A series of PLA/ZnO bionanocomposite films were prepared by introducing positively surface charged zinc oxide nanoparticles (ZnO NPs) into biodegradable poly(lactic acid) (PLA) by the solvent casting method, and their physical properties and antibacterial activities were evaluated. The physical properties and antibacterial efficiencies of the bionanocomposite films were strongly dependent on the ZnO NPs content. The bionanocomposite films with over 3% ZnO NPs exhibited a rough surface, poor dispersion, hard agglomerates, and voids, leading to a reduction in the crystallinity and morphological defects. With the increasing ZnO NPs content, the thermal stability and barrier properties of the PLA/ZnO bionanocomposite films were decreased while their hydrophobicity increased. The bionanocomposite films showed appreciable antimicrobial activity against Staphylococcus aureus and Escherichia coli. Especially, the films with over 3% of ZnO NPs exhibited a complete growth inhibition of E. coli. The strong interactions between the positively charged surface ZnO NPs and negatively charged surface of the bacterial membrane led to the production of reactive oxygen species (ROS) and eventually bacterial cell death. Consequently, these PLA/ZnO bionanocomposite films can potentially be used as a food packaging material with excellent UV protective and antibacterial properties.

Nowadays, infectious diseases persist as a global crisis by causing significant destruction to public health and the economic stability of countries worldwide. Especially bacterial infections remain a most severe concern due to the prevalence and emergence of multi-drug resistance (MDR) and limitations with existing therapeutic options. Antibacterial photodynamic therapy (APDT) is a potential therapeutic modality that involves the systematic administration of photosensitizers (PSs), light, and molecular oxygen (O₂) for coping with bacterial infections. Although the existing porphyrin and non-porphyrin PSs were effective in APDT, the poor solubility, limited efficacy against Gram-negative bacteria, and non-specific distribution hinder their clinical applications. Accordingly, to promote the efficiency of conventional PSs, various polymer-driven modification and functionalization strategies have been adopted to engineer multifunctional hybrid phototherapeutics. This review assesses recent advancements and state-of-the-art research in polymer-PSs hybrid materials developed for APDT applications. Further, the key research findings of the following aspects are considered in-depth with constructive discussions: i) PSs-integrated/functionalized polymeric composites through various molecular interactions; ii) PSs-deposited coatings on different substrates and devices to eliminate healthcare-associated infections; and iii) PSs-embedded films, scaffolds, and hydrogels for regenerative medicine applications.

Cellulose from different species of bamboo (Thyrsostachys siamesi Gamble, Dendrocalamus sericeus Munro (DSM), Bambusa logispatha, and Bambusa sp.) was converted to cellulose nanocrystals (CNCs) by a chemical–mechanical method. First, bamboo fibers were pre-treated (removal of lignin and hemicellulose) to obtain cellulose. Next, the cellulose was hydrolyzed with sulfuric acid using ultrasonication to obtain CNCs. The diameters of CNCs are in the range of 11–375 nm. The CNCs from DSM showed the highest yield and crystallinity, which was chosen in the film fabrication. The plasticized cassava starch-based films with various amounts (0–0.6 g) of CNCs (from DSM) were prepared and characterized. As the number of CNCs in cassava starch-based films increased, water solubility and the water vapor permeability of CNCs decreased. In addition, the atomic force microscope of the nanocomposite films showed that CNC particles were dispersed uniformly on the surface of cassava starch-based film at 0.2 and 0.4 g content. However, the number of CNCs at 0.6 g resulted in more CNC agglomeration in cassava starch-based films. The 0.4 g CNC in cassava starch-based film was found to have the highest tensile strength (4.2 MPa). Cassava starch-incorporated CNCs from bamboo film can be applied as a biodegradable packaging material.

The development of eco-friendly methods for the synthesis of nanomaterial shape and size is an important area of research in the field of nanotechnology. The present investigation deals with the extracellular rapid biosynthesis of gold nanoparticles using Fusarium solani culture filtrate. The UV–vis spectra of the fungal culture filtrate medium containing gold ion showed peak at 527 nm corresponding to the plasmon absorbance of gold nanoparticles. FTIR spectra provide an evidence for the presence of heterocyclic compound in the culture filtrate, which increases the stability of the synthesized gold nanoparticles. The X-ray analysis respects the Bragg’s law and confirmed the crystalline nature of the gold nanoparticles. AFM analysis showed the results of particle sizes (41 nm). Transmission electron microscopy (TEM) showed that the gold nanoparticles are spherical in shape with the size range from 20 to 50 nm. The use of F. solani will offer several advantages since it is considered as a non-human pathogenic organism. The fungus F. solani has a fast growth rate, rapid capacity of metallic ions reduction, NPs stabilization and facile and economical biomass handling. Extracellular biosynthesis of gold nanoparticles could be highly advantageous from the point of view of synthesis in large quantities, time consumption, eco-friendly, non-toxic and easy downstream processing.

Recently, functional nanomaterials with unique sizes, shapes, and surface chemistry have been fabricated for various applications in all facets of science and technology. Among these diverse nanomaterials, copper oxide nanoparticles (CuO NPs) have garnered considerable attention due to their unique physicochemical parameters and semiconductor properties. Doping various functional materials in CuO NPs and the fabrication of CuO nanofillers functionalized with natural or synthetic moieties delivers improved antibacterial efficacy in food packaging applications. Moreover, the bactericidal effect of modified CuO NPs against foodborne pathogens largely contributes to their usage in food packaging technology. Therefore, it is essential to fabricate effective antimicrobial CuO nanofillers with minimal or no adverse side effects. This review discusses the synthesis, characterization, surface modification, antibacterial properties, food packaging applications, and toxicological implications of the diverse CuO nanofillers integrated in films and composites. In addition, it highlights their adverse side effects and ways to combat adverse situations. The forthcoming generation is expected to lead a groundbreaking surge of inventive food packaging systems (FPS) based on CuO hybrid nanofillers in food packaging industries.

The development of antimicrobial agents with excellent antimicrobial activity, high thermal stability, and non-toxic properties is an essential demand in food packaging, pharmaceutical, and biomedical applications. In the present study, MgO nanoflakes were synthesized via the co-precipitation method by varying calcination temperatures at 400, 500, and 600 °C. The effect of calcination temperature on the morphology, thermal stability, antimicrobial activity, and cytotoxicity of the MgO nanoflakes was analyzed. All synthesized MgO samples showed a Face-Centered Cubic (FCC) structure. As the calcination temperature increased, the MgO crystallite and particle sizes increased, whereas the surface area decreased. In addition, the MgO synthesized from higher calcination temperatures showed higher thermal stability and crystallinity. The MgO synthesized from the lower calcination temperatures (400 and 500 °C) showed superior antimicrobial activity against Escherichia coli (100% R) and Staphylococcus aureus (100% R) than that from the higher calcination temperature (600 °C). The cytotoxicity test demonstrates slight cytotoxicity in MgO-400 °C at concentrations ranging from 100 to 200 µg/mL. Interestingly, MgO-500 °C and MgO-600 °C demonstrate biocompatibility and exhibit non-cytotoxic effects, respectively, highlighting their potential for practical applications in active food packaging and biomedical fields.