title: Lysozyme-mediated formation of protein-silica nano-composites for biosensing applications.
abstract: We demonstrate a rapid method for enzyme immobilization directly on a waveguide surface by encapsulation in a silica matrix. Organophosphate hydrolase (OPH), an enzyme that catalytically hydrolyzes organophosphates, was used as a model enzyme to demonstrate the utility of lysozyme-mediated silica formation for enzyme stabilization. Silica morphology and the efficiency of OPH encapsulation were directly influenced by the precursor choice used in silica formation. Covalent attachment of the lysozyme template directly to the waveguide surface provided a stable basis for silica formation and significantly increased the surface area for OPH encapsulation. OPH conjugated to a pH-responsive fluorophore was encapsulated in silica and patterned to a waveguide surface to demonstrate the immobilization strategy for the development of an organophosphate array biodetector. Silica-encapsulated OPH retained its catalytic activity for nearly 60 days with a detection limit of paraoxon of approximately 35 microM. The encapsulation technique provides a potentially versatile tool with specific application to biosensor development.
authors.affiliation: Materials Research and Education Center, Samuel Ginn College of Engineering, Auburn University, Auburn, AL 36849, USA.
authors.forename: Madhumati
authors.initials: M
authors.lastname: Ramanathan
authors.forename: Heather R
authors.initials: HR
authors.lastname: Luckarift
authors.forename: Ainur
authors.initials: A
authors.lastname: Sarsenova
authors.forename: James R
authors.initials: JR
authors.lastname: Wild
authors.forename: Erlan K
authors.initials: EK
authors.lastname: Ramanculov
authors.forename: Eric V
authors.initials: EV
authors.lastname: Olsen
authors.forename: Aleksandr L
authors.initials: AL
authors.lastname: Simonian
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002645:Chickens; D004800:Enzymes, Immobilized / Q000378:metabolism; D005139:Eyeglasses; D005260:Female; D006868:Hydrolysis; D008855:Microscopy, Electron, Scanning; D015394:Molecular Structure; D009113:Muramidase / Q000378:metabolism*; D053758:Nanoparticles / Q000737:chemistry / Q000648:ultrastructure; D009596:Nitrophenols / Q000737:chemistry / Q000378:metabolism; D010261:Paraoxon / Q000737:chemistry / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry* / Q000378:metabolism; D012822:Silicon Dioxide / Q000737:chemistry*
chemical_list: D004800:Enzymes, Immobilized; D009596:Nitrophenols; D012822:Silicon Dioxide; C045290:phosphorylphosphatase; D010744:Phosphoric Monoester Hydrolases; D009113:Muramidase; D010261:Paraoxon