Complex Pattern Formation in Sessile Droplets of Protein-Salt Solutions with Low Protein Content. What Substance Fabricates These Patterns?

Complex and elegant patterns of rosette, scallop, Chinese arrow and dendrite shapes on microscopic length scales formed as a result of salt-induced protein self-assembly in sessile drying droplets of protein-salt solutions were described in the literature. The authors are confident in protein nature of these patterns because they used fluorochrom-labeled albumin, and carried out their observations under luminescent microscope at the appropriate wavelength. But this point of view seems to be disputable. In this paper, some data are presented to highlight the salt nature of the above-mentioned patterns.