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An Australian scientist claims to hold international patents on the
method of producing the recently discovered form of carbon known as fullerenes.
He says that fullerenes, more commonly known as ‘buckyballs’, are the key
element of a medical imaging system he developed in 1984.

Å®ÉúСÊÓƵs around the world are still striving to determine the chemical
and physical properties of fullerenes which were discovered in 1985 and
consist of closed cages of 60 or more carbon atoms. But there is some confusion
among researchers on whether the Australian system does actually produce
fullerenes.

Bill Burch, a biomedical engineer at the Australian National University
in Canberra, claims to hold the patents along with an industrial partner,
Tetley Technologies of Sydney. Ian Tetley, chairman of the company, believes
the patents are strong enough for the Australians to control the world market
on the commercial production of the material.

Burch says that he did not realise he had stumbled onto fullerenes until
he saw the paper published in 1985 by Harry Kroto of the University of Sussex,
Richard Smalley of Rice University in Houston, and colleagues. ‘I’m not
a carbon scientist,’ says Burch, ‘but it was immediately obvious that my
technique was an approximation to his (Kroto’s). The only difference between
my particles was that they were about 10 times the diameter of Kroto’s’
Burch estimates that his giant fullerenes contain at least 540 carbon atoms.

Burch’s system uses carbon molecules as a carrier for a radioisotope,
technetium-99m. The technique encloses the technetium inside the sphere
of carbon atoms to produce what he calls ‘Technegas’. This gas is used in
a lung scanning system. Patients inhale some of the gas and it lodges in
their lungs. Radiation emitted by the technetium is then detected using
a camera sensitive to gamma rays to produce an image of the interior of
the lungs.

Today, 150 Technegas systems are in use in 18 countries, including Britain,
Australia, Scandinavia, Germany, France and Italy. Trial machines are operating
in Japan, and Burch has just returned from the US where he was setting up
trials for approval from the Food and Drug Administration.

John Ogle of the British company Amersham International says that it
is on the verge of signing an agreement to sell Technegas systems in Europe.
He says Amersham collaborated with Burch and Tetley in the mid-1980s to
develop the system but then broke off the partnership.

Kroto, Smalley and their colleagues were the first to identify the C₆₀
molecule as having unusual properties and to propose a structure for it
(‘Great balls of carbon’, this issue). The spherical structure was only
confirmed last year. Researchers have proposed numerous possible applications
for the new material, such as lubrication – with the spherical molecules
acting as microscopic ball bearings – as a semiconductor or as a catalyst.
Several chemicals companies in the US are now producing small quantities
of the material, but if Burch and Tetley are correct about their patent,
any commercial production will require a licence from them. Burch began
work on the system in 1984 on behalf of the Australian Capital Territory
Health Commission and later teamed up with Ian Tetley. Technegas machines
were in use in Australia in 1985. After Burch saw the paper by Kroto and
Smalley in 1985, he and Tetley sought patents to protect their technique
and its potential spinoffs, not because they were concerned about fullerenes.

To make Technegas, Burch places a saline solution of technetium-99m
into a stainless steel chamber which is lined with pure graphite and filled
with an inert gas such as argon. The crucible is then heated to 2500 °C.
During heating, the graphite lifts off the crucible in molecular sheets
and wraps around the technetium.

Burch has limited information about the underlying chemistry of his
molecules. He is, nonetheless, confident that they are true fullerenes.
Electron microscope pictures clearly show the pentagon and hexagon mosaic
on the surface of the molecules. ‘It’s way beyond randomness to see such
patterns’, he maintains.

Anthony Vassallo and his colleagues at the Minerals Research Laboratories
of the CSIRO, the Australian government’s scientific research organisation,
have seen the electron microscope image of Burch’s molecule and are familiar
with his work. Vassallo agrees that Burch probably has the real thing. ‘It
would be highly unusual if he didn’t produce them (fullerenes) under those
conditions. You’d want to to know why,’ he says.

‘The whole question is, is it what they say it is?’ says Richard Smalley.
‘I have yet to see an electron micrograph of C₆₀ that’s convincing.
It could be just a spiralling graphitic particle.’ Kroto says of the Australians’
technique that ‘I think they probably do have some C₆₀ in there’.
But he also says that the particles are much larger than C₆₀,
which measures about 1 nanometre across. ‘It’s possible they’re getting
higher fullerenes,’ Kroto says, but adds that they are more likely to be
concentric shell structures, icosahedral spiralling graphite particles that
fit together like a Russian doll. ‘I think what they are seeing are facets
on the surface, not the basic C₆₀ structure. It may be the first
commercial application of C₆₀. It has to be proven.’ Burch and
Tetley’s patent lawyer, Chris Hirsz of Spruson and Ferguson in Sydney, confirms
that all their patent applications covered ‘the method of forming an inhalable
composition’ for the Technegas system, and separately ‘the apparatus for
forming an inhalable composition’. Patents for the technique have been granted
in Australia and Canada, and in the US as recently as January this year.

‘The way we wrote the patent was to cover the lift off of carbon from
a graphite crucible at an elevated temperature. It’s as general as that,’
Burch says. ‘It doesn’t really matter what you call the stuff that comes
´Ç´Ú´Ú.’

Burch says that if a company came up with a commercial application using
a technique he and Tetley thought fell under their patents, they would have
to make a ‘commercial decision’.

John Agnew and his colleagues at the medical physics department of the
Royal Free Hospital in London carried out the first trials of the Technegas
system in Britain in 1986. They still use the technique to diagnose pulmonary
embolism, a blockage of the blood supply to the lungs.

The main advantage of Technegas, according to Agnew, is that it is there
when you want it: ‘For us it’s an availability question,’ he says. ‘For
people who are suddenly brought into the hospital, in emergencies it’s very,
very important.’ The alternative is to use another radioactive isotope,
krypton-81m, which is more expensive and is only available at the hospital
on two afternoons each week.