Biomedical Engineering Reference
In-Depth Information
niques that include physical adsorption, electrostatic binding, and covalent
coupling. These materials, which are modified with DNA/oligonucleotides,
have been tried for numerous biotechnological applications: improvement of
surface compatibility, dental and medical implantology, and cell cultures.
DNA has been used to modify the PSf membrane by blending and immobi-
lizing DNA onto its surface [123, 124]. PSf is one of the most important poly-
meric materials and is widely used in artificial and medical devices. However,
when used as a hemodialysis hollow fiber, the blood compatibility of the PSf
membrane is not adequate. The hydrophilicity of the DNA-modified surface
increased, but the amount of adsorbed protein did not decrease significantly,
which indicates that the DNA-modified membrane might have a better blood
compatibility.
Jansen et al. fabricated multilayered DNA coatings on titanium sub-
strates using the electrostatic self-assembly technique, with poly-
D
-lysine
or poly(allylamine hydrochloride) as the cationic counterparts of anionic
DNA [125, 126]. In vitro experiments with rat primary dermal fibroblasts in-
dicated that the presence of multilayered DNA coatings do not affect RDF
cell viability but did increase proliferation. An in vivo rat model experiment
on implants inserted into soft tissue revealed that the presence of a multilay-
ered DNA coating did not induce any adverse effects in terms of inflammation
and wound healing. The cyto- and histocompatibility of multilayered DNA
coatings demonstrated in this study allows their use and functionalization
with appropriate compounds to modulate cell and tissue responses in dental
and medical implantology (Fig. 16). The DNA-chitosan complexes have also
been investigated for biotechnology applications. The DNA-chitosan bilayer
membranes were prepared by applying chitosan solution on UV-irradiated
DNA membranes [127]. For the purpose of wound therapeutic application,
the bonding strength of the membranes to rabbit peritoneum was tested.
These membranes showed an adhesive property to rabbit peritoneum tissue
(Fig. 17), and the DNA in the layer retained the double stranded structure.
The specific property of DNA in the bilayer membrane can be used as a drug
carrier or reservoir. Another work on the DNA-chitosan complexes showed
no cytotoxicity for MG-63 osteoblast-like cells and caused only a mild tissue
response when implanted subcutaneously in the backs of rats [128].
In other reports, Salmon milt DNA was utilized in oral delivery applica-
tions to protect functional materials that are sensitive to the gastric acid-
ity [129-131]. By forming a DNA-based complex gel with gelatin and car-
rageenan, lactic acid-producing bacteria were protected from extreme acidic
conditions. The DNA-based complex gel also showed the desirable conditions
for bacterial growth and division in the simulated intestinal juice. Since the
electrostatic interaction of the DNA-gelatin complex behaves differently in
the simulated intestinal juice and the simulated the gastric condition, this
delivery system provided a high protective capability and showed effective
results for the survival of the probiotic bacteria.
