In this study, raw and calcined eggshell-based biomaterials were modified with Ag⁺ ions, and their structural, surface, optical, and antimicrobial properties were systematically investigated. A sustainable approach was used to valorize eggshell waste, with AgNO₃ providing Ag-related species immobilized onto the material surface. X-ray diffraction confirmed the transformation of CaCO₃ to CaO upon calcination, while the absence of metallic silver peaks indicated incorporation of Ag⁺ within the nanocomposite. Zeta potential measurements showed increased positive surface charge after Ag⁺ modification, particularly in calcined samples, suggesting enhanced surface reactivity and colloidal stability. EDX analysis revealed localized Ag accumulation on non-calcined eggshells, whereas calcined composites exhibited more homogeneous Ag distribution. Photoluminescence studies showed green emission for ES@Ag⁺, while PL intensity was suppressed in C-ES@Ag⁺ due to Ag⁺-induced surface defects and charge transfer. Ag⁺ emission confirmed by UV-Vis. In addition, minimum inhibitory concentration (MIC) analysis revealed that ES@Ag⁺ exhibited superior antimicrobial efficiency at lower concentrations compared to C-ES@Ag⁺, demonstrating consistent performance across both liquid and solid media. Antimicrobial activity was tested against Candida albicans ATCC 10239 and Escherichia coli ATCC 8739 via the agar well diffusion method. ES@Ag⁺ exhibited inhibition zones of 17.00 ± 0.05 mm and 16.00 ± 0.07 mm, while C-ES@Ag⁺ showed 15.00 ± 0.02 mm and 9.00 ± 0.05 mm for C. albicans and E. coli, respectively. These results demonstrate the potential of Ag⁺-modified eggshell nanocomposites as sustainable materials for biomedical and environmental applications. While antimicrobial efficacy is promising, further cytotoxicity and biocompatibility studies are needed to assess safety and performance.
Büşra Şensoy Gün (Mon,) studied this question.