Mehdi Dadmehr - Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran#PayameNoor University, Tehran, Iran
Morteza Hosseini - Department of Biochemistry, Tarbiat Modares University, Tehran, Iran
Saman Hosseinkhani - Department of Chemistry, University of Tehran, Tehran, Iran
Mohammad Reza Ganjali - Department of Molecular Biology, Tofigh Daru Co., Tehran, Iran

Nanobiosensors are the biosensors that exploit nanomaterials for improve recognition ofbiomolecules including DNA, RNA, proteins and etc. Nanomaterials have the potential toimprove the biosensors utilities and may result in cheaper, faster and easy to use analyticaltools for rapid detection. Among epigenetic Phenomena, DNA methylation of tumorsuppressor genes regarded as the most common DNA modification and best knownepigenetic marker that almost found on the 5ʹ position of the pyrimidine ring of cytosinebase in the CpG dinucleotides. Currently we have conducted and developed different andnovel DNA nanobiosensor for detection of methylated DNA. Specific site of CpG islands ofadenomatous polyposis coli (APC), a well studied tumor suppressor gene, was used as thedetection target DNA sequence in the current approaches. Distinguished interaction ofspecific fluorophore with methylated and unmethylated DNA based on Fe@AU nanoparticlesshowed fluorescence intensity increased in linear range by concentration of unmethylatedssDNA from 1.6×10-15 to 6.6×10-13M with detection limit of 1.2×10-16 M and on theother hand, fluorescence intensity declined linearly with concentration of 3.2×10-15 to 8.0×10-13M methylated DNA and detection limit was 3.1×10-16 M. We also reported acolorimetric and fluorimetric technique for direct detection of DNA methylation for the firsttime. So DNA is being used as an effective template for fluorescent silver nanoclustersformation without any chemical modification or DNA labeling. The sensitivity test showed thatupon the addition of target methylated DNA, the fluorescence intensity is decreased in alinear range when the concentration of methylated DNA is increased from 2.0×10-9to6.30×10-7 M with the detection limit of 9.4×10--10 M. These novel methods provide avery simple, rapid and quantitative tool for DNA methylation detection that avoids utilizing ofcomplicated procedures such as bisulfite treatment. Regarding to significant reproducibility ofmethods in human serum plasma, they could have important medical applications such ascancer early diagnosis and/or prognosis.

Nanobiosensor, DNA Methylation, Cancer, Early Diagnosis, Nanomaterial