Biohybrid of methylotrophic yeast and organically modified silica gels from sol–gel chemistry of tetraethoxysilane and dimethyldiethoxysilane

Abstract

The sol–gel process is an effective method to encapsulate living cells into a three-dimensional silica network under mild conditions. In this work, the structure and properties of biohybrids obtained by immobilizing methylotrophic yeast in a one-step sol–gel synthesis process (pH 7.6) from tetraethoxysilane (TEOS) and dimethyldiethoxysilane (DDS) in the presence of polyethylene glycol (PEG) were investigated. When using DDS organic modifier, gel shells forming around the cells are thinner than those when using MTES. Biohybrid material based on methylotrophic yeast immobilized in organically modified silica (ORMOSIL) gels with TEOS to DDS ratio of 15:85% (vol.), shows the greatest respiration activity during methanol biodegradation. The structure of this material is formed by the smallest number of Si-O-Si-bonds and, therefore, the largest number of free silanol groups. We believe that this creates a comfortable environment for encapsulated microorganisms. This study showed that there was a delicate balance between hydrophilic and hydrophobic components in ORMOSIL matrices for immobilized microorganisms.