Immobilization of lysozyme on layer-by-layer self-assembled electrospun nanofibers treated by post-covalent crosslinking

Versatile Keratin Fibrous Adsorbents with Rapid-Response Shape-Memory Features for Sustainable Water Remediation

Biodegradable shape-memory polymers derived from protein substrates are attractive alternatives with strong potential for valorization, although their reconstruction remains a challenge due to the poor processability and inherent instability. Herein, based on Maillard reaction and immobilization, a feather keratin fibrous adsorbent featuring dual-response shape-memory is fabricated by co-spinning with pullulan, heating, and air-assisted spraying ZIF-8-NH2. Maillard reaction between the amino group of keratin and the carbonyl group of pullulan improves the mechanics and thermal performance of the adsorbent. ZIF-8-NH2 immobilization endows the adsorbent with outstanding multipollutant removal efficiency (over 90%), water stability, and photocatalytic degradation and sterilization performance. Furthermore, the adsorbent can be folded to 1/12 of its original size to save space for transportation and allow for rapid on-demand unfolding (12 s) upon exposure to water and ultraviolet irradiation to facilitate the adsorption and photocatalytic activity with a larger water contact area. This research provides new insight for further applications of keratin-based materials with rapid shape-memory features.

Application of hydrophobic eutectic solvent in efficient biotransformation of total flavonoids of Herba Epimedii

Icaritin, a hydrolysate from total flavonoids of Epimedii (TFE), which has better anti-hepatoma activity than its glycosylated form. In this work, immobilized enzymes 4LP-Tpebgl3@Na-Y and DtRha@ES-107 were used to hydrolyze TFE to prepare icaritin. Five different hydrophobic deep eutectic solvents (HDES) were prepared and the most ideal HDES was successfully selected, which was composed of dodecyl alcohol and thymol with the molar ratio of 2:1. The relative enzyme activity of 4LP-Tpebgl3@Na-Y and DtRha@ES-107 was about 102.4 % and 112.5 %, respectively. In addition, the thermal and binding stability of 4LP-Tpebgl3@Na-Y and DtRha@ES-107 in HDES was not affected negatively. In the biphasic system composed of 50 % (v/v) HDES and Na2HPO4-citric acid buffer (50 mM, pH 5.5), 4LP-Tpebgl3@Na-Y (1.0 U/mL) and TFE (1 g/L) were reacted at 80 °C for 1 h, and then reacted with DtRha@ES-107 (20 U/mL) at 80 °C for 2 h. Finally, TFE was completely converted to 301.8 mg/L icaritin (0.82 mM). After 10 cycles, 4LP-Tpebgl3@Na-Y/DtRha@ES-107 still maintained 84.1 % original activity. In this study, we developed an efficient methodology for icaritin preparation through the integration of enzymatic catalysis and adsorption separation, presenting a viable approach for large-scale, cost-effective production of icaritin.

Improving structural and functional properties of starch-catechin-based green nanofiber mats for active food packaging by electrospinning and crosslinking techniques

The hydrophilic and low mechanical properties limited the application of starch-based films. In this work, a hydrophobic starch-based nanofiber mat was first successfully prepared from aqueous solution at room temperature by using electrospinning and glutaraldehyde (GTA) vapor phase crosslinking techniques for active packaging applications. Catechin (CAT) was immobilized in the nanofibers by electrospinning, resulting in higher thermal stability (Tdmax = 315.23 °C), antioxidant (DPPH scavenging activity = 94.31 ± 2.70 %) and antimicrobial (inhibition zone diameter = 15.6 ± 0.3 mm) of the fibers, which further demonstrated hydrogen bonding and electrostatic interaction between CAT and fibers. Nanofibers after GTA vapor phase crosslinking exhibited enhanced hydrophobicity (water contact angle: 15.6 ± 1.5° → 93.5 ± 2.3°) and mechanical properties (tensile strength: 1.82 ± 0.06 MPa → 7.64 ± 0.24 MPa, elastic modulus: 19.35 ± 0.63 MPa → 45.34 ± 0.51 MPa). The results demonstrated that preparation of starch-based electrospun nanofiber mats in aqueous system at room temperature overcame the challenges of organic solvent pollution and thermosensitive material encapsulation, while GTA vapor phase crosslinking technique improved the hydrophobicity and mechanical properties of nanofiber mats, which facilitated the application of starch-based materials in the field of packaging.

The Recent Advances of Polymer-POSS Nanocomposites With Low Dielectric Constant

This study provides a comprehensive overview of the preparation methods for polyhedral oligomeric silsesquioxane (POSS) monomers and polymer/POSS nanocomposites. It focuses on the latest advancements in using POSS to design polymer nanocomposites with reduced dielectric constants. The study emphasizes exploring the potential of POSS, either alone or in combination with other materials, to decrease the dielectric constant and dielectric loss of various polymers, including polyimides, bismaleimide resins, poly(aryl ether)s, polybenzoxazines, benzocyclobutene resins, polyolefins, cyanate ester resins, and epoxy resins. In addition, the research investigates the impact of incorporating POSS on improving the thermal properties, mechanical properties, surface properties, and other aspects of these polymers. The entire study is divided into two parts, discussing systematically the role of POSS in reducing dielectric constants during the preparation of POSS composites using both physical blending and chemical synthesis methods. The goal of this research is to provide valuable strategies for designing a new generation of low dielectric constant materials suitable for large-scale integrated circuits in the semiconductor materials domain.

A sustained-release microcarrier effectively prolongs and enhances the antibacterial activity of lysozyme

Bacterial infections have become a great threat to public health in recent years. A primary lysozyme is a natural antimicrobial protein; however, its widespread application is limited by its instability. Here, we present a poly (N-isopropylacrylamide) hydrogel inverse opal particle (PHIOP) as a microcarrier of lysozyme to prolong and enhance the efficiency against bacteria. This PHIOP-based lysozyme (PHIOP-Lys) formulation is temperature-responsive and exhibits long-term sustained release of lysozyme for up to 16 days. It shows a potent antibacterial effect toward both Escherichia coli and Staphylococcus aureus, which is even higher than that of free lysozyme in solution at the same concentration. PHIOPs-Lys were demonstrated to effectively inhibit bacterial infections and enhance wound healing in a full-thickness skin wound rat model. This study provides a novel pathway for prolonging the enzymatic activity and antibacterial effects of lysozyme.

Electrospun fiber-mediated delivery of neurotrophin-3 mRNA for neural tissue engineering applications

Aligned electrospun fibers provide topographical cues and local therapeutic delivery to facilitate robust peripheral nerve regeneration. mRNA delivery enables transient expression of desired proteins that promote axonal regeneration. However, no prior work delivers mRNA from electrospun fibers for peripheral nerve regeneration applications. Here, we developed the first aligned electrospun fibers to deliver pseudouridine-modified (Ψ) neurotrophin-3 (NT-3) mRNA (ΨNT-3mRNA) to primary Schwann cells and assessed NT-3 secretion and bioactivity. We first electrospun aligned poly(L-lactic acid) (PLLA) fibers and coated them with the anionic substrates dextran sulfate sodium salt (DSS) or poly(3,4-dihydroxy-L-phenylalanine) (pDOPA). Cationic lipoplexes containing ΨNT-3mRNA complexed to JetMESSENGER® were then immobilized to the fibers, resulting in detectable ΨNT-3mRNA release for 28 days from all fiber groups investigated (PLLA+mRNA, 0.5DSS4h+mRNA, and 2pDOPA4h+mRNA). The 2pDOPA4h+mRNA group significantly increased Schwann cell secretion of NT-3 for 21 days compared to control PLLA fibers (p < 0.001-0.05) and, on average, increased Schwann cell secretion of NT-3 by ≥ 2-fold compared to bolus mRNA delivery from the 1µgBolus+mRNA and 3µgBolus+mRNA groups. The 2pDOPA4h+mRNA fibers supported Schwann cell secretion of NT-3 at levels that significantly increased dorsal root ganglia (DRG) neurite extension by 44% (p < 0.0001) and neurite area by 64% (p < 0.001) compared to control PLLA fibers. The data show that the 2pDOPA4h+mRNA fibers enhance the ability of Schwann cells to promote neurite growth from DRG, demonstrating this platform's potential capability to improve peripheral nerve regeneration. STATEMENT OF SIGNIFICANCE: Aligned electrospun fibers enhance axonal regeneration by providing structural support and guidance cues, but further therapeutic stimulation is necessary to improve functional outcomes. mRNA delivery enables the transient expression of therapeutic proteins, yet achieving local, sustained delivery remains challenging. Previous work shows that genetic material delivery from electrospun fibers improves regeneration; however, mRNA delivery has not been explored. Here, we examine mRNA delivery from aligned electrospun fibers to enhance neurite outgrowth. We show that immobilization of NT-3mRNA/JetMESSENGER® lipoplexes to aligned electrospun fibers functionalized with pDOPA enables local, sustained NT-3mRNA delivery to Schwann cells, increasing Schwann cell secretion of NT-3 and enhancing DRG neurite outgrowth. This study displays the potential benefits of electrospun fiber-mediated mRNA delivery platforms for neural tissue engineering.

Preparation of robust and fully bio-based modified paper via mussel-inspired layer-by-layer assembly of chitosan and carboxymethyl cellulose for food packaging

A green and facile method was proposed to prepare robust and fully bio-based modified paper in this study, which involved in layer-by-layer deposition of chitosan (CS) and mussel adhesive protein-mimetic polymer (dopamine-grafted carboxymethyl cellulose, CMC-g-DA) on paper surface and subsequent oxidative cross-linking by sodium periodate. The mechanical, barrier and antibacterial properties of the cross-linked multilayer-modified paper significantly improved with the increased bilayer numbers. Compared with unmodified paper, cross-linked (CS/CMC-g-DA)₆ multilayer-modified paper exhibited 71.6 % improvement in tensile strength, 69.2 % and 56.3 % decline in air and water vapor permeability, as well as above 90 % antibacterial efficiency against S. aureus and E. coli. Particularly, the cross-linked multilayer-modified paper maintained outstanding functional stability even after suffering from vigorously corrosive treatment. The obtained functional paper effectively extended the shelf-life of Agaricus bisporus to 6 days under ambient conditions. We believed that the prepared robust functional paper in this study will have promising application prospect in food packaging field.

Electrospun Core–Sheath Nanofibers with Variable Shell Thickness for Modifying Curcumin Release to Achieve a Better Antibacterial Performance

The inefficient use of water-insoluble drugs is a major challenge in drug delivery systems. Core–sheath fibers with various shell thicknesses based on cellulose acetate (CA) were prepared by the modified triaxial electrospinning for the controlled and sustained release of the water-insoluble Chinese herbal active ingredient curcumin. The superficial morphology and internal structure of core–sheath fibers were optimized by increasing the flow rate of the middle working fluid. Although the prepared fibers were hydrophobic initially, the core–sheath structure endowed fibers with better water retention property than monolithic fibers. Core–sheath fibers had flatter sustained-release profiles than monolithic fibers, especially for thick shell layers, which had almost zero-order release for almost 60 h. The shell thickness and sustained release of drugs brought about a good antibacterial effect to materials. The control of flow rate during fiber preparation is directly related to the shell thickness of core–sheath fibers, and the shell thickness directly affects the controlled release of drugs. The fiber preparation strategy for the precise control of core–sheath structure in this work has remarkable potential for modifying water-insoluble drug release and improving its antibacterial performance.

Characterization of glycosylated gelatin/pullulan nanofibers fabricated by multi-fluid mixing solution blow spinning

In this work, multi-fluid mixing solution blow spinning was applied to develop gelatin/pullulan composite nanofibers, and then the nanofibers were glycated to enhance the physical properties. The results show that the grafting degree of the nanofibers increased significantly from 17.5 % to 36.0 % as the glycation time increased, and the morphology results indicated that 72 h of glycation did not destroy the structure of the nanofibers. FTIR results show that the glycation consumed the the-NH₂ groups, cleaved sugar units of polysaccharide, and affected the secondary structure of the protein. The glycation enhanced the thermal stability and improved the rigidity of the nanofibers. Besides, after 120 h of glycation, the water contact angle of nanofibers increased from 0° to 79.1°, and the water vapor transmission rates decreased from 12.49 to 8.97 g mm/m² h kPa, indicating the enhanced hydrophobicity and barrier properties. In addition, the glycation improved the water stability of the nanofibers, which increased the applicability of the gelatin/pullulan nanofibers in food packaging. The present work provides a green and efficient method for improving the physical properties of gelatin/pullulan nanofibers.