An international collaboration by American, Canadian, and Spanish researchers has developed a smart membrane that may serve as a dosage regulator for drug administration. The material is made out of an ethyl cellulose membrane combined with poly (N-isopropylacrylamide) (PNIPAM), a substance that is swollen naturally but collapses when heat is applied. The combination product opens up its pores when heated, allowing substances to flow through.
The researchers embedded nanoscale particles of PNIPAM-based gels in an ethyl cellulose membrane so that clumps of the particles spanned the width of the membrane. They also entrapped magnetite nanoparticles within the membrane matrix.
If the membrane is exposed to an oscillating magnetic field, the magnetite nanoparticles heat up, in turn warming the PNIPAM by a few degrees – sufficient to cause the particles to collapse but not so high as to affect surrounding tissue. This leaves voids in the membrane, opening up channels from one side to the other.
In this way the membrane’s porosity can be remotely switched on and off. To demonstrate the potential effectiveness of the system in drug release, the research team encapsulated the dye sodium fluorescein in the membrane and implanted it in rats. They showed that the membrane remained intact and ‘switchable’ over multiple cycles, that the amount of dye released was in proportion to the length of time that the magnetic field was applied, and that the membrane was non-toxic and biocompatible. By modulating the magnetic field it should be possible to fine-tune the rate of drug release, in addition to the frequency and duration of treatment.
Press release: New ‘on-off’ membrane for drug delivery…
Abstract in Nano Letters: A Magnetically Triggered Composite Membrane for On-Demand Drug Delivery