Introduction

  Light scattering techniques are most commonly used for determining properties of small particles in solution: their concentration, distribution of sizes, shapes, and orientation. Practical applications are found in a variety of industries: in biotechnology for the study of protein-protein interactions, stoichiometry of protein-protein complexes, and protein aggregation phenomena; in pharmaceuticals for study of protein-ligand interactions and binding, characterization of pre-crystallization parameters in macromolecular crystal growth prior to x-ray structure determination; in petrochemicals for study of the molecular weights, sizes and branching properties of olefins, synthetic rubber, polyethylene, and synthetic lubricants, in colloidal chemistry; and in other industries.

Our Instrument

  The high quality, research grade instrument was purchased from Brookhaven Corporation. The instrument allows students to perform a variety of basic experiments which demonstrate physical principles at work in inter-disciplinary fields such as molecular biology, biotechnology, biophysics and physical chemistry.  The emphasis is placed on demonstrating physical phenomena at a molecular level.  The apparatus has been used for experiments at both the introductory level (PHYS110 First Year Seminar in Physics: Biological Physics) and advanced level (PHYS480 and 481 Research Methods for Experimental Physics and Experimental Physics).

Light Scattering in the Curriculum

  Our instrument is capable of both static light scattering and dynamic light scattering, allowing students to measure not only parameters such as molecular weight of an unknown macromolecule (biological molecule or a polymer), but also its hydrodynamic radius, the translation diffusion coefficient, and conformational stability. An emphasis is placed on demonstrating the basic principles behind the laws of probability, friction, and diffusion that are central to understanding Brownian motion and are so fundamental to understanding many aspects of the molecular machinery of living cells and other biological systems. In addition, upper level students can learn about the light scattering theory, easily extendable to other scattering methods (Campton, Rutherford, etc.) and about photon correlation spectroscopy, involving mathematical skills ubiquitous in statistical methods.