Nanofysiikka
FYS-1350
Ilpo Vattulainen
Department of Physics, Tampere Univ of Tech
E-mail: Ilpo.Vattulainen@tut.fi
Center of Excellence in Biomembrane Research (Academy of
Finland 2014-2019)
The Biological and Soft Matter Physics Group
www.tut.fi/biophys/
Course home page:
butler.cc.tut.fi/~vattula2/
Literature
Ben Rogers & Sumita Pennathur & Jesse Adams:
Nanotechnology – Understanding Small Systems
(CRC Press / Taylor & Francis)
This book is essentially the material of the course.
Additional material includes these lecture notes, if you consider
them useful.
Outline of the course
•  Principles of the Small World
•  Introduction to Miniaturization
•  Introduction to Nanoscale Physics
•  Nanomaterials
•  Nanomechanics
•  Nanoelectronics
•  Nanoscale Heat Transfer
•  Nanophotonics
•  Nanoscale Fluid Mechanics
•  Nanobiotechnology
Some practical matters
•  Lectures on Tuesdays at 10 am – 12 am (2 hours / week) (S2)
•  Exercises on Tuesdays at 2-4 pm & on Fridays at 12 – 14 hours (SJ204)
Exercises:
•  Contact person: Joni Vuorio (joni.vuorio@tut.fi)
•  They give up to 6 additional points for the exam
•  Joni will grade/check all/some of the answers
•  Return your exercises (those you have completed) to Joni by Monday 12 am of the
corresponding week
Exam:
•  Exam will reflect the exercises together with other issues
Why nano? Size of molecules
What is the size of typical molecules?
Benjamin Franklin estimated that in the 18th century as follows.
Olive oil of given quantity was found to cover the same area of water when
spread on it: a tea spoon of oil (about 5 cm3) covered about 2000 m2.
Assuming a one-molecule thick (mono)layer, the linear size of a molecule
would be about 2.5 nm.
Where is physics?
Diffusion of a protein in the plane of a lipid
membrane
Physics – understanding the physical
principles that govern any system
Main strategy:
Simplify the systems and problems as
much as possible and neglect all
unimportant details
Having done that, one has a model which
is simple enough to understand its key
properties
”Describe your mother-in-law by a
sphere”
Protein diffusion described in terms of a
random walk of a colloidal particle, all
atomistic details of the protein being
being irrelevant.
Solids, soft matter, liquids, gas
University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
artment of Applied Physics, Aalto University, FI-00076 Aalto, Finland
pounds, Russian Academy of Sciences, Bolshoi Prospect 31, V.O., St. Petersburg 199004, Russia
cs, Faculty of Physics, St. Petersburg State University, St. Petersburg 198504, Russia
University of Technology, P.O. Box 692, FI-33101 Tampere, Finland
mistry, Nanoscience Center, University of Jyvas̈ kyla,̈ FI-40014 Jyvas̈ kyla,̈ Finland
(MEMPHYS), University of Southern Denmark, Odense DK-5230 Denmark
D-52425 Jülich, Germany
From bulk to smaller scales
hemically inert as a bulk material,
ul side effects to living organisms. In
les (AuNP+) of 2 nm diameter or less
membranes and induce cell death. We
tionic Au nanoparticles interacting with
t solvent using a model system that
ents, extracellular and cytosolic, divided
. The membrane−AuNP+ binding and
es are discovered to be governed by co+
1: Visualization
of Au leaflets
nanoparticles.all
(a) The
cationic Au144 (SRNH
)60 andextracellular
(b) the anionic
3 the
ounterions, water, and theFigure
two
membrane
contribute.
On
side, we
–
Au144 (SRCOO )60 , where R = C11 H22 . Color code: Au (core), gold; Au (interface), orange; S,
ross a free energy barrier ofgreen;
about
5 katom),
forming
a H,stable
C (united
grey; N, blue;
O, red; and
white. contact with the membrane. This
BT prior
witterionic lipids and nanoparticle side groups in the contact area, giving rise to the initial stage
placing the AuNP inside the box, the box was filled with water, and 60 counter-ions were added for
A sense of scales
2 ◾ Nanotechnology
TABLE 1.1
Units of scales
Some Prefixes for SI Units
yotta (Y)
zetta (Z)
exa (E)
peta (P)
tera (T)
giga (G)
mega (M)
kilo (k)
hecto (h)
deka (da)
deci (d)
1024
1021
1018
1015
1012
109
106
103
102
10
10−1
1 septillion
1 sextillion
1 quintillion
1 quadrillion
1 trillion
1 billion
1 million
1 thousand
1 hundred
1 ten
1 tenth
centi (c)
10−2
1 hundredth
milli (m)
10−3
1 thousandth
micro (μ)
nano (n)
10−6
1 millionth
10−9
1 billionth
pico (p)
10−12
1 trillionth
femto (f )
10−15
1 quadrillionth
atto (a)
10−18
1 quintillionth
zepto (z)
10−21
10−24
1 sextillionth
yocto (y)
1 septillionth
Typical length scales
Heino ja Vuento: Solubiologia (2002)
Typical time scales
Fluctuations of bonds
over times scales
~1fs
Collisions of small
molecules in a liquid
separated by
~1 ps
Decay of velocity
correlations
~1 ps
Macroscopic motion
to be observed takes
place over time scales
of t = l2 / D, l being
~200 nm, and D for
water ~10-9 m2 / s.
Then t is about
~40 µs
Protein folding
•  short peptides
~100 µs
•  short proteins
~1s - minutes
Lifetime of a cell
~ days (or longer)
There is no single time scale
but a variety of different ones
that all are relevant.
The time scale, or its
relevance depends on the
process in question.
Overall, the question is about
a multiscale problem where
different processes should be
looked at over distinct time
scales whose choice depends
on the phenomenon one
aims to address.
Big Picture and Principles of the
There is plenty of room at the bottom
"There's Plenty of Room at the Bottom"
was a lecture given by physicist Richard
Feynman at an American Physical
Society meeting at Caltech on
December 29, 1959. Feynman
considered the possibility of direct
manipulation of individual atoms as a
more powerful form of synthetic
chemistry than those used at the time.
The talk is considered to be a seminal
event in the history of nanotechnology,
as it inspired the conceptual beginnings
of the field decades later.
- Wikipedia
pico (p)
10
1 trillionth
femto (f )
10−15
1 quadrillionth
atto (a)
10−18
1 quintillionth
10−21
10−24
1 sextillionth
zepto (z)
yocto (y)
Nanotechnology
1 septillionth
The word “nanotechnology” was first used in 1974 by Norio Taniguchi in a paper titled
“On the Basic Concept of Nano-Technology” (with a hyphen) (Taniguchi, 1974). He wrote:
In the processing of materials, the smallest bit size of stock removal, accretion or
flow of materials is probably of one atom or one molecule, namely 0.1–0.2 nm in
length. Therefore, the expected limit size of fineness would be of the order of 1 nm.
. . .“Nano-technology” mainly consists of the processing . . . separation, consolidation and deformation of materials by one atom or one molecule.
By the 1980s, people were regularly using and spreading the word “nanotechnology.”
The late Richard Smalley (Figure 1.1), who shared the 1996 Nobel Prize in Chemistry
with Harry Kroto and Robert Curl, was a champion of the nanotech cause. In 1999 he told
Congress that “the impact of nanotechnology on the health, wealth, and lives of people will
be at least the equivalent of the combined influences of microelectronics, medical imaging,
computer-aided engineering and manmade polymers” (full written statement available at
http://www.er.doe.gov/bes/House/smalley.htm). Many scientists share Smalley’s bullish
assessment.
Nanotechnology has ambitiously been called the next industrial revolution, a wholly
different approach to the way human beings rearrange matter. People have always tinkered
with what the earth has to offer—there is nothing else with which to work. Technology is
in many respects just the rearrangement of chunks of the Earth to suit our needs and our
Fullerene
Big Picture and Principles of the Small World ◾ 3
Richard Smalley. Until 1985, graphite and diamond were believed the only naturally
occurring forms of carbon. Then Dr. Smalley, Harold Kroto, James Heath, Sean O’Brien, and Robert
Curl discovered another one. It was a soccer-ball-type arrangement they called buckminsterfullerenes (“buckyballs,” for short) after Richard Buckminster Fuller, the renowned architect credited
with popularizing the geodesic dome. Similar molecules were soon discovered, including nanotubes. These new forms of carbon are called fullerenes. (Photo used with permission of Dr. Richard
E. Smalley and Rice University.)
FIGURE 1.1
wants. And the Earth is nothing more than atoms. Ever since we dwelled in caves, we have
put atoms over fires to heat them, bashed them against rocks to regroup them, and
swallowed them for lunch. We just did not know about them, and we certainly could not
see them, nor control them one at a time.
Those days are over.
1.1 UNDERSTANDING THE ATOM: EX NIHILO NIHIL FIT
Take a block of gold. If we slice the block in two, it is still gold. Half it again, and again, and
Kroto, Smalley, Curl
Nobel Prize in Chemistry in 1996
Nanomaterials
Big Picture and Principles of the Small World
◾ 23
$2500
Price per Gram
$2000
$1500
$1000
$500
$1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
2007 2008
2009
2010 2011
Year
FIGURE 1.11 Carbon nanotube prices over time. Nanotube production processes originally devel-
Carbon nanotube prizes in time
oped at Rice University were later used for production and sale of nanotubes by Tubes@Rice (1998)
and subsequently by Carbon Nanotechnologies Incorporated (CNI). The price shown is for a single
gram of pure, single-walled nanotubes (SWNTs). All data for 1998–2006 are from Tubes@Rice and
CNI. The 2011 data point ($97) is the average price of a single gram of >90% pure SWNTs from
three suppliers—Nano-C, mknano, and CheapTubes.
Nanotechnology is the epitome of bottom-up engineering.
The STM belongs to a family of versatile, small systems tools called scanning probe
microscopes (SPMs). Figure 1.5 shows a ring of atoms arranged and imaged using an STM.
This tool is a great example of a small system that bridges the gap between size scales—it
has microscale parts used to do nanoscale work. We learn more about the STM later.
Masses of atoms
BACK-OF-THE-ENVELOPE 1.2
How much does an atom weigh?
This prompts another question: which kind of atom? The Periodic Table has 116 different
elements in it. Each atom has a different number of protons and neutrons, and so their atomic
masses are different. Also, since atoms are so minute, we often perform atomic computations
using large groups of them. One particularly useful group is called a mole (mol), which consists
of Avogadro’s number, NA, of whatever one is counting—atoms, molecules, apples. Avogadro’s
number is 6.02 × 1023. It is defined as the number of carbon-12 atoms in exactly 12 g. Therefore,
12 g/mol is the atomic mass of carbon-12. The atomic mass of lead is 207 g/mol, and that of
aluminum is 27 g/mol.
To determine the mass of a single atom, divide the atomic mass by Avogadro’s number:
Mass of 1 aluminum atom =
27 g/mol
= 4.5 × 10−23 g/atom
NA
So, an aluminum atom weighs 45 yoctograms.
Big Picture and Principles
of the Small World
Can we see individual
atoms?
◾ 9
FIGURE 1.5 IBM’s Quantum Corral. In 1993, a ring of 48 iron atoms was arranged one at a time
(four steps are shown) on a copper surface using the tip of a low-temperature STM. (We will learn
more about the STM in Chapters 5 and 6.) The STM was then used to capture an image of the ring,
McLellan tediously did just that, using tweezers and a microscope, within four months of
the speech. The motor had 13 parts, weighed 250 μg, and rotated at 2000 rpm. Feynman
had been home from his honeymoon less than a week when he had to explain to his wife
Atoms used in printing a book
BACK-OF-THE-ENVELOPE 1.4
What does fitting the Encyclopedia Britannica on a pinhead entail?
The head of a pin measures about 1/16th of an inch across; therefore,
2
⎛ 0.0625 ⎞
Area = π ⎜
= 0.00307 in.2
⎟
⎝
2 ⎠
The Encyclopedia Britannica has approximately 30 volumes and each volume has about
1000 pages, each measuring 9 in. × 11 in. Thus,
Area = (30)(1000)(9)(11) = 2,970,000 in.2
A pinhead large enough to fit the regular-sized Encyclopedia Britannica would need to
have a diameter X times bigger than a real pinhead:
2
⎛ 0.0625X ⎞
Area = π ⎜
= 2, 970, 000 in.2
⎟
⎝
⎠
2
Solving for X shows that the encyclopedia would need to be about 32,000 times smaller
in order to fit on the head of a pin. Is that feasible? The diameter of the dot on an “i” in a fine
printing of a book is about 1/120 of an inch wide (which, by the way, is about the smallest
feature the human eye can resolve). If that dot is reduced 32,000 times, it would be about
7 nm across. In an ordinary metal, an atom is about 0.25 nm in diameter, so the dot would be
about 28 atoms wide. The whole dot would contain about 1000 atoms. So there are definitely
enough atoms on the head of a pin to accommodate all the letters in the encyclopedia.
For nano, water is different
Legos of living systems
Lipids
ATP
DNA
Sugars, e.g., glucose
Proteins
Water
Nano in biology
5 nm
10 µm
7 nm
1m
~20 nm
Nano in health
Enzymes acting on lipids in a cell membrane
Enzyme PLA2
hydrolyses
one bond,
thus breaking
the lipid into
two pieces
23
Nano in health
24
Nano in health
25
Nano as a threat
”For a fibre to be harmful, it has to be thin,
long and insoluble in the lung”
Ken Donaldson
UNIVERSITY OF EDINBURGH
Carbon nanotubes (top) show similarities
with asbestos (bottom).
Carbon nanotubes, the poster child of the
burgeoning nanotechnology industry, could
trigger diseases similar to those caused by
asbestos, a study suggests.
http://news.bbc.co.uk/2/hi/7408705.stm
Nano as a threat
This transmission electron microscope image
shows carbon nanotubes (dark areas) within a
cell nucleus.
For the first time, scientists
have directly imaged carbon
nanotubes entering and
migrating within human cells,
determining as a result that
whether the nanotubes cause
cell death depends on the dose
and exposure time. The work,
published in the October 28
online edition of Nature
Nanotechnology (2007), may
lead to better ways of
determining carbon nanotubes'
toxicity to humans.
This study is the first to show definitively that carbon nanotubes have the
ability to cross into the cytoplasm and nucleus of a cell.
Atomic hypothesis & Boyle’s law
Dimensional analysis can be employed to find that the product of
pressure and volume, also, corresponds to energy:
[ p ] = force/area
[ V ] = length3
[ p V ] = force × length = energy!
In dilute gases this leads
to the equation of state
pV = N kB T
Physically, this equation is beautiful! (Think it over)
More generally at room temperature of T = 295 K,
kB T ≈ 4 pN nm.
Forces in nanoscale
Overstretching of dsDNA:
Wenner et al.
Biophysical J. 82, 3160 (2002)
See also the M.Sc. Thesis by
Olli Punkkinen (2004)
Forces in nanoscale
Force = energy / distance
Given that the scales in biomolecular systems are dictated by the thermal energy and
the nanoscopic regime, one has
f ≈ kBT / 1 nm ~ 4 pN
Forces are thus of the order of piconewtons.
Examples of interactions:
- hydrogen bonds
~3 - 8 kBT
- ionic bonds
~8 - 21 kBT
- electrostatic int.
~depends
- van der Waals
~1 - 2 kBT
- covalent bonds
~170 kBT
Overstretching of dsDNA:
Wenner et al. Biophysical J. 82, 3160 (2002)
kBT = 4.12 x 10-21 J = 25.7 meV (around 300 K)
For nano, gravity is not a big deal
Gravitational force acting on an aluminum atom?
Mass
m = 4.5 x 10-23 kg
Force
F = mg = 4.5 x 10-22 N
Energy required to displace the atom by a distance of L = 1 nm:
W
= F x L = 4.5 x 10-22 N x 10-9 m
= 4.5 x 10-31 J
That is negligible compared to thermal forces/energies.
kBT = 4.12 x 10-21 J = 25.7 meV (around 300 K)
Lengths in nanoscale
Alternatively we may extract the scale of force from experiments, that is pico-Newtons.
Also we may take it for granted that the energy scale is obviously given by kBT.
Then
Length scale = energy / force
Given that the scales in biomolecular systems are
dictated by the thermal energy and
pico-Newtons, we find
length ≈ kBT / 1 pN ~ nm
Length scale in biomolecular processes is
of the order of nanometers.
kBT = 4.12 x 10-21 J = 25.7 meV (around 300 K)