Page 12 - Periodic Issue 01

Medi3Ense:

#OMMERCIALISING #HEMISTRY n

THE 3TORY OF -EDI3ENSE Chemical Landmark plaque celebrating the
Awarded in July 2012, this RSC National
glucose sensor can be seen on the wall outside
For sufferers of diabetes, monitoring blood sugar levels on to a positively the Inorganic Chemistry Laboratory.
is vital to prevent hypoglycaemia (low blood sugar) which charged form of the
may induce a coma and hyperglycaemia (high blood ferrocene, which
sugar) which can pose serious health risks such as kidney in turn gives them to the electrode. The electrons flow
damage and blindness. through a circuit thereby generating a current which can
be measured. The larger the concentration of glucose
Until the late 1980s, glucose (blood sugar) monitoring present, the more electrons reach the electrode and
was achieved by bringing a drop of blood into contact hence the larger the current. The most convenient aspect
with a strip which then changed colour to varying degrees of this technique is that it was eventually shown to work
depending upon the concentration of glucose in the with blood straight from the body - the tiniest pinprick of
blood. These ‘colorimetric’ methods required a large blood dropped on to the device (to cover the electrodes)
droplet of blood and were not very accurate - clearly new allows the glucose concentration can be measured! The
approaches were needed. small volume of blood required together with the accuracy
At the beginning of the eighties an -EDISENSE WAS A GREAT of the measurement made this a
innovative area of research began far superior form of glucose testing
to develop in Oxford, paving the success—the company than the old fashioned colorimetric
way for a new type of device. methods.
Professor Allen Hill, working in WAS SOLD IN THE
the Department of Chemistry, MID NINETIES FOR With the chemistry in place, the
began to investigate how certain scene was set for a new era in
proteins (termed ‘redox proteins’) APPROXIMATELY M glucose monitoring. Allen Hill and
gain or lose electrons when the rest of the team sought investors
linked in to an electrical circuit. It was difficult to study such to take the system through to manufacture, but it was a
electrochemical behaviour as the redox proteins tended struggle to secure enough money. With the running of
to stick to the electrical conductors (electrodes) creating research groups taking up time and with little business
a buildup of material which prevented a current from training, the team found it difficult to attract investors.
flowing. However, working with his undergraduate student, Finally, Harvard business graduate Ron Zwanziger saw the
Mark Eddowes, Hill developed a method of protecting the potential of the glucose testing device and provided much
electrodes by binding another molecule to them which needed financial backing. A new company, Medisense,
did not interfere with the current. The redox protein could was born.
now pick up an electron from one electrode via the surface
bound molecule and lose it at the other electrode in a The greatest difficulty in the project according to Allen Hill
similar fashion. This new technique allowed a huge range was undoubtedly navigating the complicated path from
of redox proteins, including enzymes, to be investigated university research to the formation of a viable business.
electrochemically for the first time. Now-a-days Oxford has ‘Isis Innovation’ to manage the
commercialisation of academic work, but in the late 1980s,
Enzymes are proteins which speed up certain reactions - there was little support for academics who wanted to
there are lots of them inside our bodies to help us digest market the fruits of their laboratory labours. In the end,
food by breaking down large molecules into small ones. it cost about $40m to take the device through to the
Enzymes which gain or lose electrons in this process are marketing stage - four times the predicted cost. Medisense
called ‘redox’ enzymes, and it is these redox enzymes was however a great success - the company was sold
which can be exploited in electrochemical sensors. By to Abbott Research Laboratories in the mid-nineties for
using the redox enzyme which breaks down glucose approximately $800m!
(glucose oxidase) as the protein component in the
electrochemical device, Hill and his colleagues, Graham The new glucose monitoring device was finally launched
Davies and Tony Cass, were able to construct a new on the market in 1989 and 26 billion sensors have been
type of sensor. When glucose is present it reacts with the sold since that time - a testimony to its great and enduring
glucose oxidase and, in doing so, gives up two electrons success.
to the enzyme. The enzyme then passes these electrons

Our thanks to Professor Allen Hill who kindly gave permission for us to reproduce this piece.

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Periodic The Magazine of the Department of Chemistry