Recent advances in chemical particle synthesis complemented by highly precise numerical simulations have clearly emphasized the fundamental role of surface colloidal heterogeneities and their detailed chemical compositions. This means that directional (anisotropic) interactions cannot be neglected even at the minimal level. I will discuss the importance of this feature within the framework of a minimal model where short-range attractive interactions are distributed over one or more circular regions of otherwise hard spheres. The fluid-fluid separation curves strongly depend upon the ratio of the attractive/repulsive interactions, as demonstrated by integral equation theories supported by Monte Carlo simulations. The relevance of these findings in terms of very recent experimental results in self-assembly materials and globular proteins is discussed.

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