Systematic approach to electrostatically induced 2D crystallization of nanoparticles at liquid interfaces

Sumit Kewalramani, Suntao Wang, Yuan Lin, Huong Giang Nguyen, Qian Wang, Masafumi Fukuto*, Lin Yang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


We report an experimental demonstration of a strategy for inducing two-dimensional (2D) crystallization of charged nanoparticles on oppositely charged fluid interfaces. This strategy aims to maximize the interfacial adsorption of nanoparticles, and hence their lateral packing density, by utilizing a combination of weakly charged particles and a high surface charge density on the planar interface. In order to test this approach, we investigated the assembly of cowpea mosaic virus (CPMV) on positively charged lipid monolayers at the aqueous solution surface, by means of in situ X-ray scattering measurements at the liquid-vapor interface. The assembly was studied as a function of the solution pH, which was used to vary the charge on CPMV, and of the mole fraction of the cationic lipid in the binary lipid monolayer, which set the interface charge density. The 2D crystallization of CPMV occurred in a narrow pH range just above the particle's isoelectric point, where the particle charge was weakly negative, and only when the cationic-lipid fraction in the monolayer exceeded a threshold. The observed 2D crystals exhibited nearly the same packing density as the densest lattice plane within the known 3D crystals of CPMV. The above electrostatic approach of maximizing interfacial adsorption may provide an efficient route to the crystallization of nanoparticles at aqueous interfaces.

Original languageEnglish (US)
Pages (from-to)939-945
Number of pages7
JournalSoft Matter
Issue number3
StatePublished - Feb 7 2011

ASJC Scopus subject areas

  • General Chemistry
  • Condensed Matter Physics


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