Drugs released by magnets
Magnetic nanoparticle-vesicle aggregates (MNPVs) are microscopic drug delivery systems that release their contents in response to a magnetic signal. Particles approximately a billionth of a metre in size are attached to drug-containing lipid vesicles, which are in turn embedded in a tissue-like hydrogel. For applications like tissue engineering or regenerative medicine, MNPVs need to deliver drugs or other bioactive materials to the affected site at the correct time. To do this, scientists turned MNPVs into magnetically responsive smart biomaterials in the EU-funded project MAGNANOVES (Magnetically responsive nanoparticle-vesicle hydrogels as "smart" biomaterials for the spatiotemporal control of cellular responses). The idea behind MAGNANOVES was to make MNPVs release drugs when exposed to a magnetic field, and then self-destruct once the payload is delivered. After working out how to chemically attach magnetic nanoparticles to lipid vesicles, scientists developed methods for magnetically releasing drugs from the resulting MNPVs in suspension. One of their objectives entailed releasing two molecules that work together to trigger a cellular response – for example, an enzyme and its substrate. By magnetically releasing the digestive enzyme trypsin into a protein solution, researchers demonstrated that large biomolecules could be released from MNPVs in suspension rather than gels. The fact that trypsin remained active and digested the protein demonstrated the system's potential for delivering enzymes to cells to initiate a cellular response. In a further innovation, researchers reversibly attached proteins and enzymes onto the surface of magnetic particles. This method could be used to convert an inactive prodrug into an active form after it is magnetically released from an MNPV. Although researchers still need to overcome some hurdles, MAGNANOVES' nanoparticle-vesicle system shows great promise for delivering treatments to cells without affecting the surrounding tissues. Having demonstrated that it works using a model enzyme/substrate system, this method could also be used to develop biosensors and industrial catalysts.
Keywords
Smart biomaterials, magnetic trigger, magnetic nanoparticle-vesicle, drug delivery, hydrogel
