2016 Fiscal Year Annual Research Report
藻類毒素発生の早期警報スクリーニング用のグラフェン電気化学的センサの開発
| Project/Area Number |
15F15712
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| Research Institution | The University of Tokyo |
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Principal Investigator |
古米 弘明 東京大学, 大学院工学系研究科(工学部), 教授 (40173546)
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| Co-Investigator(Kenkyū-buntansha) |
ZHANG WEI 東京大学, 大学院工学系研究科(工学部), 外国人特別研究員
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| Project Period (FY) |
2015-10-09 – 2018-03-31
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| Keywords | Microcystin-LR / Electrochemical sensor / Environmental water / Detection |
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| Outline of Annual Research Achievements |
Cyanobacterial toxin production is concerned, when water intake is conducted for drinking water supply from eutrophic lakes such as Lake Kasumigaura. Microcystin (MC) is one of frequently detected toxins and the provisional standard value (1 μg / L) of MC-LR is recommended for drinking water by the World Health Organization in 1998. Therefore, it is meaningful to rapidly detect cyanobacterial toxin in lake waters and to grasp the behavior during the purification treatment process.
A fit-for-purpose graphene biosensors grown by a modified chemical vapour deposition (CVD) method for Microcystin-LR (MC-LR) detection as alternatives to the time-consuming, expensive, non-portable and often skills-demanding conventional methods of analysis involved in water quality assessment has been proposed. A two-step linking procedure that enabled the immobilization of MC-LR onto the graphene electrodes and conjugation of monoclonal antibodies specific to MC-LR in the incubation solutions has been employed to provide the required specificity for detecting MC-LR toxin. Cyclic voltammetry (CV) can reveal well-defined redox peaks in the presence of redox species, which can indicate efficient interface charge-transfer. After conjugation of MC-LR and antibodies to graphene, the increase of electrochemical impedance spectroscopy (EIS) was used to detect the change of MC-LR concentration. Good linear sensing response (R^2=0.99) was established over a wide MC-LR concentration range (i.e. 0.05 to 100 μg/L), which can detect MC-LR at much lower detection limits than WHO guideline value 1 μg/L.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Electrochemical biosensors fabricated by CVD grown graphene film composite has been accomplished. A biomolecular linking method via 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and N-hydroxysuccinimide (EDC-NHS) coupling mechanism that enabled the immobilization of MC-LR onto the graphene electrodes and conjugation of monoclonal antibodies specific to MC-LR in the incubation solutions has been developed. Variation of graphene biosensor EIS was found to correlate with the change of MC-LR concentration. A good linear sensing correlation (R^2=0.99) between MC-LR concentration (i.e. 0.05 to 100 μg/L) and EIS signals was established. Repeatability and reproducibility of developed method and materials has been tested. To date, planned research has been progressing step-by-step smoothly according to what is described in the project proposal.
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| Strategy for Future Research Activity |
1) Characterization of graphene electrode and developed sensor will be carried out using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Scanning Electron Microscope (SEM), Atomic Force Microscope (AFM), and Transmission Electron Microscope (TEM).
2) Developed graphene biosensor will be applied to different environmental water samples such as tap water, local lake or river water. This is to investigate the potential interference factors during the graphene biosensor detection of MC-LR in the water.
3) Graphene MC-LR biosensing results will be further validated against other established analytical technique in literature, considering potential interfering organic matters some of which can be identified by Orbitrap-Mass Spectrometry (MS).
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