Martina Ferri

For accelerating the shift from fossil-derived plastics toward biopolymers, there is an urgent need to develop efficient and versatile biobased plasticizers to improve biopolymer performance without compromising biodegradability and/or safety. This study explores the versatility of the emerging triphenylacetic glyceroate (TPAG) bioplasticizer by incorporating it into a range of biobased and conventional polymers. An increasing content of TPAG, from 5 to 20 parts per hundred of resin (phr), has been compounded with polyhydroxybutyrate (PHB), polyhydroxybutyrate-co-valerate (PHBV), polyvinyl chloride (PVC), and polybutylene succinate (PBS), which present complicated processability and/or limited mechanical properties as bare polymers. Differential scanning calorimetry reveals a clear reduction in glass-transition temperatures (T _g) for PHB, PHBV, and PVC, with the most significant drop observed for PVC (ΔT _g = −25 °C at 20 phr TPAG), confirming the significant plasticizing efficiency of TPAG. A melting temperature decrease is also noted for PHB and PBS, with PHB exhibiting β-crystalline phase formation at high TPAG contents, which is attributed to enhanced chain mobility. Mechanical tests demonstrate that only 10 phr TPAG reduces Young’s modulus across all polymers, importantly enhancing their flexibility. Furthermore, 20 phr of TPAG increases the elongation at break of PVC and PHBV up to 349% and 22%, respectively. Volatility and migration studies demonstrate minimal plasticizer loss with values remaining well below safety limits. Moreover, TPAG addition also tailors both water contact angle and UV-blocking activity of the tested polymers, clearly indicating the versatility and multifunctionality of TPAG as a potentially suitable additive for consumer-facing applications.

In order to develop modern polymer films intended for food packaging, materials based on cellulose acetate propionate (CAP) with the addition of Tween 80 as a plasticizer and cinnamic acid (CA), known for its antibacterial properties, were prepared. It should be emphasized that materials based on CAP combined with Tween 80 have not been previously reported in the literature. Therefore, not only is the incorporation of cinnamic acid into these systems an innovative approach, but also the use of the CAP-Tween80 matrix itself represents a novel strategy in the context of the proposed applications. The conducted studies made it possible to assess the properties of the obtained materials with and without the addition of cinnamic acid. The obtained results showed that the addition of cinnamic acid significantly influenced the crucial properties relevant to food storage. The introduction of CA into the polymer matrix notably enhanced the UV barrier properties achieving complete (100%) blockage of UVB radiation and approximately a 20% reduction of UVA transmittance. Furthermore, the modified films exhibited pronounced antibacterial activity, with over 99% reduction in Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa populations observed for samples containing 2 and 3% CA. This antibacterial effect contributed to the extended freshness of stored blueberries. Moreover, the addition of cinnamic acid did not significantly affect the transparency of the films, which remained high (97–99%), thereby allowing the fruit to remain visible.

The development of multifunctional materials that actively enhance the wound healing process is critically important in addressing clinical and public healthcare challenges. Here, we report a multifunctional hydrogel obtained through physical cross-linking of chitosan and wood tannins for active wound management. Tannins, as polyphenolic wood-waste derivatives, act both as multifunctional additives and cross-linking agents, resulting in a stable and highly swellable hydrogel (>2000%·mg^-1). The dressing is produced in the form of a dry and rigid film for easy transportation. After swelling, the material exhibits adequate Young's modulus (∼7 MPa, comparable to the stratum corneum's stiffness), improved flexibility, and suitable adhesion strength to adapt to joint movements. Polyphenolic tannins also provide the material with high antioxidant activity against DPPH radicals (100% RSA), showing potential for preventing complications during the inflammation phase. Moreover, tannins can completely block skin-damaging UV light without significantly altering the material's transparency, thus allowing constant visual wound monitoring. Wound healing investigations on abdominoplasty-derived skin demonstrated that tannins enhance the normal skin barrier restoration process, thereby facilitating the transition toward wound regeneration. This work offers a sustainable strategy for valorizing agri-food waste in a fully biobased material to address active wound management.

Polymeric thin films based on polylactide with an addition of poly(ethylene glycol) as a plasticizer and flavonoids in the form of quercetin and berberine were subjected to tests that were particularly relevant from the point of view of contact with food. A comparative analysis of the effect of individual flavonoids on the antioxidative properties of tested films and blueberry storage was carried out. The influence of active compounds on the water vapor permeability, as well as UV protection, of the obtained materials was investigated. Also, the specific migration of individual flavonoids from obtained materials to food simulants in the form of acetic acid and ethyl alcohol was determined. The crucial point of this study is the storage of blueberries. The obtained results indicate that the selection of packaging, containing individual active compounds, depends on the purpose and requirements that the packaging must meet for particular types of food.

Fully biobased and biodegradable materials have attracted a growing interest in the food packaging sector as they can help to reduce the negative impact of fossil-based plastics on the environment. Moreover, the addition of functionalities to these materials by introducing active molecules has become an essential requirement to create modern packaging able to extend food's shelf-life while informing the consumer about food quality and freshness. In this study, we present an innovative bioplastic formulation for food packaging based on poly(hydroxybutyrate-co-valerate) (PHBV) and tannins as multifunctional additives. As a proof of concept, PHBV/tannin films were prepared by solvent casting, increasing the tannin content from 1 to 10 per hundred of resin (phr). Formic acid was used to reach a homogeneous distribution of the hydrophilic tannins into hydrophobic PHBV, which is remarkably challenging by using other solvents. Thanks to their well-known properties, the effect of tannins on the antioxidant, UV protection, and gas barrier properties of PHBV was evaluated. Samples containing 5 phr bioadditive revealed the best combination of these properties, also maintaining good transparency. Differential scanning calorimetry (DSC) investigations revealed that films are suitable for application from the fridge to potentially high temperatures for food heating (up to 200 °C). Tensile tests have also shown that Young's modulus (900-1030 MPa) and tensile strength (20 MPa) are comparable with those of the common polymers and biopolymers for packaging. Besides the improvement of the PHBV properties for extending food's shelf-life, it was also observed that PHBV/tannin could colorimetrically detect ammonia vapors, thus making this material potentially applicable as a smart indicator for food spoilage (e.g., detection of fish degradation). The presented outcomes suggest that tannins can add multifunctional properties to a polymeric material, opening up a new strategy to obtain an attractive alternative to petroleum-based plastics for smart food packaging applications.

A significant mechanical properties mismatch between natural bone and the material forming the orthopedic implant device can lead to its failure due to the inhomogeneous loads distribution, resulting in less dense and more fragile bone tissue (known as the stress shielding effect). The addition of nanofibrillated cellulose (NFC) to biocompatible and bioresorbable poly(3-hydroxybutyrate) (PHB) is proposed in order to tailor the PHB mechanical properties to different bone types. Specifically, the proposed approach offers an effective strategy to develop a supporting material, suitable for bone tissue regeneration, where stiffness, mechanical strength, hardness, and impact resistance can be tuned. The desired homogeneous blend formation and fine-tuning of PHB mechanical properties have been achieved thanks to the specific design and synthesis of a PHB/PEG diblock copolymer that is able to compatibilize the two compounds. Moreover, the typical high hydrophobicity of PHB is significantly reduced when NFC is added in presence of the developed diblock copolymer, thus creating a potential cue for supporting bone tissue growth. Hence, the presented outcomes contribute to the medical community development by translating the research results into clinical practice for designing bio-based materials for prosthetic devices.