title: Magnetic Graphene Nanosheet-Based Microfluidic Device for Homogeneous Real-Time Electronic Monitoring of Pyrophosphatase Activity Using Enzymatic Hydrolysate-Induced Release of Copper Ion.
abstract: A novel flow-through microfluidic device based on a magneto-controlled graphene sensing platform was designed for homogeneous electronic monitoring of pyrophosphatase (PPase) activity; enzymatic hydrolysate-induced release of inorganic copper ion (Cu(2+)) from the Cu(2+)-coordinated pyrophosphate ions (Cu(2+)-PPi) complex was assessed to determine enzyme activity. Magnetic graphene nanosheets (MGNS) functionalized with negatively charged Nafion were synthesized by using the wet-chemistry method. The Cu(2+)-PPi complexes were prepared on the basis of the coordination reaction between copper ion and inorganic pyrophosphate ions. Upon target PPase introduction into the detection system, the analyte initially hydrolyzed pyrophosphate ions into phosphate ions and released the electroactive copper ions from Cu(2+)-PPi complexes. The released copper ions could be readily captured through the negatively charged Nafion on the magnetic graphene nanosheets, which could be quantitatively monitored by using the stripping voltammetry on the flow-through detection cell with an external magnet. Under optimal conditions, the obtained electrochemical signal exhibited a high dependence on PPase activity within a dynamic range from 0.1 to 20 mU mL(-1) and allowed the detection at a concentration as low as 0.05 mU mL(-1). Coefficients of variation for reproducibility of the intra-assay and interassay were below 7.6 and 9.8%, respectively. The inhibition efficiency of sodium fluoride (NaF) also received good results in pyrophosphatase inhibitor screening research. In addition, the methodology afforded good specificity and selectivity, simplification, and low cost without the need of sample separations and multiple washing steps, thus representing a user-friendly protocol for practical utilization in a quantitative PPase activity.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Youxiu
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Zhou
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Jian
authors.initials: J
authors.lastname: Shu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Zhenli
authors.initials: Z
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Yuping
authors.initials: Y
authors.lastname: Lin
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Institute of Nanomedicine and Nanobiosensing, Department of Chemistry, Fuzhou University , Fuzhou 350108, People's Republic of China.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D003300:Copper / Q000737:chemistry / Q000378:metabolism*; D011756:Diphosphates / Q000737:chemistry / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004583:Electrons; D004789:Enzyme Activation / Q000187:drug effects; D006108:Graphite / Q000737:chemistry*; D006868:Hydrolysis; D007477:Ions / Q000737:chemistry / Q000378:metabolism; D060328:Magnetic Phenomena; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation*; D049329:Nanostructures / Q000737:chemistry*; D010316:Particle Size; D011755:Pyrophosphatases / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology; D013329:Structure-Activity Relationship; D013499:Surface Properties; D013997:Time Factors
chemical_list: D011756:Diphosphates; D007477:Ions; C107241:diphosphoric acid; D006108:Graphite; D003300:Copper; D012969:Sodium Fluoride; D011755:Pyrophosphatases