Electrochemical immunosensor for ultrasensitive detection of microcystin-LR based on graphene-gold nanocomposite/functional conducting polymer/gold nanoparticle/ionic liquid composite film with electrodeposition

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• 作者：Li Ruiyi^d ; Xia Qianfang^a ; Li Zaijun^a ; ^b ; ^{1489539656@qq.com} ; ^{zaijunli@263.net} ; Sun Xiulan^c ; Liu Junkang^a ; ^b
• 关键词：Microcystin-LR ; Sensor ; Graphene&ndash ; gold nanocomposite ; Functional conducting polymer ; Ionic liquid ; Electrodeposition
• 刊名：Biosensors and Bioelectronics
• 出版年：2013
• 出版时间：15 June, 2013
• 年：2013
• 卷：44
• 期：Complete
• 页码：235-240
• 全文大小：698 K

文摘

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¡À0.16 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¡Á10^-16-8.0¡Á10^?15 M and detection limit of 3.7¡Á10^?17 M (S/N=3). The peak current change of the sensor after and before incubation with 2.0¡Á10^?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 % .