Institute for Medicine and Engineering Papers

Document Type

Journal Article

Date of this Version

July 1999


Postprint version. Published in Science, Volume 285, Number 5426, July 1999, pages 394-97.
Publisher URL:


A positively charged, mixed bilayer vesicle in the presence of negatively charged surfaces (for example, colloidal particles) can spontaneously partition into an adhesion zone of definite area, and another zone that repels additional negative objects. Although the membrane itself has nonnegative charge in the repulsive zone, negative counterions on the interior of the vesicle spontaneously aggregate there, and present a net negative charge to the exterior. Beyond the fundamental result that oppositely charged objects can repel, our mechanism helps explain recent experiments on surfactant vesicles.



Date Posted: 13 August 2007

This document has been peer reviewed.