Oligonucleotide-based signal amplification for ultrasensitive electrochemical biosensor

There is a need for an inexpensive, non-invasive and quick investigation with high sensitivity and specificity for early and accurate diagnosis of cancers. The present amplified bioassay takes advantage of the state-of-the-art electrical DNA detection methods, including the highly sensitive stripping response based on the intrinsic electroactivity of guanine and adenine nucleobases, and the amplification potential of latex microspheres carrying numerous oligonucleotide tags. The dramatic signal amplification advantage of this type of detection has been combined with efficient magnetic removal of non-complementary DNA for maximum selectivity, use of microlitre sample volumes and disposable transducers. The advantages of this procedure were demonstrated by its application in the detection of DNA segments related to the BRCA1 breast cancer gene.