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Comparative Study between Two Simple Synthesis Methods for Obtaining Green Gold Nanoparticles Decorating Silica
Karen M Soto1, Angelica Gódinez-Oviedo2, José M López-Romero1
1Centro de Investigaciones y de Estudios Avanzados del I.P.N., Unidad Querétaro, Querétaro 76230, Mexico.
Materials (Basel, Switzerland)
|November 11, 2022
Summary
Silica-coated gold nanoparticles (AuNPs) were synthesized using two sol-gel methods. Both methods yielded effective antibacterial agents, with no significant difference in efficacy between them.
Area of Science:
- Materials Science
- Nanotechnology
- Biotechnology
Background:
- Silica (SiO2) particles are widely used to stabilize colloidal metal systems like gold nanoparticles (AuNPs).
- This stabilization prevents aggregation and preserves the activity of AuNPs, crucial for applications.
- Green synthesis of AuNPs using plant extracts offers an eco-friendly alternative.
Purpose of the Study:
- To fabricate silica-coated green gold nanoparticles (AuNPs) using two distinct sol-gel methods.
- To characterize the synthesized nanoparticles and evaluate their antibacterial activity.
- To investigate the influence of synthesis conditions on nanoparticle morphology and properties.
Main Methods:
- Green synthesis of AuNPs using mullein extract.
- Fabrication of silica-coated AuNPs via two different sol-gel methods.
- Characterization using Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier Transformed Infrared (FTIR), and Energy-Dispersive Spectroscopy (EDS).
- Antibacterial activity testing against *Staphylococcus aureus*, *Listeria monocytogenes*, *Escherichia coli*, and *Salmonella enterica*.
Main Results:
- Two distinct nanoparticle morphologies were observed: kidney-shaped and uniform (Synthesis-1) versus spherical and non-uniform (Synthesis-2).
- Synthesis temperature significantly impacted AuNP distribution within the silica matrix, influencing Janus-type formation and gold concentration.
- FTIR spectra were similar for both syntheses, while XRD revealed synthesis-dependent preferential growth of AuNPs.
- Both silica-coated AuNP formulations demonstrated significant antibacterial activity, particularly against *S. aureus* and *L. monocytogenes*.
- No significant difference in antibacterial efficacy was found between the two sol-gel methods.
Conclusions:
- Sol-gel methods are effective for producing silica-coated green gold nanoparticles with varying morphologies.
- Temperature control is critical for tailoring nanoparticle structure and gold distribution.
- The synthesized silica-coated AuNPs exhibit potent antibacterial properties against common pathogens, with comparable efficacy from both synthesis routes.
