Functional Materials Derived from DNA - Functional Materials and Biomaterials - page 168

trices as sorbent. Several polymers have been reported. By coagulation with
bivalent calcium ions, the DNA-alginic acid hybrid matrix could be conve-
niently insolubilized [101]. The DNA in the hybrid complex was found to be
able to adsorb intercalating materials such as ethidium bromide. Following
this work, a procedure for immobilizing DNA molecules in a semi-IPN poly-
acrylamide hydrogel was proposed [102]. Salmon milt DNA was immobilized
in the hydrogel beads synthesized by an inverse suspension polymeriza-
tion of acrylamide in the continuous phase of cyclohexane (Fig. 15c). These
DNA hydrogel beads are stable in aqueous medium, more than 82% (w/w)
of the DNA can be retained in the hydrogel after soaking in water. Com-
paring with normal adsorbents such as activated carbon and alumina, this
DNA matrix showed a selective adsorption of the dioxin derivatives. Column
methods were used to compare DNA hydrogel beads, activated carbon, and
alumina. As shown in Table 2, although activated carbon and alumina adsorb
more dioxins than the DNA hydrogel beads, they do not exhibit selective ad-
sorption. This property makes the DNA hybrid materials advantageous for
removing dioxins from a complex environment containing nutritional com-
pounds. Reusability of the hydrogel beads after washing with organic solvent

Fig. 15 Optical images of DNA-based materials for environmental purpose. a DNA-alginic
acid hybrid matrix coagulated by Ca 2+ ,infiber,film,andgelform. b DNA-immobilized
porous glass beads prepared by UV-irradiation. c DNA-polyacrylamide hydrogel beads
synthesized by inverse suspension polymerization

Table 2 Relative accumulation of dioxins and some nutritional compounds by the columns
of DNA hydrogel bead (I), activated carbon (II), and alumina (III)

Removal rate a
I

Chemical compound Concentration

II III

µ

( M) (%) (%) (%)

Dibenzo- p -dioxin 0.65 95.1 98.4 96.5

Dibenzofuran 0.60 95.4 96.2 95.2

Biphenyl 0.60 93.0 95.8 94.3

Vitamin B2 0.75 13.0 93.1 91.0

Vitamin B12 0.75 10.6 95.1 90.8