negativos hasta -49 mV con una concentraci on de citrato_x000D_
de (7.87466 mM), valor en el que se invirti o hacia valores de zeta potencial menos negativos_x000D_
posiblemente debido a la reducci on en los di ametros de las nanoesferas de oro._x000D_
La funcionalizaci on se realiz o controlando el pH y variando el volumen de la ciste na_x000D_
desde 0.2 mL hasta 2 mL. Los espectros UV-Vis reportaron dos picos de m axima resonancia,_x000D_
uno correspondiente a la banda de plasm on caracter stico de las nanoesferas_x000D_
de oro alrededor de 530 nm y otro pico alrededor de 670 nm cuyas intensidades de_x000D_
absorbancia disminuye a medida que se incrementa la concentraci on de ciste na, con-_x000D_
rmando la modi caci on super cial de las nanoesferas de oro; este comportamiento_x000D_
estuvo acompa~nado de un cambio de color del coloide de rojo rub a azul, asi como con valores de zeta potencial que tiende a ser cada vez menos negativo
Description
The development of this work consisted of obtaining gold nanospheres functionalized_x000D_
with L-cysteine. For this, gold nanospheres were prepared by the Turkevich method_x000D_
modi ed by Frens. In the synthesis, a xed volume of 1.7 mL of tetrachloroauric acid_x000D_
trihydrate (HAuCl4.3H2O) (0.005 M) was used as the precursor in all preparations and_x000D_
di erent volumes of citrate (C6H5Na3O7.2H2O) (0.017 M) from 13 mL to 23 mL in_x000D_
increments of 2 ml. Characterization studies were performed with UV-Vis, DLS and_x000D_
potential zeta, as well as pH measurements; in these studies it was possible to con-_x000D_
rm what Frens and other authors reported, that at a higher concentration of citrate,_x000D_
nanospheres with smaller diameters were obtained, with a super cial plasmon resonance_x000D_
at a lower wavelength and higher pH. Potential zeta values became more negative up_x000D_
to -49 mV with a citrate concentration of (7.87466 mM), at which value was inverted_x000D_
towards potential minus zeta values possibly due to the reduction in diameters of gold_x000D_
nanospheres. Functionalization was performed by controlling the pH and varying the_x000D_
volume of the cysteine from 0.2 mL to 2 mL. The UV-Vis spectra reported two peaks_x000D_
of maximum resonance, one corresponding to the characteristic plasmon band of gold_x000D_
nanospheres at about 530 nm and another peak around 670 nm whose absorbance intensities_x000D_
decrease as the cysteine concentration increases, con rming surface modi cation_x000D_
of gold nanospheres; this behavior was accompanied by a color change from ruby red_x000D_
to blue colloid, as well as potential zeta values that tend to be less negative.
Keywords
Nanoesferas, Funcionalización, Citrato