Environ. Sci. Technol. 2002, 36, 949-954
UV-Irradiated DNA Matrixes Selectively Bind Endocrine Disruptors with a Planar Structure M A S A N O R I Y A M A D A , †,‡ K O Z U E K A T O , † MOTOYOSHI NOMIZU,† KOUSAKU OHKAWA,‡ HIROYUKI YAMAMOTO,‡ AND N O R I O N I S H I * ,† Division of Bioscience, Graduate School of Environmental Earth Science, Hokkaido University, Sapporo 060-0810, Japan, and Faculty of Textile Science and Technology, Shinshu University, Ueda 386-8567, Japan
DNA has unique chemical properties and is readily purified from salmon milts and shellfish gonads. DNA has few commercial uses and is generally discarded as an industrial waste. Recently, we prepared water-insoluble and nuclease-resistant DNA-films by UV irradiation. The DNAfilms removed DNA-intercalating compounds. Here, we immobilized double-stranded DNA onto porous glass beads by UV irradiation and prepared DNA-immobilized glass bead columns. The DNA-immobilized columns effectively accumulated more DNA-intercalating materials than the DNAfilms. The DNA-immobilized columns bound endocrine disruptors with a planar structure, such as dioxin-derivatives, polychlorobiphenyl (PCB)-derivatives, and benzo[a]pyrene. Bisphenol A and diethylstilbestrol, which lack a planar structure, did not bind to the DNA-immobilized columns. These results suggest that DNA-immobilized glass bead columns could selectively remove chemical compounds with a planar structure by intercalation into the doublestranded DNA. DNA-immobilized glass beads and DNAfilms prepared by UV irradiation have the potential to serve as useful biomaterials for medical, engineering, and environmental applications.
1. Introduction Due to its unique double-stranded structure, DNA has highly specific functions, such as intercalation, groove binding interactions, and electrostatic interactions (1-3). These functions are specific for DNA molecules and are difficult to reproduce in synthetic polymers. DNA can be purified from either salmon milts or shellfish gonads, which are generally discarded as waste. DNA is a natural product and is safe for humans and for the environment. Therefore, the utilization of double-stranded DNA as a functional biomaterial has various advantages. Although films and fibers can be prepared from DNA, these products are water-soluble, biochemically unstable, and mechanically weak. These properties make DNA alone * Corresponding author phone: +81 11 7062256; fax: +81 11 7062256; e-mail:
[email protected]. Corresponding address: Laboratory of Bio-Material Chemistry, Division of Bioscience, Graduate School of Environmental Earth Science, Hokkaido University, Kita-10, Nishi-5, Kita-ku Sapporo 060-0810, Japan. † Hokkaido University. ‡ Shinshu University. 10.1021/es011008r CCC: $22.00 Published on Web 01/29/2002
2002 American Chemical Society
difficult to utilize as a functional material. There are several reports on the utilization of modified DNA as a functional material, including DNA-columns (4, 5), DNA/nanoparticle hybrid materials (6, 7), DNA-films (8-10), DNA-gels (1115), and DNA-immobilized nonwoven cellulose fabric (16). DNA materials have been used for the isolation of DNAbinding proteins, molecular devices, and optical materials. Recently, we prepared water-insoluble and nuclease-resistant DNA-films with a three-dimensional network by UV irradiation (17). The DNA-films were found to remove harmful DNAintercalating compounds (2, 3, 18, 19), such as ethidium bromide and acridine orange. Endocrine disruptors in food, water, and soil have become a worldwide problem (20-22). Endocrine disruptors are active at low concentrations and disturb hormone activities. Some endocrine disruptors, such as dioxin, polychlorobiphenyl (PCB), and benzo[a]pyrene, have planar and hydrophobic molecular structures with multiple aromatic rings. These compounds are extremely harmful and can induce malignant alterations as well (20-22). It is important to effectively remove even low concentrations of these harmful chemical compounds. Although normal adsorbents, such as activated carbon and alumina, can accumulate these chemical compounds, molecular selectivity is not achieved; i.e., normal adsorbents bind not only these harmful chemical compounds but also various nutrients in foods. In the present study, we have immobilized of DNA onto porous glass beads by UV irradiation. These immobilized DNA glass beads were used to remove endocrine disruptors and harmful DNA-intercalating compounds from water. Molecular selectivity of the DNA-immobilized glass bead columns is also described.
2. Experimental Sections 2.1. Materials. Double-stranded DNA (Na salt from salmon milt, molecular weight; ∼5 × 106) was obtained from Yuki Fine Chemical Co. Ltd., Tokyo, Japan. Single-stranded DNA (Na salt from salmon milt, molecular weight; 2-3 × 105) was purchased from Nissan Chemical Industries, Ltd., Tokyo, Japan. These DNAs were used without further purification. Dibenzo-p-dioxin, dibenzofuran, biphenyl, benzo[a]pyrene, bisphenol A, diethylstilbestrol, ethidium bromide, and acridine orange were purchased from Wako Pure Chemical Industries Ltd., Osaka, Japan or Tokyo Kasei Industries Ltd., Tokyo, Japan. Porous glass beads MIS-20 (particle size; 1-2 mm, pore size;
