| Abstract [eng] |
This thesis investigated nanoparticle-functionalized fibrous air filtration materials designed to reduce the viability of microorganisms on the filter surface. The study utilized electrospun poly[ε] caprolactone fibrous materials incorporating synthesized 1D ZnO structures as well as commercially available Ag, Cu, TiO2, and ZnO nanoparticles. The study evaluated the morphological properties of the formed materials, the suitability of different methods for determining antibacterial activity, and the influence of nanoparticle composition and concentration on antibacterial efficacy. The morphology of the fibrous materials was evaluated using scanning electron microscopy, while the distribution of nanoparticles was analyzed using energy-dispersive spectroscopy. The fiber diameter, pore size, and distribution of nanoparticles within the fibrous structure were analyzed. It was found that the incorporation of nanoparticles influences the morphology of the materials; however, no clear linear relationship between fiber diameter and pore size and nanoparticle concentration was observed. The most pronounced structural changes were observed in the 50 % 1D ZnO sample, which exhibited a larger average fiber diameter and pore size. SEM and EDS analysis confirmed the presence of nanoparticles in the formed fiber materials and showed that some of the nanoparticles are distributed unevenly within the fibers. The study also evaluated the suitability of various methods for determining antibacterial activity. It was found that the disk diffusion method is not suitable for testing fiber materials functionalized with nanoparticles, as the nanoparticles embedded in the polymer matrix do not diffuse into the agar medium. The well diffusion method was used to evaluate the antibacterial effect of individual nanoparticle suspensions, while the ASTM E2180-07 method was used to determine the contact activity of fiber materials. The well diffusion assay showed that the effect of ZnO suspensions on S. aureus bacteria increases with increasing nanoparticle concentration; however, no significant inhibitory effect was observed against E. coli. Among the materials studied, the samples functionalized with 1D ZnO exhibited the highest antibacterial activity. As the concentration of 1D ZnO increased, the reduction in S. aureus bacteria also increased, reaching 99,1 % in the 50 % sample. The effect of these materials was greater than that of commercially available ZnO and TiO2 functionalized samples. Against E. coli bacteria, the effect of the 1D ZnO samples was weaker – the maximum reduction in bacteria at a 50 % concentration reached 74,8 %. The results obtained indicate that 1D ZnO structures are promising for the development of active fibrous air filtration materials capable of trapping microorganisms and reducing their viability on the filter surface. |
