title: Enzyme-encapsulated silica monolayers for rapid functionalization of a gold surface.
abstract: We report a simple and rapid method for the deposition of amorphous silica onto a gold surface. The method is based on the ability of lysozyme to mediate the formation of silica nanoparticles. A monolayer of lysozyme is deposited via non-specific binding to gold. The lysozyme then mediates the self-assembled formation of a silica monolayer. The silica formation described herein occurs on a surface plasmon resonance (SPR) gold surface and is characterized by SPR spectroscopy. The silica layer significantly increases the surface area compared to the gold substrate and is directly compatible with a detection system. The maximum surface concentration of lysozyme was found to be a monolayer of 2.6 ng/mm(2) which allowed the deposition of a silica layer of a further 2 ng/mm(2). For additional surface functionalization, the silica was also demonstrated to be a suitable matrix for immobilization of biomolecules. The encapsulation of organophosphate hydrolase (OPH) was demonstrated as a model system. The silica forms at ambient conditions in a reaction that allows the encapsulation of enzymes directly during silica formation. OPH was successfully encapsulated within the silica particles and a detection limit for the substrate, paraoxon, using the surface-encapsulated enzyme was found to be 20 microM.
authors.affiliation: Air Force Research Laboratory, 139 Barnes Drive, Suite # 2, Tyndall AFB, FL 32403, USA.
authors.forename: Heather R
authors.initials: HR
authors.lastname: Luckarift
authors.forename: Shankar
authors.initials: S
authors.lastname: Balasubramanian
authors.forename: Sheetal
authors.initials: S
authors.lastname: Paliwal
authors.forename: Glenn R
authors.initials: GR
authors.lastname: Johnson
authors.forename: Aleksandr L
authors.initials: AL
authors.lastname: Simonian
mesh_terms: D043303:Aryldialkylphosphatase / Q000378:metabolism; D002214:Capsules / Q000138:chemical synthesis; D004800:Enzymes, Immobilized / Q000378:metabolism; D006046:Gold / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D009113:Muramidase / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D020349:Surface Plasmon Resonance / Q000295:instrumentation / Q000379:methods*
chemical_list: D002214:Capsules; D004800:Enzymes, Immobilized; D006046:Gold; D012822:Silicon Dioxide; D043303:Aryldialkylphosphatase; D009113:Muramidase