Hot-Melt-Extruded Active Films Prepared from EVOH/Trans-Cinnamaldehyde Blends Intended for Food Packaging Applications

Double-Layered Electrospun Nanofiber Filter for the Simultaneous Removal of Urea and Ammonium from Blood

A major challenge in the development of wearable artificial kidneys (WAKs) lies in the efficient removal of urea, which is found at an extremely high concentration in the blood of patients with chronic kidney disease (CKD). Urease is an enzyme that hydrolyzes urea. While it can efficiently remove urea, toxic ammonium is produced as a byproduct. In this study, nanofibers capable of removing both urea and ammonium from the blood were fabricated. Specifically, urease was immobilized on electrospun poly(ethylene-co-vinyl alcohol) (EVOH)/chitosan nanofiber membranes via covalent cross-linking. Chitosan not only helped covalent immobilization via its free amino groups but also improved hemocompatibility by suppressing protein adhesion. The resulting urease-immobilized EVOH/chitosan nanofibers exhibited an outstanding urea removal performance of 690 mg/g per hour. For ammonium removal, EVOH nanofiber membranes containing sodium cobalt(II) hexacyanoferrate(II) (NaCoHCF), an ammonium adsorbent, were prepared. The fabricated EVOH/NaCoHCF membranes exhibited an ammonium adsorption capacity of 135.5 mg/g. The two types of nanofiber membranes were combined to form a double-layered nanofiber membrane that was placed in a filter holder for continuous-flow cycling experiments. Under such conditions, all urea at a concentration similar to that in the blood of CKD patients was degraded within 1 h, and ammonium production was reduced by approximately 90% of the normal level. This double-layered nanofiber membrane can achieve both urea degradation and ammonium adsorption and is expected to advance the development of WAKs, a game changer in the treatment of CKD.

Transparent and Mechanically Robust Janus Nanofiber Membranes for Open Wound Healing and Monitoring

The electrospun nanofiber membrane has demonstrated great potential for wound management due to its porous structure, large surface area, mechanical strength, and barrier properties. However, there is a need to develop transparent bioactive nanofibers with strong mechanical properties to facilitate the monitoring of the healing process. In this study, we present an electrospinning-based method for creating transparent (∼80-90%), strong (∼11-13 MPa), and Janus nanofiber membranes. The innovative square pattern architecture of the membrane includes a thin hydrophobic polycaprolactone layer on top of a layer of hydrophilic ethylene-vinyl alcohol nanofiber, which enables the absorption of excess biofluid from the wound and exhibits Janus wettability for water. Furthermore, incorporating 5% chitosan into the composition of the nanofibers accelerates the healing process through its antioxidant properties and antimicrobial activity against various bacteria, including drug-resistant strains. The developed membrane also demonstrates skin-repairing function, quick blood clotting (around 145 ± 12 s), and biocompatibility with keratinocyte (≥90%), as well as in vitro quick cell migration (∼24 h). With a tensile strength of 11-13 MPa, the membrane effectively adheres to the knee joint even after running 4 km. These optimal properties of the electrospun nanofiber membrane make it suitable for effective wound management and inspection of the healing process, without the need for frequent dressing changes.

Electrospun EVOH/AST-120 hybrid nanofiber membranes for removal of indoxyl sulfate from blood

Nanofibers containing activated carbon using poly(ethylene-co-vinyl alcohol) (EVOH) were prepared to remove indoxyl sulfate (IS) from the blood. IS is a urinary toxin that is highly toxic and triggers the progression of chronic kidney disease (CKD). Here, nanofibers containing activated carbon (AST-120), which has been used practically as an adsorbent for indole (a precursor of IS), were fabricated via electrospinning for the adsorption and removal of IS from the blood. EVOH containing different ethylene ratios was used as the nanofiber material; moreover, the effect of the ethylene ratio on various properties of the nanofibers, such as surface wettability and the IS adsorption rate, was investigated. As a result, EVOH/AST-120 nanofibers comprising EVOH with a low ethylene ratio exhibited faster IS adsorption behavior. This adsorption behavior agreed well with the pseudo-second-order model, suggesting that the diffusion of IS into the nanofibers is the rate-limiting step of the process of adsorption. Furthermore, the nanofibers successfully reduced the IS concentration in the blood under circulating conditions. Therefore, these EVOH/AST-120 nanofibers are expected to greatly improve the prognosis of patients with CKD when used in combination with the current hemodialysis therapy as an IS-adsorbing filter.

Characterization of antimicrobial multilayer film based on ethylcellulose-pectin incorporated with nanoemulsions of trans-cinnamaldehyde essential oil

In this study, polymer solution casting was utilized to fabricate a multilayer film with ethylcellulose (EC) as the outer layers and trans-cinnamaldehyde-loaded pectin as the inner layer. A significant increase in whiteness and UV-visible light blocking capability and a remarkable decrease in total color difference and yellowness of the films were seen via increasing the thickness of EC outer layers. Scanning electronic microscopy observation showed that the inner and outer layers had a smooth and uniform surfaces with clear boundary. The thicker film has better stretchability and strength, but is less flexible than thinner film. Glass transition temperature did not change remarkably with increasing thickness of EC outer layers, but thermal stability was slightly improved. FTIR-ATR spectra revealed the formation of hydrogen bonds between the two adjacent layers. The multilayer films exhibited excellent antimicrobial efficacy against Gram-positive and Gram-negative foodborne pathogens. The results suggested that this multilayer film has potential applications in active food packaging.

Plant Bioactive Compounds in Foods and Food Packages

There has been growing interest in the use of numerous plant bioactive compounds (PBCs) in food and nutrition technology due to their properties that promote human health by reducing the risk of various serious diseases [...].

Pilot-Scale Processing and Functional Properties of Antifungal EVOH-Based Films Containing Methyl Anthranilate Intended for Food Packaging Applications

Antimicrobial packaging has emerged as an efficient technology to improve the stability of food products. In this study, new formulations based on ethylene vinyl alcohol (EVOH) copolymer were developed by incorporating the volatile methyl anthranilate (MA) at different concentrations as antifungal compound to obtain active films for food packaging. To this end, a twin-screw extruder with a specifically designed screw configuration was employed to produce films at pilot scale. The quantification analyses of MA in the films showed a high retention capacity. Then, the morphological, optical, thermal, mechanical and water vapour barrier performance, as well as the antifungal activity in vitro of the active films, were evaluated. The presence of MA did not affect the transparency or the thermal stability of EVOH-based films, but decreased the glass transition temperature of the copolymer, indicating a plasticizing effect, which was confirmed by an increase in the elongation at break values of the films. Because of the additive-induced plasticization over EVOH, the water vapour permeability slightly increased at 33% and 75% relative humidity values. Finally, the evaluation of the antifungal activity in vitro of the active films containing methyl anthranilate showed a great effectiveness against P. expansum and B. cinerea, demonstrating the potential applicability of the developed films for active food packaging.

An insight to potential application of synbiotic edible films and coatings in food products

Edible films and coatings have gained significant consideration in recent years due to their low cost and decreasing environmental pollution. Several bioactive compounds can be incorporated into films and coatings, including antioxidants, antimicrobials, flavoring agents, colors, probiotics and prebiotics. The addition of probiotics to edible films and coatings is an alternative approach for direct application in food matrices that enhances their stability and functional properties. Also, it has been noted that the influence of probiotics on the film properties was dependent on the composition, biopolymer structure, and intermolecular interactions. Recently, the incorporation of probiotics along with prebiotic compounds such as inulin, starch, fructooligosaccharide, polydextrose and wheat dextrin has emerged as new bioactive packaging. The simultaneous application of probiotics and prebiotics improved the viability of probiotic strains and elevated their colonization in the intestinal tract and provided health benefits to humans. Moreover, prebiotics created a uniform and compact structure by filling the spaces within the polymer matrix and increased opacity of edible films. The effects of prebiotics on mechanical and barrier properties of edible films was dependent on the nature of prebiotic compounds. This review aims to discuss the concept of edible films and coatings, synbiotic, recent research on synbiotic edible films and coatings as well as their application in food products.

Bio-based antibacterial food packaging films and coatings containing cinnamaldehyde: A review

As a typical bioactive compound from the bark and leaves of the trees of the genus Cinnamomum, cinnamaldehyde (CIN) is natural and safe. Its excellent antibacterial activity against various foodborne microorganisms is growingly regarded as a promising additive for improving and enhancing the properties of bio-based packaging films/coatings. This review systematically summarized the bio-based food packaging films/coatings containing CIN developed recently. The effects of CIN incorporation on physical and chemical properties of the antibacterial food packaging films/coatings, including thickness, color index, transparency, water content, water solubility, water contact angle, mechanical performances, water barrier performances, and antibacterial performances, were discussed. Simultaneously, this work also concluded that an explanation of the antibacterial mechanism of CIN and preparation methods of bio-based packaging films/coatings containing CIN/CIN carriers. Notably, the incorporation of CIN into the films/coatings could enhance their antibacterial performance extend the shelf-life of various foods, such as fish, meats, vegetables, fruits, and other perishable food, while improving their physical and chemical properties. Although incorporating CIN into food packaging films/coatings has been extensively studied, long-term follow-up research on the human safety of active food packaging films/coatings containing CIN needs to be carried out.