title: Label free colorimetric and fluorimetric direct detection of methylated DNA based on silver nanoclusters for cancer early diagnosis.
abstract: Epigenetic changes such as DNA methylation of CpG islands located in the promoter region of some tumor suppressor genes are very common in human diseases such as cancer. Detection of aberrant methylation pattern could serve as an excellent diagnostic approach. Recently, the direct detection of methylated DNA sequences without using chemical and enzymatic treatments or antibodies has received great deal of attentions. In this study, we report a colorimetric and fluorimetric technique for direct detection of DNA methylation. Here, the DNA is being used as an effective template for fluorescent silver nanoclusters formation without any chemical modification or DNA labeling. The sensitivity test showed that upon the addition of target methylated DNA, the fluorescence intensity is decreased in a linear range when the concentration of methylated DNA has increased from 2.0×10(-9) to 6.3 ×10(-7) M with the detection limit of 9.4×10(-10) M. The optical and fluorescence spectral behaviors were highly reproducible and clearly discriminated between unmethylated, methylated and even partially methylated DNA in CpG rich sequences. The results were also reproducible when the human plasma was present in our assay system.
authors.affiliation: Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Dadmehr
authors.affiliation: Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran. Electronic address: smhosseini@khayam.ut.ac.ir.
authors.forename: Morteza
authors.initials: M
authors.lastname: Hosseini
authors.affiliation: Department of Biochemistry, Tarbiat Modares University, Tehran, Iran.
authors.forename: Saman
authors.initials: S
authors.lastname: Hosseinkhani
authors.affiliation: Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran; Biosensor Research Center, Endocrinology and Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Reza Ganjali
authors.affiliation: Department of Molecular Biology, Tofigh Daru Co, Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Sheikhnejad
mesh_terms: D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D003124:Colorimetry / Q000379:methods*; D018899:CpG Islands; D019175:DNA Methylation; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D055088:Early Detection of Cancer / Q000379:methods* / Q000706:statistics & numerical data; D044127:Epigenesis, Genetic; D005470:Fluorometry / Q000379:methods*; D006801:Humans; D053768:Metal Nanoparticles; D009369:Neoplasms / Q000175:diagnosis / Q000235:genetics; D011401:Promoter Regions, Genetic; D015203:Reproducibility of Results; D012834:Silver
chemical_list: D004273:DNA, Neoplasm; D012834:Silver
keywords: Cancer diagnosis; DNA methylation; Detection; Fluorescence; Silver nanoclusters