title: Optical Detection of Enzymatic Activity and Inhibitors on Non-Covalently Functionalized Fluorescent Graphene Oxide.
abstract: It has been of great interest to measure the activity of acetylcholinesterase (AChE) and its inhibitor, as AChE is known to accelerate the aggregation of the amyloid beta peptides that underlie Alzheimer's disease. Herein, we report the development of graphene oxide (GO) fluorescence-based biosensors for the detection of AChE activity and AChE inhibitors. To this end, GO was non-covalently functionalized with phenoxy-modified dextran (PhO-dex-GO) through hydrophobic interaction; the resulting GO showed excellent colloidal stability and intense fluorescence in various aqueous solutions as compared to pristine GO and the GO covalently functionalized with dextran. The fluorescence of PhO-dex-GO remarkably increased as AChE catalyzed the hydrolysis of acetylthiocholine (ATCh) to give thiocholine and acetic acid. It was found that the turn-on fluorescence response of PhO-dex-GO to AChE activity was induced by protonation of carboxyl groups on it from the product of the enzymatic hydrolysis reaction, acetic acid. On the basis of its turn-on fluorescence response, PhO-dex-GO was able to report kinetic and thermodynamic parameters involving a maximum velocity, a Michaelis constant, and an inhibition dissociation constant for AChE activity and inhibition. These parameters enable us to determine the activity of AChE and the efficiency of the inhibitor.
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Tae Woog
authors.initials: TW
authors.lastname: Kang
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Su-Ji
authors.initials: SJ
authors.lastname: Jeon
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Hye-In
authors.initials: HI
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Jung Hyun
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: DaBin
authors.initials: D
authors.lastname: Yim
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Hye-Rim
authors.initials: HR
authors.lastname: Lee
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Jong-Min
authors.initials: JM
authors.lastname: Ju
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Man-Jin
authors.initials: MJ
authors.lastname: Kim
authors.affiliation: Department of Chemical Engineering, Hanyang University , Ansan 426-791, Republic of Korea.
authors.forename: Jong-Ho
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000110:Acetylcholinesterase / Q000737:chemistry*; D000122:Acetylthiocholine; D016229:Amyloid beta-Peptides; D015374:Biosensing Techniques; D002800:Cholinesterase Inhibitors; D006108:Graphite; D010087:Oxides
chemical_list: D016229:Amyloid beta-Peptides; D002800:Cholinesterase Inhibitors; D010087:Oxides; D000122:Acetylthiocholine; D006108:Graphite; D000110:Acetylcholinesterase
keywords: GO fluorescence; acetylcholinesterase; graphene oxide; inhibitor detection; optical biosensor