solubilization

Solubilization is the process by which the apparent solubility of a solute in a solvent is increased by interactions with solubilizing agents or by changing the solvent environment. It enables dissolution of substances that are poorly soluble under ordinary conditions and is a common objective in pharmaceuticals, cosmetics, and environmental engineering. The term covers several mechanisms. Micellization: surfactants above their critical micelle concentration form micelles with hydrophobic cores that sequester nonpolar solutes, increasing their apparent solubility in water. Complexation: host molecules such as cyclodextrins or polymers form inclusion or coordination complexes that stabilize the solute in solution. Cosolvency: adding water-miscible solvents (e.g., ethanol, glycerol, propylene glycol) alters solvent polarity and hydrogen-bonding, raising solubility. Solid dispersions, micellar solutions, and microemulsions are other solubilization approaches that physically solubilize the solute. Solubilization can also occur by pH adjustment or salt formation for ionizable compounds.

Applications include improving oral bioavailability of poorly soluble drugs, formulation of topical or parenteral products, food and cosmetic additives, and remediation of hydrophobic contaminants in soil and water. The effectiveness of solubilization is described by factors such as the type and concentration of solubilizer, temperature, and the thermodynamics of solubilization, including micellar binding or inclusion-complex stability. Experimental assessment and system-specific optimization are required to achieve desired solubility enhancement.