Gel and Film Composites of Silver Nanoparticles in κ-, ι-, and λ-Carrageenans: One-Pot Synthesis, Characterization, and Bioactivities

Electron Beam-Supported Fabrication of Biocompatible Silver/iota-Carrageenan for Wound Healing Application

Silver nanoparticles (AgNPs) are a potent antibacterial agent, especially when used to treat bacteria that are multidrug resistant. However, it is challenging to eliminate the hazardous reducing agents that remain in AgNPs produced by the conventional chemical reduction process. To overcome these challenges, the presented research demonstrates the fabrication of AgNPs using iota-carrageenan (ι-carra) as a carbohydrate polymer using electron beam (EB) irradiation. Well-characterized ι-carra@AgNPs have a face-centered cubic (FCC) structure with spherical morphology and an average size of 26 nm. Herein we explored the approach for fabricating ι-carra@AgNPs that is suitable for scaling up the production of nanoparticles that exhibit excellent water stability. Further, the optimized ι-carra@AgNPs exhibited considerable antibacterial activity of 40% and 30% inhibition when tested with Gram-negative Escherichia coli ATCC 43895 and Gram-positive Staphylococcus aureus (S. aureus) (ATCC 6538), respectively, and low cytotoxicity at 10-50 μg/mL. To establish the potential biomedical application, as proof of the concept, the ι-carra@AgNPs showed significant antibiofilm activity at 20 μg/mL and also showed 95% wound healing abilities at 50 μg/mL compared to the nontreated control groups. Electron beam assisted ι-carra@AgNPs showed significant beneficial effects against specific bacterial strains and may provide a guide for the development of new antibacterial materials for wound dressing for large-scale production for biomedical applications.

Optimizing Sustainable Energy Generation in Ethanol Fuel Cells: An Exploration of Carrageenan with TiO2 Nanoparticles and Ni/CeO2 Composites

Based on the search for new biodegradable materials that are low cost and easy to synthesize by environmentally friendly methods, we report the use of carrageenan membranes (mixture of κ and λ carrageenans) with different concentrations of titanium dioxide nanoparticles (TiO₂ NPs) and Ni/CeO₂ (10 wt % Ni) for the fabrication of a novel fuel cell electrode for the oxidation of ethanol. Each membrane was characterized to determine its physicochemical properties using X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. Using impedance spectroscopy (IS), a maximum value of 2.08 × 10^-4 S/cm in ionic conductivity was found for the carrageenan nanocomposite with a concentration of 5 wt % TiO₂ NPs (CR5%). Due to its high conductivity values, the CR5% membrane was mixed with Ni/CeO₂ to prepare the working electrode for cyclic voltammetry measurements. Using a solution of 1 M ethanol and 1 M KOH, the oxidation of ethanol over CR5% + Ni/CeO₂ resulted in peak current density values at forward and reverse scan voltages of 9.52 and 12.22 mA/cm², respectively. From our results, the CR5% + Ni/CeO₂ membrane proves to be more efficient in the oxidation of ethanol compared with commercially available Nafion membranes containing Ni/CeO₂.