Modulation of the silica sol-gel composition for the promotion of direct electron transfer to encapsulated cytochrome

The direct electron transfer between indium-tin oxide electrodes (ITO) and cytochrome c encapsulated in different sol-gel silica networks was studied. Cyt c@silica modified electrodes were synthesized by a two-step encapsulation method mixing a phosphate buffer solution with dissolved cytochrome c and a silica sol prepared by the alcohol-free sol-gel route. These modified electrodes were characterized by cyclic voltammetry, UV-vis spectroscopy, and in situ UV-vis spectroelectrochemistry. The electrochemical response of encapsulated protein is influenced by the terminal groups of the silica pores. Cyt c does not present electrochemical response in conventional silica (hydroxyl terminated) or phenyl terminated silica. Direct electron transfer to encapsulated cytochrome c and ITO electrodes only takes place when the protein is encapsulated in methyl modified silica networks.We gratefully acknowledge Jesus Yanez and Prof. Jose Miguel Martin-Martinez from the Laboratory of Adhesion and Adhesives (University of Alicante) for their assistance in the measurements of contact angle. We also acknowledge the Financial support from the Spanish Ministerio de Economia y Competitividad and FEDER y Ciencia (MAT2010-15273), Generalitat Valenciana (PROMETEO2013/038), and the Fundacion Ramon Areces (CIVP16A1821). Alonso Gamero-Quijano is grateful to Generalitat Valenciana (Santiago Grisolia Program) for the funding of his research fellowship.Gamero-Quijano, A.; Huerta, F.; Morallón, E.; Montilla, F. (2014). Modulation of the silica sol-gel composition for the promotion of direct electron transfer to encapsulated cytochrome. Langmuir. 30(34):10531-10538. https://doi.org/10.1021/la5023517S1053110538303

Synthesis and bio-adsorptive properties of large-pore periodic mesoporous organosilica rods

Highly ordered large-pore periodic mesoporous organosilica (PMO) with a rodlike morphology was successfully synthesized at low acid concentrations and in the presence of inorganic salt using triblock copolymer P123 as a template. The inorganic salt can not only promote the formation of highly ordered mesoporous structure but also control the morphology of PMO materials. The adsorption of bovine heart cytochrome c (cyt c) on PMO was studied at different ionic strengths and pHs by comparing with the adsorption on pure silica materials with similar morphology and pore structure. The results show that the adsorbed amount reaches the maximum around the isoelectric point of cyt c and the PMO materials do not have higher adsorbed capacity than SBA-15 silica. The specific adsorption amounts of cyt c on PMO or pure silica decrease as ionic strengths increase at all pH conditions. Our results directly support the conclusion that the electrostatic interaction between cyt c and PMO/pure silica surface is more dominant than hydrophobic forces in the bioadsorption of cyt c