Yoctowell cavities on magnetic silica nanoparticles for pH stimuli-responsive controlled release of drug molecules.

Drug-delivery systems that medically transport active molecules to diseased cells, in a controlled manner, have gained much attention in recent years. Yoctowell (1 yL=8 nm(3) that is, 10(-24)  L volume) cavities on magnetic silica nanoparticles were used for the encapsulation and release of the drug molecule, "mitoxantrone (MTZ)", and controlled using naturally occurring stimuli, that is, pH. First, MTZ was encapsulated from a bulk solution under physiological conditions, and then released from the yoctowells, in a controlled manner, by manipulating the pH (7.2-3.0). The sustained release of MTZ, the recovery of active yoctowells after the release process and magnetic properties of nanoparticles provide potential for development of a new generation of drug-delivery system.