Biomedical Engineering Reference
In-Depth Information
Fig. 13
Schematic representation of DNA intercalation: the small molecules with planar
structure intercalate into the interspaces between two adjacent base pairs
potential human carcinogens or endocrine-disrupting chemicals. They ex-
ert physiological effects at very low concentrations. It was suggested that
DNA be used to remove harmful chemicals before their interaction with
human DNA. The DNA-based adsorbents may be have inherent selectiv-
ity, as only chemical compounds with special structure would be adsorbed.
In contrast, for common adsorbents such as activated carbon and alumina,
molecular selectivity is not achieved. However, there is a serious disad-
vantage in use of DNA for environmental purposes: DNA is highly water-
soluble and biochemically unstable. Overcoming these undesirable proper-
ties is important for the utilization of DNA as a water cleaning material. In
order to manufacture water-insoluble DNA materials, various methods have
been reported.
Yamada et al. [96, 97] prepared a dsDNA film with a 3D network by using
UV irradiation. A dsDNA solution was applied on glass plates and dried.
After treatment with UV light irradiation for more than 1 h, a water-insoluble
DNA film was produced. The UV-irradiated DNA films were examined by
CD spectra. No change in the CD spectra (max. of 280 nm,min.of240 nm)
was observed, even at a irradiation time of more than 6 h, indicating that
UV-irradiated DNA film retains the B-form structure in aqueous solution. To
test the biochemical stability, the UV-irradiated DNA films were incubated
with
Micrococcal nuclease
. Hydrolyzation results showed that the DNA films
have nuclease-resistant characteristics, because of the UV-induced cross-
linking between DNA molecules. Although some damages to DNA by UV
light have been reported previously, the effect of small changes in the DNA
by UV irradiation is not a significant problem for the purpose of carcino-
gen removal. In subsequent studies, the DNA films were immobilized onto
porous glass beads [98] and non-woven cellulose fabric [99] by UV irradi-
ation. These DNA-based materials could effectively accumulate endocrine
disruptors and harmful DNA intercalating pollutants, such as dibenzo-
p
-
dioxin, dibenzofuran, biphenyl, benzo[a]pyrene and ethidium bromide. The
porous beads that had dsDNA immobilized onto the surface by UV irradi-
ation were further used to prepare a DNA-coated glass bead column [98]
