In‐situ Synthesis of Highly Potent Antibacterial Copper‐Based MOFs/Sodium Alginate Composite Beads

This study presents an eco-friendly approach to synthesize novel antibacterial copper-based MOFs within sodium alginate hydrogel networks. Two types of composite beads are prepared by treating copper-ion-crosslinked alginate hydrogels with tartaric acid and oxalic acid ligands solutions. Characterizations via FTIR, XRD, TGA, and SEM confirm their formation. Antibacterial testing reveals potent efficacy against diverse bacterial strains, highlighting their potential as effective antibacterial agents.

Abstract

The present study reports an environmentally friendly in-situ synthesis of novel antibacterial copper-based MOFs within the hydrogel network of sodium alginate. Two different copper-based MOF/sodium alginate composite beads were prepared via the post-treatment of copper-ion-crosslinked alginate hydrogels with two different ligand solutions, namely, tartaric acid and oxalic acid, at 100 °C for 24 h. The structural, thermal, and morphological properties of the prepared samples were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM), and their antibacterial activities against gram-positive (Staphylococcus aureus and Bacillus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) strains were examined using the conventional disc diffusion method. The results demonstrated the success of the in-situ synthesis of two distinct copper-based MOFs with FTIR spectra, confirming the existence of characteristic bands of the ligands complexed to the sodium alginate matrix. Moreover, the XRD diffractograms revealed the formation of two distinct crystalline structures with well-defined morphologies observed in the SEM images. In addition, thermal analysis showed that the prepared composite beads had enhanced thermal stability compared to the copper-ion-crosslinked alginate beads. Antibacterial testing revealed the strong capacity of the copper-based MOFs/sodium alginate composite beads to deactivate the growth of all the bacterial strains used, with a minimum inhibition zone of 23 mm, which highlights the potential of the synthesized materials as highly potent antibacterial agents.

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