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Advances in Science and Technology Vol. 53
Title:
Biomedical Applications of Nano Technologies
Subtitle:
CIMTEC 2006
Edited by:
P. VINCENZINI and R. BARBUCCI
DOI:
ToC:
Paper Title Page
Abstract: Success in surgical joint replacements has resulted in a huge demand amongst patients.
Coupled with the lowered average age of patients requiring hip replacements, younger patients are
demanding longer life expectancy from such devices. The increasing need and demand for more
durable implants have led to new formulations of high performance nanomaterials (materials with
basic structural units of 1-100 nm). Nanotubes in particular have shown great promise because they:
1) have sizes that approach biological structures and 2) possess efficient channels for displaying
chemistries relevant to living systems at high densities and well-controlled spatial distribution.
Helical rosette nanotubes (HRN) are a new class of soft organic nanomaterials composed of a
guanine-cytosine building block that self-assembles in aqueous environments into stable nanotubular
structures with an inner diameter of ~1.1 nm. HRN can be decorated with biologically active
chemical functionalities such as cell attracting peptide fragments. Previously, we have showed that
HRN coated Ti can enhance OB attachment. In addition, proteins were seen to interact favorably
with HRN networks in a manner favorable toward OB attachment. Furthermore, in the absence of
proteins, HRN were seen to play the role of proteins in promoting OB attachment. The studies
herein, attempt to understand the role of the lysine clusters on HRN toward OB attachment. Results
show that OB do respond to lysine and molecular orientation considerations were shown to be
important. Detailed structural considerations from molecular modeling further present the possibility
of topographical influences (nanotube network architecture) towards OB attachment.
1
Abstract: To solve the shortage of the donor cornea in Japan, we are developing a poly(vinyl alcohol)
hydrogel based keratoprosthesis. Minimum requirements for a keratoprosthesis include light transparency,
non-toxicity, and nutrition and fluid permeability. Earlier clinical trials had frequently failed because corneal
epithelial down growth occurred between the host cornea and the materials, and the materials were finally
rejected from the host cornea. The major cause of this rejection is the weak adhesion between the host cornea
and the prosthesis. In order to achieve the firm fixation of the artificial cornea to host cornea, composites of
collagen-immobilized poly(vinyl alcohol) hydrogel with hydroxyapatite(PVA-HAp nano composites) were
synthesized. The preparation method, characterization, and the results of corneal cell adhesion and
proliferation on the composite materials were studied. The PVA-HAp nano composites were successfully
synthesized. Chick embryonic keratocyto-like cells were well attached and proliferated on the PVA-HAp
composites. This material showed potential for keratoprosthesis.
9
Abstract: Self-assembled niobium oxide microcones produced by potentiostatic anodization with varied
NaF content (between 100 and 250 mg) in an HF electrolyte are shown to nucleate mineral when
immersed in supersaturated solutions emulating mineral content in saliva and blood. The most
extensive mineral coverage in 100 mL of 2.5 wt. % HF electrolyte occurs when NaF content is
about 100 mg with substantial mineral formation occurring within 24 hours. Higher salt content
apparently alters the conditions favoring mineral nucleation by generating smaller nucleation
centers that ultimately diminish the extent of mineral coverage. Additionally, nucleation kinetics
and morphological contrasts between mineral formed from saliva and blood is briefly discussed in
terms of the relative degree of supersaturation with respect to hydroxyapatite. Finally, we show that
the integrity of the microcone shape is not critical for mineral nucleation, an observation that builds
on our prior hypothesis by promoting the importance of self-assembly and crystal formation. Based
on these results, we demonstrate the influence of NaF and stress the role of the self-organization
process in producing effective mineral nucleation sites.
17
Abstract: Membrane channel proteins play crucial roles in governing the transport of material and energy
across every cellular membrane. Accordingly, they are the subjects of interest for science and
medicine as well as major targets of drug discovery efforts. Recent work has also shown their
potential as highly rapid and sensitive single molecule sensors. However, techniques conventionally
used to measure the electrical transport through these proteins can be problematic to form and are
extremely fragile, limiting the range and scope of possible studies. We have developed two new
technologies which alleviate these shortcomings: in situ encapsulation of lipid membranes in
hydrogels and automated microfluidic formation. The hydrogel encapsulated membranes are
mechanically robust and long-lived as a result of the intimate contact between the hydrogel and the
membrane, enabling measurements of single channel currents for a week or longer. The automated
microfluidic formation apparatus enables the creation and manipulation of lipid membranes and the
incorporation and measurement of channel proteins in these membranes through an entirely
computer controlled process. We are working to apply these technologies toward DNA sequencing,
drug discovery, and single molecule biophysics.
22
Size-Controlled Hydroxyapatite Nanoparticles as Self-Organized Organic-Inorganic Composite Materials
Abstract: Sodium salt carboxymethyl cellulose (CMC) was used to prepare HAp-CMC
composites through co-precipitation process. HAp nanorods with well controlled
particle size were welll aligned along the c axis in the final composites. TEM, XRD,
FTIR analysis were used to characterized the samples. It was found that the carboxyl
groups in cellulose might be the main guiding site for the precipitation and growth of
HAp and the formation of the resulting composites.
32
Abstract: DP-bioglass is one of biodegradable glasses, which can be used as bioactive material in
soft tissue and bone. It was often used in orthopedy and plastic surgery. Recently, bioglass was also
used as a carrier for drug and gene delivery systems. Additionally, ferrimagnetic DP-bioglass can be
potential candidates for magnetic induction hyperthermia, by using a magnetic field. The aim of this
work is the preparation and characterization of surface-modified ferrimagnetic DP-bioglass. First
DP-bioglass has to be surface-modified with polyethylene glycol (PEG) and folic acid (FA) to
improve its intracellular uptake and ability to target specific cells. PEG-FA complex was synthesized
using carbodiimide (DCC) to link PEG with FA. Then PEG-FA complex were immobilized on the
surface of DP-bioglass by using amino-silane (AEAPS) as a coupling agent. Fourier transform
infrared spectroscopy (FTIR), nuclear magnetic resonance (1H NMR), and thermogravimetric
analysis (TGA) was used to demonstrate this immobilization process. In biological study showed that
immobilized ferromagnetic DP-bioglass with PEG-FA was non-cytotoxicity and significantly
enhanced the intracellular uptake of DP-bioglass by target cells.
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