Figure 4.

Link between L–L separation and polymer formation in deoxy-HbS solutions. Concentration of HbS is 22 g/dl, with 1% (wt/vol) PEG 8000. (a–d) When temperature is lowered from 42 to 35°C, the smaller of the dense liquid droplets disappear, while the larger ones serve as nucleation centers for HbS spherulites. Spherulites also appear at the locations where smaller droplets have been, apparently because of the undissipated locally higher concentration. (e–h) Upon raising the temperature to 42°C, the spherulites melt into droplets. The whole sequence a–h can be repeated more than 10 times by varying the temperature between these two settings. The reproducibility of the locations of droplets and spherulites emphasizes the link between them.