INQUIMAE   12526
INSTITUTO DE QUIMICA, FISICA DE LOS MATERIALES, MEDIOAMBIENTE Y ENERGIA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
ADSORPTION AND LONG-RANGE ELECTRON TRANSFER IN HEME-PROTEIN GOLD NANOPARTICLE HYBRID SYSTEMS
Autor/es:
DAIANA CAPDEVILA; WALDEMAR MARMISOLLÉ; DANIEL MURGIDA
Lugar:
San Pedro
Reunión:
Congreso; VII Meeting of the Society for Free Radical Biology and Medicine South American Group; 2011
Institución organizadora:
Society for Free Radical Biology and Medicine South American Group
Resumen:
A key challenge in the development of electronic biodevices is to improve the efficiency of long−range charge transfer. Recent results hint at the possibility of achieving this goal by manufacturing novel materials which combine nanoparticles with biological samples showing notable Gold nanoparticles−induced enhancement of the electron transfer rates. This interesting result added new facets in nanobioeletronics, although the enhancement mechanism is not yet completely understood. Our goal is to contribute to the eluctidation of such mechanism and to optimize these devices in terms of Raman and electron transfer enhancement for biophysical applications as well as for the rational design of nanobiodevices. Gold nanoparticles (AuNP) stabilized by acid water soluble thiols ligands were synthesized according to the Brust-Schiffrin method by two-step procedure. A two- dimensional array of AuNPs was prepared by a crosslinking reaction with a functionalized nanostructured Ag electrode surface. In order to characterize the water soluble AuNPs and nanoelectrodes arrays SEM microscopy measurements were perform showing a 25% coverage of the Ag surface with gold nanoparticles with a 4nm diameter. Cytochrome c (Cyt) was electrostatically immobilized on the 2-D array. The adsorbed protein retains the native structure as judged from the comparison between the Surface Enhance Resonance Raman Spectra (SERRS) of the system and the Resonance Raman Spectra of the Cyt in solution. SERRS Spectroelectrochemistry of the immobilized Cyt indicates that is redox active and presents the same E 0 value (8 mV vs. Ag/AgCl) as in solution. In order to fully describe Cyt immobilization on the 2-D array, we also studied the adsorption on the functionalized nanostructured Ag electrode surface. Because of the positive charge of both, Cyt and the electrode surface, no adsorption was expected. However, our results have shown that Cyt can be efficiently immobilized (Kads=8+3 M -1) on an amine terminated monolayer (positively charged SAM). The electron transfer rate was determined under these conditions and is only four times lower than the one obtained on negatively charged SAM (k neg=200seg-1vs. kpos=40+10seg-1). This results suggest Cyt is adsorbed with the heme group facing the SAM, just as on negatively charged SAM.