Silica microcapsules as containers for protein drugs: Direct and indirect encapsulation

Hollow silica particles are promising platform for development of novel oral dosage forms of protein drugs with improved pharmacological and consumer properties. Encapsulation of proteins in silica containers can be carried out using two different approaches: direct (one-step) or indirect (multi-step). In this work, the influence of the encapsulation approaches of model protein in porous silica capsules on functional properties of the obtained particles as drug delivery systems (the protein loading, structural state of the encapsulated protein and in vitro kinetics of its release) was studied for the first time. Direct encapsulation of bovine serum albumin (BSA) and preparation of silica capsules for indirect encapsulation was performed using sol-gel/W/O/W emulsion technology. The effects of nature of silica precursor (tetraethoxysilane and sodium silicate) and composition of oil phase on the indicated functional properties were investigated. The comparative analysis of the obtained data allowed ascertaining the optimal conditions of BSA encapsulation in hollow silica particles by sol-gel/emulsion method for the protein delivery application. (C) 2019 Elsevier B.V. All rights reserved.