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Professor Bum Jun Park's research team from the Department of Chemical Engineering makes the first-ever prediction of interactions between polar and nonpolar molecules

Professor Bum Jun Park's team from the Department of Chemical Engineering achieved a pioneering prediction of interactions between polar and nonpolar molecules in Van der Waals forces using colloidal-based optical laser tweezers. This outstanding achievement earned a place in the latest issue of Nature Communications (IF=16.6). Optical laser tweezers, which use light to manipulate nanoparticles, are widely employed in both colloid and bio-related sectors.

The research led by Professor Park highlighted the potential of employing colloidal particles to understand molecular behavior. Given the inherent complexities of directly observing phenomena at atomic or molecular scales, the team used colloidal particles as an effective model for such studies. Colloids, being small particles, serve as model systems that mimic molecular processes.

In the research, optical laser tweezers were utilized to adhere micro-sized colloidal particles to fluidic interfaces, resulting in the formation of an asymmetric surface charge on the particle surface. This induced a permanent dipole on the particles affixed to the interface. Simultaneously, another set of particles dispersed in the solution was drawn near the adhered particles using the optical tweezers. The electric field generated by the permanent dipole then induced a polarization in the ionic diffusion layer around the immersed particle, leading to the formation of an induced dipole.

Broadening the scope: Impacts on ligand-receptor interactions and subsequent research plans
The experiment’s outcomes align perfectly with the simulations performed by Professor Sang Kyu Kwak's team from Korea University and Dr. Eun Min Go's team from Ulsan National Institute of Science and Technology. Their findings have been lauded as the world’s first experimental measurement of the Debye force.

The research topic has been Professor Park’s passion since his doctoral student days. Reflecting on his journey, he noted, "My fascination with this subject kindled during my doctorate. Upon joining Kyung Hee University, I readied the essential infrastructure for experimentation. A decade of relentless pursuit later, we reaped significant outcomes. This journey underscored that research is indeed an endless expedition, a realization I've come to appreciate anew."

The research leader emphasized the significance of their findings by stating, "Our results experimentally substantiate a previously theoretical molecular model, marking a monumental stride in the domain." This insight transcends colloids, hinting at potential ramifications on ligand-receptor dynamics within biological systems. The team is gearing up for subsequent studies in this avenue.