Bioactive Electrospun Fibers of Poly(ε-Caprolactone) Incorporating α-Tocopherol for Food Packaging Applications.

Antioxidant activity is an important feature for food contact materials such as packaging, aiming to preserve freshness and retard food spoilage. Common bioactive agents are highly susceptible to various forms of degradation; therefore, protection is required to maintain functionality and bioavailability. Poly(ε-caprolactone) (PCL), a biodegradable GRAS labeled polymer, was used in this study for encapsulation of α-tocopherol antioxidant, a major component of vitamin E, in the form of electrospun fibers. Rheological properties of the fiber forming solutions, which determine the electrospinning behavior, were correlated with the properties of electrospun fibers, e.g., morphology and surface properties. Interactions through hydrogen bonds were evidenced between the two components. These have strong effect on structuration of macromolecular chains, especially at low α-tocopherol amounts, decreasing viscosity and elastic modulus. Intra-molecular interactions in PCL strengthen at high α-tocopherol amounts due to decreased solvation, allowing good structural recovery after cease of mechanical stress. Morphologically homogeneous electrospun fibers were obtained, with ~6 µm average diameter. The obtained fibers were highly hydrophobic, with fast release in 95% ethanol as alternative simulant for fatty foods. This induced good in vitro antioxidant activity and significant in vivo reduction of microbial growth on cheese, as determined by respirometry. Therefore, the electrospun fibers from PCL entrapping α-tocopherol as bioactive agent showed potential use in food packaging materials.

Synthesis of Bioactive Materials by In Situ One-Step Direct Loading of Syzygium aromaticum Essential Oil into Chitosan-Based Hydrogels.

Hydrogel conjugates based on chitosan and an essential oil were synthetized by an ultrasound-assisted emulsification approach. Rheology studies revealed a gel-type structure with pronounced compactness and flexibility while SEM showed the formation of a two-level ordered network with highly interconnected pores. The swelling studies indicated a pH-dependent behavior with a significant overshooting effect. The synergistic effects of the components in clove essential oil led to a strong antioxidant character and an enhanced antimicrobial activity of the conjugate hydrogels. The bioactivity was maintained for 6 months, despite a slight decrease in the antimicrobial effect. Hydrogel conjugates were found to be very stable even after two months immersed in acidic solutions that would otherwise dissolve the chitosan matrix. Ultrasound emulsification was proved as an efficient one-step loading method of hydrophobic clove essential oil into hydrophilic chitosan matrix. It was found that clove oil and its components have a double role. Besides providing bioactivity, they also behave as gelation-inducing agents, acting as an alternative to the classical chemical cross-linkers to ensure the good physical and chemical stabilization of chitosan.

Stimuli Responsive Scaffolds Based on Carboxymethyl Starch and Poly(2-Dimethylaminoethyl Methacrylate) for Anti-Inflammatory Drug Delivery.

The purpose of the study is to obtain multicomponent polyelectrolyte hydrogels with optimal synergistic properties by combining a modified starch with a synthetic one. Thus, new low-cost and biocompatible semi-interpenetrating polymer network (semi-IPN) hydrogels of carboxymethyl starch and poly(2-dimethylaminoethyl methacrylate) are prepared and investigated. The synthesized hydrogels are studied with respect to the specific characteristics of the gels: swelling kinetics, thermal analysis, viscoelastic characteristics, and their ability to be used as a matrix in drug delivery systems. Therefore, the semi-IPN gels are loaded with ibuprofen, followed by additional tests to assess the in vitro drug release. The cytocompatibility of the hydrogels with respect to their composition is evaluated in vitro on fibroblast cell culture. The investigations confirm the obtainment of new semi-IPN hydrogels with pH and temperature responsiveness, good mechanical strength, and potential for use as drug delivery systems or transdermal patches.