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Sensors 2011, 11(11), 10063-10073; doi:10.3390/s111110063
Article

Solid Phase Biosensors for Arsenic or Cadmium Composed of A trans Factor and cis Element Complex

1
,
2
,
1,2
 and
1,2,*
1 United Graduate School of Agricultural Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwaicho, Fuchu 183-8509, Japan 2 Faculty of Agriculture, Utsunomiya University, 350 Minemachi, Utsunomiya 321-8505, Japan
* Author to whom correspondence should be addressed.
Received: 16 September 2011 / Revised: 18 October 2011 / Accepted: 24 October 2011 / Published: 25 October 2011
(This article belongs to the Section Biosensors)
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Abstract

The presence of toxic metals in drinking water has hazardous effects on human health. This study was conducted to develop GFP-based-metal-binding biosensors for on-site assay of toxic metal ions. GFP-tagged ArsR and CadC proteins bound to a cis element, and lost the capability of binding to it in their As- and Cd-binding conformational states, respectively. Water samples containing toxic metals were incubated on a complex of GFP-tagged ArsR or CadC and cis element which was immobilized on a solid surface. Metal concentrations were quantified with fluorescence intensity of the metal-binding states released from the cis element. Fluorescence intensity obtained with the assay significantly increased with increasing concentrations of toxic metals. Detection limits of 1 μg/L for Cd(II) and 5 μg/L for As(III) in purified water and 10 µg/L for Cd(II) and As(III) in tap water and bottled mineral water were achieved by measurement with a battery-powered portable fluorometer after 15-min and 30-min incubation, respectively. A complex of freeze dried GFP-tagged ArsR or CadC binding to cis element was stable at 4 °C and responded to 5 μg/L As(III) or Cd(II). The solid phase biosensors are sensitive, less time-consuming, portable, and could offer a protocol for on-site evaluation of the toxic metals in drinking water.
Keywords: biosensor; ArsR; CadC; GFP; metals; cis element; trans factor; lyophilization biosensor; ArsR; CadC; GFP; metals; cis element; trans factor; lyophilization
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).
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Siddiki, M.S.R.; Kawakami, Y.; Ueda, S.; Maeda, I. Solid Phase Biosensors for Arsenic or Cadmium Composed of A trans Factor and cis Element Complex. Sensors 2011, 11, 10063-10073.

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