title: Biomarkers of cigarette smoking and DNA methylating agents: Raman, SERS and DFT study of 3-methyladenine and 7-methyladenine.
abstract: 3-Methyladenine and 7-methyladenine are biomarkers of DNA damage from exposure to methylating agents. For example, the concentration of 3-methyladenine increases significantly in the urine of cigarette smokers. Surface-enhanced Raman spectroscopy (SERS) has shown much potential for detection of biomolecules, including DNA. Much work has been dedicated to the canonical nucleobases, with comparatively fewer investigations of modified DNA and modified DNA nucleobases. Herein, Raman spectroscopy and SERS are used to examine the adsorption orientations of 3-methyladenine and 7-methyladenine on Ag nanoparticles. Density functional theory (DFT) calculations at the B3LYP level are used to support the conclusions via simulated spectra of the nucleobases and of Ag+/nucleobase complexes. The results herein show that 7-methyladenine adsorbs upright via its N3 and N9 atoms side, similarly to adenine. 3-Methyladenine adsorbs in a very tilted or flat orientation on the Ag nanoparticles. These findings will be useful for future SERS or other nanoparticle-based bioanalytical assays for detection of these methyladenines or other modified nucleobases.
authors.affiliation: Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Scott G
authors.initials: SG
authors.lastname: Harroun
authors.affiliation: Department of Chemistry, Queen's University, 90 Bader Lane, Kingston, Ontario K7L 3N6, Canada.
authors.forename: Yaoting
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
authors.forename: Tzu-Heng
authors.initials: TH
authors.lastname: Chen
authors.affiliation: De Lin Institute of Technology, 1, Lane 380, Qingyun Road, Tucheng District, New Taipei City 23654, Taiwan.
authors.forename: Ching-Rong
authors.initials: CR
authors.lastname: Ku
authors.affiliation: Department of Chemistry, National Taiwan University, 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan; Department of Chemistry, Chung Yuan Christian University, Chungli District, Taoyuan City 32023, Taiwan. Electronic address: changht@ntu.edu.tw.
authors.forename: Huan-Tsung
authors.initials: HT
authors.lastname: Chang
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D000327:Adsorption; D015415:Biomarkers / Q000378:metabolism*; D000073865:Cigarette Smoking / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D006046:Gold / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D008958:Models, Molecular; D011789:Quantum Theory; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D015415:Biomarkers; C025946:3-methyladenine; D006046:Gold; C059225:7-methyladenine; D000225:Adenine
keywords: 3-Methyladenine; 7-Methyladenine; Adenine analog; Cancer biomarker; DNA methylation; SERS