IRFP: Determination of Solvent Effects and Interactions of Silica-Polypeptide Colloidal Particles by Small-Angle Neutron Scattering

Hollingsworth Javoris V, Baton Rouge LA

Investigators

Abstract

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award will support a twenty-four-month research fellowship by Dr. Javoris V. Hollingsworth to work with Prof. Charles Han at the Institute of Chemistry, Chinese Academy of Science in Beijing, China. The aim of this research project is to investigate the solvent effects, structural variations and the resulting shell interpenetration of silica-polypeptide colloidal particles. These particles are composed of a silica core, which may or may not possess a superparamagnetic inclusion (Co or Fe3O4). The shell consists of polypeptides covalently bonded to the core. Depending on the properties of the attached polymers, the particles can exhibit solubility in water or organic solvents. Also, the polypeptide coil-helix transition is a useful feature for modifying the surface configuration and particle interactions. These particles are candidates for several potential applications such as responsive materials, chiral separations, catalysis, colloidal crystallization, biomimetic membrane supports and drug delivery systems. A number of features about the particles have been described-for example, they can form colloidal crystals'but very little is known about the dynamic response of the particles under applied fields. An overall goal is to understand these properties and concurrently the findings will have a positive impact on the approach used to design novel responsive materials and devices. Small angle neutron scattering (SANS) studies are performed at the Neutron Scattering Laboratory, China Institute of Atomic Energy. This SANS device is one of the most recently built neutron systems in the world. After gaining experience with similar particles of interest developed by the host group, the general objective is to investigate shell structural properties as the particles are brought together under applied magnetic fields using SANS, coupled with dynamic light scattering (DLS). The combination of SANS and DLS is ideal for this study because both techniques permit real-time monitoring of structure variations. Particle interactions are detectable by SANS using deuterated and hydrogenous polypeptides covalently attached to silica cores. In addition to the usual development of international partnerships, publications and presentations, the PI will adapt his acquired skills to U.S. neutron sources. This continued research endeavor will contribute to the advancement of materials science by providing insight on microstructural and responsive properties of versatile core-shell colloidal systems.