The aim of the presented dissertation was to create combined antimicrobial nanostructured materials with potential applications in biomedicine and cosmetics. Natural antimicrobial substances were tested with the aim of reducing antibiotic resistance. Combinations of various natural substances, or natural antimicrobial substances and antibiotics, were tested to determine their synergistic effect and to design combined biomaterials with gradual controlled release
of active ingredients.
Selected plant bioactive substances and antibiotics were characterized in terms of their antimicrobial, antiparasitic, antioxidant, and synergistic effects against selected strains of microorganisms, including clinical isolates. Ten synergistic antimicrobial combinations were identified. The active substances were initially encapsulated in nanoparticles and nanofibres in order to determine the appropriate concentration of the encapsulated substance. The functionalized materials were characterized in terms of stability in model environments, encapsulation efficiency, antimicrobial, antiparasitic, and cytotoxic effects. Functionalized liposomal particles have been shown to have potential use in gynecology or as preservatives in cosmetic products. Functionalized nanofibres exhibited high antimicrobial activity but increased cytotoxicity on keratinocytes.
In order to preserve biological activity while reducing the amount of active substances, combined nanopreparates containing synergistic pairs of bioactive substances were proposed in the next part of the work. Combined biomaterials formulations were optimized for systems consisting of liposomes, liposomes with polyhydroxybutyrate (PHB), and nanofibres based on PHB, gelatine, alginate, and chitosan. Two types of composites were successfully prepared: PHB nanofibres with adsorbed liposomes containing PHB and layered nanostructures of PHB and gelatine fibres, with the individual nanocomponents carrying different active substances. The most significant synergistic pairs were incorporated into the resulting combined nanostructures: eugenol–thymol, ampicillin–thymol, eugenol–carvacrol, berberine–streptomycin, and berberine–thymol. In the case of layered systems, an analgesic was also added to create a material with antibacterial and analgesic effects.
Both types of combined nanostructures were then tested for in vitro release of incorporated substances and biological effects. Developed composites showed increased antimicrobial activity in combination with antioxidant properties, low cytotoxicity on human keratinocytes and fibroblasts, and significant immunomodulatory effects, manifested by an increase in IL-6 and IL-8 markers. These findings confirm the potential of combined carriers based on PHB and gelatine nanofibres and PHB-liposomes functionalized with synergistic phytochemicals
as promising bioactive materials for the treatment of superficial wounds or cosmetic erosions.