title: Single cell DNA damage/repair assay using HaloChip.
abstract: The molecular level damage to DNA is important due to DNA's susceptibility to free radical attacks and crucial roles in maintaining cell functions. Although a panel of techniques can be used to detect DNA damages, most of them are limited due to low sensitivity, low throughput, incompatibility for automated data analysis, and labor-intensive operations. We have developed a cell array based DNA damage assay in which mammalian cells are attached on an array of microfabricated patterns through electrostatic interactions. After trapping patterned cells inside gels, damaged DNA fragment can diffuse out of the nucleus and form a halo around each cell inside gels. The halo array can be observed fluorescently after labeling DNA with ethidium bromide. DNA damages can be determined sensitively at the single cell level, accurately due to the symmetric shape of the halo, and automatically due to the spatial registry of each cell and the nonoverlapping halos surrounding cells. The HaloChip can be used to detect DNA damages caused by chemicals and ultraviolet and X-ray irradiations with high efficiency. A major advantage of HaloChip is the ability to increase throughout by spatially encoding multiple dosing conditions on the same chip. Most importantly, the method can be used to measure variations in response to DNA damaging agents within the same cell population. Compared with halo assay or comet assay alone, this method allows automated analysis of a million cells without an overlapping issue. Compared with the microwell array based comet assay, this method can selectively capture and analyze cells, and the results can be easily analyzed to provide precise information on DNA damage. This method can be used in a broad range of clinical, epidemiological, and experimental settings.
authors.affiliation: NanoScience Technology Center, University of Central Florida, Orlando, Florida 32826, United States.
authors.forename: Yong
authors.initials: Y
authors.lastname: Qiao
authors.forename: Chaoming
authors.initials: C
authors.lastname: Wang
authors.forename: Ming
authors.initials: M
authors.lastname: Su
authors.forename: Liyuan
authors.initials: L
authors.lastname: Ma
mesh_terms: D001681:Biological Assay; D001859:Bone Neoplasms / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D020552:Comet Assay; D004249:DNA Damage / Q000235:genetics* / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics* / Q000528:radiation effects; D005453:Fluorescence; D006367:HeLa Cells; D006801:Humans; D012516:Osteosarcoma / Q000378:metabolism*; D012825:Silicon / Q000737:chemistry; D046888:Tissue Array Analysis; D014407:Tumor Cells, Cultured; D014965:X-Rays
chemical_list: D012825:Silicon