An amperometric algal biosensor for herbicide detection employing a carbon cathode oxygen electrode

Abstract

A method is described for continuous monitoring of the photosynthetic oxygen evolution of the microalga Chlorella uulgaris, which was immobilized between alumina filters on the surface of a teflon-covered carbon electrode. Sensitivity of the algal biosensor to herbicides was tested using an electrochemical flow cell with illumination provided by light-emitting diodes. This configuration also allows the biosensor to be used in real-time environmental monitoring. The herbicides atrazine, isoproturon, and propanil were detected within 30 min at concentrations below 100 Fg dm-3, while the herbicide bromoxynil was only detected after several hours at mg dm-3 concentrations. Good sensor stability was obtained in the absence of pollutants, with more than 24 h of continuous monitoring being achieved.

Integrated electrochemical biosensor based on algal metabolism for water toxicity analysis

“…Monitoring of species such as oxygen, hydrogen peroxide and pH related ions that participate in algae's metabolism and photosynthesis can indicate the presence of herbicides. For instance, amperometric microalgae sensors are designed to monitor photosynthetic oxygen production and can therefore indicate pollutant related photosynthetic activity inhibition (Pandard and Rawson, 1993).…”

Biosensors for the detection of pesticides

“…Herbicides such as atrazine (s-triazine), isoproturon (phenylurea) block electron flow in PSII, others like propanil (acylanilide) or bromoxynil (halogenated benzonitrile) also act on phosphorylation. The detection of these herbicides by sensors has been described using va rious biological re c ep t o rs such as cya n o b a c t e ri a [73], the microalga Chlorella vulgaris [74], chloroplast [75] or thylakoid membranes [76], Synechoccus sp. prokaryotic cells [73], i s o l ated reaction center from the bacteri u m Rhodobacter sphaeroides [77].…”

“…prokaryotic cells [73], i s o l ated reaction center from the bacteri u m Rhodobacter sphaeroides [77]. The inhibitory effect of herbicides can be assessed by using a modified grating coupler [77], an oxygen electrode [74], an amperometric detection of an electron mediator such as fe rrycianide or p-b e n zoquinone [73]. Contrary to eucaryotic algae or chloroplasts from higher plants which can be coupled to oxygen meas u re m e n t , cya n o b a c t e ria re q u i re a mediator such as fe rricyanide for ampero m e t ric detection of the photosynthetic reaction [78].…”

“…For instance, the limit of detection fo r atrazine varies from 10 ppb to 650 ppb using cyanobacteria [73,78], unicellular algae [74], thylakoids [76], and reaction centers [77]; whereas using immunosensors, concentrations as low as 0.03 ppb can be detected [13].…”

Wavelet Transformation of Amperometric Algal Biosensor Response

“…There has been considerable recent interest in an amperometric algal biosensor for a water toxicity test, owing to its importance in environmental monitoring and industrial safety. [1][2][3][4][5][6][7][8] Normally, it is difficult to measure the toxicity of individual chemicals contained in water, since a wide variety of chemicals exist in environmental water, and their mixture may exhibit complex toxicity. In these cases, it is more effective to evaluate the overall toxicity of a sample solution to living organisms, rather than to determine individual chemicals using traditional biosensors based on enzymes and antibodies.…”