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

AbstractThe 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. HighlightsThe structure of ORMOSIL material obtained in a one-step sol–gel synthesis process (pH 7.6) from TEOS and DDS (15:85(vol)) in the presence of PEG is formed by the smallest number of Si-O-Si-bonds and, therefore, the largest number of free silanol groups.Immobilization of yeast cells by one-step sol–gel synthesis (pH 7.6) from TEOS, alkylalkoxysilane (MTES or DDS) as hydrophobic organic modifier and PEG as hydrophilic organic modifier leads to the spontaneous formation of ORMOSIL shells around living cells, regardless of the type of alkylalkoxysilane.There was a delicate balance between hydrophilic and hydrophobic components in ORMOSIL matrices for immobilized microorganisms and for design of “living” hybrid materials.“Living” hybrid materials based on encapsulated methylotrophic yeast show high respiration activity during methanol biodegradation and present promising functional materials in the design of biocatalysts and biosensitive surfaces of biosensors.