The present study describes production of bacterial cellulose composites with silver nanoparticles and antibiotics and compares their properties. Bacterial cellulose (BC) composites synthesized in the culture of the strain of acetic acid bacterium Komagataeibacter xylinus VKPM B-12068 with silver nanoparticles, BC/AgNps, were produced hydrothermally, under different AgNO 3 concentrations (0.0001, 0.001, and 0.01 M) in the reaction medium. The presence of silver in the BC/AgNp composites was confirmed by elemental analysis conducted using scanning electron microscopy with a system of X-ray spectral analysis. Analysis showed that the average atomic number of silver particles in composite samples depended on the concentration of AgNO 3 : as AgNO 3 concentration in the reaction solution was increased, silver content in the composites increased from 0.044 to 0.37 mg/cm 2. BC composites with amikacin and ceftriaxone were prepared by immersing dry BC films in solutions containing different concentrations of the antibiotics. The surface structure and properties and physicochemical and mechanical characteristics of composites were investigated using SEM, DSC, X-ray analysis, the system for measuring water contact angles, and electromechanical tensile testing machine. The disk-diffusion method and the shake-flask culture method used in this study showed that all experimental composites had pronounced antibacterial activity against E. coli, Ps. eruginosa, K. pneumoniae, and St. aureus, and the BC/antibiotic composites were more active than BC/AgNp ones; S. aureus was the most susceptible to the effect of BC composites. No potential cytotoxicity was detected in any of the BC/AgNp composites in the NIH 3T3 mouse fibroblast cell culture, in contrast to the BC/antibiotic composites. These results suggest that BC composites constructed in the present study hold promise as dressings for managing wounds, including contaminated ones.

Biodegradable polymer poly(3-hydroxybutyrate) (P3HB) has been used as a matrix to construct slow-release formulations of the fungicide tebuconazole (TEB). P3HB/TEB systems constructed as films and pellets have been studied using differential scanning calorimetry, X-ray structure analysis, and Fourier transform infrared spectroscopy. TEB release from the experimental formulations has been studied in aqueous and soil laboratory systems. In the soil with known composition of microbial community, polymer was degraded, and TEB release after 35 days reached 60 and 36 % from films and pellets, respectively. That was 1.23 and 1.8 times more than the amount released to the water after 60 days in a sterile aqueous system. Incubation of P3HB/TEB films and pellets in the soil stimulated development of P3HB-degrading microorganisms of the genera Pseudomonas, Stenotrophomonas, Variovorax, and Streptomyces. Experiments with phytopathogenic fungi F. moniliforme and F. solani showed that the experimental P3HB/TEB formulations had antifungal activity comparable with that of free TEB.

A series of 3D implants and filling materials prepared from powdered biodegradable polymers, polyhydroxyalkanoates (PHAs), have been designed for the purposes of reparative osteogenesis. The 3D implants are made of resorbable polymer of hydroxybutyric acid (poly-3-hydroxybutyrate, P3HB) and a composite of this polymer with hydroxyapatite (HA) (P3HB/HA). The properties of the implants were studied in vivo in a model of segmental osteotomy and compared with commercial material Bio-Oss(®). All implants containing P3HB as the main component facilitate reconstructive osteogenesis. P3HB and P3HB/HA show pronounced osteoplastic properties; their in vivo degradation is slow and corresponds to the growth of a new bone tissue, facilitating normal reparative osteogenesis. Also, powdered P3HB and P3HB/tienam can be used as filling materials for osteoplasty of bone cavities infected by Staphylococcus aureus. Biodegradable 3D implants and P3HB-based filling materials show pronounced osteoplastic properties and degrade in vivo at a slow rate, enabling normal reparative osteogenesis.

Biodegradable poly-3-hydroxybutyrate [P(3HB)] and natural materials (fillers)clay, peat, and birch wood powderwere used to prepare powdered blends and, then, pellets and granules. Pellets were produced by cold pressing of polymer and filler powders; granules were produced from the powders wetted with ethanol. Properties of initial P(3HB) and fillers and blends thereof were studied using IR spectroscopy, DSC, X-ray analysis, and electron microscopy. No chemical bonds between the components were revealed: the blends were physical mixtures. The degree of crystallinity of the blends was lower than that of the initial polymer, suggesting different crystallization kinetics of the blends. Introduction of increasing amounts of the fillers into the polymer progressively decreased mechanical strength of the pellets, as confirmed by the decrease in Young's modulus. The study of degradation of the blends in soil showed that the mass loss of the blends over 35 days of incubation in soil varied between 30 and 50% of the initial mass of the products, depending on the type of the filler.

The study describes preparation and testing of porous 3D implants of natural degradable polymer of 3-hydroxybutyric acid P(3HB) for regeneration of bone tissue defects. The ability of the P(3HB) implants to favor attachment and facilitate proliferation and directed differentiation of mesenchymal stem cells (MSCs) was studied in the culture of MSCs isolated from bone marrow and adipose tissue. Tissue-engineered hybrid systems (grafts) constructed using P(3HB) and P(3HB) in combination with osteoblasts were used in experiments on laboratory animals (n = 48) with bone defect model. The defect model (5 mm in diameter) was created in the rat parietal bone, and filling of the defect by the new bone tissue was monitored in the groups of animals with P(3HB) implants, with commercial material, and without implants (negative control). Computed tomography (CT) and histologic examination showed that after 120 days, in the group with the osteoblast-seeded P(3HB) implants, the defect was completely closed; in the group with the cell-free P(3HB) implants, the remaining defect was no more than 10% of the initial one (0.5 mm); in both the negative and positive controls, the size of the defect was about 1.0-1.2 mm. These results suggest that P(3HB) has good potential as osteoplastic material for reconstructive osteogenesis. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 566-577, 2017.