title: Enzyme-modified nanoparticles using biomimetically synthesized silica.
abstract: The entrapment of enzymes within biomimetic silica nanoparticles offers unique and simple immobilization protocols that merge the stability of proteins confined in solid phases with the high loading and reduced diffusion limitations inherent to nano-sized structures. Herein, we report on the biomimetic silica entrapment of chemically derivatized horseradish peroxidase for amperometric sensing applications. Scanning electron microscopy shows evidence of the formation of enzyme-modified nanospheres using poly(ethylenimine) as a template for silicic acid condensation. When these nanospheres are directly deposited on graphite electrodes, chemically modified anionic peroxidase shows direct electron transfer at 0 mV vs Ag|AgCl. Microgravimetric measurements as well as SEM images demonstrate that negatively charged peroxidase is also entrapped when silica precipitates at gold electrodes are modified with a self-assembled monolayer of poly(ethylenimine). Electrostatic interactions may play a crucial role for efficient enzyme entrapment and silica condensation at the PEI template monolayer. The in-situ biomimetically synthesized peroxidase nanospheres are catalytically active, enabling direct bioelectrocatalysis at 0 mV vs Ag|AgCl with long-term stability.
authors.affiliation: Department of Analytical Chemistry and Chemical Engineering, Faculty of Pharmacy, University of Alcalá, 28871 Alcalá de Henares, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Zamora
authors.forename: Arántzazu
authors.initials: A
authors.lastname: Narváez
authors.forename: Elena
authors.initials: E
authors.lastname: Domínguez
mesh_terms: D055162:Biocatalysis; D032701:Biomimetics; D004563:Electrochemistry; D004566:Electrodes; D004579:Electron Transport; D004798:Enzymes / Q000737:chemistry* / Q000378:metabolism*; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism; D005949:Glucose Oxidase / Q000737:chemistry / Q000378:metabolism; D006046:Gold / Q000737:chemistry; D006108:Graphite / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry / Q000378:metabolism; D053761:Nanocomposites / Q000737:chemistry; D053758:Nanoparticles / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry; D010544:Peroxidases / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D012822:Silicon Dioxide / Q000737:chemistry* / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D004798:Enzymes; D004800:Enzymes, Immobilized; D037742:Nanotubes, Carbon; D006046:Gold; D012822:Silicon Dioxide; D006108:Graphite; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase; D006735:Horseradish Peroxidase; D010544:Peroxidases; C120494:anionic peroxidase; D009113:Muramidase