Materials that recognise neurotransmitter molecules, important for neurological disorders research, have been made.

Toshifumi Takeuchi and colleagues from Kobe University, Japan, have synthesised a highly selective receptor for the neurotransmitter dopamine using the well-known molecular imprinted polymer technique. Reduction in dopamine levels has been identified as a cause of Parkinson's disease and also linked to a decline in memory, attention and problem solving ability. 

Molecular imprinting involves assembling monomers around a template molecule (one with complementary reactive sites). The template molecule is removed to leave a polymer with binding sites that enable it to act as a receptor. In traditional molecular imprinting the target molecule itself is used as the template molecule. However, to obtain improved selectivity a route to polymers with tailor-made binding sites is needed. 

The group used a made-to-measure template molecule with a core similar to dopamine and performed reactions on the resulting polymer. After template removal, the cavity left in the receptor had the right dimensions for an actual dopamine molecule to bind. It also had a sacrificial section that stayed in the polymer when the template was removed. 

This sacrificial section allowed the template to be easily removed; leaving behind a boronic acid and a thiol functional group. The thiol group was oxidised to a sulfonic acid and the two acid groups in the receptor then worked together to bind strongly to dopamine's functional groups. 

When asked about the future of this area of research, Takeuchi said, 'if you can construct any reaction sites you like, it will contribute to further development of our industrial society and I believe our technique could be one of the ways to do it.'

Nina Athey-Pollard