Electrochemically assisted fabrication of size-exclusion films of organically modified silica and application to the voltammetry of phospholipids.
Modification of electrodes with nm-scale organically modified silica films with pores diameters controlled at 10- and 50-nm is described. An oxidation catalyst, mixed-valence ruthenium oxide with cyano crosslinks or gold nanoparticles protected by dirhodium-substituted phosophomolybdate (AuNP-Rh2PMo11), was immobilized in the pores. These systems comprise size-exclusion films at which the biological compounds, phosphatidylcholine and cardiolipin, were electrocatalytically oxidized without interference from surface-active concomitants such as bovine serum albumin. 10-nm pores were obtained by adding generation-4 poly(amidoamine) dendrimer, G4-PAMAM, to a (CH3)3SiOCH3sol. 50-nm pores were obtained by modifying a glassy carbon electrode (GC) with a sub-monolayer film of aminopropyltriethoxylsilane, attaching 50-nm diameter poly(styrene sulfonate), PSS, spheres to the protonated amine, transferring this electrode to a (CH3)3SiOCH3sol, and electrochemically generating hydronium at uncoated GC sites, which catalyzed ormosil growth around the PSS. Voltammetry of Fe(CN)63-and Ru(NH3)63+demonstrated the absence of residual charge after removal of the templating agents. With the 50-nm system, the pore structure was sufficiently defined to use layer-by-layer electrostatic assembly of AuNP-Rh2PMo11therein. Flow injection amperometry of phosphatidylcholine and cardiolipin demonstrated analytical utility of these electrodes.
Department of Chemistry and Biochemistry, Miami University, Oxford, OH USA 45056.
B Layla
BL
Mehdi
Iwona A
IA
Rutkowska
Pawel J
PJ
Kulesza
James A
JA
Cox
Cardiolipin; Dirhodium polyoxometalate; Electrocatalysis; Layer-by-layer assembly; Macroporous ormosils; Mesoporous ormosils; Phospholipids; Ruthenium oxide