Secrets of the World

 

Handheld devices for rapid se­quencing of DNA in the field; im­plantable drug pumps working on the nanoscale — these are two of the applications Jadranka Travas-Sejdic envisions for her ongoing investiga­tions into new polymer electronics materials.

Working at the crossroads of nanotech­nology and biotechnology, Travas-Sejdic sees “exceptional opportunities for advancements” in her field that extend beyond chemistry and electrical engineer­ing to biomedicine and forensics. “There are lots of promising technologies for the future that this area can offer. This is re­ally what’s driving my interest.”

Jadranka Travas-Sejdic is director of the Polymer Electronics Research Centre and senior lecturer in macromolecular chemistry at the University of Auckland. Originally from Croatia, she completed her undergraduate and Master’s degrees in chemistry at the University of Zagreb. She relocated to Auckland in 1995. “Troubled times in my country prompted me to decide to leave there. New Zealand seemed like a very nice country to start a new life.”

She traces her interest in science to her childhood in Croatia. “I liked science since my early days, since my first con­tacts with chemistry, biology and phys­ics…chemistry just happened to interest me the most. I had a very good teacher who was responsible for my developing that love of science.”

Her early experiences with science made a deep impression on her. “It was like opening up the door of the secrets of the world for me. Everything can be explained in very logical ways.”

After moving to New Zealand in 1995, she completed her PhD in polymer chemistry at the University of Auckland. She received an Early Career Research Excellence Award from her university in 2005 and the Easterfield award from the Royal Society of Chemistry in 2007.

Since the beginning of 2007, she hasbeen a principal investigator for the MacDiarmid Institute, pursuing her research interests in polymer electronics. “Being a PI for MacDiarmid presents me with a great honour because the institute and its members strive for research excel­lence and are committed to advancing our society through science. Being a part of such team of extraordinary scientists is very exciting. It provides me with an opportunity for regular interaction with them and the chance to start new col­laborative projects that may not have happened otherwise.”

Polymer electronics is the develop­ment of conducting polymers, a field that Travas-Sejdic describes as, “truly cutting edge science.” Her team’s work carries on the legacy of Alan MacDiarmid, whose groundbreaking discovery that plastic materials can be modified to conduct electricity earned him a share in the 2000 Nobel Prize in Chemistry.

“Basically until then, it was considered that polymers were very good insula­tors. That was abruptly changed by [MacDiarmid’s] discovery, which showed that oxidation or reduction — the removal or addition of electrons — can actually transform insulating polymers into con­ducting or ‘metallic-like’ polymers”.

The Polymer Electronics Research Centre (PERC) at the University of Auckland, which Travas-Sejdic’s heads, unites researchers across several dis­ciplines, including chemistry, biology, medicine, and a range of engineering fields. Their work is centered on design­ing new conducting polymers at the molecular scale. The materials they have created have already been put to use in light-emitting diodes and solar cells. Travas-Sejdic’s current interests have turned to developing materials for use in medical devices and biosensors.

One avenue her team is pursuing is the development of actuators or micro­pumps. Past research has shown that conducting polymers can change in volume and size during the oxidation and reduction cycle as they take up and expel solvated ions. By carefully controlling the cycle, this property can be exploited to move very small quantities of fluids, ef­fectively creating a molecular-scale pump that functions with no moving parts.

“Such pumps can be used in different areas of nanotechnology or microfluidics, or as the pumps for implantable devices which can deliver drugs into the human body. To make such a complex device, one really needs scientists with expertise in diverse backgrounds, like materials science, electrical engineering, or, for example, mathematical modeling. It’s a quite a challenging, exciting research programme that requires expertise across disciplines.”

A second research stream at PERC is the development of biosensors. “This is another quite exciting area of research where polymer electronics overlaps with biotechnology. It’s called bioelectron­ics. This is basically the application of conducting polymers to make devices which can be suitable for use in medical research or health care.”

Travas-Sejdic’s recent work has cen­tered on the refinement of gene microar­rays – chips designed to detect and iden­tify specific sequences of DNA. The abil­ity to identify the presence or absence of particular genes using these devices has a wide range of applications, including disease diagnostics, drug discovery, food technology, and forensics.

Current microarray technology relies on fluorescent labeling of samples. When the target DNA binds to specific probes laid down on the chip, the results can be detected visually using a scanner. However, this process can be time-con­suming, expensive, and it relies on the use of cumbersome equipment that is not well-suited for use in the field.

According to Traves-Sejdic, one way to improve on current technology would be to shift from fluorescent labeling to a direct electrical readout of the results. She believes that conducting polymers are promising candidates for this application. Her team has been making conducting polymer films that incorporate anchor points for fragments of probe DNA. When the target DNA joins up with probes on the film, this disturbs the elec­trical properties of the conducting poly­mers. The resulting change in resistance can be detected and used to provide a direct readout of the experimental results.

She says that conducting polymer films are particularly well-suited for use as DNA sensors because they are easily miniaturised, limited only by the size of the metal electrodes required to produce a current.

The ultimate goal of this research would be create handheld devices for forensic scientists to use for DNA de­tection in the field. To be successful, Travas-Sejdic says such a device would need to rely on technology that is very fast and compact, would not require any labeling of target genes, and is highly sensitive to small quantities of DNA.

In pursuing those ends, her team has had some initial successes. The films they’ve created are able to detect nano- to pico-molar quantities of target DNA, and provide a clear readout based on the changing electrical properties of the conducting polymers. The results are available within an hour or two, rather than the several days required using current gene microarray technologies. Their future research efforts will be focused on further increasing the sen­sitivity of the films, by looking at how the chemical properties of the polymer used, the shape of the probe and the way in which the probe binds to its sub­strate all affect the electrical signal that the sensor produces. If they can amplify the signal enough to increase the new material’s sensitivity by a few orders of magnitude, their conducting polymers may become the basis for the next gen­eration of DNA chips.

On being a woman in a leadership role within the sciences:

“Generally speaking, there is still prejudice present in our society about a woman having a leading senior or management role in an organisation, and I think women need to work harder to ‘prove’ themselves and to get there. In my career so far I have been in a posi­tion to work in business environments where I was the only one or one of very few women in a leadership role, which may have influenced my leadership style, making it conform to a more ‘masculine’ standard in those situations. Saying that, I should say that in academic circles such distinction is much less pronounced, and I have been working and collaborating on various projects with very supportive male colleagues where gender is not an issue and I experienced only a mutual professional respect…. Being director of the [Polymer Electronics Research] Centre has been a great responsibility and challenge for me, but it is also a great opportunity for learning and self-development which I enjoy enormously.”