Flash Nano-Complexation: A Tunable Technique for Electrostatically Driven Nanoparticle Fabrication

Abstract

Flash nanoprecipitation is a kinetically controlled technique of creating uniform nanoparticles by precipitation during rapid mixing between a polymer solution and an anti-solvent in a device called a controlled impingement jet mixer. Flash nanocomplexation is a technique that uses this controlled impingement jet mixer to rapidly mix a stream of aqueous polycation with a stream of aqueous polyanion. Rather than solvent displacement, electrostatic interactions between oppositely charged polymer units cause complexation in the controlled impingement jet mixer, leading to the fabrication of uniform nano-complexes. The size of these nano-complexes can be modulated in several different ways. A minimum threshold velocity of stream injection into the controlled impingement jet mixer is required. Altering volumetric flow rates of streams above this threshold results in significant changes to the diameter of the nano-complexes produced without statistically significant changes to particle uniformity. This correlation holds if the injection rate of only one stream is modified. Nano-complex diameter can also be tuned by varying the ratio of positive to negative charge available in solution. Among several possibilities to achieve this, the simplest is by altering concentrations of polymer in the input streams to the controlled impingement jet mixer.