Preparation and antibacterial activities of chitosan-gallic acid/polyvinyl alcohol blend film by LED-UV irradiation

Preparation, characterization, and application of gallic acid-mediated photodynamic chitosan-nanocellulose-based films

In this study, an active film composed of gallic acid (GA), chitosan (CS), and cellulose nanocrystals (CNC) was prepared using a solution casting method and synergistic photodynamic inactivation (PDI) technology. Characterization of the film showed that the CS-CNC-GA composite film had high transparency and UV-blocking ability. The addition of GA (0.2 %-1.0 %) significantly enhanced the mechanical properties, water resistance, and thermal stability of the film. The tensile strength increased up to 46.30 MPa, and the lowest water vapor permeability was 1.16 × e-12 g/(cm·s·Pa). The PDI-treated CS-CNC-GA1.0 composite film exhibited significantly enhanced antibacterial activity, with inhibition zone diameters of 31.83 mm against Staphylococcus aureus and 21.82 mm against Escherichia coli. The CS-CNC-GA composite film also showed good antioxidant activity. Additionally, the CS-CNC-GA1.0 composite film generated a large amount of singlet oxygen under UV-C light irradiation. It was found that using the CS-CNC-GA1.0 composite film for packaging and storage of oysters at 4 °C effectively delayed the increase in pH, total colony count, and lipid oxidation in oysters. In conclusion, the CS-CNC-GA composite film based on PDI technology has great potential for applications in the preservation of aquatic products.

Microplastics from petroleum-based plastics and their effects: A systematic literature review and science mapping of global bioplastics production

The use of bioplastics is a new strategy for reducing microplastic (MP) waste caused by petroleum-based plastics. This problem has received increased attention worldwide, leading to the development of large-scale bioplastic plants. The large amount of MPs in aquatic and terrestrial environments and the atmosphere has raised global concern. This article delves into the profound environmental impact of the increasing use of petroleum-based plastics, which contribute significantly to plastic waste and, as a consequence, to the increase in MPs. We conducted a comprehensive analysis to identify countries that are at the forefront of efforts to produce bioplastics to reduce MP pollution. In this article, we explain the development, degradation processes, and research trends of bioplastics derived from biological materials such as starch, chitin, chitosan, and polylactic acid (PLA). The findings pinpoint the top 10 countries demonstrating a strong commitment to reducing MP pollution through bioplastics. These nations included the United States, China, Spain, Canada, Italy, India, the United Kingdom, Malaysia, Belgium, and the Netherlands. This study underscores the technical and economic obstacles to large-scale bioplastic production. Integr Environ Assess Manag 2024;00:1-20. © 2024 SETAC.

Preparation and performance testing of corn starch/pullulan/gallic acid multicomponent composite films for active food packaging

The present study investigated the mechanical characteristics, hydrophobicity, antioxidant and antibacterial properties, FTIR, SEM and XRD of films fabricated with corn starch and pullulan (CS/PUL) by adding different concentrations of Gallic acid (GA) (0%, 0.5%, 1.0%, 1.5% w/v). The mechanical strength and opacity of CS/PUL films were enhanced by the addition of 1.0% GA. The water vapor permeability (WVP) of CS/PUL films was significantly lower in films with GA compared to those without (P < 0.05). The addition of GA, especially at concentrations of 1.0% and 1.5%, resulted in considerably better free radical scavenging activities on DPPH than films without GA (P < 0.05). Interestingly, the highest water contact angle (WCA) value was observed in films with 0.5% GA, indicating stronger hydrophobicity. Furthermore, the antibacterial capabilities of the films, particularly against E. coli and P. aeruginosa, improved with an increase in GA concentration. The results of FTIR, SEM and XRD analyses showed that GA was well distributed in the CS/PUL matrix.

Ixiolirion tataricum mucilage/chitosan based antioxidant films activated by free and nanoliposomal fennel essential oil

Ixiolirion tataricum mucilage (ITM) was characterized and applied in fabrication of ITM/chitosan (CH) blend films activated by Foeniculum vulgare essential oil (FEO) in free and nanoliposomal forms. Uniform smooth surface structure, viscoelastic solid-like behavior and Newtonian nature of ITM were confirmed by morphological and rheological analyses. The prepared FEO nanoliposomes (FEO-NLPs) showed desirable properties in terms of particle size (57.2 nm), polydispersity index (0.243), zeta-potential (-17.6 mV), and encapsulation efficiency (85.2 %). The enhancing effects of FEO-NLPs and the adverse effects of free FEO on the crystalline, morphological and structural properties of films were confirmed by XRD, FE-SEM and ATR-FTIR tests. FEO-NLPs loaded films had better mechanical, thermal, water and gas barrier and antioxidant properties than neat film. Analysis also indicated the high controlled release of FEO from the films containing the nanoliposomal form of FEO. The films containing free FEO showed higher antibacterial activity against E. coli and S. aureus in comparison with FEO-NLPs loaded ones. The results showed the potential of FEO-NLPs loaded ITM/CH films for antioxidant food packaging applications.

The use of essential oils in chitosan or cellulose-based materials for the production of active food packaging solutions: a review

In recent decades, interest in sustainable food packaging systems with additional functionality, able to increase the shelf life of products, has grown steadily. Following this trend, the present review analyzes the state of the art of this active renewable packaging. The focus is on antimicrobial systems containing nanocellulose and chitosan, as support for the incorporation of essential oils. These are the most sustainable and readily available options to produce completely natural active packaging materials. After a brief overview of the different active packaging technologies, the main features of nanocellulose, chitosan, and of the different essential oils used in the field of active packaging are introduced and described. The latest findings about the nanocellulose- and chitosan-based active packaging are then presented. The antimicrobial effectiveness of the different solutions is discussed, focusing on their effect on other material properties. The effect of the different inclusion strategies is also reviewed considering both in vivo and in vitro studies, in an attempt to understand more promising solutions and possible pathways for further development. In general, essential oils are very successful in exerting antimicrobial effects against the most diffused gram-positive and gram-negative bacteria, and affecting other material properties (tensile strength, water vapor transmission rate) positively. Due to the wide variety of biopolymer matrices and essential oils available, it is difficult to create general guidelines for the development of active packaging systems. However, more attention should be dedicated to sensory analysis, release kinetics, and synergetic action of different essential oils to optimize the active packaging on different food products. © 2022 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Laccase-mediated functionalization of natamycin by gallic acids for the therapeutic effect on Aspergillus fumigatus keratitis

To improve the therapeutic effect of natamycin on fungal keratitis (FK), the grafted derivatives of natamycin and gallic acid were obtained, and the effects of the grafted derivatives on Aspergillus fumigatus (A. fumigatus) keratitis were investigated. The structure of natamycin grafted with gallic acid was identified by FT-IR and UV-Vis, and the successful synthesis of Gallic-Natamycin (GA-NAT) was proved. CCK-8 and the Draize eye test showed that GA-NAT had less cytotoxicity. Then, through in vitro antibacterial experiments such as minimum inhibitory concentration (MIC), adhesion, biofilm formation, and calcium fluorescence staining and in vivo experiments such as clinical score and plate counting, the results showed that GA-NAT had similar antifungal activity to natamycin, but had a better therapeutic effect than natamycin. Myeloperoxidase assay and immunofluorescence staining also showed that GA-NAT significantly inhibited neutrophil recruitment and activity. Moreover, It was further found that GA-NAT could inhibit the mRNA and protein expressions of LOX-1, TNF-α, and IL-1β. These results indicated that GA-NAT inhibited the fungal growth, reduced the neutrophil infiltration into cornea, and down-regulated the expression of inflammatory factors in lesions, which provides a new choice for FK treatment.

Zn2+ adsorption from wastewater using a chitosan/β-cyclodextrin-based composite membrane

In this study, a β-cyclodextrin polymer (β-CDP) was synthesized by pretreating β-cyclodextrin (β-CD) with citric acid (CA), and then, chitosan (CTS) and β-CDP were cross-linked to prepare a biomass-based (CTS/β-CDP) composite membrane. The effects of the preparation conditions in sodium hydroxide on the adsorption amount and adsorption rate of zinc ions (Zn²⁺ ) from simulated wastewater were investigated. The results showed that a maximum adsorption amount 123.7 μg/g and adsorption rate 94.14% of Zn²⁺ were obtained when the reaction between CTS and β-CDP was performed at 50°C, the concentration of acetic acid was 2%, dissolving β-CDP water dosage was 30 ml, and the soaking time in sodium hydroxide was 1 hr. Comparative studies on the adsorption of CTS membranes, β-CD, β-CDP, and CTS/β-CDP composite membrane showed that the CTS/β-CDP composite membrane had the highest Zn²⁺ adsorption efficiency. The CTS/β-CDP composite membrane was characterized by FTIR, SEM, and XRD. Characteristic absorption peaks of CTS and β-CDP appeared in the FTIR spectra of the CTS/β-CDP composite membrane, confirming its synthesis. The SEM images showed that the surface of the composite membrane was rougher than the porous CTS membrane, which increased the number of adsorption sites and the adsorption efficiency. XRD patterns showed that the CTS/β-CDP composite membrane was amorphous, indicating that β-CDP changed the crystal structure of the CTS. The swelling degree and transmittance of the CTS/β-CDP composite membrane were lower than the CTS membrane, which should be conducive to recycling after wastewater treatment. PRACTICAL APPLICATIONS: Industrial wastewater often contains heavy metal ions such as Zn²⁺ , which are difficult to degrade and are highly toxic, and direct wastewater discharge can greatly harm the ecosystems and humans. In this study, CTS and β-CD were cross-linked to synthesize a biomass membrane for adsorbing Zn²⁺ to reduce the Zn²⁺ content in wastewater via adsorption.The results show that the CTS/β-CDP composite membrane can be applied to small-scale wastewater treatment fields such as food and chemical industry. After the Zn²⁺ -containing wastewater underwent pretreatment, the composite membrane was placed into the wastewater for effective adsorption, which could achieve high adsorption efficiency. The process played a major role in effectively treating Zn²⁺ and other difficult to degrade heavy metal ions; thereby, simplifying Zn²⁺ -containing wastewater. The treatment process reduces the investment and operating costs of sewage treatment, and at the same time, has a significant removal effect, and hence, can meet the requirements of environmental protection discharge.

Effect of plasticizer and surfactant on the properties of poly(vinyl alcohol)/chitosan films

The objective of this study was to develop eco-friendly films based on poly(vinyl alcohol) (PVA) and chitosan (CTS) with the addition of plasticizer (glycerol or sorbitol) and surfactant (cocamidopropyl betaine). The properties of the obtained polymeric films were determined by contact angle measurements, attenuated total reflection infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), mechanical tests, and moisture content analysis. The results indicated that four-component blends had high surface hydrophilicity and surface roughness due to the presence of the surfactant. Glycerol incorporation into PVA/CTS blends resulted in higher flexibility and greater water absorption capacity of the three- and four-component polymeric blends compared with these blends with sorbitol. By contrast, the addition of the surfactant to the materials is essential for their application in personal hygiene products as disposable wipes.

Preparation of chitosan-sodium alginate films through layer-by-layer assembly and ferulic acid crosslinking: Film properties, characterization, and formation mechanism

Chitosan-alginate films were prepared through layer-by-layer assembly combined with ferulic acid crosslinking. Their mechanical properties, opacity, and hydrophobicity were compared to films prepared by direct mixing, crosslinking alone, and LBL assembly alone. Thermogravimetric analysis, X-ray diffraction, scanning electron microscopy and Fourier-transform infrared spectroscopy were used to characterize the films and analyze their formation mechanism. The results indicated that the layer-by-layer assembly and ferulic acid crosslinking combination increased the tensile strength and light-blocking ability of the films. In addition, the films had a lower water vapor transmission rate, swelling degree, and water solubility, as well as higher hydrophobicity. Scanning electron microscopy showed a good compatibility between the film components of the film prepared by the combination technique. The structural characterization results revealed some strong interactions among the amino, carboxyl, and hydroxyl groups of the ferulic acid, chitosan, and sodium alginate in the film. The driving force for film formation was the generation of non-covalent bonds among the film components rather than covalent bonds.

Development of Dermal Films Containing Miconazole Nitrate

This study aims to develop new antifungal dermal films based on their mechanical properties (elongation, adhesion, behaviour towards vapour moisture) and the in vitro availability of miconazole nitrate, used as a pharmaceutical active ingredient in various concentrations. The three polymeric films prepared were translucent or shiny, with the surface of 63.585 cm², 0.20⁻0.30 mm thickness, and content of miconazole nitrate of 3.931 or 15.726 mg·cm². The mechanical resistance and elongation tests demonstrated that the two films based on hydroxyethyl cellulose (HEC) polymer were more elastic than the one prepared with hydroxypropyl methylcellulose (HPMC). The vapour water absorption and vapour water loss capacity of the films revealed that the HPMC film did not dry very well in the process of preparation by the evaporation of the solvent technique, unlike the HEC films that jellified more evenly in water and had higher drying capacity at 40 °C. The in vitro availability of miconazole nitrate from dermal films was evaluated using the Franz diffusion cell method, through a synthetic membrane (Ø 25 mm × 0.45 µm) and acceptor media with pH 7.4 (phosphate buffer and sodium lauryl sulphate 0.045%), resulting a release rate of up to 70%.