ISIS Report 31/03/08
ISIS Exclusive!
New Age of Water
Liquid Crystalline Water at the Interface
Just add sunlight for energy and life Dr. Mae-Wan Ho
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The most significant scientific discovery of this century
Why does water vaporized
into the sky form clouds instead of just spreading out evenly in space? Where
does lightning come from in a storm? How does Jello hold so much water inside
without it leaking out? How does the water bug walk on water?
If you never had your curiosity aroused by these natural phenomena that have
exercised generations of scientists still in search of a definitive answer,
try this.
Two identical beakers
are almost filled with water and placed next to each other with the rims touching.
The beakers of water are connected to a power pack and a current is passed
through a positive electrode placed in one beaker and the negative electrode
in the other. Instantly, a bridge of water forms between the beakers, looping
over the adjoining rims and connecting the two bodies of water. The beakers
are then moved apart slowly, the water bridge stretches and lengthens, but
remains intact, even when the beakers are separated by a gap of several centimetres.
And furthermore, the water bridge is still passing electricity from one beaker
to the other, like a stiff, transparent cable. There is no doubt that water
conducts electricity, as our readers will be aware [1] (Positive Electricity Zaps Through Water
Chains, SiS 28). But what
makes the water stiffen up to make a bridge?
The beginning of
an answer to all of these questions, and the key to many more surprisingly
phenomena readily demonstrated on the ordinary lab bench and some even on
the kitchen table, turns out to be “liquid crystalline water”, water that
is ordered and aligned like liquid crystals [2]. It gets my vote for the most
significant discovery of the present century so far. It also turns out that
liquid crystalline water and sunlight are practically all we need for energy
and life.
Water is one of the simplest chemical compounds (see Fig. 1). Yet its remarkable
‘anomalous’ properties have resisted all attempts at a consistent scientific
explanation; that is, until quite recently. A remarkable collection of dedicated
researchers on ‘interfacial water’ have been homing in on the secret of water
[3] (see New Age of Water series
(SiS 23, 24, 28, 32); and one of them may have just got it.
Figure 1. The water molecule with positive and negative
charges at opposite ends and how it could stack up with opposite charges next
to each other (courtesy of physicalgeography.net)
Bioengineer who loves water
Gerald Pollack, Prof. of
bioengineering, recently received the highest honour that the University
of Washington at Seattle in the United States could confer on its own staff.
He was to give the 2008 Annual Faculty Lecture on his research, entitled,
“Water, energy and life: Fresh views from the water’s edge”. I watched the
hour-long lecture via the video link [2] with great fascination.
I am no stranger
to Pollack’s work, having reviewed his book, Cells,
Gels and the Engines of Life [4] published in 2001 (see Biology of Least Action, SiS 18)[5]; and featured the amazing discovery
from his laboratory a couple of years later [6] (Water Forms Massive Exclusion Zones,
SiS 23).
What strikes me above all is the elegant simplicity of his experimental approach
that takes our understanding of the most abundant, most vital substance for
life on earth a quantum leap forward. Many of the experiments can be done on
the kitchen table, and you don’t even need a microscope to see the results.
Add to that a highly congenial and unassuming personality, and no wonder Pollack
is attracting undergraduates and graduates like flies, not to mention many collaborators
around the world.
EZ water is liquid crystalline
The initial discovery that
Pollack and his colleague Zheng Jian-ming reported in 2003 [6] was that water
forms a massive ‘exclusion zone’ (EZ) next to the surface of hydrophilic (water-loving)
gels. The EZ is so-called because it excludes solutes, i.e., substances dissolved
in the water. By putting into the water solutes large enough to be seen under
the microscope, or even with the naked eye, the EZ shows up as a region completely
clear of the solute. Thus, when a suspension of microspheres 0.5 to 2 mm in diameter is put into a chamber with the gel, a clear
zone, free of microspheres soon develops next to the gel and typically ends
up hundreds of microns thick (see Fig. 2). This EZ is stable if undisturbed,
for days and weeks once it is formed.
The scientific community greeted the initial discovery with much scepticism.
Interfacial water – water next to surfaces – is generally recognized as being
restricted in motion, relatively ordered, and having somewhat different properties
from water existing in the bulk. Using sophisticated techniques and big machines
such as NMR (nuclear magnetic resonance) X-rays, and more recently, neutron
diffraction, researchers have found no more than one or two layers that have
altered properties compared to bulk water [6]. But the EZ is so enormous that
at least hundreds of thousands of layers are involved.
Figure 2. Clear exclusion zone next to gel surface free
of microspheres
Gilbert Ling, doyen
of the breakaway biological water researchers, had long argued that all water in the cell (typically 70 percent
by weight) is ordered with very unusual properties [7] (see Strong Medicine for Cell Biology
[8], SiS 24). More recently,
Ling proposed on theoretical grounds that the ordered layers could extend
infinitely under ideal conditions [9].
Pollack and his team spent a year ruling out all kinds of artefacts and extended
their results, showing that the EZ of water is a very general phenomenon. What’s
more, it had been discovered as far back as a hundred years ago; only to be
consigned to oblivion after the ‘polywater’ controversy of the late 1960s, when
the claim of ‘polymerised’ water was finally attributed to contaminants [10].
Pollack’s team found that a wide range of hydrophilic gels gave EZ in water:
polyvinyl alcohol, polyacrylamide, polyacrylc acid, Nafion (used as a proton
exchange membrane in fuel cells), and biological tissues such as a bundle of
rabbit muscle or collagen [11]. In fact, a single layer of hydrophilic charged
groups coated on any surface is sufficient to give an exclusion zone. The requirement
is to have chemical groups that can form hydrogen bonds with water molecules.
Similarly, solutes need not be microspheres, they could be red blood cells,
bacteria [2], colloidal gold, and even molecules such as serum albumin labelled
with a fluorescent dye, and a fluorescent dye molecule as small as 200-300 daltons.
All of these are excluded from EZ water.
Most interestingly, EZ water was found at the air-water interface. The EZ layer,
thick enough to be seen easily with the naked eye, was sufficiently stiff to
be lifted up with a glass rod without breaking (Fig. 3). This readily explains
how the strong surface tension of the EZ layer allows water bugs to walk over
it without falling in. Also if such water forms next to hydrophilic surfaces
inside the Jello, it would not fall out. And, we can see how the water bridge
of EZ water could form between the separated beakers. Of course, an electric
field will improve the alignment of the water molecules and hence its crystallinity
and stiffness .
Figure 3. Glass rod lifts up stiff EZ layer at water
air interface
Now that EZ water can be
produced in bulk, it is easy to demonstrate other altered properties. NMR
measurements confirm that the layer is associated with decreased mobility
(increased ordering) relative to the bulk water, while infrared imaging showed
it emitted much less than bulk water, again indicative of increased order.
Pollack refers to EZ water as “liquid crystalline water”, and says it was in
fact biologist William Bate Hardy who first suggested almost a hundred years
ago that water molecules at the interface could exist in many layers approaching
crystalline order. This is very much in line with the discovery in my laboratory
that organisms and cells are liquid crystalline [12] (The
Rainbow And The Worm), and that water is intrinsic to the liquid crystallinity
of organisms [13] (The
Liquid Crystalline Organism and Biological Water, ISIS scientific publication).
But more surprises
are in store.
A water battery
There was already a hint
that the EZ has unusual electrical potential when pH sensitive dyes were used
as solutes to see if they too, were excluded from the EZ. Indeed, they were,
but they also showed up a zone of unusually low pH (red band) right above
the clear EZ (see Fig. 4). A low pH means high concentration of protons (H+)
immediately next to the EZ, and decreasing away from it.
Figure 3. Proton rich region above EZ with dye excluded
when a pH sensitive dye was used (still captured from video [2])
An excess of protons
suggests that charge separation has taken place in the water molecules as
follows:
H2O —› H+ + OH-
(1)
So where did the negatively
charged OH- ions go? A measurement of electrical potential
shows that away from the EZ, the bulk solution had the same electrical potential
everywhere, however, as soon as the measuring electrode enters the EZ, the
electrical potential dropped sharply to –120mV or more, depending on the gel
involved, remaining at that level well into the gel itself (see Figure 5).
Figure
5 Electrical potential measured at different distances from the gel surface located at 0
This macroscopic
separation of charges is stable, as is the EZ itself. It is in fact a water
battery. A battery, like any other, could be used to power light bulbs or
your labtop, and could be the most exciting application of liquid crystalline
water (see Fig. 6). But what charges up the water battery? It takes energy
to separate the charges, so where does the energy come from? That too was
a surprise.
Figure 6. A water battery
Light charges up water
It turns out that water
is sensitive to light, as is revealed by the exclusion zone next to a gel.
It thickens on being exposed to light, which means that light enhances the
formation of liquid crystalline water. The entire spectrum of sunlight is
effective, but the peaks are in the visible blue and especially the invisible
near-infrared (3 000 nm) regions. A mere 5 minutes exposure to the infrared
light will cause the EZ to thicken several-fold. And if you connect up the
EZ and the bulk water above to an external circuit, there is a measurable
current, which lasts for a considerable time after the infrared light is turned
off.
Green plants and
especially blue-green bacteria have been splitting water according to equation
(1) for billions of years, in order to obtain energy from the sun; and in
the process fixing carbon dioxide to make carbohydrates and other macromolecules
to feed practically the entire biosphere. The separation of charges in the
formation of liquid crystalline water is essentially the same process.
Pollack asks tantalisingly: Can water replace oil? The applications of liquid
crystalline water are wide-open. His laboratory is already working on a water-purification
device based on separating liquid crystalline water of the EZ from the bulk
water. (Liquid crystalline water is reputed to have health-promoting properties,
though that is still unconfirmed.) Another application is anti-fouling agent:
a coating that essentially prevents any impurities in water from sticking.
One invention I would love is a web suit that would enable me to glide over
the water like a water bug!
Pollack’s findings have fundamental implications for our understanding of physics,
chemistry and biology.
Of colloid crystals, thunder clouds and self-organisation
One puzzle that is immediately
solved is the formation of colloid crystals (see Fig. 7) – literally crystals
made of colloid particles arranged in an orderly way in solvents - which is
very topical in the manufacture of nano-structured electronic and photonic
devices.
Figure 7. Colloid crystals, scale bar 20 microns
Norio Ise and his colleagues in Osaka, Japan, first discovered colloid crystals
forming in water more than 20 years ago [14] (Water and Colloid Crystals,
SiS 32), and they explained the colloid crystals in terms of a long-range
attraction between the colloid particles, though the precise mechanism has remained
elusive. The major difficulty is that the colloid particles have the same charge
and it is impossible, according to conventional theory for like charges to attract
one another.
Pollack’s findings provide just the mechanism required. Colloid particles and
microspheres are like the hydrophilic gel surfaces that form layers of liquid
crystalline water or EZ. In the case of the gel, the EZ has an excess of negative
charges with excess positive charges in the region outside (see Fig. 6). In
the case of the microspheres and colloid particles, each is enclosed in a shell
of liquid crystalline water with excess negative charges, while the positive
charges are also driven outside (see Fig. 8). The repulsion between the negatively
charged particles is exactly balanced by the attraction to the positive charges
in between. In the space between two particles, there will be an excess of positive
charges compared to elsewhere, which is why the particles end up being attracted
to one another.
Figure
8. How like attracts like (see main text)
The same mechanism may explain
why clouds form. Clouds are essentially minute water droplets nucleated on
particles, and these too would end up attracting one another. The mechanism
of charge separation explains at least where the enormous amount of energy
unleashed in a lightning flash comes from. Storms could perturb the equilibrium
of charged swarms in the atmosphere, leading to violent electrostatic discharges.
The discharge heats up the air so much that it set up a shock wave, which
is why thunder follows lightning. Obviously the details need to be worked
out, but at least the major mechanism is clear.
The long-range attraction
between like particles is also the main mechanism for self-assembly of molecules
and particles inside the cells. It is the organizing principle that has long
eluded biology, or as Albert Szent-Gyorgyi, Nobel Laureate and father of biochemistry
said: “Life is water dancing to the tune of molecules.”
Perhaps it is the other
way around as well: Life is molecules dancing to the tune of sunlight and
water
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