Detecting harmful molecules

A novel sensor that can detect environmental contaminants as miniscule as one pinch of salt in an Olympic-sized swimming pool has been developed by Victoria University researchers.

Shalen Kumar and Omar Alsager holding the sensors they developed.
Shalen Kumar and Omar Alsager holding the sensors they developed.

Work by PhD students Shalen Kumar and Omar Alsager has resulted in a tool that can quickly detect hormones, additives used in plastics, cocaine and other molecules.

Supervised by Professor Ken McNatty from the School of Biological Sciences and Dr Justin Hodgkiss from the School of Chemical and Physical Sciences, Shalen and Omar worked together to develop the test, which could hit the market within a couple of years.

The sensor is able to recognise a specific molecule and changes colour when a target is recognised.

Shalen and Omar’s PhD research proved the perfect combination for the design of the sensors, which can show whether a sample is contaminated within just a few minutes.

“Our test works by mixing strands of DNA with gold nanoparticles, forming a pink-coloured liquid,” explains Omar, whose PhD was funded by King Abdulaziz City for Science and Technology, Saudi Arabia. “When the DNA recognises a targeted molecule it turns the liquid blue.”

In theory, adds Shalen, whose study was funded by a Te Tipu Pūtaiao Fellowship, the DNA developed could have multiple applications. One application is detecting environmental levels of oestrogenic compounds in drinking water—molecules that can have adverse effects on human and animal reproductive cycles.

Currently, the only way to measure the amount of oestrogen in water is to send a sample to a lab for analysis, which is expensive and takes time to get results. “With our new sensors, those in the field, such as a regional council officer or water board inspector, could add a sample to the test vial and get a yes or no answer almost immediately,” says Ken.

“It is crucial to be aware if there’s oestrogen in the environment, especially as it is not uncommon for water in many countries, including New Zealand, Australia and the United Kingdom, to be recycled. We have no idea how much oestrogenic material is in there.”

Another concern is that the additives in everyday plastic items such as drink bottles, containers and rubbish bags, can accumulate over time and behavelike oestrogen. However, measuring contamination from these additives is expensive. “We don’t know yet what the safe level is for these additives over 30 years of exposure,” says Ken.

The team will focus next on refining the sensitivity of the sensors and developing them to target other molecules.

There’s also a possibility of starting a company, with the support of Viclink, Victoria’s commercialisation company, says Ken. “It’s a case of carving out the right niche and finding the right application. Because it’s a generic technology, there is a range of areas we could explore.”