Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150258

150258 - Combining Non-Self-Limiting Materials to Achieve Self-Limiting Electrospray Deposition 

In the context of advanced materials, the increasing demand for high-performance materials that balance environmental sustainability and cost-effectiveness makes microscale coatings and thin films relatively desirable. One reliable method of creating these coatings and films is electrospray deposition (ESD).

ESD is a manufacturing process in which a high voltage is applied to a flowing solution. Through the interactions between electrostatic forces and surface tension, the solution atomizes at the end of the capillary, dissipating monodisperse, charged microdroplets towards a grounded substrate where the solvent evaporates and the solid payload remains. This process allows for the fabrication of thin surface coatings for various applications.

Though ESD is capable of fabricating these films, the process can be modified to a thickness-limited regime known as self-limiting electrospray deposition (SLED). To satisfy the criteria for SLED, the solvent material must be insulating and below its glass transition temperature. Additionally, the substrate must be conductive. Rather than accumulating in a single spot, new droplets are redirected to uncoated regions of the substrate, thus capable of coating a larger surface area and achieving near-uniform thickness. In addition, the repulsion of these charged droplets from one another allows for the coating of 3D objects or other small, intricate geometries. However, despite these advantages, not all materials innately exhibit the ability to be self-limiting. As a result, the aim of this work was to create blends of non-SLED materials such that the material characteristics could be manipulated to achieve the aforementioned criteria for SLED (e.g.: increasing the glass transition temperature).

Using ESD, we created coatings varying in composition of plasmid deoxyribonucleic acid (DNA) and trehalose. In preliminary studies, we found that solutions of pure DNA and pure trehalose do not result in self-limiting sprays; however, by blending the two materials together in a solvent system of 3:2 water:ethanol, we hypothesized that a blend of the two materials could achieve a self-limiting spray.

To test this hypothesis, we tested 7 different blends of DNA:trehalose (1:0, 3:1, 2:1, 1:1, 1:2, 1:3, and 0:1). The central thickness of the coatings were measured after smoothing the films with water vapor. Using both the size of the spray spot in addition to the thickness, the average thicknesses were plotted in relation to the ratios to determine how self-limiting each of the blends were in comparison to each other. Though pure DNA and pure trehalose were not self-limiting, blends of 1:1 and 2:1 DNA:trehalose yielded thinner thicknesses and lower variability in thickness measurements, indicating a blend that is much more uniform in coating.

The ability to accurately determine when a blended material becomes SLED-compatible is one that opens up many possibilities in regards to creating bioactive coatings. In particular, this allows for the future fabrication of medical devices such as DNA vaccines and other biocompatible polymers.

Presenting Author: Isha Shah Rutgers University

Presenting Author Biography: Undergraduate research intern at Rutgers University.

Authors:

Isha Shah Rutgers University
Sarah Park Rutgers University
Emily Li Rutgers University
Emily Li Rutgers University
Jonathan Singer Rutgers University