SURFACE TECHNIQUES FOR AN ELECTROCHEMICAL DNA BIOSENSOR

The surface of platinum electrodes was modified by a technique that pr ovides binding sites for covalent site-specific immobilization of DNA. In the course of immobilization certain substances such as thiols, io dine and iodide were brought in contact with the metal. The effect on the electrochemical characteristics of thin film platinum electrodes c aused by chemisorption of these substances was investigated. Voltage p ulsing was very effective in restoring the electrocatalytical properti es of the electrodes. A 20 bp oligonucleotide was immobilized via prim ary amino groups or terminal phosphate and immobilization efficiency o f the different immobilized strands was determined. Mercapto-silane co atings and controlled introduction of charged groups in the course of immobilization prevented unspecific DNA binding caused by adsorption. (C) 1997 Elsevier Science Limited.