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<p>In this study, silver-doped phosphate-functionalized chitosan nanocomposite films were synthesized via the sol–gel method and solution casting. X-ray diffraction, FTIR, and electron microscopy (SEM, EDX, TEM) confirmed that we successfully phosphorylated the chitosan and produced well-dispersed AgNPs at the nanoscale. Adding phosphate groups disrupted the original crystalline structure of chitosan, making the matrix mostly amorphous. This shift stabilized the nanoparticles and strengthened the physicochemical interactions in the film. UV–Vis spectroscopy shows clear changes as the silver content increased (from 0 to 0.5 wt%). The films became more transparent, and their optical band gap energy increased from 3.28 to 3.81&#xa0;eV. The refractive index also increased, from 1.69 to 1.81 at 700&#xa0;nm. These effects come from better matrix uniformity, fewer defect states, and changes in the electronic structure caused by the interaction between the AgNPs and the phosphate groups. Antimicrobial analysis revealed strong activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger. Adding more AgNPs further improved inhibition, especially against fungi. This antimicrobial action results from a combination of Ag⁺ ion release, generation of reactive oxygen species, and electrostatic interactions between the polymer and the microbes’ membranes. The results establish a direct correlation between structural modifications, optical tuning, and antimicrobial performance, highlighting the potential of phosphate-chitosan/Ag nanocomposites as multifunctional materials for integrated optoelectronic, biomedical, and antimicrobial applications.</p>

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Phosphate-Functionalized Chitosan/Ag Nanocomposites: Enhanced Optical Tunability and Antimicrobial Activity

  • 期刊论文

  • 发表日期：

    2026年4月9日

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  • M. K. Seddeek,
  • A. M. A. Shamekh

摘要

In this study, silver-doped phosphate-functionalized chitosan nanocomposite films were synthesized via the sol–gel method and solution casting. X-ray diffraction, FTIR, and electron microscopy (SEM, EDX, TEM) confirmed that we successfully phosphorylated the chitosan and produced well-dispersed AgNPs at the nanoscale. Adding phosphate groups disrupted the original crystalline structure of chitosan, making the matrix mostly amorphous. This shift stabilized the nanoparticles and strengthened the physicochemical interactions in the film. UV–Vis spectroscopy shows clear changes as the silver content increased (from 0 to 0.5 wt%). The films became more transparent, and their optical band gap energy increased from 3.28 to 3.81 eV. The refractive index also increased, from 1.69 to 1.81 at 700 nm. These effects come from better matrix uniformity, fewer defect states, and changes in the electronic structure caused by the interaction between the AgNPs and the phosphate groups. Antimicrobial analysis revealed strong activity against Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, and Aspergillus niger. Adding more AgNPs further improved inhibition, especially against fungi. This antimicrobial action results from a combination of Ag⁺ ion release, generation of reactive oxygen species, and electrostatic interactions between the polymer and the microbes’ membranes. The results establish a direct correlation between structural modifications, optical tuning, and antimicrobial performance, highlighting the potential of phosphate-chitosan/Ag nanocomposites as multifunctional materials for integrated optoelectronic, biomedical, and antimicrobial applications.