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A bi-enzymatic whole cell conductometric biosensor for heavy metal ions and pesticides detection in water samples
A conductometric biosensor using immobilised Chlorella vulgaris microalgae as bioreceptors was used as a bi-enzymatic biosensor. Algae were immobilised inside bovine serum albumin membranes reticulated with glutaraldehyde vapours deposited on interdigitated conductometric electrodes. Local conductiv...
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Published in: | Biosensors & bioelectronics 2005-08, Vol.21 (2), p.273-281 |
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Main Authors: | , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that cite this one |
Online Access: | Get full text |
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Summary: | A conductometric biosensor using immobilised
Chlorella vulgaris microalgae as bioreceptors was used as a bi-enzymatic biosensor. Algae were immobilised inside bovine serum albumin membranes reticulated with glutaraldehyde vapours deposited on interdigitated conductometric electrodes. Local conductivity variations caused by algae alkaline phosphatase and acetylcholinesterase activities could be detected. These two enzymes are known to be inhibited by distinct families of toxic compounds: heavy metals for alkaline phosphatase, carbamates and organophosphorous (OP) pesticides for acetylcholinesterase. The bi-enzymatic biosensors were tested to study the influence of heavy metal ions and pesticides on the corresponding enzyme. It has finally appeared that these biosensors are quite sensitive to Cd
2+ and Zn
2+ (limits of detection (LOD)
=
10
ppb for a 30
min long exposure) while Pb
2+ gives no significant inhibition as this ion seems to adsorb on albumin preferably. For pesticides, first experiments showed that paraoxon-methyl inhibits
C. vulgaris AChE contrary to parathion-methyl and carbofuran. Biosensors were then exposed to different mixtures (Cd
2+/Zn
2+, Cd
2+/paraoxon-methyl) but no synergetic or antagonist effect could be observed. A good repeatability could be achieve with biosensors since the relative standard deviation did not exceed 8% while response time was 5–7
min.
A comparison between inhibition levels obtained with biosensors (after a 30
min long exposure) and bioassays (after a 240
min long exposure) has finally shown a similar LOD for both Cd and Zn (LOD
=
10
ppb). |
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ISSN: | 0956-5663 1873-4235 |
DOI: | 10.1016/j.bios.2004.09.032 |