College of Engineering News • Iowa State University

Shan Jiang’s Janus particle discovery lands Langmuir cover

Cover of academic journal showing a layer of gold and white spheres.

Cover of academic journal showing a layer of gold and white spheres.

Shan Jiang, assistant professor of materials science and engineering, led a discovery that made the cover of Langmuir. The first author is Ayuna Tsyrenova, graduate student in materials science and engineering. Coauthors include graduate Kyle Miller and Emily Olson, both graduate students in materials science and engineering; Jing Yan, assistant professor of molecular, cellular and developmental biology at Yale University, and Stephen Anthony, a research scientist at Sandia National Laboratories.

Jiang and his team investigated how amphiphilic Janus particle assembly structures are influenced by the addition of surfactant molecules. Janus particles are made using silica particles coated with gold on one side, which is further modified with a hydrophobic self-assembled monolayer.

In this work, Janus particles can form intriguing two-dimensional crystal structures with long range orientation order. In addition, Jiang and his team discovered the importance of van der Waals force in determining the assembly structures, which was often ignored in previous studies.

The study offers fundamental understanding of self-assembly principles and a simple approach to changing the assembly structures of Janus particles. The research also offers principles and guidance for future applications in coatings, biomedication, sensors and disease diagnosis using Janus particles coupled with small amphiphilic molecules.