A Powerful Strategy for Carbon Reduction: Recyclable Mono-Material Polyethylene Functional Film.

Given the abundant plastics produced globally, and the negative environmental impacts of disposable plastic products throughout their life cycle, there has been significant attention drawn by the general public and governments worldwide. Mono-material multilayer packaging is a potent strategy to address the challenge of carbon emissions as it offers specific functionalities (such as strength and barrier properties) through its layers and facilitates recycling. In this study, a five-layer co-extruded polyethylene composite film LLDPE/mPE/PVA/mPE/LLDPE was taken as a model to investigate its mechanical properties and barrier properties after four recycling cycles. The result revealed that the longitudinal tensile strength and transvers tensile were, respectively, dropped from 29.66 MPa and 24.9 MPa to 21.972 MPa and 19.222 MPa after the recycling; it is shown that the film still has good mechanical properties after the recycling cycle. However, a noticeable decline in the barrier properties was observed after the second recycling. In contrast to traditional plastics, a mono-material film with a 10 wt.% circulating mass could reduce CO2 emissions by 3692.25 kg for every 1.0 ton of plastic products after four recycling cycles.

Preservation effects of photodynamic inactivation-mediated antibacterial film on storage quality of salmon fillets: Insights into protein quality.

The preservation effects of a photodynamic inactivation (PDI)-mediated polylactic acid/5-aminolevulinic acid (PLA/ALA) film on the storage quality of salmon fillets were investigated. Results showed that the PDI-mediated PLA/ALA film could continuously generate reactive oxygen species by consuming oxygen to inactivate native pathogens and spoilage bacteria on salmon fillets. Meanwhile, the film maintained the content of muscle proteins and their secondary and tertiary structures, as well as the integrity of myosin by keeping the activity of Ca2+-ATPase, all of which protected the muscle proteins from degradation. Furthermore, the film retained the activity of total superoxide dismutase (T-SOD), suppressed the accumulation of lipid peroxides (e.g., MDA), which greatly inhibited four main types of protein oxidations. As a result, the content of flavor amino acids and essential amino acids in salmon fillets was preserved. Therefore, the PDI-mediated antimicrobial packaging film greatly preserves the storage quality of aquatic products by preserving the protein quality.

Antibacterial efficiency of the curcumin-mediated photodynamic inactivation coupled with L-arginine against Vibrio parahaemolyticus and its application on shrimp.

The aim of this study was to investigate the antibacterial potency of a novel photodynamic inactivation (PDI) system with an enhanced bactericidal ability against Vibrio parahaemolyticus in vitro and in vivo. The synergistically bactericidal action of curcumin (Cur) and L-arginine (L-Arg) was firstly investigated, and then a novel curcumin-mediated PDI coupled with L-Arg was developed. Meanwhile, its potent inactivation mechanism against V. parahaemolyticus and preservation effects on shrimp were explored. Results showed that L-Arg disrupted the cell membrane by binding to membrane phospholipids and disrupting iron homeostasis, which helped curcumin to damage DNA and interrupt protein synthesis. Once irradiated by blue LED, the curcumin-mediated PDI produced the reactive oxygen species (ROS) which reacted with L-Arg to generate NO, and the NO was converted to reactive nitrogen species (RNS) with a strong bactericidal ability by consuming ROS. On this basis, the curcumin-mediated PDI coupled with L-Arg potently killed >8.0 Log CFU/mL with 8 µM curcumin, 0.5 mg/mL L-Arg and 1.2 J/cm2 irradiation. Meanwhile, this PDI also effectively inhibited the colour and pH changes, lipids oxidation and protein degradation of shrimp. Therefore, this study proposes a new potent PDI system to control microbial contamination in the food industry.

Fabrication, Characterization, and Antimicrobial Activity of Carvacrol-Loaded Zein Nanoparticles Using the pH-Driven Method.

To reduce the application of synthetic additives in the field of food preservation, this study utilized carvacrol as an antibacterial agent, and zein and sodium caseinate as carriers, to prepare composite nanoparticles loaded with carvacrol by the pH-driven method. The composite nanoparticles of zein/sodium caseinate had an excellent encapsulation efficiency (77.96~82.19%) for carvacrol, and it had remarkable redispersibility. The results of Fourier transform infrared spectroscopy showed that the formation of the composite nanoparticles mainly depended on the hydrogen bond and the hydrophobic zone force, and thermal gravimetric analysis showed that carvacrol was loaded successfully into nanoparticles, and loading efficiency reached 24.9%. Scanning electron microscopy showed that the composite nanoparticles were spherical, with a particle size range of 50~200 nm, and through the free radical scavenging method and the plate counting method to confirm the particle has stronger antioxidant and antibacterial properties, and with the composite nanoparticles with poly (vinyl alcohol) film applied to the preservation of banana together, it was found that PVA film containing 5 wt% CA-loaded composite NPs can significantly extend the storage period of banana. Therefore, when the composite nanoparticles were applied to food packaging, they could effectively inhibit food spoilage and lengthen the shelf life of food, which displays potential application prospects in the food industry.

Preparation and Characterization of Carvacrol-Loaded Caseinate/Zein-Composite Nanoparticles Using the Anti-Solvent Precipitation Method.

Extending shelf life and maintaining the high quality of food are arduous challenges. In this study, the self-assembly properties of zein were used to load carvacrol essential oil, and then sodium caseinate was selected as a stabilizer to fabricate carvacrol-loaded composite nanoparticles. The results showed that the composite nanoparticles had a high encapsulation efficiency for carvacrol (71.52-80.09%). Scanning electron microscopy (SEM) indicated that the carvacrol-loaded composite nanoparticles were spherical and uniformly distributed, with particle sizes ranging from 80 to 220 nm. First and foremost, the carvacrol-loaded nanoparticles exhibited excellent water-redispersibility, storage-stability, and antioxidant properties, as well as antibacterial properties against Staphylococcus aureus and Escherichia coli. Benefiting from the antimicrobial and antioxidative abilities, the films with carvacrol-loaded composite nanoparticles effectively inhibited food spoilage and prolonged the shelf-life of cherry tomatoes and bananas. Therefore, carvacrol-loaded composite nanoparticles may have potential application prospects in the food industry.

A yolk-shell structure construction for metal-organic frameworks toward an enhanced electrochemical water splitting catalysis.

NiFe-based transition metal catalysts are widely used in electrocatalysis, especially in the field of water splitting, due to their excellent electrochemical performance. Herein, a simple method was designed to synthesize a Ni MOF based on nickel foam and it was modified with Fe. After the introduction of Fe, the resulting material exhibits an obvious yolk-shell structure, which greatly increases the specific surface area and facilitates the construction of active sites. At the same time, the synergy between Ni and Fe is conducive to optimizing the electronic structure and effectively improving the poor stability of the MOF. As a result, the synthesized Ni MOF-Fe-2 only needs an overpotential of 229 mV to achieve the OER at a current density of 10 mA cm-2, which is better than most reported transition metal-based electrocatalysts. To our surprise, it showed extraordinary stability under the voltage used for water splitting.

Ultrasonic-electrodeposition of PtPd alloy nanoparticles on ionic liquid-functionalized graphene paper: towards a flexible and versatile nanohybrid electrode.

Here we fabricate a new type of flexible and versatile nanohybrid paper electrode by ultrasonic-electrodeposition of PtPd alloy nanoparticles on freestanding ionic liquid (IL)-functionalized graphene paper, and explore its multifunctional applications in electrochemical catalysis and sensing systems. The graphene-based paper materials demonstrate intrinsic flexibility, exceptional mechanical strength and high electrical conductivity, and therefore can serve as an ideal freestanding flexible electrode for electrochemical devices. Furthermore, the functionalization of graphene with IL (i.e., 1-butyl-3-methylimidazolium tetrafluoroborate) not only increases the electroactive surface area of a graphene-based nanohybrid paper electrode, but also improves the adhesion and dispersion of metal nanoparticles on the paper surface. These unique attributes, combined with the merits of an ultrasonic-electrodeposition method, lead to the formation of PtPd alloy nanoparticles on IL-graphene paper with high loading, uniform distribution, controlled morphology and favourable size. Consequently, the resultant nanohybrid paper electrode exhibits remarkable catalytic activity as well as excellent cycle stability and improved anti-poisoning ability towards electrooxidation of fuel molecules such as methanol and ethanol. Furthermore, for nonenzymatic electrochemical sensing of some specific biomarkers such as glucose and reactive oxygen species, the nanohybrid paper electrode shows high selectivity, sensitivity and biocompatibility in these bio-catalytic processes, and can be used for real-time tracking hydrogen peroxide secretion by living human cells. All these features demonstrate its promising application as a versatile nanohybrid electrode material in flexible and lightweight electrochemical energy conversion and biosensing systems such as bendable on-chip power sources, wearable/implantable detectors and in vivo micro-biosensors.