Electroactive controlled release thin films

doi:10.1073/pnas.0706994105

Electroactive controlled release thin films

Departments of *Chemical Engineering and
^†Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139; and
^‡Department of Chemical Engineering, University of Rochester, Rochester, NY 14627

Edited by David A. Tirrell, California Institute of Technology, Pasadena, CA, and approved December 10, 2007 (received for review July 25, 2007)

Abstract

We present the fabrication of nanoscale electroactive thin films that can be engineered to undergo remotely controlled dissolution in the presence of a small applied voltage (+1.25 V) to release precise quantities of chemical agents. These films, which are assembled by using a nontoxic, FDA-approved, electroactive material known as Prussian Blue, are stable enough to release a fraction of their contents after the application of a voltage and then to restabilize upon its removal. As a result, it is possible to externally trigger agent release, exert control over the relative quantity of agents released from a film, and release multiple doses from one or more films in a single solution. These electroactive systems may be rapidly and conformally coated onto a wide range of substrates without regard to size, shape, or chemical composition, and as such they may find use in a host of new applications in drug delivery as well as the related fields of tissue engineering, medical diagnostics, and chemical detection.

Footnotes

^§To whom correspondence should be addressed. E-mail: hammond{at}mit.edu
Author contributions: K.C.W., N.S.Z., and D.J.S. contributed equally to this work; K.C.W., N.S.Z., D.J.S., and P.T.H. designed research; K.C.W., N.S.Z., D.J.S., S.N.W., and B.J.A. performed research; K.C.W., N.S.Z., D.J.S., and P.T.H. analyzed data; and K.C.W. and P.T.H. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0706994105/DC1.
↵ ¶ After holding at the oxidizing potential of 1.25 V for the indicated time intervals, a potential of 0.6 V was applied to accelerate the reversion of PX back to its fully charged PB state.
↵ ‖ Differences in total mass release between films used in a and b are due to slight variations in the pH and ionic strength of dipping baths used during the deposition processes.
↵ ** Release rates are calculated by using a simple linear fit of the increasing and plateau regions of the release curve.