Classical dot-blot format implemented as an amperometric hybridisation genosensor

A new electrochemical hybridisation genosensor has been designed. This geno sensor is based on a concept adapted from classical dot-blot DNA analysis, but implemented in an electrochemical biosensor configuration. The use of a mperometric transduction and the enzyme label method-that increases the gen osensor sensitivity-are the main features of this new approach. The analyti cal procedure consists of five steps: DNA target immobilisation by adsorpti on onto a nylon membrane, hybridisation between DNA tar-et and biotin-DNA p robe, complexation reaction between biotin-DNA probe and an enzyme (horsera dish peroxidase) streptavidin conjugate; integration of the modified membra ne onto an electrochemical transducer; and finally, amperometric detection using a suitable substrate for the enzyme labelled duplex, Besides the adap ted dot-blot format, a competitive assay in which the target is in solution is reported as well. This procedure, based on amperometric transduction, r epresents certain advantages with respect to dot-blot analysis: labelled hy brid detection is far simpler, quicker and requires more ordinary or simple reactives; the response obtained is a direct analytical signal via low-cos t instrumentation, a nonisotopic labelling is used, and the membranes can b e reused. These characteristics are ideal in implementing the procedure dev eloped in kit form. (C) 2001 Elsevier Science B.V. All rights reserved.