Abstract

Composites based on bacterial cellulose (BC) and synthetic polymers are attracting research interest as promising functional materials due to the ability to control their properties. In this study, the interactions between BC and synthetic polymers, poly(vinyl alcohol) (PVA), polylactide (PLA), and polycaprolactone (PCL), were investigated using computer modeling, and the biosynthesis, characteristics, and protein sorption capacity of the resulting composites were evaluated. In silico analysis using dissipative particle dynamics predicted a decrease in compatibility with BC in the order PVA > PLA > PCL. The calculated Flory–Huggins interaction parameters for BC/PVA, BC/PLA, and BC/PCL systems were 1.75, 3.93, and 6.03, respectively, indicating a gradual decrease in thermodynamic compatibility. These predictions were experimentally confirmed by in situ biosynthesis of BC/synthetic polymer composites under static and dynamic cultivation conditions. BC/PVA composites exhibited homogeneous morphology with pore size below 100 nm and improved structural integrity. BC/PLA and BC/PCL systems showed phase separation and broader pore size distributions, reaching up to 900 nm. The functionalization of the obtained composites via adsorption of different proteins (bovine serum albumin, lysozyme, and His6-organophosphate hydrolase) revealed a high dependence of the results on the polymer type, the conditions applied for composite synthesis, and the molecule size of the proteins. Estimations of protein–composite interactions were conducted in silico and confirmed in vitro. The maximal sorption capacity was revealed for composites obtained during the cultivation of BC-producing microorganisms under static conditions, with the addition of synthetic polymers to the nutritional medium. In the case of enzymes used for the functionalization of composites, a partial activity loss after sorption was revealed. In BC/PVA composites, the maximal decrease in enzyme activity (~30% from the activity level of the same enzymes in the BC samples) was observed. BC/PLA and BC/PCL composites demonstrated preferences in the sorption of large protein molecules, making them attractive platforms for enzyme immobilization and biocatalytic applications of the obtained catalytically active composites.

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