INVESTIGADORES
HAMER Mariana
congresos y reuniones científicas
Título:
Optical sensing of hydrogen peroxide reduction with nanoparticles modified with metalloporphyrins
Autor/es:
MARIANA HAMER; ROMINA CARBALLO; IRENE REZZANO
Lugar:
Strasbourgo
Reunión:
Congreso; Second International Conference on Multifunctional, Hybrid and Nanomaterials; 2011
Resumen:
Herein, we report an optical device that allowed us to evaluate the spectral changes produced during catalytic process involving metalloporphyrins. The surface modification of metal nanoparticles has been employed to design optical sensors, due to the enhanced local fields close to the particle surfaces that alter the absorption band of the chromophore attached1. We prepared immobilized gold nanoparticles on a transparent substrate by attachment to APTES (aminopropyl)-triethoxysilane)-coated indium tin oxide (ITO) surface: AuNPs-APTES/ITO. This array was modified with metalloporphyrins [Cu(II) and Fe(II) tetrapyridylporphina] by two different ways: a- Through layer-by-layer (LbL) films with a poly(vinyl sulfonate) (PVS), poly(allylamine) hydrochloride (PAH) and metalloporphrins b- The direct binding of the porphyrin ring to the nanoparticles via covalent bond of electrons of the nitrogen atom of the pyridyl group. In the last case, a significant higher absorption band than LBL approach was observed and attributed to the perpendicular orientation to the metal surface adopted by the pyridyl group which makes that the porphyrin plane parallel to the gold surface. We explored the catalytic effect observed in hetero-bimetallic porphyrins systems3 by UV-vis spectroscopy. The difference spectra had to be used since a spectrum of Fe(II)porphyrin/AuNPs-APTES/ITO is dominated by the low-spin heme center. The difference spectra of the bimetallic structures showed a very sensitive response to H2O2 concentration (figure). In this work, we also evaluate the effect of strong ligands in the catalytic process.