20 February 2011
Researchers in the US have created nanopores that can capture, concentrate and shift molecules in predictable ways. The development - inspired by the waxy coating on insect antennae - could help to characterise proteins and membranes for therapeutic drugs.
Nanopores are a type of sensor used for detecting nanoscale objects such as single proteins, DNA and the molecules involved in chemical and biological reactions. Unlike 'bulk' sensors, nanopores enable scientists to see static and dynamic variations that would otherwise be lost among numerous other processes. Several teams are working towards nanopore systems that can sequence individual DNA molecules.
Yet they do have their problems: the pores can clog; they often cannot discriminate between passing objects; and they do not always let objects pass in a predictable manner - properties that are crucial for reliable sensing.
The nanopore (right) is inspired by structures on insect antennae that concentrate pheromone signals
© Nat. Nanotechnol.
Now, Michael Mayer of the University of Michigan in Ann Arbor and colleagues have found a way around these problems. They have been inspired by insect antennae, which have a waxy fluid lipid coating their surface to help detect airborne behavioural chemicals known as pheromones. Because pheromones bind easily to wax, nanopores on the insect antennae can capture and concentrate the pheromones and deliver them to the insect's nerve cells. Using this approach, Mayer's group have created various lipid bilayer coatings for synthetic nanopores to improve their sensing ability.
In tests, the researchers found that the coatings could capture proteins even from dilute solutions, could discriminate between different molecules, and could alter the speed of a protein's passage depending on the coating's viscosity. 'It enables, for the first time, the capture, concentration and translocation of molecules in a quantitative and predictive fashion,' says Mayer.
Zuzanna Siwy, an expert in nanopores at the University of California, Irvine in the US, agrees that the development will solve several problems with current synthetic nanopores. 'The passage time of molecules through the nanopore can be very well controlled, which increases the detection resolution and detection limits,' she says. 'Moreover, the system prevents protein molecules from "sticking" to the pore walls.'
Salvador Mafé, another expert in nanopores at the University of Valencia, Spain, says several other research groups are also looking for inspiration from nature. 'The results appear to show a promising avenue towards practical devices, although future studies should also address the nanostructure stability and performance in different chemical environments,' he adds.