Preliminary Studies Towards the Development of DNA Biosensors for Detection of Cylindrospermopsin – A Cyanobacterial Toxin

 

 

E. Valério, A. Tenreiro and L.M. Abrantes*

 

Centro de Química e Bioquímica, Faculdade de Ciências, Universidade de Lisboa, Campo Grande,

1749-016 Lisboa, Portugal

 

Received 29^th June 2007; accepted 3^rd October 2007

 

 

Abstract

The suitability of polytyramine (PTy) modified electrodes for the development of DNA biosensors is analysed in this work. PTy films were synthesised potentiodynamically on Pt electrode, from acidic aqueous solution. A cylindrospermopsin coding sequence (PKSM4 probe 5’-phosphate modified) was covalently bound on the polytyramine matrix using N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC) as coupling agents. Changes of the open circuit potential were registered as a first approach to monitorise the immobilization and hybridization processes.

The modified electrodes have been characterised by cyclic voltammetry and square wave voltammetry, using methylene blue (MB), as electroactive indicator and the successful immobilization and hybridization steps are revealed by the increase of the peak currents. The hybridization has also been confirmed by measuring the fluorescence of the modified electrodes after staining with PicoGreen^® DNA dye.

Keywords: cylindrospermopsin, DNA biosensor, PicoGreen^®, polytyramine, methylene blue.

 

 

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* Corresponding authors. E-mail addresses: luisa.abrantes@fc.ul.pt