Electrochemical Detection of Short DNA Oligomer Hybridization Using the CombiMatrix ElectraSense Microarray Reader

A microarray reader named ElectraSense using an electrochemical detection technique has been developed for the CombiMatrix CustomArray 12 544 electrode semiconductor DNA microarray. The detection is based on electrochemical reduction of the enzymatic oxidization product of 3,3′,5,5′-tetramethylbenzidene (TMB). TMB oxidation is catalyzed by a horseradish peroxidase (HRP) biomarker linked to a DNA target molecule through biotin-avidin chemistry. Electrochemical signal collection is performed by a computer controlled combinatorial semiconductor addressing instrument. Electrode to electrode switching can be accomplished in hundreds of microseconds and a detection time for each electrode is less than 5 ms. The whole array detection requires less than 60 s. Numerous parameters of the measurement procedure have been optimized and assay performance has been studied and a method for array quality control has been developed. Application of electrochemical detection of Combimatrix microarrays has been demonstrated for DNA detection over 4 orders of magnitude of target concentrations and detection of avian influenza subtype H5N1.