Angelats Silva, Luis ManuelRodríguez Laiza, Alex Leodan6/25/20186/25/20182017https://hdl.handle.net/20.500.14414/10359The 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.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 negativospainfo:eu-repo/semantics/openAccessNanoesferas, Funcionalización, Citratoinfo:eu-repo/semantics/bachelorThesis