Detection of breast cancer-related point-mutations using screen-printed and gold-plated electrochemical sensor arrays suitable for point-of-care applications

For anticancer therapy and disease prognosis in breast cancer, three PIK3CA point-mutations (H1047R, E545K, and E542K) play a significant role. To allow for specific and sensitive detection of these point-mutations with a hybridization-based detection concept, the assay conditions were optimized on a microarray technology platform. The resulting fluorescence-based microarray assay enables simultaneous and specific detection of three PIK3CA point-mutations. The optimized protocol was then adapted for use on a screen-printed and gold-plated silver sensor array with twelve working electrodes, one common counter electrode, and one common reference electrode. Chronoamperometric measurements employing an enzyme-amplified electrochemical assay allow for detecting PIK3CA point-mutations with a detection limit of 10 pM for short 24-mer target DNA. The mutant and the wild-type target DNA sequences gave significantly different signals in a broad concentration range of 1 nM – 100 nM, with the best separation found at 10 nM – 20 nM. Comparing the hybridization of short 24-mer and long 80-mer target DNA sequences reveals that the hybridization efficiency is reduced for long target DNA sequences. However, both the 24-mer and the 80-mer target DNA lead to successful detection of point-mutations. Finally, the electrochemical sensor allows for multiplexed detection of the three PIK3CA point-mutations.