Nanopores that mimic the pores in biological membranes could be used to detect the early stages of diseases like cancer.

In the membranes of living cells are tiny holes, or nanopores, that connect the outside world to the inside world of the cell. Charles Martin and colleagues at the University of Florida, Gainesville, US, have developed artificial nanopores that can mimic these natural pores. The researchers' aim is for these artificial pores to serve as ultra-sensitive biosensors to detect proteins that act as disease biomarkers.

'There is a revolution underway in disease diagnosis, which allows the disease, for example cancer, to be diagnosed very early on,' said Martin. 'This new approach entails detecting in the patient's blood a very minute amount of a chemical substance, a biomarker, that indicates that the disease is present, but in its very early stages.' 

The sensors work by detecting changes in the current applied across the membrane when the biomarker is present.  When the biomarker binds to the tip of the nanopore or passes through the nanopore, it blocks the current from passing through, leaving a trace of the molecule in the current measurement.

Unlike conventional, cylindrical nanopore sensors, Martin's nanopores are cone shaped. Cone-shaped nanopores are better suited for sensing applications, said Martin. They are particularly sensitive because the voltage drop caused by the ion current is focused at the nanopore tip. 

'These synthetic conical nanopores offer the capabilities of biological channels but do not suffer from their fragility and instability,' said Silvana Andreescu, an expert in biosensors at Clarkson University, New York, US. 'These attractive features offer new and interesting possibilities for sensing and will most likely result in the development of a new generation of chemical and biological sensors with enhanced sensitivity and selectivity.' 

'The ultimate goal,' said Martin, 'is to have reliable, rugged, selective and sensitive biosensors that could be used in your doctor's office.' 

Sarah Corcoran