In-Out Surface Modification of Halloysite Nanotubes (HNTs) for Excellent Cure of Epoxy: Chemistry and Kinetics Modeling

Conductive hydrogels based on tragacanth and silk fibroin containing dopamine functionalized carboxyl-capped aniline pentamer: Merging hemostasis, antibacterial, and anti-oxidant properties into a multifunctional hydrogel for burn wound healing

Hydrogels possessing both conductive characteristics and notable antibacterial and antioxidant properties hold considerable significance within the realm of wound healing and recovery. The object of current study is the development of conductive hydrogels with antibacterial and antioxidant properties, emphasizing their potential for effective wound healing, especially in treating third-degree burns. For this purpose, various conductive hydrogels are developed based on tragacanth and silk fibroin, with variable dopamine functionalized carboxyl-capped aniline pentamer (CAP@DA). The FTIR analysis confirms that the CAP powder was successfully synthesized and modified with DA. The results show that the incorporation of CAP@DA into hydrogels can increase the porosity and swellability of the hydrogels. Additionally, the mechanical and viscoelastic properties of the hydrogels are also improved. The release of vancomycin from the hydrogels is sustained over time, and the hydrogels are effective in inhibiting the growth of Methicillin-resistant Staphylococcus aureus (MRSA). In vitro cell studies of the hydrogels show that all hydrogels are biocompatible and support cell attachment. The hydrogels' tissue adhesiveness yielded a satisfactory hemostatic outcome in a rat-liver injury model. The third-degree burn was created on the dorsal back paravertebral region of the rats and then grafted with hydrogels. The burn was monitored for 3, 7, and 14 days to evaluate the efficacy of the hydrogel in promoting wound healing. The hydrogels revealed treatment effect, resulting in enhancements in wound closure, dermal collagen matrix production, new blood formation, and anti-inflammatory properties. Better results were obtained for hydrogel with increasing CAP@DA. In summary, the multifunctional conducive hydrogel, featuring potent antibacterial properties, markedly facilitated the wound regeneration process.

Halloysite Nanotube as a Functional Material for Active Food Packaging Application: A Review

Halloysite nanotubes (HNTs) are naturally occurring nanomaterials with a tubular shape and high aspect ratio, a promising functional additive for active food packaging applications. HNTs have been shown to possess unique properties such as high surface area, thermal stability, and biocompatibility, making them attractive for active food packaging materials. This review summarizes recent research on the use of HNTs as functional additives in active food packaging applications, including antimicrobial packaging, ethylene scavenging packaging, moisture, and gas barrier packaging. The potential benefits and challenges associated with the incorporation of HNTs into food packaging materials are discussed. The various modification methods, such as the physical, chemical, biological, and electrostatic methods, along with their impact on the properties of HNTs, are discussed. The advantages and challenges associated with each modification approach are also evaluated. Overall, the modification of HNTs has opened new possibilities for the development of advanced packaging materials with improved performance for various functional food packaging materials with enhanced properties and extended shelf life.

Synergies in antimicrobial treatment by a levofloxacin-loaded halloysite and gold nanoparticles with a conjugation to a cell-penetrating peptide

Herein, a novel designed antimicrobial therapeutic drug delivery system is presented, in which halloysite nanotubes (HNTs) encapsulate a determined dosage of levofloxacin (lvx). Moreover, gold nanoparticles (AuNPs) have been embedded into the structure for plasmonic heating under irradiation of the green LED light (7 W, 526 nm). It was revealed that the plasmonic heating of the AuNPs leads to a controlled trend in the lvx release process. Also, a synergistic effect on the antimicrobial activity of the prepared therapeutic system has been observed through photothermal heating of the structure. To enhance the cell adhesion, a cell-penetrating peptide sequence (CPP) is conjugated to the surfaces. This CPP has led to quick co-localization of the prepared nano-cargo (denoted as lvx@HNT/Au-CPP) with the bacterial living cells and further attachment (confirmed by confocal microscopy). Concisely, the structure of the designed nano-cargo has been investigated by various methods, and the in vitro cellular experiments (zone of inhibition and colony-counting) have disclosed that the antimicrobial activity of the lvx is significantly enhanced through incorporation into the HNT/Au-CPP delivery system (drug content: 16 wt%), in comparison with the individual lvx with the same dosage. Hence, it can be stated that the bacterial resistance against antibiotics and the toxic effects of the chemical medications are reduced through the application of the presented strategy.

Epoxy Compositions with Reduced Flammability Based on DER-354 Resin and a Curing Agent Containing Aminophosphazenes Synthesized in Bulk Isophoronediamine

A method for the synthesis of an amine-containing epoxy resin curing agent by dissolving hexakis-[(4-formyl)phenoxy]cyclotriphosphazene in an excess of isophoronediamine was developed. The curing agent was characterized via NMR and IR spectroscopy and MALDI-TOF mass spectrometry, and its rheological characteristics were studied. Compositions based on DER-354 epoxy resin and the synthesized curing agent with different amounts of phosphazene content were obtained. The rheological characteristics of these compositions were studied, followed by their curing. An improvement in several thermal (DSC), mechanical (compression, tension, and adhesion), and physicochemical (water absorption and water solubility) characteristics, as well as the fire resistance of the obtained materials modified with phosphazene, was observed, compared with unmodified samples. In particular, there was an improvement in adhesive characteristics and fire resistance. Thus, compositions based on a curing agent containing a 30% modifier were shown to fulfill the V-1 fire resistance category. The developed compositions can be processed by contact molding, winding, and resin transfer molding (RTM), and the resulting material is suitable for use in aircraft, automotive products, design applications, and home repairs.

Cure Kinetics of Samarium-Doped Fe3O4/Epoxy Nanocomposites

To answer the question “How does lanthanide doping in iron oxide affect cure kinetics of epoxy-based nanocomposites?”, we synthesized samarium (Sm)-doped Fe3O4 nanoparticles electrochemically and characterized it using Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), energy dispersive X-Ray analysis (EDX), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy analyses (XPS). The magnetic particles were uniformly dispersed in epoxy resin to increase the curability of the epoxy/amine system. The effect of the lanthanide dopant on the curing reaction of epoxy with amine was explored by analyzing differential scanning calorimetry (DSC) experimental data based on a model-free methodology. It was found that Sm3+ in the structure of Fe3O4 crystal participates in cross-linking epoxy by catalyzing the reaction between epoxide rings and amine groups of curing agents. In addition, the etherification reaction of active OH groups on the surface of nanoparticles reacts with epoxy rings, which prolong the reaction time at the late stage of reaction where diffusion is the dominant mechanism.

Linear and star-shaped π-conjugated oligoanilines: a review on molecular design in syntheses and properties

Molecular Design and Synthesis of Linear and Star-shaped π-conjugated Oligoanilines with reversible optoelectrochemical properties.