Paris, 27 January 2010 In order to deliver an encapsulated
substance, such as a therapeutic agent in medicine, silica
substrates are often used. Release then takes place via the
pores in the silica or by dissolution of the latter, but this
occurs in an uncontrolled, or practically uncontrolled, manner.
To overcome this major disadvantage, three researchers from the
Paul Pascal Research Center (1), one of CNRS's own units, have
developed an ingenious and totally novel method: capsules that
can release their contents on demand, under the effect of
heating. The idea is simple, and the system is easy to produce.
The scientists disperse oil, which can contain a specific agent,
in water. Stabilized in the form of droplets by silica
particles, the emulsion's distinctive characteristic is that it
is made up of oil that is liquid at the production temperature
(65 °C), but solid at ambient temperature. A silica shell is
then polymerized around the cooled droplets, and stable capsules
that can be stored are obtained. It