The preparation of mono- and multicomponent nanoparticle aggregates with layer-by-layer structure using emulsion templating method in microfluidics

Abstract

We report on the preparation of multicomponent hollow aggregates by an emulsion templating method adapted to microfluidic format. The method exploits partial miscibility of aqueous colloidal solutions as discrete phase and n-butanol as continuous phase. The aggregates consisted of an inner inorganic shell composed of iron oxide (IO) and gold nanoparticles (Au NPs) covered with polycaprolactone (PCL) NPs. The aggregates of smaller sizes were prepared compared to immiscible phases due to the diffusion-controlled shrinkage of aqueous droplets. The aggregate surface properties were controlled by using different mobilities and affinities of IO, Au, and PCL NPs to the water:n-butanol interface. The biocompatible surface layer enclosing an inorganic shell with a core space for possible cargo loading endowed these constructs with properties appreciated in medicinal applications. A computational fluid dynamics model enabled the prediction of the droplet size and formation frequency together with flow field properties at the point of droplet detachment.