Morphological Investigation of Lysozyme-Liquid Crystal dried Droplet Pattern formation

Drying liquid drops are important physical systems in understanding the basic science and technology. A sessile droplet forms innumerable patterns when evaporating with a free boundary condition. A recent study of drying dynamics of a lyotropic liquid crystal has illuminated details of the evaporation dynamics. This paper will report on the pattern formation of a dried droplet of a mixture of lysozyme, a nematic thermotropic liquid crystal (LC) 5CB (4-cyano-4’-pentylbiphenyl), and deionized water as a function of LC concentrations for different boundary conditions. We use cross-polarizing microscopy to investigate the optical activity and morphology of the final dried droplet at various sample angles. The overall morphology reveals a complex pattern of protein-rich regions separated by nearly pure LC material that varies with distance from the droplet edge and LC concentration. The quantitative analysis is done by ImageJ/Fiji software yielding parameters that characterize the morphology and are related to the initial composition of the mixture. This paper demonstrates the utility of using a thermotropic LC as a probe material in a protein mixture, revealing new information on the protein aggregation.