Publication: Ph interno en geles de polivinilimidazol
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2011
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2011-06-30
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Abstract
En el presente trabajo se ha establecido un método para medir el pH en el interior de hidrogeles hinchados de poli(N‐vinilimidazol) a través de las variaciones en el tiempo de vida de una sonda fluorescente sensible al pH. Se han contrastado el modelo teórico de hinchamiento y los estudios precedentes sobre este tipo de hidrogeles con nuestras observaciones, encontrando en este método de caracterización fotofísica una herramienta útil y prometedora, a pesar de que la sonda fluorescente escogida para el estudio tiene un comportamiento fotofísico complejo que no permite una medida unívoca del pH interno. Para conseguir este tipo de medidas, se ha instalado un dispositivo instrumental consistente en un fluorímetro de resolución temporal que realiza la excitación de las sondas fluorescente con dos lámparas LED pulsadas. Junto con este fluorímetro, el método descrito para obtener el pH interno de los hidrogeles integra un protocolo basado en medidas de absorción que completa la caracterización fotofísica de la sonda y da una descripción detallada de sus cambios en el interior del hidrogel. ________________________________________________________________________________________________________
A new method that measures the pH inside swollen poly(N‐vinylimidazole) hydrogels through changes in the fluorescence lifetimes of a pH‐sensitive probe has been established. The theoretical model behind as well as other preceding research work have been put in contrast to our experimental observations, finding in this photophysical method a very useful and promising tool, in spite of the probe chosen for this research work, that exhibits a complex behavior which hinders the univocal measurement of the pH inside the swollen gel. In order to accomplish these measurements a device consisting of a fluorometer for time‐resolved measurements was installed, using two pulsed LED‐lamps in order to enable the excitation of the fluorescent probes. Together with this fluorometer, the above‐described method to measure the pH inside the hydrogels combines a protocol based on absorption measurements that completes the photophysical characterization of the fluorescent probe as well as it provides a detailed descriptions of its changes inside the hydrogel.
A new method that measures the pH inside swollen poly(N‐vinylimidazole) hydrogels through changes in the fluorescence lifetimes of a pH‐sensitive probe has been established. The theoretical model behind as well as other preceding research work have been put in contrast to our experimental observations, finding in this photophysical method a very useful and promising tool, in spite of the probe chosen for this research work, that exhibits a complex behavior which hinders the univocal measurement of the pH inside the swollen gel. In order to accomplish these measurements a device consisting of a fluorometer for time‐resolved measurements was installed, using two pulsed LED‐lamps in order to enable the excitation of the fluorescent probes. Together with this fluorometer, the above‐described method to measure the pH inside the hydrogels combines a protocol based on absorption measurements that completes the photophysical characterization of the fluorescent probe as well as it provides a detailed descriptions of its changes inside the hydrogel.
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Coloides, Electroquímica, Espectroscopía de fluorescencia