The importance of antibacterial materials for biomedical applications is growing nowadays. The presented article deals with the characterization of structural, mechanical and thermal properties and of antibacterial polymeric films based on polyvinyl alcohol (PVA) and silver nitrate, which can find their applicability in wound dressing components and protective coating. The methods of transmission electron microscopy, UV-vis and XRD spectroscopy, optical microscopy, differential scanning calorimetry, stress-strain analysis, and agar diffusion test were used to characterize the polymer films prepared. The results showed strong antibacterial activity against Escherichia coli and Staphylococcus aureus already at the lowest addition level of silver nitrate. An improvement of mechanical properties (Young's modulus) was also noticed due to a modification of PVA with silver nitrate up to 1 wt. % of silver content. Furthermore, the results show a strong effect of the thermal history of the sample preparation on the degree of silver-ion reduction and formation of nanoparticles.
Antimicrobial biopolymer films and coatings are of great interest for many applications. Different chitosan systems were prepared and characterized to evaluate the effect of their composition on the physical and antimicrobial properties. Three types of emulsifiers (Tween 20, 80, and 85) were used as stabilizing agents, combined with thyme essential oil (from two producers) applied as an active substance. A predominant role of the applied stabilizer and its hydrophilic–lipophilic balance value was proven. The incorporation of thyme essential oil and surfactant into the chitosan matrix led to a significant decrease of particle size in film-forming solutions, as well as a thickness increase and the enhancement of the barrier properties in chitosan films. Antimicrobial effects were provided even at the lowest tested concentration of thyme essential oil. Hence, the prepared chitosan films represent promising candidates in antimicrobial packaging applications.
The effect of two essential oils (EOs), from Origanum vulgare and Origanum majorana, their structural properties, and concentration on physical and antimicrobial characteristics of chitosan based solutions as well as films was investigated. Results showed that significantly different behaviour was induced by variation in the compositions of given essential oils. Film-forming solutions (FFS) containing oregano oil comprised considerably greater particles in comparison with the marjoram samples. Similarly, structural changes were confirmed by SEM analysis of chitosan films modified with the EOs; the smaller particles of the marjoram oil demonstrated better compatibility with chitosan matrix. However, chitosan films enriched with the oregano oil showed significantly superior antimicrobial activity compared to the marjoram. The dissimilar effects of the two EOs were also observed by water vapour pressure (WVP) measurement; increasing the amount of oregano oil triggered a drop in the WVP of the prepared films, whereas the marjoram oil had a negligible impact in this respect. These results suggest that the structural features of active substances in the EOs play a crucial role in determining the final properties of FFS and biofilm systems.
Summary: Commercially available polymer Bioflex 1 219F, blend of polylactic acid and biodegradable co-polyester, was used for film preparation, performed on monoextrusion blown moulding machine. Resulting thin film was investigated on biodegradability in composting conditions for 6 weeks. The influence of microbial attack on mechanical, physico-chemical properties, weight loss and surface morphology was tested weekly. The results obtained during 6 weeks of composting indicate relatively good accessibility to biological degradation. Moreover, the time course of studied properties was observed through the test period.
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