title: Label-free and real-time imaging of dehydration-induced DNA conformational changes in cellular nucleus using second harmonic microscopy.
abstract: Dehydration-induced DNA conformational changes have been probed for the first time with the use of second harmonic microscopy. Unlike conventional approaches, second harmonic microscopy provides a label-free and real-time approach to detect DNA conformational changes. Upon dehydration, cellular DNA undergoes a transition from B- to A-form, whereas cellular nuclei change from invisible to visible under second harmonic microscopy. These results showed that DNA is a second order nonlinear optical material. We further confirmed this by characterizing the nonlinear optical properties of extracted DNA from human cells. Our findings open a new path for SHG imaging. DNA can change its conformations under many circumstances. For example: normal cells turning into cancerous cells and drug molecules binding with DNA. Therefore, the detection of DNA conformational changes with second harmonic microscopy will be a useful tool in cancer therapy and new drug discovery.
authors.affiliation: Fujian Provincial Key Laboratory for Photonics Technology, Key Laboratory of OptoElectronic Science and Technology for Medicine of Ministry of Education, Fujian Normal University, Fuzhou 350007, China.
authors.forename: Shuangmu
authors.initials: S
authors.lastname: Zhuo
authors.affiliation: Institute of Bioengineering and Nanotechnology, 31 Biopolis Way, The Nanos, Singapore 138669, Singapore.
authors.forename: Ming
authors.initials: M
authors.lastname: Ni
mesh_terms: D002467:Cell Nucleus / Q000737:chemistry* / Q000473:pathology; D004273:DNA, Neoplasm / Q000737:chemistry*; D003890:Desiccation; D006367:HeLa Cells; D006801:Humans; D008853:Microscopy; D009690:Nucleic Acid Conformation
chemical_list: D004273:DNA, Neoplasm