ChemComm
Communication
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from the appearance of Hg , it can be attributed to the crucial to the improvement of the sensing performance of the
complex formation between the ions and the PG molecules ERGO based electronic sensor device.
adsorbed on the ERGO surface, which may inhibit the electron
In conclusion, the PG modified ERGO-based electronic sensor
transmission on the modified ERGO surface, implying decreased device can be used as a highly sensitive and selective sensor for
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conductivity.
detecting Hg in aqueous phase. The DL of the sensor to the
Fig. 3b shows the plot of the conductivity changes (DG/G) analyte is 0.1 nM, which is about 10 times as low as that reported
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against the concentrations of Hg ions. It is observed in this previously. The superior sensor performance is based on the
figure that there are two regions in the plot: the linear region introduction of the PG compound as the modifier. The simple
and the saturation region. In the linear region, the conductivity fabrication method and excellent sensor performance suggest
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changes linearly increase with increasing Hg concentrations that the modified ERGO sensor device has the potential to be
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from 0.1 nM to 4 nM. As shown in the inset of the figure, developed into an integratable Hg practical detector.
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the correlation coefficient, R , of the measurements is 0.972.
This work was supported by the NSF of China (60911130231,
Compared with the linear region, the conductivity changes in 51233006, 91027017 61171054, 61101051 and 21273141), the Major
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the saturation region in which the Hg concentration is greater State Basic Research Development Program (2013CB 733700,
than 4 nM are nearly constant. These two regions may be 2011CB932303, 2011CB932700, 2011CB808403) and Chinese
ascribed to an adsorption accumulation process. In the linear Academy of Sciences.
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region, the amount of Hg adsorbed on the ERGO surface
increases with the increasing analyte concentrations. In the Notes and references
saturation region, increasing the analyte concentrations has
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little effect on the amount of Hg adsorbed on the ERGO sheet
due to its exhausted binding sites.
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The selectivity of the ERGO modified Hg sensor was also
evaluated through examining its responses to common inter-
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+
2+
2+
3+
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fering ions, such as K , Na , Cu , Zn , Fe and Cd . Com-
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pared with its response to 10 nM of Hg , very weak
conductivity change was observed for the modified sensor upon
addition of any of the interfering metal ions at a concentration
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of 100 nM, except for Cd . The results are collectively pre-
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7
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in less than 1/8th response to Hg . As for Cd , its interference
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see Fig. S4, ESI†). The selectivity of our Hg sensor device could
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(
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be attributed to the high binding affinity of PG to Hg .
Responses of the sensor developed to the interfering ions
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with the exception of Cd at even higher concentrations were
also studied. The results are shown in Fig. S5–S9 (ESI†) displayed
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presence of Hg , but also highly selective to it. Furthermore,
a control experiment was also performed to demonstrate the key
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role of PG. In the control, no PG was used, and the results 18 Y. Zhou, C. Y. Zhu, X. S. Gao, X. Y. You and C. Yao, Org. Lett., 2010,
1
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obtained for this control are shown in Fig. S10 (ESI†). The figure
reveals that 4 nM of Hg only results in a change of ꢀ10.2% in
1
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a change more than 60%, observed using the PG modified device
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to conduct the same measurement. Additionally, the detection
performances of the unmodified ERGO sensor for other ions
were also explored. The results are depicted in Fig. 3c (red).
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3 I. B. Kim, B. Erdogan, J. N. Wilson and U. H. F. Bunz, Chem.–Eur. J.,
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Clearly, this sensor is not only insensitive to the presence of Hg
4 Y. Huang, X. Dong, Y. Shi, C. M. Li, L. J. Li and P. Chen, Nanoscale,
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but also less selective to it, indicating that introduction of PG is
This journal is c The Royal Society of Chemistry 2013
Chem. Commun.