INDICATOR-FREE ELECTROCHEMICAL DNA HYBRIDIZATION BIOSENSOR

A new electrochemical hybridization biosensor protocol without an exte rnal indicator is described. The biosensor format involves the immobil ization of inosine-substituted (guanine-free) probe onto the carbon pa ste transducer, and a direct chronopotentiometric detection of the dup lex formation by the appearance of the guanine oxidation peak of the t arget. Such a use of the intrinsic DNA electrochemical response for mo nitoring hybridization events offers several advantages (over the comm on use of external indicators), including the appearance of a new peak , a Aat background, or simplicity. A 4 min short hybridization period allows a detection limit around 120 ng/ml. Performance characteristics of the sensor are described along with future prospects. (C) 1998 Els evier Science B.V. All rights reserved.