Bacterial polyesters are a well-known group of polymers with excellent biocompability and biodegradability. They are also a renewable source of a wide array of enantiopure (R)-3-hydroxycarboxylic acids. In this study, a series of ternary deep eutectic solvent (DES) systems were prepared using a mixture of microorganism-derived (R)-3-hydroxynonanoic and (R)-3-hydroxyheptanoic acids in a molar ratio of 7 : 3 as hydrogen-bond donors (HBDs) and selected quaternary ammonium salts as hydrogen-bond acceptors (HBAs), namely choline, 1-ethyl-3-methylimidazolium and tributylmethylammonium chlorides. For comparison, DESs based on aliphatic carboxylic acid analogues, i.e. nonanoic and heptanoic acids, were also studied. The systems were characterised by ¹H NMR and FT-IR techniques and the formation of hydrogen bonds between the HBDs and HBAs was proved. The thermal properties, including the melting temperatures and thermal stabilities, as well as the polarity and wetting properties were determined by DSC, TGA, the Nile Red method and dynamic contact angle methods, respectively. The viscosity and density were measured over a temperature range of 30–60 °C. Cytotoxicity and biodegradation studies were conducted and revealed the non-toxic character of the choline-based DES. The ability of the DESs to dissolve lignin was also evaluated. The results demonstrated the potential for a new area of application of bacterial polyesters for the synthesis of novel bio-based solvents.

Development of new composite materials for bone tissue engineering is a constantly growing field of medicine. Therefore there is a continuous need in creating novel materials that can not only regenerate the defected tissue but also nourish it while the healing process progresses. Here we present a novel type of composite material that fulfils these requirements. The study describes creation of a composite with macroporous bioceramic core that is infiltrated with a thin biopolymer layer. The ceramic component, namely tricalcium phosphate (TCP), due to its mechanistic and bioactive properties may promote new bone creation as shown through the in vitro studies. To the best of our knowledge the coating layer was created for the first time from a representative of bacterially derived medium chain length polyhydroxyalkanoate polymers (mcl-PHA), namely polyhydroxyoctanoate (PHO). This polymer layer not only profoundly changed the stress-strain characteristics of the bioceramic foam but also released (R)-3-hydroxyacids and their dimers/trimers to the investigated environment. In the manuscript we have in depth characterised these materials employing a set of basic procedures, through 3D structure reconstruction and finishing with prolonged in vitro experiments.

Nowadays, regenerative medicine faces a major challenge in providing new, functional materials that will meet the characteristics desired to replenish and grow new tissue. Therefore, this study presents new ceramic-polymer composites in which the matrix consists of tricalcium phosphates covered with blends containing a chemically bounded diclofenac with the biocompatible polymer—poly(3-hydroxyoctanoate), P(3HO). Modification of P(3HO) oligomers was confirmed by NMR, IR and XPS. Moreover, obtained oligomers and their blends were subjected to an in-depth characterisation using GPC, TGA, DSC and AFM. Furthermore, we demonstrate that the hydrophobicity and surface free energy values of blends decreased with the amount of diclofenac modified oligomers. Subsequently, the designed composites were used as a substrate for growth of the pre-osteoblast cell line (MC3T3-E1). An in vitro biocompatibility study showed that the composite with the lowest concentration of the proposed drug is within the range assumed to be non-toxic (viability above 70%). Cell proliferation was visualised using the SEM method, whereas the observation of cell penetration into the scaffold was carried out by confocal microscopy. Thus, it can be an ideal new functional bone tissue substitute, allowing not only the regeneration and restoration of the defect but also inhibiting the development of chronic inflammation.