UV-shielding alginate films crosslinked with Fe3+ containing EDTA

Microwave-assisted Lewis acid catalysis for one-step preparation of high-performance buckwheat peptide-based films: Efficacy, mechanism, and applications

This study presents a novel method for the efficient preparation of peptide-based films through microwave-assisted Lewis acid catalysis (MALC) of buckwheat globulin (BG). The MALC process efficiently degraded BG into small molecular peptides (1.6-1.8 kDa) within 10 min. These peptides formed aggregates with a high β-sheet content through coordination with metal ions, which demonstrated a strong ability to create highly cross-linked network structures. The peptide-based films (PFs), without the addition of any cross-linking agents, exhibited excellent tensile strength (1.65-3.62 MPa), elongation at break (11.52-44.61 %), superior oxygen barrier properties (0.06-2.45 cm3/m2·day), and low swelling rates (20-36 %). Notably, the PFs also possessed strong antibacterial, antioxidant, and ultraviolet resistance capabilities, extending the shelf life of fresh chili peppers by approximately 7 days. This study enhances our understanding of the interactions between transition metal ions and plant proteins, establishing a technological foundation for the large-scale application of plant protein films.

In-situ printing of an oxygen-generating tubular alginate hydrogel embedding Chlorella vulgaris

Immobilizing microalgae in hydrogels offers advantages over suspension culture, allowing for a compact design of a photosynthetic system in air. Despite the bioactivity of microalgae embedded in a hydrogel, a continuous supply of water and nutrients is crucial to sustain photosynthesis for extended periods. A tubular structure of an alginate (ALG) hydrogel can be formed using matrix-assisted three-dimensional printing encapsulating Chlorella vulgaris through ion crosslinking. A silicon-nanoparticle matrix with multivalent cations enables spontaneous solidification of ALG liquid inks with high-fidelity printing, creating optimal printing and ion-diffusion parameters for the fabrication of tubular hydrogel structures. The bioactivity of C. vulgaris in hydrogels is confirmed by measuring the level of generated oxygen about 13 mg/L at 0.1 mL/min of flow rate through the tubular hydrogel structures, and the generation efficiency supports the application of microalgae in purification in the future.

Recent developments in alginate-based nanocomposite coatings and films for biodegradable food packaging applications

Packaging made of plastic harms the environment. Thus, polysaccharide edible films are becoming a popular food packaging solution. Alginate is a biopolymer derived from seaweed that has the potential to create food packaging materials that are environmentally friendly and biodegradable. This article explores the potential use of nanocomposite coatings and films made from alginate as an alternative to petroleum-based polymers in the food industry. Alginate is desirable for food packaging due to its low cost, high nutritional value, renewability, low oxygen permeability, biodegradability, and biocompatibility. This article delves into alginate's history and extraction processes and covers techniques for modifying its physical and chemical properties using blended polymers and additives. Alginate-based coatings and films have been found to improve the mechanical properties and sensory characteristics of various food items and prolong the shelf life of perishable items by regulating oxygen and moisture levels and as a barrier against microbial growth. Further investigation is necessary to maximize the performance of alginate-based polymers in various food industry applications. Future prospects call on advancements in their physicochemical and functional characteristics to increase the acceptability of alginate-based nanocomposite coatings and films for biodegradable food packaging applications.

Transparent cellulose-lignin films containing Fe3+ with high UV absorption for thermal management

In this paper, cellulose-lignin films containing Fe3+ were prepared by the codissolution-precipitation method, and the films have high transparency as well as high UV absorption. In this process, kraft lignin chelates with Fe3+ and then bonds with cellulose through hydrogen bonding, evenly distributing within the film. The morphological results showed that the kraft lignin chelated with Fe3+ bound tightly linked to cellulose within the Fe@cellulose-lignin composite films. The addition of Fe3+ made the composite film (C-Fe-0.7-L) maintain a high transmittance of 66.9 % at 600 nm with excellent UV absorption. Excellent UV absorption performance, completely shielded from both Ultraviolet A (UVA), Ultraviolet B (UVB), and Ultraviolet C (UVC), and improved the thermal stability of the film. Under 100 mW cm-2 solar irradiation, the temperature of C-Fe-0.7-L rose rapidly to 60.7 °C. Based on this property, solar energy is transformed into kinetic energy, which realizes the photothermal conversion of solar energy. This work realizes the use of transparent films for energy utilization.

Preparation and Keep-Refreshing Effect of Chitosan/Sea Buckthorn Polysaccharide Composite Film on the Preservation of Yellow Cherry Tomatoes

In this study, sea buckthorn polysaccharides (SBP) were added as functional substances to chitosan (CS), and chitosan/sea buckthorn polysaccharide (SCS) composite films were prepared using the casting method. The effects of SBP addition on the optical properties, physical properties, mechanical properties, structure, antioxidant activity, and antibacterial activity of the SCS composite films were studied, and the prepared SCS composite films were used to preserve yellow cherry tomatoes. The results showed that SCS composite films exhibited good UV resistance, water solubility, and antioxidant activity, but its apparent structure, hydrophobicity, and mechanical properties needed further improvement. Meanwhile, SBP has inhibitory effects on all 8 experimental strains. In addition, the SCS composite film with the addition of 200 mg/L SBP could reduce the weight loss rate of yellow cherry tomatoes, maintain hardness, delay the decrease of total soluble solids, titratable acid, and Vitamin C content, and inhibit the accumulation of malondialdehyde. SCS composite films are beneficial for enhancing the quality of yellow cherry tomatoes during storage, and their application in fruit and vegetable preservation has development prospects.

Review on improvement of physicochemical properties of sodium alginate-based edible films

Sodium alginate (SA) is favored for its film-forming ability, biodegradability, and non-toxicity, often serving as a substrate for edible films. However, the application of SA-based edible films in the food industry is limited due to their inherent strong hydrophilicity and high brittleness. To enhance their physical and chemical properties, various exogenous compounds are frequently incorporated. This review summarizes the advancements in the physicochemical properties (mechanical, optical, thermal, hydrophobic, and barrier properties) of SA-based edible films over the past decade. It discusses the types of exogenous additives used and their effects on the properties of these films. Additionally, it highlights the applications of SA-based edible films enriched with functional compounds in areas such as food freshness detection, antioxidation, and antibacterial activity. It has been observed that the characteristics of SA-based edible films vary depending on the properties and structures of the exogenous compounds used, as well as their interactions with the SA matrix. SA-based edible films with functional additives demonstrate significant potential for extending food shelf life and enhancing freshness detection. However, challenges such as scalability, high production costs, and limited application scope still need to be addressed in future research.

Pharmacological Effects of Antioxidant Mycosporine-Glycine in Alleviating Ultraviolet B-Induced Skin Photodamage: Insights from Metabolomic and Transcriptomic Analyses

Mycosporine-glycine (M-Gly), a member of the mycosporine-like amino acid (MAA) family, is known for its potent antioxidant and anti-inflammatory properties. However, its in vivo efficacy in alleviating acute skin photodamage, primarily caused by oxidative stress, has not been well explored. In this investigation, 30 female ICR mice were divided into four groups: a control group and three Ultraviolet B (UVB)-exposed groups treated with saline or M-Gly via intraperitoneal injection for 30 days. At the end of the experiment, UVB exposure caused erythema, wrinkling, collagen degradation, and mast cell infiltration in mouse dorsal skin. M-Gly treatment improved skin appearance and reduced mast cell numbers, while also elevating antioxidant levels, including superoxide dismutase (SOD), catalase (CAT), and glutathione (GSH). Furthermore, M-Gly reduced inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and IL-1β, typically upregulated after UVB exposure. M-Gly also protected skin collagen by upregulating type I procollagen and decreasing MMP-1 levels. Skin metabolomic profiling identified 34 differentially abundant metabolites, and transcriptomic analysis revealed 752 differentially expressed genes. The combined metabolomic and transcriptomic data indicate that M-Gly's protective effects may involve the regulation of ion transport, cellular repair, metabolic stability, collagen preservation, and the Nrf2/HO-1 pathway. These findings highlight M-Gly's potential as an endogenous antioxidant for protecting skin from UVB-induced damage.

Ultraviolet (UV) radiation: a double-edged sword in cancer development and therapy

It has long been widely acknowledged that ultraviolet (UV) light is an environment risk factor that can lead to cancer, particularly skin cancer. However, it is worth noting that UV radiation holds potential for cancer treatment as a relatively high-energy electromagnetic wave. With the help of nanomaterials, the role of UV radiation has caught increasing attention in cancer treatment. In this review, we briefly summarized types of UV-induced cancers, including malignant melanoma, squamous cell carcinoma, basal cell carcinoma, Merkel cell carcinoma. Importantly, we discussed the primary mechanisms underlying UV carcinogenesis, including mutations by DNA damage, immunosuppression, inflammation and epigenetic alterations. Historically limited by its shallow penetration depth, the introduction of nanomaterials has dramatically transformed the utilization of UV light in cancer treatment. The direct effect of UV light itself generally leads to the suppression of cancer cell growth and the initiation of apoptosis and ferroptosis. It can also be utilized to activate photosensitizers for reactive oxygen species (ROS) production, sensitize radiotherapy and achieve controlled drug release. Finally, we comprehensively weigh the significant risks and limitations associated with the therapeutic use of UV radiation. And the contradictory effect of UV exposure in promoting and inhibiting tumor has been discussed. This review provides clues for potential clinical therapy as well as future study directions in the UV radiation field. The precise delivery and control of UV light or nanomaterials and the wavelength as well as dose effects of UV light are needed for a thorough understanding of UV radiation.

Mechanism of the G/M ratio and zein in enhancing the mechanical and hydrophobic properties of sodium alginate films

This study developed an edible film based on calcium-crosslinked sodium alginate (SA) using the casting method. The investigation assessed how the α-L-guluronic acid/β-D-mannuronic acid (G/M ratio) and zein addition influence the film's physicochemical properties. Fourier transform infrared spectroscopy and scanning electron microscopy findings suggest that the G/M ratio modulates the film's physicochemical characteristics by altering SA molecular cross-linking strength and the film's network structure density. At a G/M ratio of 0.85, the film exhibits a more uniform network structure, enhanced moisture resistance, hydrophobicity, and mechanical properties. Zein, evenly dispersed within the film matrix, establishes strong hydrogen bonds and electrostatic interactions with SA, enhancing the film's network structure and boosting its thermophysical, mechanical, and moisture resistance characteristics. The study demonstrates that modifying the G/M ratio and incorporating zein enhances the film's mechanical and hydrophobic properties, broadening its potential applications in food packaging.

Preparation of Activated Carbon-Reinforced Composite Beads Based on MnO2/MCM-41@Fe3O4 and Calcium Alginate for Efficient Removal of Tetracycline in Aqueous Solutions

Tetracycline (TC) is a common antibiotic; when untreated TC enters the environment, it will cause a negative impact on the human body through the food chain. In the present study, MnO2/MCM-41@Fe3O4 (FeMnMCM) prepared using a hydrothermal and redox method and Camellia oleifera shell-activated carbon (COFAC) prepared through alkali activation were encapsulated using alginate (ALG) and calcium chloride as a cross-linking matrix to give the composite beads COFAC-FeMnMCM-ALG. The resultant COFAC-FeMnMCM-ALG composite beads were then carefully characterized, showing a high immobilization of MnO2/MCM-41@Fe3O4, with porous COFAC as an effective bioadsorbent for enriching the pollutants in the treated samples. These bead catalysts were subsequently applied to the oxidative degradation of TC in a Fenton oxidation system. Several parameters affecting the degradation were investigated, including the H2O2 concentration, catalyst dosage, initial TC concentration, and temperature. A very high catalytic activity towards the degradation of TC was demonstrated. The electron paramagnetic resonance (EPR) and quenching results showed that ·OH and ·O2- were generated in the system, with ·OH as the main radical species. In addition, the COFAC-FeMnMCM-ALG catalyst exhibited excellent recyclability/reusability. We conclude that the as-prepared COFAC-FeMnMCM-ALG composite beads, which integrate MnO2 and Fe3O4 with bioadsorbents, provide a new idea for the design of catalysts for advanced oxidation processes (AOPs) and have great potential in the Fenton oxidation system to degrade toxic pollutants.

Mechanically robust, transparent, and UV-shielding composite of Na-Alginate and maleic acid-functionalized boron nitride nanosheets with improved antioxidant property

Maleic acid functionalized boron nitride nanosheets (BNNS-MA)/Na-Alginate composite with enhanced mechanical, UV-shielding and antioxidation properties have been fabricated for the first time by solvent evaporation from a homogeneous aqueous dispersion of BNNS-MA/Na-Alginate composite solution. The composite fabrication was driven by homogenous nano-integrations and chemistry of compatibilization of BNNS-MA with Na-Alginate through H-bonding interactions between -COOH functional group of BNNS-MA and -OH, -COONa groups of Na-Alginate. The BNNS-MA/Na-Alginate composites show significant enhancement of mechanical, UV-blocking and antioxidant properties compared to the Na-Alginate. Integrating only 1 wt% BNNS-MA improved the UV-blocking, tensile strength, and antioxidant properties of Na-Alginate film by 99.1%, 73% and 60.3%, respectively. Overall, our findings of BNNS-MA integrated Na-Alginate composite films with improved physical, mechanical, UV shielding, and antioxidant functionalities is very promising to open new insight in the field of transparent UV-protected biopolymer film for consumer products, packaging, cosmetics, and engineering applications.

Food packaging films based on ionically crosslinked konjac glucomannan incorporating zein-pectin nanoparticle-stabilized corn germ oil-oregano oil Pickering emulsion

This study addresses the limitations of konjac glucomannan (KGM) films in mechanical properties, hydrophobicity and antibacterial activities. For the first time, a zein-pectin nanoparticle-stabilized corn germ oil-oregano essential oil Pickering emulsion (ZPCEO) was incorporated into KGM, with the resulting film being further ionically crosslinked with Ca2+, Cu2+ or Fe3+. FTIR, SEM and EDS results showed that the metal ions were crosslinked with the hydroxyl and carbonyl groups of polysaccharides and uniformly distributed throughout the films (degree of crosslinking: Fe3+ > Cu2+ > Ca2+). Compared with pure KGM films, the ionic crosslinked ZPCEO/KGM (IL-ZPCEO/KGM) films have superior water resistance mechanical properties, and exhibit unique UV-blocking properties, antioxidant and antibacterial activities. The ZPCEO/KGM-Fe3+ film offered the best all-round properties, including the highest tensile strength, water resistance, UV-blocking capacity, and antimicrobial activity. Thus, ionic crosslinking of ZPCEO/KGM films can be applied to the preparation of food packaging for use in high humidity environments.

Application of Tannic Acid and Fe3+ Crosslinking-Enhanced Pectin Films for Passion Fruit Preservation

In this work, the role of tannic acid (TA) and Fe3+ in crosslinking pectin (PE) to enhance its physicochemical properties was investigated. Specifically, PE/TA/Fe3+ composite films were prepared using the solution casting method, and the UV-blocking properties, transparency, water content, physico-mechanical properties, antioxidant properties and degradability of the PE composite films were investigated. The microstructure of the PE composite films and the interactions between the contained components were analyzed using FTIR, X_crystal diffraction and SEM scanning electron microscopy. The results showed that the addition of TA and Fe3+ can significantly improve the UV barrier properties and antioxidant properties of PE films. Meanwhile, Fe3+ could form a metal phenol network with TA and crosslink with the PE film, which makes the structure of the PE film denser and thus significantly reduces the water vapor permeability of the PE film. In addition, this work also indicated that the PE composite coatings have a favorable preservation effect on passion fruit, which leads to the lowest weight loss rate and wrinkle index of the passion fruit within 7 days of storage and shows good appearance quality and commercial value. This work indicates that the addition of tannic acid and Fe3+ significantly improved the mechanical and barrier properties of pectin films, and the composite pectin coating extended the shelf life of passion fruit.

Polymeric hydrogels-based materials for wastewater treatment

Low-cost and reliable wastewater treatment is a relevant issue worldwide to reduce the concentration of environmental pollutants. Industrial effluents containing dyes, heavy metals, and other inorganic and organic compounds can pollute water resources; therefore, novel technologies are required to mitigate and control their release into the environment. Adsorption is one of the simplest methods for treating contaminated water in which a wide spectrum of adsorbents can be used to remove emerging compounds. Hydrogels are interesting materials with high adsorption capacities that can be synthesized via green routes. These adsorbents are promising for large-scale industrial wastewater treatment applications; however, gaps still exist in achieving sustainable commercial implementation. This review focuses on the discussion and analysis of preparation, characterization, and adsorption properties of hydrogels for water purification. The advantages of these polymeric materials for water treatment were analyzed, including their performance in the removal of different organic and inorganic contaminants. Recent advances in the functionalization of hydrogels and the synthesis of novel composites have also been described. The adsorption capacities of hydrogel-based adsorbents are higher than 500 mg/g for different organic and inorganic pollutants, and can reach values of up to >2000 mg/g for organic compounds, significantly outperforming other materials reported for water cleaning. The main interactions involved in the adsorption of water pollutants using hydrogel-based adsorbents were described and explained to allow the interpretation of their removal mechanisms. The current challenges in the implementation of hydrogels for water purification in real-life operations are also highlighted. This review provides an updated picture of hydrogels as interesting materials to address water depollution worldwide.

Natural Solid-State Hydrogel Electrolytes Based on 3D Pure Cotton/Graphene for Supercapacitor Application

A conductive cotton hydrogel with graphene and ions can come into contact with electrodes in solid electrolytes at the molecular level, leading to a more efficient electrochemical process in supercapacitors. The inherently soft nature of cotton mixed with hydrogel provides superior flexibility of the electrolyte, which benefits the devices in gaining high flexibility. Herein, we report on the current progress in solid-state hydrogel electrolytes based on 3D pure cotton/graphene and present an overview of the future direction of research. The ionic conductivity of a complex hydrogel significantly increased by up to 13.9 × 10^-3 S/cm at 25 °C, due to the presence of graphene, which increases ionic conductivity by providing a smooth pathway for the transport of charge carriers and the polymer. Furthermore, the highest specific capacitance of 327 F/g at 3 mV/s was achieved with cyclic voltammetry measurement and a galvanostatic charge-discharge measurement showed a peak value of 385.4 F/g at 100 mA/g current density. Furthermore, an electrochemical analysis demonstrated that a composite cotton/graphene-based hydrogel electrolyte is electrically stable and could be used for the design of next-generation supercapacitors.

Preparation of MIL100/MIL101-alginate composite beads for selective phosphate removal from aqueous solution

Numerous studies have reported various approaches for synthesizing phosphate-capturing adsorbents to mitigate eutrophication. Despite the efforts, concerns about production cost, the complexity of synthesis steps, environmental friendliness, and applicability in industrial settings continue to be a problem. Herein, phosphate-selective composite adsorbents were prepared by incorporating alginate (Alg) with MIL100 and MIL101 to produce the MIL100/Alg and MIL101/Alg beads, where Fe³⁺ served as the crosslinker. The unsaturated coordination bond of MIL100 and MIL101 serves as a Lewis acid that can attract phosphate. The adsorption equilibrium isotherm, uptake kinetics, and effects of operating parameters were studied. The phosphate adsorption capacity of MIL100/Alg (103.3 mg P/g) and MIL101/Alg (109.5 mg P/g) outperformed their constituting components at pH 6 and 30 °C. Detailed evaluation of the adsorbent porosity using N₂ sorption reveals the formation of mesoporous structures on the Alg network upon incorporation of MIL100 and MIL101. The composite adsorbents have excellent selectivity toward anionic phosphate and can be easily regenerated. Phosphate adsorption by MIL100/Alg and MIL101/Alg was driven by electrostatic attraction and ligand exchange. Preliminary economic analysis on the synthesis of the adsorbents indicates that the composites, MIL100/Alg and MIL101/Alg, are economically viable adsorbents.

A visual bi-layer sensor based on Agar/TiO2/butterfly bean flower anthocyanin/κ-carrageenan with photostability for monitoring Penaeus chinensis freshness

Visual indicator bi-layer films were manufactured incorporating κ-carrageenan, butterfly pea flower anthocyanin, varying Nano‑titanium dioxide (TiO₂) content and agar for Penaeus chinensis (Chinese white shrimp) freshness detection. The κ-carrageenan-anthocyanin (CA) layer served as indicator, while the TiO₂-agar (TA) layer functioned as the protective layer to improve the photostability of film. The bi-layer structure was characterized by scanning electron microscopy (SEM). The TA2-CA film had the best tensile strength with a value of 17.8 MPa and the lowest water vapor permeability (WVP) value of bi-layer films was 2.98 × 10^-7 g.m^-1.h^-1.pa^-1. The bi-layer film protected anthocyanin against exudation when immersed in aqueous solution of varying pH. The TiO₂ particles filled the pores of the protective layer, increasing the opacity from 1.61 up to 4.49 significantly improving the photostability with a consequent slight color change under illumination of UV/visible light. Under UV irradiation, the TA2-CA film had no significant color change with a ΔE value of 4.23. Finally, the TA2-CA films showed an obvious color change from blue to yellow green in the early stages of Penaeus chinensis putrefaction (≤48 h) then the color change and Penaeus chinensis freshness were well correlated (R² = 0.8739).

Nano-MIL-88A(Fe) Enabled Clear Cellulose Films with Excellent UV-Shielding Performance and Robust Environment Resistance

While tremendous efforts have been dedicated to developing cellulose-based ultraviolet (UV)-blocking films, challenges still remain in simultaneously achieving high transparency, low haze and excellent UV shielding properties via simple and green strategy. Here, we present a facile and eco-friendly route to fabricate flexible, biodegradable and clear UV-shielding nano-MIL-88A(Fe)@carboxymethylated cellulose films (M(Fe)CCFs) via in situ synthesis of nano-MIL-88A(Fe) in carboxymethylated cellulose hydrogel followed by natural drying. The carboxymethylated cellulose film has high transmittance (93.2%) and low haze (1.8%). The introduction of nano-MIL-88A(Fe) endowed M(Fe)CCFs superior UV-shielding ability, while retaining high transmittance (81.5-85.3%) and low haze (2.5-4.9%). Moreover, M(Fe)CCFs showed stable UV blocking performance under UV irradiation, high temperature, acidic or alkaline conditions. Quite encouragingly, the UV-shielding ability of M(Fe)CCFs did not deteriorate, even after 30 days of immersion in aqueous solution, providing films with a long-term use capacity. Thus, M(Fe)CCFs show high potential in the UV protection field. Overall, these UV-blocking films with outstanding performances are a promising candidate to replace conventional film materials made from synthetic polymers in fields such as packaging and flexible electronics.

Improved mechanical and ultraviolet shielding performances of hydroxyethyl cellulose film by using aramid nanofibers as additives

Recently, aramid nanofibers (ANFs) have drawn the attention of scientist due to the high mechanical strength, high-temperature resistance, and high electrical and thermal insulation properties. In this work, we aimed at improving the mechanical and ultraviolet shielding properties of hydroxyethyl cellulose (HEC) film by using ANFs as additives. Mechanical results show that the 1.0 % ANFs could improve the tensile strength of pure HEC film by 176.6 %. Meanwhile, the ANFs additives can also enable the HEC film excellent ultraviolet (UV) shielding and visible light transmittance, as well as high UV radiation resistance ability. It is believed that the high mechanical strength of the HEC/ANFs composites is derived from the rearrangement of HEC chains along the tensile direction after the addition of hard ANFs and the enhanced hydrogen bonds between HEC and ANFs.

Fundamental Concepts of Hydrogels: Synthesis, Properties, and Their Applications

In the present review, we focused on the fundamental concepts of hydrogels-classification, the polymers involved, synthesis methods, types of hydrogels, properties, and applications of the hydrogel. Hydrogels can be synthesized from natural polymers, synthetic polymers, polymerizable synthetic monomers, and a combination of natural and synthetic polymers. Synthesis of hydrogels involves physical, chemical, and hybrid bonding. The bonding is formed via different routes, such as solution casting, solution mixing, bulk polymerization, free radical mechanism, radiation method, and interpenetrating network formation. The synthesized hydrogels have significant properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. These properties are substantial for electrochemical and biomedical applications. Furthermore, this review emphasizes flexible and self-healable hydrogels as electrolytes for energy storage and energy conversion applications. Insufficient adhesiveness (less interfacial interaction) between electrodes and electrolytes and mechanical strength pose serious challenges, such as delamination of the supercapacitors, batteries, and solar cells. Owing to smart and aqueous hydrogels, robust mechanical strength, adhesiveness, stretchability, strain sensitivity, and self-healability are the critical factors that can identify the reliability and robustness of the energy storage and conversion devices. These devices are highly efficient and convenient for smart, light-weight, foldable electronics and modern pollution-free transportation in the current decade.

High performance of alginate/polyvinyl alcohol composite film based on natural original melanin nanoparticles used as food thermal insulating and UV-vis block

Light is a major factor in promoting food aging and deterioration, especially for ultraviolet (UV) light. Herein, bioinspired dopamine-melanin solid nanoparticles with strong absorption at a wide range of 200-2500 nm were first incorporated into alginate/polyvinyl alcohol to fabricate film materials in this work for UV-vis block, and this also brings excellent thermal insulating properties to the materials. In addition, in order to obtain a material with excellent performance, particles of uniform size of about 100 nm are obtained by fractional centrifugation. It was found the mechanical, UV-vis block and thermal insulating properties were improved significantly compared with the control samples. This study provides a strategy to design a non-polluting, biodegradable, biocompatible film with excellent mechanical properties that can be used in UV-vis barriers and has potential applications in thermal insulating materials for food preservation.