Yoctowells as a simple model system for the encapsulation and controlled release of bioactive molecules.

The development of nanosized drug delivery systems to transport drugs to target cells, are promising tools to improve the drug therapeutic index. Transport systems should have a simple design to control the release of loaded drug to the target areas, thereby increasing concentration and prolonging retention. Herein, we demonstrate the use of yoctoliter wells (1 yL = 10(-24) L) as simple model systems for the encapsulation and release of biologically active molecules, by manipulating pH. The drug molecule employed here is doxorubicin, which diffuses into the bottom of yoctowells from a bulk solution at pH 7. Capping of the yoctowells is achieved by addition of an anionic-porphyrin by electrostatic interaction. Furthermore, controlled release of the Doxorubcin and capping agent from the yoctowells is achieved by pH control. The effectiveness of the sustain release of the bioactive molecule from yoctowells, provides potential for development of a new generation of drug-delivery system for practical application.