MILOS IADR

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Nano-Bio-Technology
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What is Nano-Bio-Technology?
Nanobiotechnology is the unification of
biotechnology and nanotechnology. This
inter-disciplinary technology can also mean
making atomic-scale machines by imitating or
incorporating biological systems at the molecular
level, or building tiny tools to study or change
natural structure properties atom by atom.
Nanobiotechnology uses the knowledge and
techniques of biology to manipulate molecular,
genetic, and cellular processes to develop
products and services, and is used in diverse
fields from medicine to agriculture. Convergence
is an activity or trend that occurs based on
common materials and capabilities-in this case
the discipline that enables convergence is
nanotechnology and biotechnology. The potential
opportunities offered by this interface is truly
outstanding the overlap of biotech, nanotech and
information technology is bringing to fruition
many important applications in life sciences.
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Nanobiotechnology is expected to create
innovations and play a vital role in various
biomedical applications. Eight areas of
nanoscience and nanotechnology are believed to be
the most pertinent to the biomedical researches.
These areas include syntheses and uses of
nanostructures, applications of nanotechnology to
therapy, bio-mimetic and biologic nanostructures,
electronic-biology interface, devices for early
detection of disease, tools for the study of
single molecules, nanotechnology for tissue
engineering.
Nano-Bio-Technology
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Nature Did It First 1 Collagen
Collagen is the main protein constituent of
muscular arteries where it serves a major
structural role. It is in fact, the most abundant
protein in the animal kingdom. It is present in
almost all tissues ranging from bones, cartilage,
tendons, ligaments and all other soft tissues
(skin, muscles and all other organs). It is
characterized by great tensile strength in
molecular and fiber form.
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Nature Did It First 2 Tooth Enamel
Enamel crystals are some of the most astounding
structures in nature featuring extremely long and
parallel organized hydroxyapatite crystals
organized in bundles which are called prisms.
Rows of enamel prisms are often organized
perpendicular to each other.
Tooth Anatomy
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Nature Did It First 3 Abalone Shell
Abalone (shellfish with pearly shell ) shell is
comprised of alternating layers of protein and
oriented calcite (calcium carbonate) crystals.
The fracture toughness of nacre is about 1000x
that of calcite itself because of the ability of
the soft protein layers to dissipate the impact
energy of a predator attack on the shell.
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Nano-Bio-Tecnhology for Pharmaceutical Development
The most important biomedical application of
nanobiotechnology will probably be in
pharmaceutical development. These applications
take advantage of the unique properties of
nanoparticles as drugs or constituents of drugs
or are designed for new strategies to controlled
release, drug targeting, and salvage of drugs
with low bioavailability. Nanoscale polymer
capsules can be designed to break down and
release drugs at controlled rates, to allow
differential release in certain environments,
such as an acid medium, and to promote uptake in
tumours versus normal tissues. A lot of research
is now focused on creating novel polymers and
exploring specific drug-polymer combinations.
Nanocapsules can be synthesized directly from
monomers or by means of nanodeposition of
preformed polymers. Nanocapsules have also been
formulated from albumin and liposomes.
Implantable drug delivery systems that are being
developed will make use of nanopores to control
drug release.
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Nano-Tools/Devices for Biomedical Applications
There are many interesting ideas for the use of
nanomechanical tools in biomedical researches.
Such nanotools are awaiting construction, and
presently are more like a fantasy. Nevertheless,
they might be quite useful, and become a reality
in the future. Nanodevices in medical sciences
could function to replace defective or improperly
functioning cells. Nanorobots, operating in the
human body, could monitor levels of different
compounds and record the information in the
internal memory. They could be rapidly used in
the examination of a given tissue, surveying its
biochemical, biomechanical, and histometrical
features in greater detail. It has also been
reported that nanomachines could administer drugs
within a patients body. Such nanoconstructions
could deliver drugs to peculiar sites making
treatment more accurate and precise. Similar
machines with specific weapons could be used to
remove obstacles in the circulatory system or in
the identification and killing of tumour cells.
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Nanoparticles as Biomarkers
Nanoparticles can be used for both quantitative
and qualitative in vitro detection of tumour
cells. They can enhance the detection process by
concentrating and protecting a marker from
degradation, in order to render the analysis more
sensitive. These nanoparticles, with their bound
diagnostic cargo, can be directly queried via
mass spectrometry to reveal the low molecular
weight and enriched biomarker signatures.
Ultimately, utility of any approach for detecting
disease is assessed on its clinical impact to
patient outcome and disease-free survival. What
is urgently required in the study of diseases in
general, is the development of biomarkers that
can detect curable diseases earlier, and/or can
detect advanced disease better. In the future,
nanoparticles that will be engineered with
specific binding affinities can be resuspended
into the collected body fluids, or perhaps even
injected directly into the circulation. The
nanoparticles, together with the bound molecules,
could be directly captured on engineered filters
and directly questioned by ultra high-resolution
mass spectrometry (such as Fourier Transform Ion
Cyclotron Resonance).
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Applications of Nano-Bio-Technology for Tissue
Engineering
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Millions of people suffer from a variety of
diseases that could be aided from therapies such
as organ transplantation. However, despite the
widespread need for transplantable tissues, many
patients die while waiting for donor organs. It
is from this need that the field of tissue
engineering has emerged.
Tissue engineering is an interdisciplinary field
that involves the use of biological sciences and
engineering to develop tissues that restore,
maintain, or enhance tissue function. Tissue
engineering has particular advantages over other
therapies such as drugs because it can provide a
permanent solution to the problem of organ
failure.
In general, there are three main approaches to
tissue engineering (i) to use isolated cells or
cell substitutes as cellular replacement parts,
(ii) to use a cellular biomaterials capable of
inducing tissue regeneration, and (iii) to use a
combination of cells and materials (typically in
the form of scaffolds).
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Challenges in Tissue Engineering
Despite significant advances in tissue
engineering, which have resulted in successful
engineering of organs such as skin and cartilage,
there are a number of challenges that remain in
making off-the-shelf tissue-engineered organs.
These barriers include (1) the lack of a
renewable source of functional cells that are
immunologically compatible with the patient (2)
the lack of biomaterials with desired mechanical,
chemical, and biological properties and (3) the
inability to generate large, vascularized tissues
that can easily integrate into the hosts
circulatory system with the architectural
complexity of native tissues.
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Nano-Bio-Technology for Tissue Engineering
Nano-bio-technologies are potentially powerful
tools for addressing some of the challenges in
tissue engineering. (A) the technologies can be
used directly to fabricate improved scaffolds and
bioreactors or indirectly to study cellular
behavior in controlled conditions or through the
use of high-throughput experimentation. (B) A
poly(dimethylsiloxane) microfabricated tissue
engineering scaffold with the vasculature
directly embedded into the scaffold. (C) Various
microscale techniques used to control different
aspects of cellmicroenvironment interactions.
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Soft Lithography
In the recent decade, microfabrication has been
increasingly used in biomedical and biological
applications, partly because of the emergence of
techniques such as soft lithography to fabricate
microscale devices without the use of expensive
clean rooms and photolithographic equipment.
Soft lithography is a set of microfabrication
techniques that use elastomeric stamps fabricated
from patterned silicon wafers to print or mold
materials at resolutions as low as several
hundred nanometers. Therefore, soft lithography
can be used to control the topography and spatial
distribution of molecules on a surface, as well
as the subsequent deposition of cells. Soft
lithographic methods can also be used to
fabricate microfluidic channels and scaffolds for
tissue engineering in a convenient, rapid, and
inexpensive manner. In addition,
photolithography, a technique in which microscale
features are fabricated based on selective
exposure of a material to light, can also be used
for microfabrication of tissue engineering
structures.
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Cell-Seeded, Microfabricated Scaffolds
In many tissue engineering applications,
scaffolds are used to provide cells with a
suitable growth environment, optimal oxygen
levels, and effective nutrient transport as well
as mechanical integrity. Scaffolds aim to
provide 3D environments to bring cells in close
proximity so that they can assemble to form
tissues. Ideally, as the scaffold is degraded,
the cells deposit their own extracellular matrix
(ECM) molecules and eventually form 3D structures
that closely mimic the native tissue
architecture. Currently, tissue engineering
scaffolds are prepared by using a variety of
techniques, such as solvent casting and
particulate leaching. However, scaffold
properties such as pore geometry, size,
interconnectivity, and spatial distribution
depend on the fabrication process rather than
design. The inability to generate desired
scaffolds has hindered the construction of
engineered tissues that are larger than a few
hundred micrometers due to oxygen diffusion
limitations. Microfabrication approaches have
been explored to engineer the desired
microvasculature directly into the tissue
engineering scaffolds. Initial experiments used
micromachining technologies on silicon surfaces
to generate vascularized systems. Subsequent
work on the replica molding of biocompatible
polymers from patterned silicon wafers has
resulted in the fabrication of biocompatible
scaffolds.
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Spatial Regulated Hydrogels and Scaffolds
Many biological processes are regulated by
spatially dependent signals. For example,
gradients of molecules are commonly used in the
body to regulate cell migration, axon extension,
angiogenesis, and differentiation. Therefore,
controlling the spatial location of molecules on
a surface or throughout a material could be
potentially beneficial for tissue engineering.
Gradient hydrogels for tissue engineering. (Top)
Hydrogels can be fabricated with control over the
spatial properties of the materials by embedding
a gradient of materials, such as RGDpeptide,
directly into the material. (Middle and Bottom)
The shape of the gradient can be visualized by
using fluorescent molecules (Middle), and its
function can observed by imaging endothelial cell
adhesion after a few hours on the gels (Bottom).
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Cell Assembly for Tissue Engineering
Artificial microtissues can also be fabricated by
inducing the reaggregation of one or more cell
types.
(A) A schematic diagram of the template-based
assembly method. PEG microwells were fabricated
so that cells could dock within the
low-shear-stress regions generated within the
microstructures. Once cells had immobilized
within the microwells, other cells were washed
away, and the cells within the microwells formed
aggregates of controlled properties.
(B) A light microscope image of 100-mPEG wells
that were seeded with ES cells and washed. (C) A
scanning electron micrograph of cells within PEG
microwells
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Controlling the Cellular Microenvironment in Vitro
One of the major challenges associated with the
use of stem cells is to understand the
microenvironmental cues that regulate their fate.
Microscale approaches can be used to control
culture conditions and perform high-throughput
experimentation, hence providing a suitable tool
to study cellmicroenvironment interactions in
vitro. In most tissue culture systems, the
cellular microenvironment is vastly different
relative to in vivo conditions. In the body,
cells are exposed to a controlled
microenvironment that is tightly regulated with
respect to interactions with the surrounding
cells, soluble factors, and ECM molecules. In
particular, the spatial and temporal distribution
of these signals is tightly controlled and unique
to each organ. Furthermore, cells in the body
are exposed to a 3D environment instead of the 2D
environment experienced by cells in traditional
culture dishes.
In general, microscale approaches to control
cellmicroenvironment interactions can be
separated into cellcell, cellmatrix, and
cell-soluble factor components
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Microscale approaches for controlling the in
vitro cellular microenvironment.
(A) Light microscope images of ES cells patterned
on PEG-coated substrates as an example of surface
patterning for regulating cellECM interactions.
(B) A fluorescent image of patterned cocultures
depicting control over the degree of heterotypic
and homotypic interactions between ES cells and
fibroblasts. (C) An image of a cell and a
schematic diagram of microfluidic methods of
regulating cell-soluble signal interactions by
flowing two parallel streams of fluids on an
individual cell.
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Supplemental Reading Materials

• Geoffrey OA, Arsenault AC (2005). Chapter 10
  Biomaterials and Bioinspiration, in
  Nanochemistry A Chemistry Approach to
  Nanomaterials, RSC Publishing, Cambridge, UK.
• Ali Khademhosseini, Robert Langer, Jeffrey
  Borenstein and Joseph P. Vacanti (2006).
  Microscale Technology for Tissue Engineering and
  Biology. Proceedings of the National Academy of
  Sciences (PNAS), 103 (8), 2480-2487.