(542c) Liquid-Liquid Electrospray: A High-Throughput Nanomanufacturing Platform for the Synthesis of Micellar Nanocomposites

Authors: 
Lee, K. H., The Ohio State University
Winter, J. O., The Ohio State University
Wyslouzil, B. E., The Ohio State University
Scalable nanomanufacturing has emerged as a national need as researchers struggle to overcome the challenges associated with high throughput synthesis of high quality nanocomposites for numerous applications. The primary goal of this work is to establish a semi-continuous, tunable, and scalable platform for producing high quality micellar nanocomposites to be employed in biomedical applications, particularly cancer diagnostics and treatment. Liquid-Liquid Electrospray (LLE) is an emerging technology that incorporates electrohydrodynamic atomization (EHDA) via electrospray, an aerosol technique used to atomize fluids in the presence of electrical field, to emulsify organic solvent in water. Unlike traditional electrospray, in LLE, emulsion droplets are formed directly in the aqueous environment.

In our approach, amphiphilic block copolymers (i.e. poly(styrene-b-ethyleneoxide), PS-PEO), are added to the organic phase and processed via LLE, resulting in emulsion droplets that can undergo the â??interfacial instabilityâ?? method of block copolymer self-assembly. Hydrophobic encapsulants (i.e. quantum dots, superparamagnetic iron oxide nanoparticles) in the organic phase can be encapsulated in the hydrophobic core of the micelle, yielding micellar composites with potential applications in bio-imaging and cell manipulation/separation. In this work, we demonstrate one specific advantage of the LLE-enabled, interfacial instability approach, namely that this process does not require the addition of surfactants to preserve stability; reducing downstream purification process complexity.

Here, we report EHDA of a dielectric solvent (i.e., chloroform) successfully performed via LLE. A high voltage was applied to an insulated electrospray needle placed inside of an aqueous solvent (i.e. ultrapure water), which sprayed the dielectric solvent in the form of a cloud of emulsion droplets. Using this technique, we synthesized empty micelles, as well as micellar composites encapsulating nanoparticles. TEM images of nanocomposites were analyzed, and the results show that the products obtained were monodisperse, between 80 to 90% spheres with a characteristic length of 50 â?? 75 nm. Ellipse and worm-like micelles were also observed with characteristic lengths of ~ 70 â?? 135 nm. In our ongoing studies, we are examining the morphology shift from sphere to worm-like micelles and other complex structures in response to increasing the nanoparticle to polymer ratio. In addition, the functionalities of composites are being tested, including fluorescent and magnetic responses of encapsulated nanoparticles. In addition, we will report on a modified version of LLE (LLE-FNP) that promotes the nucleation and growth of polymer amphiphiles, similar to the kinetically driven Flash NanoPrecipitation (FNP) process developed by Prudâ??homme and colleagues. In summary, by incorporating the electrospray technique into the interfacial instability process, LLE enables the semi-continuous generation of oil/water emulsions, enhancing throughput and eliminating the need for surfactant removal to achieve high concentration purified nanocomposites.