For nearly a century the goal of many pharmacologists has been to create drugs that can be transported to a specific organ within the body and released at a controlled rate. Nobel Laureate Paul Ehrlich called it the ‘magic bullet’. With the advancement of nanotechnologies, the idea is closer to becoming a reality.

Cavalieri et al. created their own ‘magic bullets’ [Cavalieri et al., Biomacromolecules, 2008 9, 1967] liquid filled polymer microspheres. Each sphere has a 3 micron diameter along with the possibility to decorate its surface with molecules that can bind to organic tissue make it ideally suited for injection into the bloodstream.

Spheres can be thought of as ‘plastic sponges’ containing pores filled with a pharmacologically active ingredient suspended in water. In gene therapy, for example, the ingredient could be a fragment of DNA. However, special transport conditions are necessary since the DNA's pharmacological activity depends upon it strictly maintaining its 3D shape. This condition is met only if the DNA fragment is embedded in the proper environment. The behaviour of the water and the design of the microsphere are pivotal to providing such an environment. Thus it is necessary to characterise how the water moves, within the pores.

Neutrons are ideally suited for such studies because they are strongly scattered by the hydrogen atoms that make up the water molecule. Cavalieri's team used neutron spectroscopy to understand how the confined fluid moves within the pores and to characterise the environment of the DNA fragment.

Future applications of this technology could be applied to magnetic microactuators or microsensors for localised determination of temperature gradients.