A team of researchers at Indian Institute of Technology Kanpur has studied experimentally the fluid flow pattern inside the droplet in sitting drop method of protein crystallization using micro-PIV technique.

In this work, we have studied the convection inside the droplet at different stage of protein crystallization,” said Pradipta Kumar Panigrahi , Professor of Mechanical Engineering. The work is published on 7 Novemebr 2012 in Physical Review E. Different flow transition is observed during the process of protein crystallization. The lysozyme crystals are grown using vapour diffusion method of protein crystallization where the droplet is placed on a hydrophobic surface. The droplet contains solution of protein and precipitants. Effect of evaporation and precipitants leads to the growth of protein crystals. “Evaporation from the droplet surface causes circulating flow inside the droplet,” said doctoral student Tapan Kumar Pradhan, lead author of the research. “The crystal growth and flow study is done inside the droplet having volume 0.3 µL. The droplet is kept inside an enclosed chamber which is separated from the atmosphere. The strength of fluid convection inside the droplet gradually reduces with time. When crystal starts appearing inside the droplet, the fluid convection is disturbed by the presence of crystal.

Mohammed Asfer, doctoral student of mechanical engineering department is also an author of the work.