A simple colorimetric detection of DNA methylation

In this work, we describe a simple colorimetric method to detect DNA methylation. Adenomatous polyposis coli (APC) with a small CpG region containing methylated cytosine (methylated APC) was synthesized and tested. Methylated APC was first captured and enriched by anti-5-methylcytosine monoclonal antibody conjugated magnetic microspheres (MMPs). Then a probe partly complementary to the APC sequence was added, resulting in the formation of DNA duplexes. The microsphere-captured probe was then released by heat denaturation and added into unmodified gold nanoparticle (AuNP) solution. Colorimetric detection was performed by salt-induced aggregation. The limit of detection is 80 fmol. Semi-quantitative analysis was done with a UV/Vis spectrophotometer by recording the absorbance of AuNP solution at 520 nm. Thus, this method provides a simple, rapid and quantitative tool for DNA methylation detection.