Electrical microarrays for highly sensitive detection of multiplex PCR products from biological agents

For the sensitive detection of amplicons derived from diagnostic PCR, a novel electrical low-density microarray is applied and compared to state-of-the-art quantitative real-time PCR. The principle of the electrochemical method and the effective use for analysis are described. Interdigitated array gold electrodes (IDA-E) embedded into a silicon chip are the core technology of the fully automated compact biosensor system, basing on enzyme coupled electrochemical detection. The biointerface is built up with thiol-modified capture oligonucleotides on gold and mediates the specific recognition of hybridised target DNA amplified with uniplex or multiplex PCR. In here we show the potential of the designed electrical microarray to function as an advanced screening method for the parallel detection of a panel of the four pathogens Bacillus anthracis, Yersinia pestis, Francisella tularensis and ortho pox viruses (genus), which are among the most relevant biowarfare agents. PCR products, generated from 10 to 50 gene equivalents, have been detected reproducibly. The experiments with varying pathogen amounts showed the good reliability and the high sensitivity of the method, equivalent to optical real-time PCR detection systems. Without PCR the total assay time amounts to 27 min. The advantage of the combination of multiplex-PCR with electrical microarray detection avoiding intensive PCR probe labelling strategies is illustrated.