DNA coats help control particles

Researchers at the US Department of Energy’s Brookhaven National Laboratory have developed a new way of controlling the self-assembly of nanometre and micrometer-sized particles.

The method, for which a patent application has been filed, is based on designed DNA shells that coat a particle’s surface. It can be used to manipulate the structure, and therefore the properties and potential uses, of materials.

‘Our method is unique because we attached two types of DNA with different functions to particle’s surfaces,’ said Oleg Gang, who leads the team. ‘The first type – complimentary single strands of DNA – forms a double helix. The second type is non-complementary, neutral DNA, which provides a repulsive force.’

This method gives greater control allowing for fine-tuning of materials at molecular level and has potential applications in industry such as efficient energy conversion and cell-targeted systems for drug delivery.

‘The DNA acts as a molecular spring,’ said Matthew Maye, another researcher on the project. ‘This results in the repulsive force among particles, which we can regulate. This force allows is to more easily manipulate particles into different formations.’

The experiments used gold nanoparticles and polystyrene microparticles as models. DNA was synthesised to chemically react with the particles, with the fraction of complementary and non-complementary DNA being varied to give control.

The technique allowed for regulating assembly over a very broad range, from forming clusters consisting of millions of particles to almost keeping individual particles separate in a non-aggregating form.

The method was tested separately with both sizes of particle and was equally effective.