Toxin detection, screening techniques

Approaches are required for the following stages identification of toxic species, screening techniques for detecting toxicity, techniques for purifying toxins and provisionally identifying chemical nature, and techniques for tentatively identifying mechanisms of action. 

Screening Techniques for Detecting Toxicity. Simple toxicity screening techniques are necessary to identify toxic species and to monitor the efficacy of isolation and purification procedures used to purify toxins. Atterwill and Steele 108) have recently comprehensively reviewed in vitro methods for toxicology and so much of the following is in the nature of a general overview. 

Our research group is working on the development of electrochemical biosensors for the detection of microcystin and anatoxin-a(s), based on the inhibition of protein phosphatase and acetylcholinesterase, respectively. These enzyme biosensors represent useful bioanalytical tools, suitable to be used as screening techniques for the preliminary yes/no detection of the toxicity of a sample. Additionally, due to the versatility of the electrochemical approach, the strategy can be applied to the detection of other cyanobacterial toxins. 

However, problems associated with the reproducibility between electrodes derived from the screen-printing process and the partial electrode fouling have compromised the sensitivity of the biosensors. Work is in progress to improve both the reproducibility and the limits of detection by the use of new types of electrodes. The toxin overestimation observed with the amperometric biosensor, in the case of the microcystin analysis, suggests the use in parallel to other analytical techniques in order to minimise the risk of false-positive results. Nevertheless, the electrochemical strategy is appropriate to discriminate between toxic/non-toxic samples. 

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