Controlled generation of spiky microparticles by ionic cross-linking within an aqueous two-phase system

Microparticles are used in a variety of different fields, such as drug delivery. Recently, non-spherical microparticle generation has become desirable. The high surface-to-volume ratio of non-spherical microparticles allows for enhanced targeting, and attachment to cells and tissue. Current non-spherical microparticle generation techniques require complicated setup, and utilizing natural micrograins, such as pollen grains, as non-spherical delivery vehicles, requires extensive post-processing. Here, we describe a unique and facile chemical synthesis approach, for controlled generation of pollen-like microparticles, based on ionic cross-linking of alginate and calcium chloride (CaCl2), within an all-biocompatible aqueous two-phase system (ATPS) of dextran (DEX) and polyethylene glycol (PEG). Our technique controls the length of spikes that emerge on the surface of these microparticles. We anticipate that these pollen-like spiky microparticles may be used as drug delivery vehicles, and this new chemical synthesis approach may be used for generating other biomaterials.