title: Oxidase-functionalized Fe(3)O(4) nanoparticles for fluorescence sensing of specific substrate.
abstract: This study reports the development of a reusable, single-step system for the detection of specific substrates using oxidase-functionalized Fe(3)O(4) nanoparticles (NPs) as a bienzyme system and using amplex ultrared (AU) as a fluorogenic substrate. In the presence of H(2)O(2), the reaction pH between Fe(3)O(4) NPs and AU was similar to the reaction of oxidase and the substrate. The catalytic activity of Fe(3)O(4) NPs with AU was nearly unchanged following modification with poly(diallyldimethylammonium chloride) (PDDA). Based on these features, we prepared a composite of PDDA-modified Fe(3)O(4) NPs and oxidase for the quantification of specific substrates through the H(2)O(2)-mediated oxidation of AU. By monitoring fluorescence intensity at 587 nm of oxidized AU, the minimum detectable concentrations of glucose, galactose, and choline were found to be 3, 2, and 20 μM using glucose oxidase-Fe(3)O(4), galactose oxidase-Fe(3)O(4), and choline oxidase-Fe(3)O(4) composites, respectively. The identification of glucose in blood was selected as the model to validate the applicability of this proposed method.
authors.affiliation: Department of Chemistry, National Sun Yat-sen University, Taiwan.
authors.forename: Cheng-Hao
authors.initials: CH
authors.lastname: Liu
authors.forename: Wei-Lung
authors.initials: WL
authors.lastname: Tseng
mesh_terms: D000328:Adult; D000429:Alcohol Oxidoreductases / Q000737:chemistry; D000498:Allyl Compounds / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods*; D001786:Blood Glucose / Q000032:analysis*; D002794:Choline / Q000032:analysis; D005453:Fluorescence; D005692:Galactose Oxidase / Q000737:chemistry; D005947:Glucose / Q000032:analysis; D005949:Glucose Oxidase / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles; D009994:Osmolar Concentration; D010078:Oxazines / Q000737:chemistry; D010088:Oxidoreductases / Q000737:chemistry*; D010316:Particle Size; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D000498:Allyl Compounds; D001786:Blood Glucose; D010078:Oxazines; D000644:Quaternary Ammonium Compounds; C470430:Amplex Red; C508190:diallyldimethylammonium chloride; D006861:Hydrogen Peroxide; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases; C019888:choline oxidase; D005949:Glucose Oxidase; D005692:Galactose Oxidase; D005947:Glucose; D002794:Choline