Issue |
Europhys. Lett.
Volume 48, Number 3, November I 1999
|
|
---|---|---|
Page(s) | 332 - 338 | |
Section | Interdisciplinary physics and related areas of science and technology | |
DOI | https://doi.org/10.1209/epl/i1999-00485-9 | |
Published online | 01 September 2002 |
The role of long-range forces in the phase behavior of colloids and proteins
FOM Institute for Atomic and Molecular Physics Kruislaan 407, 1098 SJ Amsterdam, The Netherlands
Received:
21
April
1999
Accepted:
3
September
1999
The phase behavior of colloid-polymer mixtures, and of solutions of globular proteins, is often interpreted in terms of a simple model of hard spheres with short-ranged attraction. While such a model yields a qualitative understanding of the generic phase diagrams of both colloids and proteins, it fails to capture one important difference: the model predicts fluid-fluid phase separation in the metastable regime below the freezing curve. Such demixing has been observed for globular proteins, but for colloids it appears to be pre-empted by the appearance of a gel. In this paper, we study the effect of additional long-range attractions on the phase behavior of spheres with short-ranged attraction. We find that such attractions can shift the (metastable) fluid-fluid critical point out of the gel region. As this metastable critical point may be important for crystal nucleation, our results suggest that long-ranged attractive forces may play an important role in the crystallization of globular proteins. However, in colloids, where refractive index matching is often used to switch off long-ranged dispersion forces, gelation is likely to inhibit phase separation.
PACS: 82.70.Dd – Colloids / 87.15.Nn – Properties of solutions; aggregation and crystallization of macromolecules / 64.75.g – Solubility, segregation and mixing
© EDP Sciences, 1999
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