Biomedical Engineering Reference
In-Depth Information
anticancer agent (+)-daunorubicin and its (-)-enantiomer. The binding in-
teractions with right- and left-handed DNA have been studied quantitatively
by equilibrium dialysis, fluorescence spectroscopy, and circular dichroism.
Results indicated that (+)-daunorubicin binds selectively to right-handed
DNA, whereas the enantiomer binds selectively to left-handed DNA. Recently,
Feringa et al. [117, 118] introduced a novel DNA-based asymmetric catalysis
concept. This catalytic ensemble comprises a copper complex of a non-chiral
ligand, which incorporates a metal binding site, a spacer, and a covalently at-
tached intercalator, i.e., 9-amino acridine. As a result, the active Cu(II) center
is brought into the proximity of the chiral environment of the DNA double he-
lix, allowing for a transfer of chirality from DNA to the reaction product. With
this approach, the copper-catalyzed Diels-Alder reaction achieved very high
enantioselectivities in water.
The chirality of DNA was applied to selective separation. A DNA aptamer
as a new target-specific chiral selector for HPLC was investigated by Michaud
et al. [119, 120]. They showed that a tailor-made chiral stationary phase based
on a DNA aptamer with known stereospecific binding for the
D
-enantiomer
of the oligopeptide, arginine-vasopressin, exhibits enantioselectivity between
the
D
-and
L
-peptides. This DNA-based target-specific aptamer chiral station-
ary phase provides a powerful tool for the resolution of small (bioactive)
molecule enantiomers.
5
Biopolymer
DNA is a native substance widely existing in organisms. Irrespective of its
genetic information, DNA possesses biophysical and biochemical properties
that have been optimized over billions of years of evolution. These unique
properties of DNA offer it excellent prospects for serving as a construction
material in bioscience. The primary advantage of DNA for bio-applications is
based on the fact that DNA is biocompatible. The molecular structure of DNA
in vertebrate species is homogenous [121], unlike other biopolymers such as
proteins and sugars, and the non- or low immunogenic properties of DNA
may limit both innate and acquired immune responses [122]. The second ad-
vantage of using DNA as a biomaterial is its perfect binding properties, which
have been described in previous sections. Not only other hybrid construction
materials but also some pharmacological molecules can be incorporated into
DNA via electrostatic inaction, groove binding, and intercalation. Addition-
ally, DNA is degradable by various deoxyribonucleases present in human cells
and the digestive system. This feature provides a possibility for using DNA as
a protective biomaterial for food or drug delivery applications.
Several attempts have been made to combine DNA with other polymer
matrices, cationic lipids, and inorganic supports through a variety of tech-
