NANOTECHNOLOGY THE BIG FUTURE TECHNOLOGY OF THE VERY SMALL THE HYPE AND THE REALITY

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NANOTECHNOLOGY THE BIG FUTURE TECHNOLOGY OF THE
VERY SMALL THE HYPE AND THE REALITY

• . THE HYPE
• a) THE IMPORTANCE OF MATERIALS THROUGH THE AGES.
• b) THE HYPE ABOUT NANOMATERIALS AND ITS ORIGION
• SOME NANO-MATERIALS MADE SOME PROPERTIES AND
  POTENTIAL APPLICATIONS
• GOLD PROPERTIES AND SOME APPLICATIONS.
• POTENTIAL DIFICULTIES

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THE HYPE about nanotechnology!!
IT IS TO GIVE US MANY NEW MATERIALS
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TECHNOLOGY THROUGHOUT HISTORY IMPORTANCE OF
MATERIALS THE STONE AGE THE BRONZE AGE
THE IRON AGETHE INDUSTRIAL REVOLUTION (steam
engine, motor)THE 20TH CENTURY TECHNOLOGY AGE
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THE TECHNOLOGY AGE

• SOLID STATE SEMICONDUCTOR (Computers, 1960)

• POLYMERS (First human made industrial material).
• LASER REVOLUTION (1960)
• SOLID STATE SEMICONDUCTORS (Computers, 1960)
• BEGINNING OF NANOTECHNOLOGY (TECHNOLOGY BASED ON
  MATERIAL MADE OF NANOPARTICLES, 1980)

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MATERIAL DETERMINES SOCIETYS QUALITY OF LIFE
MAKING OR FINDING NEW MATERIALS
Some have useful properties
These open new industries
Enhance economy (Jobs) and health (Drugs)
Increase the quality of Life
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Why DOES MAKING MATERIALHAVING NANOMETER
SIZE SPECIALLY EXCITING?

• AS THE SIZE OF ANY MATERIAL DECREASES TO 1-100nm,
  ITS PROPERTY CHANGES AS ITS SIZE OR SHAPE
  CHANGES.
• THUS EVERY MATERIAL CAN GIVE US MANY DIFFERENT
  MATERIALS EACH WITH ITS OWN PROPERTIES WHEN ITS
  SIZE IS IN THE 1-100 NANOMETER SIZE RANGE.
• THIS SHOULD INCREASE THE NUMBER OF COMPANIES AND
  JOBS, THUS ENHANCES THE COUNTRYs ECONOMY.

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Nanotechnology Small things, but huge impacts
(Business Hype)

• Will impact nearly EVERY industry
• (Chemicals, Computing, Storage, Power, Energy,
  Biotech, Pharmaceuticals,
• Manufacturing, Transportation)
• Market Size Predictions
• 340B Materials
• 300B Electronics
• 180B Pharmaceuticals
• 100B Chemical Manufacture
• 70B Aerospace
• 20B Tools
• 30B Improved Healthcare
• 45B Sustainability______________
• 1 Trillion over next 10-12 years
• Sources James Murday, Mike Roco, NanoBusiness
  Alliance, CMP-Scientific

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January 21, 2000 - President Clinton announces
500M initiative on nanotechnology
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How small is one nanometer(one Billionth of a
meter)
If we use a scale in which the size of an Orange
Is ONE nm, the size of the earth would be 1/3
METER
EARTH
AN ORANGE
1 nm
1 ft(1/3 METER)
OR
1 nm/1/3 meterthe size of an orange/the size of
the Earth
The Width of a Human Hair is 50,000 nm
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THE SCIENTIFIC ORIGIN OF THE HYPEABOUT
NANOTACHNOLOGY
WHY DO MATERIAL CHANGES PROPERTIES WHEN ITS SIZE
IS REDUCED TO LESS THAN 100 nm ?
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WHY NANOMETER

• THE PROPERTIES OF MATERIAL ARE DETERMINED BY THE
  SPACE AVAILABLE FOR THEIR ELECTRONS TO EXECUTE
  THEIR CHARACTARISTIC MOTION
• THIS SPACE IS ON THE NANOMETER LENGTH SCALE
• CHANGING THE MATERIAL SIZE OR SHAPE AROUND THIS
  SPACE CHANGES ITS PROPERTIES AND MAKE IT
  SENSITIVE TO FURTHER SIZE AND SHAPE.
• THUS ON THE NANOMETER LENGTH SCALE, EVERY
  MATERIAL CAN GIVE US MANY NEW MATERIALS WITH
  DIFFERENT PROPERTIES (THUS NEW INDUSTRIES!!!
  THUS ONE REASON FOR THE HYPE.)

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WHAT DOES IT MEAN THAT THE PROPERTIES OF
MATERIAL CHANGE AS ITS SIZE DECREASES TO THE
NANOMETER SCALE?
1gm of Chocolate
This 1gm of Chocolate Would make 1 billion
(1000,000,000) piles of nanometer pieces Each
pile will have 1 billion NANOPARTICLES
1cm
1cm
1cm
The total weight of all the nanometer particles
we made is still 1gm though the taste may no
longer be sweet and may even taste bitter or make
us sick or healthy,we need to find out,i.e. do
nanoscience !!!
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ANOTHER REASON FOR THE HYPE MIGHT SOLVE THE
PROBLEM OF THE LIMITATION ON THE FUTURE SIZE OF
THE ELECTRONIC DEVICES
Moores law the density of devices on a chip
doubles every 18 months DUE TO THE DECREASE OF
THE SIZE OF THE TRANSISTOR.
HOW MUCH INFORMATION CAN WE STORE ON THIS SIZE
SCALE ?
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NATURE WORKS ON THE NANOMETER SCALE !

• 1. PROTEINS AND DNA HAVE NANOMETER SIZES.
• 2. EVERY FUNCTION IN OUR BODY THAT IS KEEPING US
  ALIVE TAKES PLACE ON THE NANOMETER SCALE.

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NANO-Bio-inspired materials and genetic
engineered manufacturing
SiO2 structures in nature
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NANOSCIENCE THE MAKING AND STUDYING THE
PROPERTIES OF NANOSTRUCTURES. NANOTECHNOLOGY
IS MAKING USE OF A PROPERTY OF NANOPARTICLES
THAT NANOSCIENCE DISCOVERED FOR HUMAN USE
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SOME OF THE NANOPARTICLESARE MADE
BY1.bottom up (combining ions, atoms or
molecules to give clusters and nanoparticles)
or2.top down breaking material into nano
size particles ( lithography).
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SYNTHESIS OF NANO-PARTICLES, Summary
A. COLLOIDAL BOTTOM UP 1.REDUCTION OF METAL
IONS OF SOLUBLE SALT TO MAKE METALLIC
NANOPARTICLES. 2.PRECIPITATION OF SMICONDUCTOR
NANOPARTICLES e.g by mixing soluble Cd salt or
oxide with Se compounds In Presence of capping
material to control size to keep them in
solution. 3.CONDENSATION FROM THE VAPOR e.g.
ZnO B. TOP DOWN TECHNIQUES 1.ELECTRON BEAM
PHOTO- LITHOGRAPHIC METHODS. 2.MILLING OR
SPIN-COATING TECHNIQUES.
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SYNTHESIZED NANOPARTICLES OF DIFFERENT SHAPES
BOTTOM UP TECHNIQUE
Synthesized by El-Sayed, Mirkin, Lieber, and Wang
groups
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STM IMAGE OF IRON ON COPPER (III)(TOP DOWN
TECHNIQUE)
http//www.almaden.ibm.com/vis/stm/corral.html
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ELECTRON BEAM LITHOGRAPHY THE SYNTHESIS OF GOLD
NANOPARTICLES OF DIFFERENT SHAPES(TOP DOWN
TECHNIQUE)
SPHERICAL
DISK SHAPE
PRISMATIC
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WHY ARE WE NOW ABLE
TO MAKE SEE THESE
SMALL MATERIALS ?
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DEVELOPMENT OF INSTUMENTS THAT SEE or FEEL ATOMS
e.g. SEM, TEM AND HRTEM.
http//www.mse.gatech.edu/academics/facilities/CNC
/cnc.html
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IMAGING VIRUSES INFECTING CELLS
http//www.lifescience.de/download/special_nanotec
h_150.pdf
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WHAT HAPPENS TO DIFFERENT MATERIALS WHEN THEIR
SIZE IS REDUCED TO THE NANO-METER SCALE?

• 1. SEMICONDUCTORS Electronic Quantum Confinement
  makes their absorption emission sensitive to
  size and shape ,(useful in biological tagging).
• 2. CARBON NANO-TUBES STRONGER THAN STEEL AT 1/6
  THE WEIGHT(USED TO STRENGTHEN MATERIALS)ALSO
  BETTER CONDUCTOR THAN COPPER (NANO CIRCUITS)
• 3. TRANSITION METALS(Pt, Pd,..)Increase in
  Surface to Volume Ratio for 1 cm3,one in 10
  million atoms is on the surface but for 1 nm3 ,
  85 of the atoms are on the surface ( Good for
  Nano-Catalysis)).
• . 4. PLASMONIC METALS(Au,AgCu)Electronic
  Surface Plasmon Oscillations Strong Surface
  Fields leading to Strong ABSORPTION, SCATTERING
  AND PHOTO-THERMAL PROPERTIES (USED IN MANY
  APPLICATIONS,SOME GIVER LATTER)

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Carbon Nanotubes on many Covers
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SOME INDUSTRIAL USES OF NANOPARTICLES

• MADE MANY MATERIAL BETTER AND STRONGER
• 2. DRUG DELIVERY.
• 3. BETTER SOLAR CELLS
• 4. OPENED UP THE FIELD OF NANO-PHTONICS.
• 5. MEDICAL DIAGNOSTICS THERAPY SOON.
• (In the US,10s of Billions of industry
  annually, GM used 0.5Million Pounds of
  nanoparticles in 2005)

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POSSIBLE APPLICATIONS IN BIOLOGYMEDICINE
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Optical Properties of Semiconductor
Nanoparticles (CdSe Quantum Dots )
ABSORPTION
EMISSION
size 2.3 nm ? 470 nm
size 5.5 nm ? 620 nm
Bawendi, M. G. et al. J. Phys. Chem. B 1997, 101,
9463. Hines, M.A. Guyot-Sionnest, P. J. Phys.
Chem. B. 1996, 100, 468.
Murray, C.B. Norris, D.J. M. Bawendi, M.G. J.
Am. Chem. Soc. 1993, 115, 8706
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Semiconductor Nanoparticles Are Excellent
Fluorophores for Biological Staining and
Diagnostics
Blue CdSe 2.1 - 4.6 nm Green InP 3.0 - 4.6
nm Red InAs 2.8 - 6.0 nm
Alivisatos A. P. et-al, Science, 281, 2013, 1998
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WHAT USEFUL THINGS WE CANIMAGINE TO MAKE
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NANO-WIRE SENSOR
Schematic of an integrated nanowire sensor
Elibol, O.H. Morisette, D. Akin, D. Denton, J.
P. Bashir, R., Appl. Phys. Lett., 2003, 22,
4613.
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Detection of protein binding/cancer cells using
a nanowire

(C.M. Lieber, Harvard)
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HYPOTHETICAL DRUG DELIVERY SYSTEM
A hypothetical magnetic drug delivery system in
which a magnet is placed outside the body so
that its magnetic field gradient could capture
magnetic carriers in the circulatory system
Pankhurst, Q. A. Connelly, J. Jones, S. K.
Dobson, J., J. Phys. D. Appl. Phys., 2003, 36,
R167.
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MORE APPLICATIONS USING GOLD NANO-PARTICLES NEXT
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GOLD NANO-PARTICLES
METALLIC GOLD IS MORE PRECIOUS ON THE NANO-SCALE
.
MOSTAFA EL-SAYED LASER DYNAMICS LAB GEORGIA
TECH,ATLANTA (http//ldl.gatech.edu/)

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BULK GOLD IS PRECIOUS BECAUSE IT DOES NOTHING (it
does not tarnish i.e. it does not react )
Death Mask of Tutankhamun 1325 B.C.
Tutankhamuns coffin
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METALLIC GOLD IS MORE PRECIOUS ON THE NANO-SCALE

• NANOGOLD IS PRECIOUS BECAUSE IT DOES MANY MANY
  THINGS IN ADDITION TO CATALYSIS, SOME OF WHICH WE
  WILL DISCUSS TODAY.

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OPTICAL PROPERTIES OF GOLD NANOPARTICLES
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GOLD NANOPARTICLES ABSORB AND SCATTER LIGHT VERY
STRONGLY (Used In Old Times)
Lidded Vases, made in China, about 1730
NOTRE DAME PARIS, FRANCE
Padovani et al., J. Appl. Phys. 2003, 93, 10058 .
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1.STRONG ABSORPTION SCATTERING USED IN
IMAGING IN MEDICINE. 2.CHANGE OF COLOR AS
NANO-PARTICLES APPROACH ONE ANOTHER.
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APPLICATION OF THE OF ENHANCED EXTINCTION IN
VIVO Cancer Detection using A Cell Phone Camera
Making use of the Strong Gold Nanorod Light
Extinction Property
(AuNR OD800nm40 , 15 µL)
(10 mM PBS, 15 µL)
extinction
rods
- rods
Dickerson, E. B. Dreaden, E. C. Huang, X.
El-Sayed, I. H. Chu, H. Pushpanketh, S.
McDonald, J. F. El-Sayed, M. A. Cancer Letters
2008, 269, 57.
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CHANGE OF PARTICLE COLORS AS THEY GET CLOSER TO
ONE ANOTHER. Silver Nano-Cubes
B
A
C
E
D
F
A
B
SEM images of Silver nanocubes adsorbed on the
surface of quartz substrate, and prepared at
different surface pressure
M. A. Mahmoud, C.E. Tabor, and M. A. El-Sayed, J
Phys. Chem. C (ASAP)
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TUNING ABSORPTION BY INTER-PARTIICLE COUPLING
Gap 2 nm
Gap 12 nm
Gap 212 nm
Gap 27 nm
The diameter of the nanodisk is 88 nm, the
thickness is 25 nm.
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TUNING ABSORPTION BY INTER-PARTICLE COUPLING Au
nanodisc pair
EXPT CALCULATED BY DDA
E
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UNIVERSAL SCALING LAW IN PLASMONIC COUPLING
INDEPENDENT OF SIZE,SHAPE,TYPE OF METAL OR
DIELECTRIC CONSTANT
K. H. Su, Q.-H. Wei, X. Zhang, J. J. Mock, D. R.
Smith and S. Schultz, Nano Lett. (2003), 3, 1087
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THE PLASMONIC RULER EQUATION (USING THE
SCALING LAW TO DETERMINE THE DISTANCE BETWEEN
PLASMONIC NANOPARTICLES BOUND TO DIFFERENT SITES
IN BIOLOGICAL SYSTEMS
S SEPARATION OF NANO-PARTICLES D SIZE OF
NANOPAERTICLES 0.23 IS A UNIVERSAL CONSTANT K
IS A CONSTANT THAT DEPENDS ON THE METAL USED (Au
OR Ag)
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TESTING THE Plasmon Ruler Equation Applications
in Biology
s

P. Alivisatos al
Au
Au
B. M. Reinhardt, M. Siu, H. Agarwal, A. P.
Alivisatos and J. Liphardt, Nano Lett. (2005), 5,
2246. P. K. Jain, W. Huang and M. A.
El-Sayed, Nano Lett. (2007),7, 2080.
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2. STRONG SCATTERING USED IN IMAGING (BIOLOGY)
AND IN MEDICINE (DIOGNOSTICS
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DETECTION OF ONE CANCER CELL USING SCATTERING
FROM SELECTIVELY BOUND GOLD NANO-PARTICLES USING
A STUDENT MICROSCOPE
HaCaT noncancerous cells
HOC cancerous cells
HSC cancerous cells
Ivan El-Sayed,Xiaohua Huang,M.A.El-Sayed
Nanoletters ,4, 829,2005.
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3. Rapid Conversion of The Strongly Absorped
light into Heat Used in Selective Photo-Thermal
Therapy of Cancer
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SELECTIVE PHOTO-THERMAL DESTRUCTION OF CANCER
CELLS
HaCaT noncancerous cells
HOC cancerous cells
HSC cancerous cells
DIAGNOSIS
Ivan El-Sayed,Xiaohua Huang,M.A.El-Sayed,Nanolette
rs ,4, 829,2005.
HOC cancerous cells
HSC cancerous cells
HaCat noncancerous cells
SELECTIVE PHOTO- THERMAL THERAPY
25 W/cm2
19 W/cm2
57 W/cm2
X.HUANG,IVAN EL-SAYED,M.A,EL-SAYED,CANCER LETTER
, 2005
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DOES IT WORK In ANIMALS ?
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UNTREATD
TREATD
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SERIOUS PROBLEMS NEEDED TO BE SOLVED IN
NANOYECHNOLOGY

• .THE NANOSURFACE
• .CONTROLLING ATOM BY ATOM SYNTHESIS FACES
  CHEMICAL LAWS OF BONDING, I.e. WE WILL NOT BE
  ABLE TO MAKE EVERY THING WE WANT.
• .THE ASSEMBLY PROBLEM
• .MISMATCH BETWEEN OUR WORLD AND THE
  NANOWORLD. Problem of interface and interconnects
• .STABILITY OF MATERIALS SO SMALL
• .BUSSINESS IMPATIENCE.
• .TOXICITY !
• Conclusion A LOT OF SCIENCE (Nano-Science) IS
  NEEDED FIRST BEFORE MASSIVE NANOTECHNOLOGY

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New Optical Photo thermal properties and
Applications of Gold Nanoparticles of different
shapes, Co-workers
Dr. Stehan Link
Dr Ivan El-Sayed. M.D , UCSF
Dr Xiaohua Huang
Preshant Jain
Dr Susie Eustis
Dr. Wei Qian
Dr Wenyu Huang
Dr. Mona Mohamed
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GROUP PICTURE, SPRING 2007
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• Laws of Technology Development
• When a scientist states that something is
  possible, he/she is always certainly right. When
  he/she states that something is impossible,
  he/she is very probably wrong.

• The only way of discovering the limits of the
  possible is to venture a little way past them
  into the impossible

• Any sufficiently advanced technology is
  indistinguishable from magic.

- Arthur C. Clarkes Three Laws of Technology
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THE LASER DYNAMICS LABORATORY FAMILY GEORGIA
INSTITUTE OF TECHNOLOGY 2002
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DNA DETECTION METHODS
Many different nanoparticle based methods of
detecting DNA
Dr. Chad Mirkins website
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Hype and Public Concerns
Dont believe the hype Nanotechnologists are
increasingly concerned about the lurid
descriptions of the dangers of their work being
promulgated by environmental campaigners. But the
fields proponents arent helping their cause by
making exaggerated claims. 17 July 2003 Volume
424 Issue no 6946 Anyone who has given a public
lecture on nanotechnology has probably been asked
the question What about the grey goo? The
term, coined by the futurist Eric Drexler back in
the 1980s, describes the ever-growing mess of
self-replicating nanorobots as they consume the
environment and manufacture more of their own
kind. For researchers working on the science of
the incredibly small, this highly improbable
scenario has become a tiresome piece of
apocalyptic baggage. The tiresome may be about to
become genuinely threatening, however. Seasoned
environmental campaigners, fresh from bloodying
the nose of the biotechnology industry over the
issue of genetically modified (GM) crops, are now
eyeing nanotechnology as their next target (see
page 246). Some are even calling for a moratorium
on research in the field. And theyve cooked up a
new goo with which to scare the public the
marriage of nanotechnology and biotechnology to
create new forms of life that will behave in
unpredictable and uncontrollable ways,
threatening natural habitats, biodiversity and
human health green goo, as it has been dubbed
was formerly known as the Rural Advancement
Foundation International, which enjoyed
considerable success in its efforts to portray
Monsanto and other agribiotech companies as
enemies of the..  
17 July 2003
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NNI GRAND CHALLENGES

• Nanostructured Materials by Design
• Manufacturing at the Nanoscale
• Chemical-Biological-Radiological-Explosive
  Detection, and Protection
• Nanoscale Instrumentation, and Metrology
• Nano-Electronics, -Photonics, and -Magnetics
• Healthcare, Therapeutics, and Diagnostics
• Efficient Energy Conversion and Storage
• Microcraft and Robotics
• Nanoscale Processes for Environmental Improvement

National Nanotechnology Initiative (www.nano.gov)
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DIP-PEN NANOLITHOGRAPHY
Examples of potential applications of dip-pen
nanolithography
Dr. Chad Mirkins website
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BIO-NANO MATERIALS
Typical configurations used in bio-nano materials
for biological or medical applications.
Dunn, W., J. Nanobiotech., 2004, 2(3)
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NANOCLINIC
Magnetic Fe2O3 nanoparticles encapsulated in thin
silica shell and fluorescent dyes and
functionalized with luteinizing hormone-releasing
hormone (LH-RH) for magnetic cancer therapy by
targeting receptor-specific cancer cells
Levy, L. Sahoo, Y.Kim, K-S. Bergey, E. J.
Prasad, P. N., Chem. Mater., 2002, 14, 3715.
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BIOSENSOR
Nanoscale biotin-streptavidin based biosensor
Haes, A. J. Van Duyne, R. J., J. Am. Chem. Soc.,
2002, 124 (35), 10596.
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New properties of Metal Nanoparticles of
different shapes
Xiaohua Huang
Wenyu Huang
Radha Narayanan
Dr Ivan El-Sayed. M.D , UCSF
Dr. Mona Mohamed
Dr. Wei Qian
Dr. Stephan Link
Dr B. Nikobakht
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TISSUE ENGINEERING
Oppurtunities in micro/nano-mediated tissue
engineering
Bashir, R., Adv. Drug Deliv. Rev., 2004, 56, 1565.
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• How Can we write the entire 24 volumes of the
  Encyclopedia Brittanica on the head of a pin?
  (Feynman 1959)
• DNA stores a great amount of information
  regarding our make up in space on the nanometer
  scale
• The head of a pin (sixteenth of an inch across)
  has an area which is 1/25000 that of all the
  pages of the Encyclopedia.
• Thus we need to write the words on the pin that
  are 1/25000 the size of the words in the
  Encyclopedia
• Doing the calculations, the size of each letter
  on the pin will have to be written with hundreds
  of atoms
• Thus if we can control putting the atoms
  together,atom by atom, we can write all the
  information in the Encyclopedia on the head of a
  pin

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THE FLYING PRISMS ARE THINNER THUS THEY LOOSE
SURFACE ATOMS BY ABLATION
THE RAPID BUILD UP OF THE PRESSURE UNDERNEATH THE
PARTICLE GIVES IT THE IMPULSE THAT MAKES IT FLY
FLIGHT INFORMATION Load3.7 Femtogram
Pressuregt 105 atm. Initial velocity gt 3 10
miles/hour ) Lift off time gt 40 picosecond.
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PHOTO-THERMAL PROPERTIES OF GOLD NANOPARTICLES
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WHAT HAPPENS TO THE STRONGLY ABSORBED LIGHT BY A
GOLD NANOPARTICLE?

• RAPIDLY TRANSFORM INTO HEAT.
• Resulting in A HOT NANOPARTICLE THAT COOLS OFF
  BY
• A.Undergoing Oscillation (could be used in
  modulating light falling on it).
• B. ABLATION metal atom sublimation (leading to
  the flying of the nanoparticle).
• C. HEATING THE SURROUNDING ( used to kill
  attached cells,Phototherapy).

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A.LIGHT MODULATION BY THE COHERENT LATTICE
OSCILLATION OF GOLD NANOPARTICLES
b
a
c
OD
Monitoring
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DEPENDENCE OF THE MODULATION PERIOD ON SIZE
T is intensity of transmitted light
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B.THE USE OF THE PHOTO THERMAL PROPERTIES IN
MAKING
NANO-MOTORS
BY NANOPARTICLE ABLATION
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FLYING NANO-PRISMS FUELLED WITH GOLD ATOM
SUBLIMATION INDUCED BY ABSORPTION OF A
FEMTOSECOND LASER PULSE.
ON THE WAY TO FLY AWAY But could not make it
4.1 mj/cm2
SUCCESSFUL TAKE OFF!! 5.1 mj/cm2
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Todays business model for nanotechnology
Business Model Intellectual Property Land
Grab Mentality for IP
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Nanotechnology in our daily life
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Photon circuit for low power and fast computer

• Photons
• Travel 1000 times faster than
• electrons
• Generate no heat
• Very little power loss
• Fast switching

(C.J. Summers, MSE, Georgia Tech)
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Self-assembly of Co Magnetic nanocrystals for
possible ultrahigh density data storage
Wang et al., Adv. Mater., 12 (2000) 1944
25 nm
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OPTICAL BIOSENSING PRINCIPLE
Thiol-functionalized gold or silver nanoparticles
and increase in absorption spectra upon binding
of analyte
Frederix, F. Friedt, J-M. Choi, K-H. Laureyn,
W. Campitelli, A. Mondelaers, D. Maes, G.
Borghs, G., Anal. Chem., 2003, 75, 6894.
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Research areas that could result from the
integration of micro- and nano-scale systems and
biomedical sciences
Bashir, R., Adv. Drug Deliv. Rev., 2004, 56, 1565.