title: Mediator-free phenol sensor based on titania sol-gel encapsulation matrix for immobilization of tyrosinase by a vapor deposition method.
abstract: A novel amperometric phenol sensor was constructed by immobilizing tyrosinase in a titania sol-gel matrix. The tyrosinase entrapped sol-gel film was obtained with a vapor deposition method, which simplified the traditional sol-gel process and avoided the shrinkage and cracking of conventional sol-gel-derived glasses. This matrix provided a microenvironment for retaining the native structure and activity of the entrapped enzyme and a very low mass transport barrier to the enzyme substrates. Phenol could be oxidized by dissolving oxygen in presence of immobilized tyrosinase to form a detectable product, which was determined at -150 mV without any mediator. The phenol sensor exhibited a fast response (less than 5 s) and sensitivity as high as 103 microA/mM, which resulted from the porous structure and high enzyme loading of the sol-gel matrix. The linear range for phenol determination was from 1.2x10(-7) to 2.6x10(-4) M with a detection limit of 1.0x10(-7) M. The apparent Michaelis-Menten constant of the encapsulated tyrosinase was calculated to be (0.29+/-0.02) mM. The stability of the biosensor was also evaluated.
authors: Department of Chemistry, Institute of Analytical Science, State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China.
authors: Jiuhong
authors: J
authors: Yu
authors: Songqin
authors: S
authors: Liu
authors: Huangxian
authors: H
authors: Ju
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D020099:Coated Materials, Biocompatible / Q000138:chemical synthesis* / Q000737:chemistry; D004563:Electrochemistry / Q000295:instrumentation* / Q000379:methods; D004784:Environmental Monitoring / Q000295:instrumentation / Q000379:methods; D004800:Enzymes, Immobilized / Q000737:chemistry; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000737:chemistry; D014442:Monophenol Monooxygenase / Q000737:chemistry*; D044367:Phase Transition; D019800:Phenol / Q000032:analysis* / Q000737:chemistry; D011522:Protons; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013696:Temperature; D014025:Titanium / Q000737:chemistry*
chemical_list: D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D005740:Gases; D011522:Protons; C009495:titanium dioxide; D019800:Phenol; D014025:Titanium; D014442:Monophenol Monooxygenase