Stimulus-Responsive Endoskeleton Droplets

P.T. Spicer
University of New South Wales, AU

Keywords: shape-change, emulsions, deposition, delivery


The delivery of suspended ingredients from a fluid to a surface is the central function of drug and other formulations. Successful delivery of a particle to a surface requires transport of the particle sufficiently near to allow contact and adhesion. Once deposited, the particle should remain even if flow continues. Solid particle shape enhances adhesion and uptake during drug delivery, while shape-change improves targeting, but many actives are delivered by liquid droplets. We have designed a droplet to optimize adhesion, retention, and delivery by blending the shape-preserving and shape-changing properties of a solid particle with a liquid’s ability to wet a surface and deliver active ingredients via diffusion: endoskeleton droplets. Endoskeleton droplets with a rod shape enhance delivery from a flow, possess a true liquid surface, and can change shape after contact to better grip the targeted surface. The stability of the endoskeleton droplets’ shape is the result of a balance between an internal elastic network and the pressure of the liquid-liquid interface. Upsetting the balance by environmental stimuli triggers shape change, improving contact with a targeted surface. Anisotropic droplets that selectively change shape can greatly improve delivery and adhesion to targeted surfaces.