Biocompatible Silica-Polyethylene Glycol-Based Composites for Immobilization of Microbial Cells by Sol-Gel Synthesis

Abstract

Biocatalysts based on the methylotrophic yeast Ogataea polymorpha VKM Y-2559 immobilized in polymer-based nanocomposites for the treatment of methanol-containing wastewater were developed. The organosilica composites with different matrix-to-filler ratios derived from TEOS/MTES in the presence of PEG (SPEG-composite) and from silicon-polyethylene glycol (STPEG-composite) differ in the structure of the silicate phase and its distribution in the composite matrix. Methods of fluorescent and scanning microscopy first confirmed the formation of an organosilica shell around living yeast cells during sol-gel bio-STPEG-composite synthesis. Biosensors based on the yeast cells immobilized in STPEG- and SPEG-composites are characterized by effective operation: the coefficient of sensitivity is 0.85 ± 0.07 mgO2 × min−1 × mmol−1 and 0.87 ± 0.05 mgO2 × min−1 × mmol−1, and the long-term stability is 10 and 15 days, respectively. The encapsulated microbial cells are protected from UV radiation and the toxic action of heavy metal ions. Biofilters based on the developed biocatalysts are characterized by high effectiveness in the utilization of methanol-rich wastewater—their oxidative power reached 900 gO2/(m3 × cycle), and their purification degree was up to 60%.

Sol-Gel Films Doped with Enzymes and Banana Crude Extract as Sensing Materials for Spectrophotometric Determination

“…Another approach for creating biocomposite sol-gel films is the employment of silicon polyethylene glycol (SPG). SPG rapidly hydrolyzes and forms gels in aqueous media without the need for any catalyst, such as hydrochloric acid, to form silica hydrogels, which are transparent, and physically stable [ 21 , 22 , 23 ]. This approach was tested with many biological molecules, such as peroxidase, catalase, various oxidases, etc.…”

“…Silicon polyethylene glycol (SPG) was synthesized under the supervision of Dr. T.G. Khonina according to the method described earlier [ 22 ].…”

“…This is an important problem that must be solved before employing the sol-gel process as a universal method of protein or other biomolecules encapsulation. In the literature, special schemes are described for the synthesis of sol-gel materials doped with enzymes to preserve the enzymatic activity of immobilized enzymes [ 18 , 19 , 20 , 21 , 22 , 23 ]. The approaches described can be divided into two groups: the use of tetraethoxysilane and its derivatives as precursors while using various ways to minimize the contact of the enzyme with ethanol released upon hydrolysis of the precursors and the use of silicate and glycerates as precursors, the hydrolysis of which does not release ethanol.…”

“…The second group implies the use of different precursors: sodium silicate [ 19 , 20 ] or glycerol-derived silicates [ 21 , 22 , 23 ], which provide an alcohol-free sol. Both these routes possess some limitations in their application: the glycerol-derived silicate precursors need to be synthesized and sodium silicate precursors produce high sodium concentration levels in the sol.…”

Biomimetic Sol–Gel Chemistry to Tailor Structure, Properties, and Functionality of Bionanocomposites by Biopolymers and Cells

“…High temperature is crucial for proteins and living cells, i.e., the proposed method cannot be fully classified as biomimetic. Therefore, heating was not used when the methylotrophic yeast Ogataea polymorpha was immobilized in [ 281 ]. Khonina et al applied a catalyst (sodium fluoride) in this instance.…”