Toward function starch nanogels by self-assembly of polysaccharide and protein: From synthesis to potential for polyphenol delivery.

Nanogels formed by self-assembly of natural proteins and polysaccharides have attracted great interest as potential carriers of bioactive molecules. Herein, we reported that carboxymethyl starch-lysozyme nanogels (CMS-Ly NGs) were prepared using carboxymethyl starch and lysozyme by green and facile electrostatic self-assembly, and the nanogels served as epigallocatechin gallate (EGCG) delivery systems. The dimensions and structure of the prepared starch-based nanogels (i.e., CMS-Ly NGs) were characterized by dynamic light scattering (DLS), ζ-potential, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermal gravimetric analyzer (TGA). FT-IR and 1H NMR spectra together confirmed the formation of CMS; FT-IR spectra confirmed the formation of CMS-Ly NGs; XRD spectra confirmed the disruption of the crystal structure of lysozyme after electrostatic self-assembly with CMS, and further confirmed the formation of nanogels. TGA demonstrated the thermal stability of nanogels. More importantly, the nanogels showed a high EGCG encapsulation rate of 80.0 ± 1.4 %. The CMS-Ly NGs encapsulated with EGCG exhibited regular spherical structure and stable particle size. Under the simulated gastrointestinal environmental conditions, CMS-Ly NGs encapsulated with EGCG showed the controlled release potential, which increased its utilization. Additionally, anthocyanins can also be encapsulated in CMS-Ly NGs and showed slow-release properties during gastrointestinal digestion in the same way. Cytotoxicity assay also demonstrated good biocompatibility between CMS-Ly NGs and CMS-Ly NGs encapsulated with EGCG. The findings of this research suggested the potential application of protein and polysaccharides-based nanogels in the delivery system of bioactive compounds.

Polyvinyl alcohol film with chlorine dioxide microcapsules can be used for blueberry preservation by slow-release of chlorine dioxide gas.

Introduction: Chlorine dioxide (ClO2) is a safe and efficient bactericide with unique advantages in reducing foodborne illnesses, inhibiting microbial growth, and maintaining the nutritional quality of food. However, gaseous ClO2 is sensitive to heat, vibration, and light, which limits its application. Methods: In this study, a ClO2 precursor-stabilized ClO2 aqueous solution was encapsulated by the double emulsion method, and a high-performance ClO2 self-releasing polyvinyl alcohol (PVA) film was prepared to investigate its performance and effect on blueberry quality during storage. Results: The self-releasing films had the best overall performance when the microcapsule content was 10% as the film's mechanical properties, thermal stability, and film barrier properties were significantly improved. The inhibition rates of Listeria monocytogenes and Escherichia coli were 93.69% and 95.55%, respectively, and the mycelial growth of Staphylococcus griseus was successfully inhibited. The resulting ClO2 self-releasing films were used for blueberry preservation, and an experimental study found that the ClO2 self-releasing antimicrobial film group delayed the quality decline of blueberries. During the 14-day storage period, no mold contamination was observed in the ClO2 self-releasing film group, and blueberries in the antibacterial film group had higher anthocyanin accumulation during the storage period. Discussion: Research analysis showed that films containing ClO2 microcapsules are promising materials for future fruit and vegetable packaging.

Constructions of synergistic photothermal therapy antibacterial hydrogel based on polydopamine, tea polyphenols and polyvinyl alcohol and effects on wound healing in mouse.

Hydrogels with significant antibacterial efficacy have enormous potential in wound healing. This work reported a series of effective antibacterial and antioxidant hydrogels based on tea polyphenols (TP), polydopamine (PDA), and polyvinyl alcohol (PVA). PDA-TP molecular chains are formed from oxidized TP and PDA. These molecular chains, which were cross-linked with PVA by cyclic freeze-thaw (FT), formed the PVA/PDA-TP hydrogel (PPTP). The number of freezing-thawing cycles and the amount of TP would affect the mechanical properties and swelling properties of hydrogel. The PPTP hydrogel exhibited high photo thermal conversion efficiency, high antibacterial efficacy, antioxidant properties, good cellular compatibility and short wound closure time. The PPTP hydrogel leaded to wound closure in approximately 10 d in a full-thickness skin defect mouse model. The preparation method of hydrogel with non-chemical cross-linked and ability of rapid high temperature generation provided a new way to apply TP to wound healing and proved that synergistic chemical and photothermal therapy can effectively inhibit resistant bacteria and accelerate wound healing.

Antimicrobial food packaging integrating polysaccharide-based substrates with green antimicrobial agents: A sustainable path.

Food spoilage and waste, human and animal poisoning, and even death caused by foodborne microorganisms remain extensive concerns in food safety. The global demand for functional, eco-friendly, and efficient antimicrobial food packaging is increasing. However, the bacteriostatic or bactericidal effects of most conventional food packaging display limited action, and their major components are petrochemical materials (non-renewable, non-biodegradable, and not environmentally friendly), and the current target microorganisms easily acquire drug-resistant. Therefore, the development of more effective, sustainable and safe antimicrobial materials has become a research hotspot in food packaging. This paper systematically reviews the latest research on antimicrobial active packaging materials combining renewable and biodegradable polysaccharide-based substrates with green organic guanidine-based polymers, inorganic chlorine dioxide, or natural antimicrobial agents (such as essential oils, other plant extracts, chitosan, propolis, protein, bacteriocin, probiotics, and bacteriophages). The compositions, characteristics, antimicrobial mechanisms, and food applications of the various types of sustainable antimicrobial materials are updated, and future trends are explored. Although they show impressive properties, further studies are required to confirm the safety and efficacy of these materials as a majority of the studies have been conducted under laboratory conditions. This review provides theoretical and technical support for the development of new antimicrobial food packaging and extending the shelf-life of foods.

Review about the Application of Fractal Theory in the Research of Packaging Materials.

The work is intended to summarize the recent progress in the work of fractal theory in packaging material to provide important insights into applied research on fractal in packaging materials. The fractal analysis methods employed for inorganic materials such as metal alloys and ceramics, polymers, and their composites are reviewed from the aspects of fractal feature extraction and fractal dimension calculation methods. Through the fractal dimension of packaging materials and the fractal in their preparation process, the relationship between the fractal characteristic parameters and the properties of packaging materials is discussed. The fractal analysis method can qualitatively and quantitatively characterize the fractal characteristics, microstructure, and properties of a large number of various types of packaging materials. The method of using fractal theory to probe the preparation and properties of packaging materials is universal; the relationship between the properties of packaging materials and fractal dimension will be a critical trend of fractal theory in the research on properties of packaging materials.