Production of Bacterial Cellulose Aerogels With Improved Physico-Mechanical Properties and Antibacterial Effect.

Viktor V Revin,Elena V Liyaskina,Natalia B Nazarova,Nikolay A Pestov,Vadim D Revin,Ekaterina E Tsareva

doi:10.3389/fbioe.2020.603407

Abstract

Aerogels have gained significant interest in recent decades because of their unique properties such as high porosity, low density, high surface area, and excellent heat and noise insulation. However, their high cost and low mechanical strength limit their practical application. We developed appropriate conditions to produce aerogels with controlled density, high mechanical strength, and thermal characteristics from bacterial cellulose (BC) synthesized by the strain Komagataeibacter sucrofermentans H-110. Aerogels produced using TEMPO oxidized BC (OBC) exhibited high mechanical strength and lower shrinkage than those from native bacterial cellulose (NBC). Compared to the NBC, the use of TEMPO-oxidized BC with oxidation degrees (OD) of 1.44 and 3.04% led to the reduction of shrinkage of the aerogels from 41.02 to 17.08%. The strength of the aerogel produced from the TEMPO-oxidized BC with an oxidation degree of 1.44% was twice that of the aerogel produced from NBC. The addition of Mg2+ at concentrations of 20 and 40 mM during the preparation of the aerogels increased the strength of the aerogels by 4.9 times. The combined use of TEMPO-oxidized BC and Mg2+ allowed pore size reduction from 1,375 to 197.4 μm on the outer part of the aerogels, thereby decreasing the thermal conductivity coefficient from 0.036 to 0.0176 W/(m•K). Furthermore, novel biocomposites prepared from the aerogels based on NBC and OBC and sodium fusidate, which have high antibiotic activity against Staphylococcus aureus, were obtained. Owing to their antibacterial properties, these aerogels can be used as functional biomaterials in a wide range of applications such as in tissue engineering and fabrication of wound dressing materials.

Highlights

Aerogels are one of the most interesting materials of the twenty-first century (Barrios et al, 2019)
The results show that the TEMPO oxidation of bacterial cellulose (BC) does not lead to changes in the thermal stability of the material the nature of the thermal degradation of the material depended on the oxidation of BC and the presence of Mg2+
The prepared biocomposites displayed no effect on L929 cells morphology. These results showed that native bacterial cellulose (NBC)/Sodium Fusidate (SF) and oxidized BC (OBC)/SF biocomposites are promising candidates for wound dressing and tissue engineering applications

Summary

Introduction

Aerogels are one of the most interesting materials of the twenty-first century (Barrios et al, 2019) They have gained considerable interest because of their unique properties such as high porosity, low density, high surface area, and excellent heat and noise insulations. Aerogels are highly porous nanostructured materials that were first created by Kistler in 1931 (Kistler, 1931; Nita et al, 2020). They can be produced by two methods–supercritical drying or freeze-drying. The microporous structure of the material is preserved during drying This material has a high porosity, an extremely low density, and a high specific surface area. The high production cost for such an aerogel combined with the above disadvantages, is the main reason that this material is not widely used

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