Scientists at the Universitat Autònoma de Barcelona and Imperial College London have discovered the origin of hydration force, a phenomenon that causes some complex chemical and biochemical species (including DNA and other electrostatically charged molecules) to repel at short distances when surrounded by water.
Through this research, improvements could be made to the design of chemical products used in the chemical, pharmaceutical and food industry.
Ever since the 1970s, scientists have been trying to establish the cause of a repulsive force occurring between different electrostatically charged molecules, such as DNA and other biomolecules, when they are very close to each other in aqueous media. This force became know as hydration force.
Jordi Faraudo, a researcher for the Department of Physics at the Universitat Autònoma de Barcelona, and Fernando Bresme of the Department of Chemistry at Imperial College London have studied this mysterious force in detail and have discovered where its origins lie.
In the same way that a flag flutters in the direction the wind is blowing, at a microscopic level water molecules are gently attracted towards the direction in which an electric field is pointing. However, when the water is in contact with surfaces that create small electric fields, such as chemical compounds like those found in many detergents, this is no longer the case: the water molecules have a remarkable capacity to organise themselves into complex structures that are strongly orientated in such a way as to cancel out the electric field, and on some occasions, to reverse it. This abnormal behaviour was discovered by the same researchers and published in Physical Review Letters in April 2004.
The scientists have now discovered that this strange property is responsible for the hydration force that acts when water is surrounded by certain types of electrostatically charged molecules, such as DNA and some biological compounds, and when thin films form in detergents. The discovery has been published in today’s edition of Physical Review Letters.