title: Electrochemical immunosensor for ultrasensitive detection of microcystin-LR based on graphene-gold nanocomposite/functional conducting polymer/gold nanoparticle/ionic liquid composite film with electrodeposition.
abstract: The study developed an electrochemical immunosensor for ultrasensitive detection of microcystin-LR in water. Graphene oxide and chloroauric acid were alternately electrodeposited on the surface of glassy carbon electrode for 20 cycles to fabricate graphene-gold nanocomposite. The composite was characterized and its apparent heterogeneous electron transfer rate constant (37.28±0.16 cm s (-1)) was estimated by Laviron's model. To immobilize microcystin-LR antibody and improve the electrical conductivity, 2,5-di-(2-thienyl)-1-pyrrole-1-(p-benzoic acid) and chloroauric acid were electrodeposited on the modified electrode in sequence. The ionic liquid was then dropped on the electrode surface and finally microcystin-LR antibody was covalently connected to the conducting polymer film. Experiment showed the electrochemical technique offers control over reaction parameters and excellent repeatability. The graphene-gold nanocomposite and gold nanoparticles enhance electron transfer of Fe(CN)6(3-/4-) to the electrode. The ionic liquid, 1-isobutyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide, improves stability of the antibody. The sensor displays good repeatability (RSD=1.2%), sensitive electrochemical response to microcystin-LR in the range of 1.0×10(-16)-8.0×10(-15)M and detection limit of 3.7×10(-17)M (S/N=3). The peak current change of the sensor after and before incubation with 2.0×10(-15)M of microcystin-LR can retain 95% over a 20-weeks storage period. Proposed method presents remarkable improvement of sensitivity, repeatability and stability when compared to present microcystin-LR sensors. It has been successfully applied to the microcystin-LR determination in water samples with a spiked recovery in the range of 96.3-105.8%.
authors: National University of Ireland, Maynooth, Co. Kildare, Ireland.
authors: Li
authors: L
authors: Ruiyi
authors: Xia
authors: X
authors: Qianfang
authors: Li
authors: L
authors: Zaijun
authors: Sun
authors: S
authors: Xiulan
authors: Liu
authors: L
authors: Junkang
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation; D000458:Cyanobacteria / Q000737:chemistry; D004553:Electric Conductivity; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004595:Electroplating; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D007118:Immunoassay / Q000295:instrumentation*; D052578:Ionic Liquids / Q000737:chemistry; D057230:Limit of Detection; D008387:Marine Toxins; D052998:Microcystins / Q000032:analysis*; D053761:Nanocomposites / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D015203:Reproducibility of Results; D014867:Water / Q000032:analysis*; D014871:Water Microbiology
chemical_list: D055910:Antibodies, Immobilized; D052578:Ionic Liquids; D008387:Marine Toxins; D052998:Microcystins; D011108:Polymers; D014867:Water; D006046:Gold; D006108:Graphite; C057862:cyanoginosin LR