The aim of this work was to prepare a new biodegradable polyhydroxybutyrate (PHB) submicron fiber mat loaded with hypericin-rich Hypericum perforatum raw extract by centrifugal spinning technology, an alternative approach to the traditional method of electrospinning to fabricate nanofibers or microfibers from solutions at high speed and low cost. Hypericins in methanol/acetone extract of H. perforatum were determined by UHPLC-MS/MS and HPLC/PDA. Submicron fiber mats composed of pure PHB or PHB enriched with H. perforatum extract were prepared using a pilot plant demonstrator for the centrifugal spinning technology and characterized by SEM. Singlet oxygen production was quantified by the 1,3-diphenylisobenzofuran (DPIBF) method in hexane. The results proved a significant production of singlet oxygen by the prepared submicron fiber mat. We also found a significant antibacterial activity against the bacterial strain Escherichia coli CCM 5417 by a method in accordance with JIS Z 2801/ISO 22196 standards. The H. perforatum extract-enriched PHB submicron fiber mats showed potential for the development of self-cleaning and antimicrobial air filters.

The purpose of the study was development of soft foams from resorbable polymers with unique micro-macro porous interconnected hierarchical structure specially designed as scaffold for engineering of soft tissues. The foams have been prepared by freeze-drying of solutions of polylactide (PLA) and polycaprolactone (PCL) in 1,4-dioxane. The foams prepared by freeze-drying had interconnected porous aerogel characteristics. The hierarchical structure with bimodal micro-macro pore size distribution were obtained after addition of sucrose or NaCl porogens with defined crystal size distributions to the solutions before freeze-drying and leaching the porogen crystals from the freeze-dried foams with demineralised water. Polyethyleneimine was chemically conjugated to the alkali-treated foams followed by conjugation of citric acid using carbodiimide chemistry. Finally, they were mineralised by immersing and incubating in a simulated body fluid with ionic concentration similar to that of human blood plasma, to obtain tissue engineering scaffolds. To verify their biocompatibility, the scaffolds were seeded with adipose-derived stem cells (ASC) and sarcoma osteogenic-2 (SaOs-2) human osteoblast-like cells. Morphology of the cells attached to the scaffolds was evaluated and their viability was verified by a metabolic test. Biocompatibility and usability of the scaffolds was successfully verified by incubation with adipose-derived stem cells and SaOs-2 human osteosarcoma cell line. Mineralised scaffolds are more suitable growth supports for both the cell types than unmineralized collagen scaffolds. The scaffolds have been specially designed for engineering of soft tissues, but they can be used in other categories of tissue engineering, too.