Natural extracts have been used in several traditional medicine applications and culinary purposes. Their biological properties (antioxidant and antimicrobial) are due to the presence of several active aromatic compounds. Herein, different natural extracts were evaluated, namely structural and thermal characterization and biological activity, in its natural form and incorporated into a polymeric matrix, to assess their effective potential as additives for active food packaging. While rosemary presented the highest thermal stability with a degradation starting at 327°C, lemon balm extract was the less stable (180°C). Regarding the thiobarbituric acid assay, all extracts presented antioxidant activity, in oxidative hemolysis inhibition; anise, cinnamon, and clove extract did not present any action. Overall, the results demonstrated that leaves (rosemary and green tea) and the rhizome (curcumin) are the plant parts with the best performance. Therefore, extracts from aromatic plants are promising natural additives that can be incorporated into polymeric matrices to produce active food packaging film, increasing products shelf‐life.

In this study, multicore-like iron oxide (Fe₃O₄) and manganese ferrite (MnFe₂O₄) nanoparticles were synthesized and combined with nanogels based on chitosan and alginate to obtain a multimodal drug delivery system. The nanoparticles exhibited crystalline structures and displayed sizes of 20 ± 3 nm (Fe₃O₄) and 11 ± 2 nm (MnFe₂O₄). The Fe₃O₄ nanoparticles showed a higher saturation magnetization and heating efficiency compared with the MnFe₂O₄ nanoparticles. Functionalization with citrate and bovine serum albumin was found to improve the stability and modified surface properties. The nanoparticles were encapsulated in nanogels, and provided high drug encapsulation efficiencies (~70%) using doxorubicin as a model drug. The nanogels exhibited sustained drug release, with enhanced release under near-infrared (NIR) laser irradiation and acidic pH. The nanogels containing BSA-functionalized nanoparticles displayed improved sustained drug release at physiological pH, and the release kinetics followed a diffusion-controlled mechanism. These results demonstrate the potential of synthesized nanoparticles and nanogels for controlled drug delivery, offering opportunities for targeted and on-demand release in biomedical applications.

Nanostructured dipeptide self-assemblies exhibiting quantum confinement are of great interest due to their potential applications in the field of materials science as optoelectronic materials for energy harvesting devices. Cyclic dipeptides are an emerging outstanding group of ring-shaped dipeptides, which, because of multiple interactions, self-assemble in supramolecular structures with different morphologies showing quantum confinement and photoluminescence. Chiral cyclic dipeptides may also display piezoelectricity and pyroelectricity properties with potential applications in new sources of nano energy. Among those, aromatic cyclo-dipeptides containing the amino acid tryptophan are wide-band gap semiconductors displaying the high mechanical rigidity, photoluminescence and piezoelectric properties to be used in power generation. In this work, we report the fabrication of hybrid systems based on chiral cyclo-dipeptide L-Tryptophan-L-Tryptophan incorporated into biopolymer electrospun fibers. The micro/nanofibers contain self-assembled nano-spheres embedded into the polymer matrix, are wide-band gap semiconductors with $4.0 \mathrm{eV}$ band gap energy, and display blue photoluminescence as well as relevant piezoelectric and pyroelectric properties with coefficients as high as $57{\mathrm{CN}}^{-1}$ and $35\times {10}^{-6} {\mathrm{Cm}}^{-2}{\mathrm{K}}^{-1}$, respectively. Therefore, the fabricated hybrid mats are promising systems for future thermal sensing and energy harvesting applications.

A systematic study was performed to provide better understanding of the effect of elastomeric materials on the behavior of polycarbonate blends (PC). Thus, blends of PC with different amounts of elastomers, such as copolyether ester elastomer (COPE), acrylonitrile–butadiene–styrene (ABS), maleic anhydride-grafted ABS (ABS-g-MA), and styrene–ethylene–butylene–styrene (SEBS-g-MA) were prepared in a co-rotating twin-screw extruder. The materials were characterized by an electronic microscopy (SEM), an infrared spectroscopy (FTIR), and thermal (DSC) and thermo-mechanical (DMA) techniques. The incorporation of elastomeric phases was observed by changes in the FTIR band’s intensity, whereas a new shoulder of the ester band of COPE at 1728 cm⁻¹ indicates the occurrence of a transesterification reaction. Unmodified and modified ABS (5% and 10%) did not affect the glass transition temperature (T_g) of PC, while 1% SEBS-g-MA slightly increased this value. PC/10% COPE showed that a decrease in T_g of 25 °C has a result of better compatibilization between both phases, which is visible via SEM. SEM analysis identified three main toughening mechanisms, depending on the type of elastomer. Unlike any other study, this work deepens the knowledge, in a comparative way, to understand the elastomeric effect at the interface and consequently, on the mechanical behavior of PC systems.

The search for new forms to extend foodstuffs’ shelf-life through the use of natural compounds and extracts continues to grow among researchers and the industry. In this line of thought, the main objective of this work was to develop, characterize and evaluate the effectiveness of an active food packaging based on polylactic acid (PLA) and incorporated with natural extracts obtained from grape and/or pomegranate by-products. In vitro, antioxidant methods were applied to evaluate the antioxidant capacity of three extracts: wort extract, freeze-dried pomegranate peels extract (PPE-FD), and natural pomegranate peels (PPE-N). Punicalagin (A + B) and ellagic acid were determined in PPE-FD, PPE-N, and active films by UHPLC-DAD. New PLA-based active packaging with PPE-FD (PLA/3PPE) and pomegranate peels (PLA/3PP) were developed, and their chemical, mechanical, and barrier properties were evaluated. Moreover, the effectiveness of the new film was carried out through the study of lipid oxidation state and microbial contamination of two high-fat content foodstuffs, almonds and beef meat. PPE-FD presented high antioxidant capacity and high content in total phenolics and flavonoid compounds. The PLA/3PPE and PLA/3PP prevented the lipid oxidation of meat and presented antimicrobial activity against Staphylococcus aureus. The addition of the PPE-FD and the pomegranate peels to the PLA did not affect the morphology of the polymer. Although both PPE-FD and pomegranate peels presented punicalagin (A + B) and ellagic acid, only ellagic acid was identified and quantified in the active PLA. Active PLA films were not effective in delaying the lipid oxidation of almonds, but they showed to be significantly effective in delaying the lipid oxidation of beef meat and reducing the microbial growth in this food matrix over time.

Microbial development, enzymatic action, and chemical reactions influence the quality of untreated natural orange juice, compromising its organoleptic characteristics and causing nutritional value loss. Active low-density polyethylene (LDPE) films containing green tea extract (GTE) were previously prepared by a blown film extrusion process. Small bags were prepared from the produced films, which were then filled with fresh orange juice and stored at 4 °C. Ascorbic acid (AA) content, sugar content, browning index, color parameters, pH, total acidity (TA) and microbial stability were evaluated after 3, 7, and 14 days of storage. The packaging containing GTE maintained the microbial load of fresh juice beneath the limit of microbial shelf-life (6 log CFU/mL) for the bacterial growth, with a more prominent effect for LDPE with 3%GTE. Regarding yeasts and molds, only the CO_LDPE_3GTE package maintained the microbial load of fresh juice below the limit for up to 14 days. At 14 days, the lowest levels of AA degradation (32.60 mg/100 mL of juice) and development of brown pigments (browning index = 0.139) were observed for the packages containing 3% of GTE, which had a pH of 3.87 and sugar content of 11.4 g/100 mL of juice at this time. Therefore, active LDPE films containing 3% of GTE increase the shelf-life of fresh juice and can be a promising option for storage of this food product while increasing sustainability.