Technologies > Drug Delivery > Sol-Gel Encapsulation
Sol-Gel Nanoencapsulation
Sol-Gel Encapsulation

NAT carries out an active R&D program in sol-gel microencapsulation of the pharmaceutical materials for topical medical applications, essential oils and fragrances, food ingredients, and polymer chemistry and catalysis.

Sol-gel encapsulation allows trapping lipophylic components inside the spherical shell of amorphous silicon dioxide (1). The process can be run, for example, in the oil-in-water (O/W) emulsion with an active material solubilized in the silicon phases such as tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS). Hydrolysis of the silicon droplets and condensation of the hydrolyzed species to silica occurs at the oil-water interface and leads to formation of the hard silica shell. The conditions of the process can be controlled by many factors including acid-base catalysis, surfactants, nature of silicon precursors, temperature, time, and mixing conditions. Both porosity and particle size that are critical for the release characteristics are highly tunable by the selection of process parameters.

In the last decade sol-gel encapsulation has matured into a better established technology platform with robust processes suitable for industrial applications. For example, Eusolex UV Pearls, a silica- encapsulated UV filter, introduced to the market by Merck in 2001 has been a significant commercial success. It currently is used by many sunscreen formulators while providing an advantage of the avobenzone photostabilization and crystallization control. Additionally it possesses superb sensory properties and flexibility in formulation due to formation of the stable transparent water colloids.  In the medical field, a silica encapsulated benzoyl peroxide has been successfully used for treatment of acne where it outperformed other commercial products and displayed significantly reduced local side effects.

(1) R. Ciriminna, M. Sciortino, G. Alonzo, A. de Schrijver, M. Pagliaro, “From Molecules to Systems: Sol-Gel Microencapsulation in Silica-Based Materials”, Chem. Rev., 2011.