Colorimetric detection of mutations in epidermal growth factor receptor using gold nanoparticle aggregation

We have detected mutations in the epidermal growth factor receptor (EGFR) of non-small cell lung cancer cells using the selective aggregations of gold nanoparticles. Mutations in exon 19 and exon 21 of EGFR gene were detected in non-amplified genomic DNAs that were isolated from both the lung cancer cell lines and the cancer tissues of non-small cell lung cancer patients. At the optimal salt concentration, addition of the mutant DNA that was hybridized with the complementary probe into the suspension of unmodified gold nanoparticles caused the substantial aggregation of the gold nanoparticles and the color change of solution. Gold nanoparticles, however, did not exhibit significant aggregation, and the solution color remained unchanged with the addition of the wild type DNA that was hybridized with the probe. In the eight specimens from non-small cell lung cancer patients, we could detect the in-frame deletion mutant form in exon 19 and the L858R point mutation in exon 21 by selective aggregation with gold nanoparticles. These results were also confirmed by an independent direct sequencing method using a DNA analyzer. We found that selective aggregation with gold nanoparticles could be successfully applied to direct detection of EGFR mutations in non-amplified genomic DNAs.