Ultrasmall, non-aggregated porous particles of uniform size for entrapping gas bubbles within and methods

A method of forming porous particles comprising:

• (a) preparing a solution which includes first and second compounds in a suitable solvent;
• (b) infusing a precipitating liquid into the solution, the two compounds having a low solubility in the precipitating liquid, so as to produce a suspension of co-precipitated substantially non-aggregated particles of a uniform size;
• and
• (c) washing the particles in a suitable washing liquid, the first and second compounds having differential solubility in the washing liquid such that the first compound has a lower solubility in the washing liquid than the second compound, so that the second compound is selectively extracted from the first compound to produce a porous matrix.

In a method of making uniformly sized particles of a solid compound comprising preparing a solution of the solid compound in a solvent, infusing a precipitating liquid into the solution so as to produce a suspension of precipitated uniformly sized particles of the solid compound, the improvement comprising:

• (a) co-dissolving a first and a second solid compound in a solvent for the two compounds;
• (b) infusing a co-precipitating liquid so as to co-precipitate particles of the first and second compounds;
• (c) selectively extracting at least some of the second compound from the co-precipitated particles in an extractive washing liquid in which the first and second compounds have differential solubility so as to produce porous particles having a porous matrix of the first compound;
• and
• (d) recovering the porous particles.