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HALS, tears and all that mass

Steve Blanksby in his lab at the University
of Wollongong

In Stephen Blanksby’s lab not even tears escape analysis.

Armed with a highly specialised ion trap mass spectrometer with tuneable lasers, Stephen Blanksby’s group in the School of Chemistry at the University of Wollongong and collaborators are investigating new technology to keep colorbond steel® colourful, characterising the lipids that make up human tears, and digging deep into fundamental chemical structures and reactivity.

In their sophisticated gas-phase ‘test tube’, the group work to understand the fundamental reactivity of particular ions and molecules in a vacuum environment without interference from other molecules. Indeed, some extremely reactive molecules can only be studied in isolation inside the mass spectrometer. Examples of such molecules are the peroxyl radicals and peroxide anions.

Peroxyl radicals and peroxides are reactive oxygen species which are formed in biological systems and the atmosphere. In our bodies they are created as a natural by-product of the metabolism of oxygen and are used in cell signalling. However when these species are produced in the wrong place or time, or at excessive levels, they can damage surrounding tissues and lead to disease. A number of diseases have been associated with peroxides including heart disease, rheumatoid arthritis, and some cancers.

The Blanksby group has developed a range of electrospray ionisation methods for producing distonic peroxyl radical anions in the gas phase. Distonic ions, a term coined by Professor Leo Radom from the Sydney node of the Free Radical Centre in 1984, have a separated charge and radical centre and can act as "charge tagged radicals". Fortunately the charge provides a convenient handle with which to isolate the anion in the mass spectrometer without perturbing the reactivity of the radical.

Together with Professor Richard O’Hair from the Melbourne node of the Free Radical Centre, the group are currently investigating novel methods for reacting their charge tagged peroxyl radicals with a range of substrates. This will provide unique insight into the structure and photochemistry of peroxyl radicals in the gas phase and the role of peroxyl radical intermediates in biochemical and atmospheric processes.

Applying the knowledge gained from these fundamental studies, some members of the Blanksby group are working with Dr Philip Barker from Bluescope Steel Research to improve the longevity of the great suburban icon, the colorbond steel® roof. Over time free radicals produced by the sun’s rays as well as the high roof temperatures (sometimes up to 90 oC) have the potential to make the surface of colorbond® fade and fail. A greater understanding of these processes combined with the development of new technology to protect the product from free radicals is of considerable benefit to the building industry.

Combining the complementary technologies of electron spin resonance (ESR) in the Barker laboratory and electrospray ionization mass spectrometry (ESI-MS) in the Blanksby laboratory, the group are uncovering the oxidation processes that occur within the polymer coating of colorbond®. ESR is powerful technology that readily identifies free radicals formed by these oxidation processes, while ESI-MS provides structural information about both radical and non-radical species formed.

Another technology under investigation by Blanksby and Barker is the use of Hindered Amine Light Stabilizers (HALS). HALS are used in the surface coating of colorbond® and other polymers, and also in paint fabrication. They are known to be efficient stabilizers against light-induced degradation of most polymers and do not absorb UV radiation, but act to inhibit degradation of the polymer, thus extending its durability.  The high efficiency and longevity of HALS are due to a cyclic process wherein the HALS are regenerated rather than consumed during the stabilization process.

Using new technology called Desorption Electrospray Ionisation (DESI) the team are analysing the surface of the polymer by generating an image of HALS distribution on the surface. From this information they are working towards creating improved HALS technology and identifying new antioxidants for use in steel coating systems.

Other members of the Blanksby laboratory are working to ascertain the structure of lipids associated with the human lens. Interestingly the distribution of lipids on the lens changes as humans age from 1 to 40 years, and these changes in lipid lens profile are proposed to be associated with the onset of cataracts.

To study the structure of various lens lipids the team have developed two new mass spectrometry tools called OzESI and OzID. These methods can precisely locate double bonds within a lipid molecule giving unique insight into its structure and biological function.

The team recently identified a number of new isomers of lens phospholipids using these methods. For this work the researchers were awarded “Lipid of the Month” on the NIH funded Lipid MAPS website. Together with Professor Roger Truscott from The University of Sydney the group are now working to identify the biochemical pathways that create these phospholipids and hopefully contribute to knowledge about the causes of cataracts.

Stephen Blanksby’s research is a fascinating insight into the power of mass spectrometry, with applications ranging from polymer coatings to human lens lipids. Furthermore it is a great reminder of how valuable chemistry is to both materials science and biology.

Stephen Blanksby is an Associate Professor in the School of Chemistry at the University of Wollongong. He will join the ARC Centre of Excellence for Free Radical Chemistry and Biotechnology as a Chief Investigator in July this year. The Blanksby group currently consists of a postdoctoral researcher, 8 PhD students and an Honours student.