Download Nanotechnology & Nanobiotechnology

Nanotechnology & Nanobiotechnology
Nanotechnology, in simple terms, means the study and exploitation
of tiny objects, whose dimensions are just a few molecules and
atoms. In strict scientific terms, nanotechnology concerns physical
dimensions ranging from 1-100 nm (1 nm = 10-9 m = 10 atoms
wide) down to 1 nm.
Nanobiotechnology is the application of nanotechnology to the life
sciences:
The technology encompasses precision engineering as well as
electronics, and electromechanical systems as well as mainstream
biomedical applications in areas as diverse as gene therapy, drug
delivery and novel drug discovery techniques.
LEADING SEGMENTS IN NANOBIOTECHNOLOGY
Demand for more advanced technologies and
innovations in nanomaterials have created three
major segments within nanobiotechnology:
Drug delivery
Biosensors
Imaging agents
Drug Delivery
Till early 1970, drugs were delivered to the human body
exclusively via oral and intravenous (靜脈內的) means.
Disadvantages:
1. High doses of drug cannot be injected into the body at one
time.
2. Intravenous (靜脈內的) delivery leads to high concentration of
drug into the blood stream and can create toxic side effects.
3. Only a very small percentage of the injected drug reaches the
affected area in the body and hence multiple injections are
often required for effective treatment.
Construct of the drug :
Delivery vehicle & Method of administration
New Drug Delivery Vehicles:
1. Organic and synthetic polymers, and other chemical
constructs that can release drugs at a sustained rate, or
release them only in certain environments
2.
Liposome
New Methods of Administration:
1. Medicated skin patches
2. Implanted devices that can release drugs with an
external remote control
3. Powder forms of traditional drugs which can be inhaled
and absorbed through the lungs.
Liposomes encapsulate active drugs to
improve their delivery. Depending on
the construction of the liposome, the
active drug can be carried within its
layers or in the hallow space created
by the encapsulation. Liposomes
mimic the natural phospholipid cell
membranes in the human body.
The immune system, which seeks out foreign material for
destruction, can be a major obstacle to liposomes. In 1992,
researchers discovered that coating liposomes with inactive
polymers, such as polyethylene glycol (PEG), drastically
increased the liposome's ability to evade recognition by the
immune system.
The main mechanism of a liposome is simply fusing to the
cell membrane or through endocytosis.
Drug Delivery Systems in Development
The creation of vehicles or constructs that can target the
disease tissue more accurately:
Smart Drugs – are designed to work only when activated by
certain components in the body. For example, a smart drug
designed to be activated by a certain enzyme will be activated
only in tissues that produces that specific enzyme.
Monoclonal Antibodies – These are antibodies (抗體) made
in the lab that can target antigens (抗原) with extreme
specificity. They are attached to a drug in order to guide it to a
specific cell. For example, cancer drugs can be attached to
monoclonal antibodies made against tumour cells, which
helps the drug target only tumour cells. This reduces the toxic
effects of cancer drugs.
Antibody (抗體) & Antigen (抗原)
Antibodies (ab) are proteins that attach to foreign material in the
body (such as bacteria and viruses) and are released by certain
cells of the immune system. They "mark" these foreign material
for removal or destruction by other components of the immune
system.
Any foreign substance that can make the immune system
release antibodies is called an antigen (ag). For example, a flu
virus is an antigen because it makes the immune system
release antibodies.
Antibodies are unique because they are made in response to
specific antigens. In fact, antigens and antibodies fit like puzzle
pieces. For example, a particular type of flu virus prompts the
immune system to produce antibodies that fit that particular type
of flu virus.
ab + ag = ab-ag
Biosensors
Biosensor = bioreceptor + transducer
(Transducer)
Transducer: a device that transfers or translates energy from one
kind of a system to another. For example, a transducer can
transfer a thermal signal into an electrical signal.
Bioreceptor is a biomaterial or a biomimic that recognizes the target
analyte:
tissue, microorganisms, organelles, cell receptors, enzymes,
antibodies, nucleic acids etc.
Transducer or transducing microsystem converts the recognition
event into a measurable signal :
optical, electrochemical, thermometric, piezoelectric or magnetic.
Specific interactions between the target analyte and recognition sites
within the bioreceptor produces a physico-chemical change which is
detected and may be measured by the transducer.
In principle, any biomolecule or molecular assembly that has the
capability of recognizing the analyte can be used as a bioreceptor.
Specificity
-remarkable ability to distinguish between the analyte of interest and
similar substances.
-measure specific analytes with great accuracy.
Speed
-the analyte tracers or catalytic products can be directly and
instantaneously measured.
-no need to wait for results from lengthy procedures carried out in
centralised laboratories.
Simplicity
-one single sensor.
-enables the measurement of target analytes without using reagents.
For example, the glucose concentration in a blood sample can be
measured directly by a biosensor (which is made specifically for glucose
measurement) by simply dipping the sensor in the sample. This is in
contrast to the conventional assay in which many steps are used and
each step may require a reagent to treat the sample.
Continuous monitoring capability
-can regenerate and reuse the immobilized biological recognition
element. For enzyme-based biosensors, an immobilized enzyme can be
used for repeated assays
Applications of Biosensors
-Clinical diagnosis and biomedicine
-Farm, garden and veterinary analysis
-Process control: fermentation control and analysis
-Food and drink production and analysis
-Microbiology: bacterial and viral analysis
-Pharmaceutical and drug analysis
-Industrial effluent control
-Pollution control and monitoring
-Mining, industrial and toxic gases
-Military applications
Imaging agents
Magnetic Resonance Imaging (MRI)
Near-Infrared Fluorescence Imaging
(NIRF) Combined with MRI
Drug Discovery
Rapid Ex-Vivo Diagnostics
Lipid Rafts
 Domains enriched in cholesterol (膽固醇) and sphingolipids
 Lipid rafts are thought to be in liquid-ordered (lo) phase
( lo-phase lipid “island” floats in the lc-phase lipid “sea”.)
Lipid rafts are postulated to be very important in signal transduction
in cells (as signaling platforms, for example).
Size of raft domain: 0 - 700 nm
Fraction of lipid rafts in cell membranes
Raft marker
Yuan et al., 2002