Findings: Diagnosis from a drop of blood

Scientists are creating synthetic chemicals that can detect a single bio-organic molecule, raising the prospect of nanoscale devices that can rapidly diagnose a range of infections.

Work on a proof-of-principle model system that can detect the presence of streptozotocin is at an advanced stage.

The chemical is being constructed from polypeptide units by a team led by Normand Voyer, director of the protein structure, function and engineering research centre at Laval University, Quebec, Canada.

He is optimistic that their approach, inspired by nature, will enable such nanoscale devices to be fabricated simply and relatively cheaply.

"In the not-too-distant future, it will be possible to do real-time bedside monitoring of numerous pathogens - bacteria, viruses and toxins - simultaneously. This will constitute a quantum leap in hospital care," he said.

Dr Voyer said his group had synthesised peptides - the organic chemicals that are used in nature as proteins and enzymes - that mimic an ion channel, a key component of living cells.

Ion channels are complex chemicals that enable cells to "communicate" with the world outside and play a central role in processes such as neurotransmission, muscle contraction and vision.

They can move 10 million ions every second, prompting a small but distinct electrical signal.

Dr Voyer's team used simple peptide elements to create the artificial ion channel and then engineered one end to carry a specific chemical reporter that will bind to a single biological molecule - in their proof-of-principle model's case, that is streptozotocin.

If any streptozotocin is present, it will bind to the chemical, end the flow of ions and produce a loss of current that can be measured.

An array of such artificial ion channels, each one with a different electrical signature and engineered to detect a different biomolecule, each linked to a particular pathogen.

This would enable a range of infections to be tested for simultaneously from a single drop of blood.

Dr Voyer revealed the team's latest findings at the International Symposium on Bio-organic Chemistry in Toronto, Canada.