ABSTRACT
Tyrosinase-immobilized biosensor was fabricated based on PAAc-g-MWNT and PMAn-g-MWNT, respectively. The poly(acrylic acid)-grafted multi-wall carbon nanotubes, PAAc-g-MWNT, and poly(maleic anhydride)-grafted multi-wall carbon nanotube, PMAn-g-MWNT, were prepared by radiation-induced graft polymerization of acrylic acid (AAc) and maleic anhydride (MAn) on the surface of MWNT. The biosensor was prepared on ITO glass electrode by coating of chitosan solution with tyrosinase-immobilized PAAc-g-MWNT and PMAn-g-MWNT, respectively. The sensing ranges of the tyrosinase-immobilized biosensor based on PAAc-g-MWNT and PMAn were in the range of 0.2-0.9 mM concentration and in the range of 0.1-0.5 mM for phenol in phosphate buffer solution, respectively. Optimal pH and temperature conditions for sensing various phenolic compounds with tyrosinase-immobilized biosensor were determined. Total phenolic content for three commercial red wines on tyrosinase-immobilized biosensor were also determined.
Subject(s)
Biosensing Techniques/instrumentation , Conductometry/instrumentation , Electrodes , Food Analysis/instrumentation , Monophenol Monooxygenase/chemistry , Nanotubes, Carbon/chemistry , Phenols/analysis , Wine/analysis , Crystallization/methods , Enzymes, Immobilized/chemistry , Equipment Design , Equipment Failure Analysis , Materials Testing , Nanotechnology/instrumentation , Nanotubes, Carbon/ultrastructure , Particle SizeABSTRACT
Silica-coated gold nanoparticles produced by gamma-ray irradiation were bombarded with neutrons in a nuclear reactor in order to activate gold nuclides into Au-198 emitting gamma radiation of 0.412-1.088 MeV. The particle size ranges from 20 to 200 nm. The physical integrity of the particles was examined by TEM before and after the neutron irradiation and the silica-gold particles were not affected in terms of structural appearance under gamma radiation environment. The gamma emitting NPs can be utilized as a tracer in petrochemical and refinery industrial processes where the internal temperature is extremely high and the conventional organic radioactive labeled compound would be decomposed.
ABSTRACT
A multi-walled nanotube (MWNT) ionic liquid was prepared by the immobilization of 1-butylimidazole bromide onto an epoxy group on a poly(glycidyl methacrylate)-grafted MWNT, which was synthesized by radiation-induced graft polymerization of glycidyl methacrylate onto MWNT in an aqueous solution. Subsequently, a MWNT ionic liquid electrode was fabricated by hand-casting MWNT ionic liquid, tyrosinase, and chitosan solution as a binder on indium tin oxide (ITO) glass. The sensing ranges of the MWNT ionic liquid electrode with immobilized tyrosinase was in the range of 0.01-0.08 mM in a phosphate buffer solution. The optimal conditions such as pH, temperature, and effects of different phenolic compounds were determined. The total phenolic compounds of three commercial red wines were also determined on the tyrosinase-immobilized biosensor.
