Influence of dewetting on the crystallization behavior of CuCl₂ in the presence of BSA during evaporation in a Petri dish

The overall structure of dihydrate cupric chloride (CuCl2 * 2H2O) crystallization patterns in the presence of bovine serum albumin (BSA) in a Petri dish is influenced by dewetting. The dewetting behavior, which can be either before or after initial CuCl2 nucleation, depends on the amount of CuCl₂ and BSA in the Petri dish. We postulate that the concentration and/or temperature gradient area in the dish, which is built up during the evaporation process, coincides with the location where dewetting predominantly starts. This hypothesis could be supported by measurements of the CuCl2 coverage of the Petri dish. During the evaporation the height of the meniscus at the rim of the Petri dish recedes in favor of the central Petri dish area. This could not be explained by the above mentioned hypothesis.