Zinc ion cross-linked sodium alginate modified hexagonal boron nitride to enhance the flame retardant properties of composite coatings

Enhanced flame retardancy and accelerated degradation of polylactic acid using a chitosan-based additive with phosphorus and zinc

Polylactic acid (PLA) is a bio-recyclable plastic, but its high flammability limits broader applications. Here, a novel flame retardant (Zn-CHP) is synthesized from chitosan (CH), diethylenetriaminepenta (methylenephosphonic) acid (DTPMP), and ZnCl₂ using a simple, solvent-free process. The Zn-CHP additive is melt-blended with PLA, achieving excellent flame retardancy at just 2 wt% loading. The modified PLA exhibits a limiting oxygen index (LOI) of 25.5 % and meets, though minor non-combustible dripping is observed, which cools significantly around 200 °C compared to the untreated PLA. Cone calorimeter tests show that the addition of 2 wt% Zn-CHP reduces the peak heat release rate (pHRR) by 16.8 %, total heat release (THR) by 9.0 %, and fire growth rate by 23.1 %. Importantly, the tensile performance of the PLA is little affected, while the additive accelerates its degradation. We believe this work offers a promising approach to enhancing flame retardancy and promoting faster recycling of PLA.

Enhanced flame retardancy of polyurethane foam with alginate-based flame-retardant coating

Polyurethane (PU) foam is widely used in industrial and civil fields, but it is highly flammable. An eco-friendly flame-retardant coating has been fabricated from sodium alginate (SA) and mica powder, it has been applied to PU foam using a facile direct dip coating method, followed by crosslinking with Ca2+ and modification with polydimethylsiloxane (PDMS), respectively. The original porous network structure is maintained in the coated PU (SMPU) foam with a porosity of 90.51 %, and exhibits good thermal stability, hydrophobicity and excellent flexibility. Moreover, the as-prepared SMPU foam exhibits reduced flammability, e.g., the limiting oxygen index (LOI) for combustion of SMPU foam is 30.5 %, whereas that for unmodified PU foam is 16 %. The SMPU foam also exhibits a self-extinguishing effect without melt dripping and passes UL-94 V-0 rating. A significant reduction in the release of heat as well as total smoke and CO2 formation during combustion was noted using cone calorimetry. These improvements in combustion behavior may be ascribed to a physical barrier formed by non-flammable mica powder, SA and PDMS which displays char forming ability. A facile strategy for improvement of the fire safety of PU foam using a green and efficient flame-retardant coating has been demonstrated.

Inhalable multi-stimulus sensitive curcumin-alginate nanogels for scavenging reactive oxygen species and anti-inflammatory co-ordination to alleviate acute lung injury

Acute lung injury (ALI) is one of the most common and extremely critical clinical conditions, which progresses with an inflammatory response and overproduction of reactive oxygen species (ROS), leading to oxidative damage to the lungs. Curcumin (Cur) has great potential in treating ALI due to its excellent antioxidant and anti-inflammatory effects. In this study, Cur and alginate were cross-linked by zinc ions and intermolecular hydrogen bonding to form an inhalable aqueous nanogel system to overcome Cur's low solubility and bioavailability. Cur-alginate (ZA-Cur) nanogels exhibited superior antioxidant properties and down-regulated inflammation-associated factors in vitro with controlled-release behavior under multi-stimulus conditions such as temperature, pH, and ions. Meanwhile, the nanogels system could effectively scavenge cellular ROS to repair oxidative stress damage. In a mice model of ALI, tracheal nebulised inhalation of ZA-Cur nanogels down-regulated the expression of inflammation-related genes such as TNF-α, IL-1β, and IL-6, as well as modulated MDA content and CAT activity to attenuate oxidative stress injury, showing promising lung-protective effects. In conclusion, this work developed inhalable ZA-Cur nanogels to decelerate the progression of lesions in ALI by scavenging intracellular ROS and alleviating inflammation simultaneously, which may be a promising strategy for treating ALI.

Quercetin-loaded sodium alginate/collagen/h-boron nitride potential wound dressings prepared using the Box-Behnken experimental design

BACKGROUND/AIMS

Natural and synthetic biocompatible polymers have received significant attention in the pharmaceutical industry due to their rapid and effective healing properties in the wound healing process. The aim of this study was to optimize the extraction of onions, the preparation of sodium alginate/collagen/hydrogen boron nitride (NaAlg/Col/h-BN) membranes using the Box-Behnken experimental design, and determine the optimal conditions for quercetin release. The study also aimed to investigate the antimicrobial and antioxidant activities of the prepared membranes and their therapeutic properties.

METHODS AND RESULTS

The prepared membranes were characterized by scanning electron microscopy (SEM), fourier transform infrared (FTIR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). Antimicrobial activities were tested against Gram-negative (Gr-) Escherichia coli ATCC 25922, Klebsiella pneumonia, Enterobacter aerogenes, Gram-positive (Gr+) Staphylococcus aureus ATCC 25923, and Candida albicans ATCC 10231 pathogens. In vitro release studies were conducted to examine the therapeutic properties of the prepared membranes. The optimum conditions for the extraction of onions and the preparation of NaAlg/Col/h-BN membranes were found to be EtOH = 75 mL, t = 2 h, T = 45°C, and NaAlg = 1.0 g, Col = 2.0 g, and h-BN = 6% wt, respectively. The prepared membranes exhibited serious antimicrobial properties against S. aureus and C. albicans. The membranes also promoted the controlled release of quercetin for 24 h in vitro, indicating their potential as a new approach in wound treatment.

CONCLUSION

The study concludes that quercetin-filled NaAlg/Col/h-BN membranes have promising therapeutic properties for wound healing. The membranes exhibited significant antimicrobial and antioxidant properties, and their controlled release of quercetin suggests their potential for use in wound healing applications.