NSF-DFG MISSION: Heterogeneous Nanoparticle Dynamics at Chromatographic Interfaces

• Applicant: Professor Dr. Frank Cichos
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry ; Analytical Chemistry
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 542019812

Liquid chromatography is an important separation technique. Its wide-ranging applications include chemical purification, pharmaceutical analysis and production, and environmental monitoring among others. Furthermore, it is foundational in understanding complex biological systems, developing new materials, and optimizing chemical processes. The basic principle of liquid chromatography involves the partitioning of components between a stationary phase and a mobile phase, with differential interactions leading to their separation based on relative retention times. The general view of the underlying principle is that smaller flexible molecular species are segregated by their retention in the porous environment of the solid substrate. This is a purely entropic concept that is now being challenged by the development of liquid chromatography for hybrid nanomaterials with inorganic hard cores and functional soft organic shells. This is because new results reveal a complex interplay of entropic and enthalpic interactions with the latter resulting from the functional shells of the hybrid materials. Surprisingly, a comprehensive microscopic picture of this interplay has not been developed due to a lack of experimental techniques that can tackle this problem in situ at the interfacial layers that govern the chromatographic process. It is the aim of this collaborative project to shed new light on the interfacial layer dynamics that occur in the chromatographic separation of nanomaterials. Our effort is based on recent advancements in the field of nanomaterials synthesis and functionalization, high resolution 3D fluorescence microscopy, and boundary layer thermofluidic manipulation. We will control enthalpic contributions by synthesizing functional quantum dots (QDs, Snee group) and modifying the solid-state phase of the chromatography column (Yang group) with complementary DNA strands. We will quantitatively explore the 3D dynamics of the functionalized QDs in situ with unprecedented spatial (10 nm) and temporal resolution (10 µs) in the Yang group. Furthermore, we will investigate the dynamics and enthalpic interaction of functionalized QDs with complementary planar interfaces (Cichos group) by controlling thermo-osmotic flows induced directly at the liquid-solid interface. We expect that our results will develop a new fundamental understanding of chromatography that will have a considerable impact on improving performance and will triggering the development of more efficient or selective separation methods based on novel osmotic flows in microfluidic environments.

• DFG Programme: Research Grants
• International Connection: USA
• Partner Organisation: National Science Foundation (NSF)
• Cooperation Partners: Professor Preston Snee, Ph.D.; Dr. Haw Yang