A promising antimicrobial bionanocomposite based poly(3-hydroxybutyrate-co-3-hydroxyvalerate) reinforced silver doped zinc oxide nanoparticles

Boosting Food Packaging Sustainability Through the Valorization of Agri-Food Waste and By-Products

The environmental concerns associated with synthetic polymers have intensified the search for sustainable and biodegradable alternatives, particularly for food packaging applications. Natural biopolymers offer promising solutions due to their biodegradability, reduced environmental impact, and reliance on renewable resources. Among these, agri-food waste and by-products have gained significant attention as valuable feedstocks for polymer production, supporting a circular economy approach. This review critically examines the current status of biopolymers derived from plant, animal, and microbial sources, focusing on their physical and chemical properties and their application in food packaging. The findings underscore that the properties of plant- and animal-based biopolymers are heavily influenced by the source material and extraction techniques, with successful examples in biodegradable films, coatings, and composite materials. However, a critical gap remains in the characterization of microbial biopolymers, as research in this area predominantly focuses on optimizing production processes rather than evaluating their material properties. Despite this limitation, microbial biopolymers have demonstrated considerable potential in composite films and fillers. By addressing these gaps and evaluating the key factors that influence the success of biopolymer-based packaging, we contribute to the ongoing efforts to develop sustainable food packaging solutions and reduce the environmental impact of plastic waste.

Processing and Properties of Polyhydroxyalkanoate/ZnO Nanocomposites: A Review of Their Potential as Sustainable Packaging Materials

The escalating environmental concerns associated with conventional plastic packaging have accelerated the development of sustainable alternatives, making food packaging a focus area for innovation. Bioplastics, particularly polyhydroxyalkanoates (PHAs), have emerged as potential candidates due to their biobased origin, biodegradability, and biocompatibility. PHAs stand out for their good mechanical and medium gas permeability properties, making them promising materials for food packaging applications. In parallel, zinc oxide (ZnO) nanoparticles (NPs) have gained attention for their antimicrobial properties and ability to enhance the mechanical and barrier properties of (bio)polymers. This review aims to provide a comprehensive introduction to the research on PHA/ZnO nanocomposites. It starts with the importance and current challenges of food packaging, followed by a discussion on the opportunities of bioplastics and PHAs. Next, the synthesis, properties, and application areas of ZnO NPs are discussed to introduce their potential use in (bio)plastic food packaging. Early research on PHA/ZnO nanocomposites has focused on solvent-assisted production methods, whereas novel technologies can offer additional possibilities with regard to industrial upscaling, safer or cheaper processing, or more specific incorporation of ZnO NPs in the matrix or on the surface of PHA films or fibers. Here, the use of solvent casting, melt processing, electrospinning, centrifugal fiber spinning, miniemulsion encapsulation, and ultrasonic spray coating to produce PHA/ZnO nanocomposites is explained. Finally, an overview is given of the reported effects of ZnO NP incorporation on thermal, mechanical, gas barrier, UV barrier, and antimicrobial properties in ZnO nanocomposites based on poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). We conclude that the functionality of PHA materials can be improved by optimizing the ZnO incorporation process and the complex interplay between intrinsic ZnO NP properties, dispersion quality, matrix-filler interactions, and crystallinity. Further research regarding the antimicrobial efficiency and potential migration of ZnO NPs in food (simulants) and the End-of-Life will determine the market potential of PHA/ZnO nanocomposites as active packaging material.

Nanotechnology-enhanced fiber-reinforced polymer composites: Recent advancements on processing techniques and applications

Incorporating nanoparticles can significantly improve the performance and functionality of fiber-reinforced polymer (FRP) composites. Different techniques exist for processing, testing, and implementing nanocomposites in various industries. Depending on these factors, these materials can be tailored to suit the specific applications of the automotive and aerospace industries, defence industries, biomedical and energy sectors etc. Nanotechnology offers several potential benefits for composites, including improved mechanical properties, surface modification, and sensing capabilities. This paper discusses the different types of nanoparticles, nanofibers, and nano-coating that can be used for reinforcement, surface modification, and property enhancement in FRP composites. It also examines the challenges associated with incorporating nanotechnology into composites and provides recommendations for potential opportunities in future work. This study is intended to offer a comprehensive understanding of the current research on using nanotechnology in FRP composites and its potential impact on the composites industry.

Recent advances in biomacromolecule-based nanocomposite films for intelligent food packaging- A review

In food packaging, biopolymer films are biodegradable films made from biomacromolecule-based natural materials, while biocomposite films are hybrids of two or more materials, with at least one being biodegradable. Bionanocomposites are different than the earlier ones, as they consist of various nanofillers (both natural and inorganic) in combination with biomacromolecule-based biodegradable materials to make good compostable bionanocomposites. In this regard, a new type of material known as bionanocomposite has been recently introduced to improve the properties and performance of biocomposite films. Bionanocomposites are primarily developed for active packaging, but their use in intelligent packaging is also noteworthy. For example, bionanocomposites developed using a hybrid of anthocyanin and carbon dots as intelligent materials have shown their high pH-sensing properties. The natural nanofillers (like nanocellulose, nanochitosan, nanoliposome, cellulose nanocrystals, cellulose nanofibers, etc.) are being employed to promote the sustainability, degradability and safety of bionanocomposites. Overall, this article comprehensively reviews the latest innovations in bionanocomposite films for intelligent food packaging over the past five years. In addition to packaging aspects, the role of nanofillers, the importance of life cycle assessment (LCA) and risk assessment, associated challenges, and future perspectives of bionanocomposite intelligent films are also discussed.

Biodegradable Polymers and Polymer Composites with Antibacterial Properties

Antibiotic resistance is one of the greatest threats to global health and food security today. It becomes increasingly difficult to treat infectious disorders because antibiotics, even the newest ones, are becoming less and less effective. One of the ways taken in the Global Plan of Action announced at the World Health Assembly in May 2015 is to ensure the prevention and treatment of infectious diseases. In order to do so, attempts are made to develop new antimicrobial therapeutics, including biomaterials with antibacterial activity, such as polycationic polymers, polypeptides, and polymeric systems, to provide non-antibiotic therapeutic agents, such as selected biologically active nanoparticles and chemical compounds. Another key issue is preventing food from contamination by developing antibacterial packaging materials, particularly based on degradable polymers and biocomposites. This review, in a cross-sectional way, describes the most significant research activities conducted in recent years in the field of the development of polymeric materials and polymer composites with antibacterial properties. We particularly focus on natural polymers, i.e., polysaccharides and polypeptides, which present a mechanism for combating many highly pathogenic microorganisms. We also attempt to use this knowledge to obtain synthetic polymers with similar antibacterial activity.

Synthesis, Characterization, and Evaluation of Antimicrobial Efficacy of Reduced Graphene-ZnO-Copper Nanocomplex

The prevalence of antibiotic-resistant diseases drives a constant hunt for new substitutes. Metal-containing inorganic nanoparticles have broad-spectrum antimicrobial potential to kill Gram-negative and Gram-positive bacteria. In this investigation, reduced graphene oxide-coated zinc oxide-copper (rGO@ZnO-Cu) nanocomposite was prepared by anchoring Cu over ZnO nanorods followed by coating with graphene oxide (GO) and subsequent reduction of GO to rGO. The synthesized nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, elemental analysis, and elemental mapping. Morphologically, ZnO-Cu showed big, irregular rods, rectangular and spherical-shaped ZnO, and anchored clusters of aggregated Cu particles. The Cu aggregates are spread uniformly throughout the network. Most of the ZnO particles were partially covered with Cu aggregates, while some of the ZnO was fully covered with Cu. In the case of rGO@ZnO-Cu, a few layered rGO sheets were observed on the surface as well as deeply embedded inside the network of ZnO-Cu. The rGO@ZnO-Cu complex exhibited antimicrobial activity against Gram-positive and Gram-negative bacteria; however, it was more effective on Staphylococcus aureus than Escherichia coli. Thus, rGO@ZnO-Cu nanocomposites could be an effective alternative against Gram-positive and Gram-negative bacterial pathogens.

Advancing PHBV Biomedical Potential with the Incorporation of Bacterial Biopigment Prodigiosin

The quest for sustainable biomaterials with excellent biocompatibility and tailorable properties has put polyhydroxyalkanoates (PHAs) into the research spotlight. However, high production costs and the lack of bioactivity limit their market penetration. To address this, poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was combined with a bacterial pigment with strong anticancer activity, prodigiosin (PG), to obtain functionally enhanced PHBV-based biomaterials. The samples were produced in the form of films 115.6-118.8 µm in thickness using the solvent casting method. The effects of PG incorporation on the physical properties (morphology, biopolymer crystallinity and thermal stability) and functionality of the obtained biomaterials were investigated. PG has acted as a nucleating agent, in turn affecting the degree of crystallinity, thermal stability and morphology of the films. All samples with PG had a more organized internal structure and higher melting and degradation temperatures. The calculated degree of crystallinity of the PHBV copolymer was 53%, while the PG1, PG3 and PG3 films had values of 64.0%, 63.9% and 69.2%, respectively. Cytotoxicity studies have shown the excellent anticancer activity of films against HCT116 (colon cancer) cells, thus advancing PHBV biomedical application potential.

Opposite Roles of Bacterial Cellulose Nanofibers and Foaming Agent in Polyhydroxyalkanoate-Based Materials

In this work, an economically feasible procedure was employed to produce poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)-based foams. Thermally expandable microspheres (TESs) were used as a blowing agent, while bacterial cellulose (BC) nanofibers served both as a reinforcing agent and as a means of improving biocompatibility. PHBV was plasticized with acetyltributylcitrate to reduce the processing temperature and ensure the maximum efficiency of the TES agent. The morphological investigation results for plasticized PHBV foams showed well-organized porous structures characterized by a porosity of 65% and the presence of both large pores (>100 µm) and finer ones, with a higher proportion of pores larger than 100 µm being observed in the PHBV nanocomposite containing TESs and BC. The foamed structure allowed an increase in the water absorption capacity of up to 650% as compared to the unfoamed samples. TESs and BC had opposite effects on the thermal stability of the plasticized PHBV, with TESs decreasing the degradation temperature by about 17 °C and BC raising it by 3−4 °C. A similar effect was observed for the melting temperature. Regarding the mechanical properties, the TESs had a flexibilizing effect on plasticized PHBV, while BC nanofibers showed a stiffening effect. An in vitro cytotoxicity test showed that all PHBV compounds exhibited high cell viability. The addition of TESs and BC nanofibers to PHBV biocomposites enabled balanced properties, along with lower costs, making PHBV a more attractive biomaterial for engineering, packaging, or medical device applications.