Interaction of Sedimenting Drops in a Miscible Solution – Formation of Heterogeneous Toroidal-Spiral Particles

Interaction of Sedimenting Drops in a Miscible Solution – Formation of Heterogeneous Toroidal-Spiral Particles

Magdalena Szymusiak¹,Vishal Sharma¹, Hao Shen¹, Ludwig C. Nitsche¹, Ying Liu¹*

¹Department of Chemical Engineering, University of Illinois at Chicago, IL 60607, USA

* To whom correspondence should be addressed. E-mail: liuying@uic.edu

Abstract

With a view toward enabling eventual applications in multi-drug-delivery and chemotherapy, we used the selfassembly of polymeric particles with a novel internal structure. The well-defined toroidal-spiral (TS) channels form due to drop interaction during their sedimentation in a miscible bulk solution, and are solidified by photopolymerization. Such particles would potentially offer an independent and quantitatively predictable pathway for protein encapsulation and sustained release, in addition to diffusion of smaller molecules through the polymer matrix. The generation of TS particles by single drops has been studied first in which case the entrainment of the bulk solution within the spiral-shaped channels offered a mechanism for encapsulating active agents under benign flow conditions (low shear with only an aqueous phase). The interaction of horizontally and vertically displaced polymeric drops provides a better control of the amount of encapsulation with the known volume of the drop and concentration of the active compounds. Multiple drops also offer the flexibility to encapsulate multiple active compounds without concern of their mutual compatibility in one solution. Furthermore, the understanding of multiple drop interaction is essential for mass production of TS particles by using parallel and sequential arrays of sedimenting drops.