Size Control Mechanism for Bio-Nanoparticle Fabricated by Electrospray Deposition

Abstract

The present work employed a molecular dynamics method to investigate the effect of NaCl concentration on the deformation, breakup, and evaporation characteristics of bio-nanodroplets under a strong electric field. It aims to reveal the size control mechanism for a nanoparticle produced by electrospray deposition. The results show that when the droplet dissolves NaCl, it is elongated to be a longer “spindle” by the electric field force, compared to the droplet without NaCl, and several small clusters are ejected from two tips of the spindle due to the hydration effect of Na⁺ and Cl⁻. In addition, the formation of ion pairs is observed when the droplet dissolves NaCl. The NaCl concentration affects the hydration degree and the formation of ion pairs significantly, which leads to different spindle lengths and number of clusters. The longer spindle and the larger cluster number could enlarge the free surface area and remarkably accelerate evaporation. Fabrication of smaller bio-nanoparticle requires both a faster evaporation rate and larger cluster number, which can be achieved by selecting an appropriate NaCl concentration.

Keywords:

• Deformation and breakup
• Electrospray deposition
• Evaporation
• Molecular dynamics
• Nanodroplet