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Glycerol-(9,10-trioxolane) trioleate (OTOA) is a promising material that combines good plasticizing properties for PLA with profound antimicrobial activity, which makes it suitable for application in state-of-the-art biomedical and packaging materials with added functionality. On the other hand, application of OTOA in PLA-based antibacterial materials is hindered by a lack of knowledge on kinetics of the OTOA release. In this work, the release of glycero-(9,10-trioxolane) trioleate (OTOA) from PLA films with 50% OTOA content was studied during incubation in normal saline solution, and for the first time, the kinetics of OTOA release from PLA film was evaluated. Morphological, thermal, structural and mechanical properties of the PLA + 50% OTOA films were studied during incubation in normal saline and corresponding OTOA release using differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy and mechanical tests. It was confirmed by DSC and XRD that incubation in the saline solution and corresponding OTOA release from PLA film does not lead to significant changes in the structure of the polymer matrix. Thus, the formation of more disturbed α' crystalline phase of PLA due to partial hydrolysis of amorphous zones and/or most unstable crystallites in the PLA/OTOA semi-crystalline structure was observed. The degree of crystallinity of PLA + OTOA film was also slightly increased at the prolonged stages of OTOA release. PLA + 50% OTOA film retained its strength properties after incubation in normal saline, with a slight increase in the elastic modulus and tensile strength, accompanied by a significant decrease in relative elongation at break. The obtained results showed that PLA + 50% OTOA film could be characterized by sustained OTOA release with the amount of released OTOA exceeding 50% of the initial content in the PLA film. The OTOA release profile was close to zero-order kinetics, which is beneficial in order to provide stable drug release pattern. Developed PLA + 50% OTOA films showed a strong and stable antibacterial effect against Raoultella terrigena and Escherichia coli, bacterial strains with multidrug resistance behavior. The resulting PLA + OTOA films could be used in a variety of biomedical and packaging applications, including wound dressings and antibacterial food packaging. [ABSTRACT FROM AUTHOR]

The product of ozonolysis, glycero-(9,10-trioxolane)-trioleate (ozonide of oleic acid triglyceride, [OTOA]), was incorporated into polylactic acid/polycaprolactone (PLA/PCL) blend films in the amount of 1, 5, 10, 20, 30 and 40% w/w. The morphological, mechanical, thermal and antibacterial properties of the biodegradable PLA/PCL films after the OTOA addition were studied. According to DSC and XRD data, the degree of crystallinity of the PLA/PCL + OTOA films showed a general decreasing trend with an increase in OTOA content. Thus, a significant decrease from 34.0% for the reference PLA/PCL film to 15.7% for the PLA/PCL + 40% OTOA film was established using DSC. Observed results could be explained by the plasticizing effect of OTOA. On the other hand, the PLA/PCL film with 20% OTOA does not follow this trend, showing an increase in crystallinity both via DSC (20.3%) and XRD (34.6%). OTOA molecules, acting as a plasticizer, reduce the entropic barrier for nuclei formation, leading to large number of PLA spherulites in the plasticized PLA/PCL matrix. In addition, OTOA molecules could decrease the local melt viscosity at the vicinity of the growing lamellae, leading to faster crystal growth. Morphological analysis showed that the structure of the films with an OTOA concentration above 20% drastically changed. Specifically, an interface between the PLA/PCL matrix and OTOA was formed, thereby forming a capsule with the embedded antibacterial agent. The moisture permeability of the resulting PLA/PCL + OTOA films decreased due to the formation of uniformly distributed hydrophobic amorphous zones that prevented water penetration. This architecture affects the tensile characteristics of the films: strength decreases to 5.6 MPa, elastic modulus E by 40%. The behavior of film elasticity is associated with the redistribution of amorphous regions in the matrix. Additionally, PLA/PCL + OTOA films with 20, 30 and 40% of OTOA showed good antibacterial properties on Pseudomonas aeruginosa, Raoultella terrigena (Klebsiella terrigena) and Agrobacterium tumefaciens, making the developed films potentially promising materials for wound-dressing applications. [ABSTRACT FROM AUTHOR]