Gold nanoparticle-based label-free detection of BRCAI mutations utilizing DNA ligation on DNA microarray

Here we describe a label-free detection strategy for point mutation in breast cancer susceptibility gene BRCAI utilizing ligation chain reaction (LCR) and zip-code array. We amplified the genomic regions containing mutation sites by polymerase chain reaction (PCR) to prepare the template for LCR. Then we ligated a primary probe extended by zip-code complementary at the 5' end with a 3'-thiol modified secondary probe. The resulting ligated product was labeled with gold nanoparticles and allowed to hybridize with corresponding zip-code sequences on the microarray. Finally, we applied silver enhancement to amplify the signals. Using this strategy, we successfully genotyped BRCAI mutation, which was detected by naked eye.