Structural Characterization, Cytotoxicity and Microbiological Activity of One-Step-Synthesized RGO/AuNPs...

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Reduced graphene oxide (RGO) and gold nanoparticles (AuNPs) are promising nanomaterials.
• Developing efficient synthesis methods for RGO-AuNPs composites is crucial for their applications.
• Understanding the biological and antibacterial properties of these composites is essential.

Purpose of the Study:

• To develop a green, single-step synthesis for RGO-AuNPs nanocomposites.
• To characterize the structural and colloidal properties of the synthesized RGO-AuNPs.
• To evaluate the cytotoxicity and antibacterial efficacy of the RGO-AuNPs composites.

Main Methods:

• Green synthesis using sodium citrate as a reducing and stabilizing agent.
• Characterization using Transmission Electron Microscopy (TEM), High Resolution TEM (HRTEM), Selected Area Electron Diffraction (SAED), Dynamic Light Scattering (DLS), and zeta potential analysis.
• Biological evaluation including cytotoxicity assays on HaCaT keratinocytes and antibacterial assays against *Escherichia coli*, *Staphylococcus aureus*, and *Bacillus subtilis*.

Main Results:

• Successful synthesis of spherical AuNPs (10-60 nm) distributed on RGO sheets.
• Colloidal instability observed with higher RGO content.
• Dose-dependent cytotoxicity in HaCaT cells, with IC50 values decreasing as RGO content increases.
• Significant synergistic antibacterial effects against tested bacterial strains, with complete *E. coli* inhibition at low Au content.
• Antimicrobial activity maintained in protein-rich media.

Conclusions:

• The green synthesis method provides a viable route to RGO-AuNPs nanocomposites.
• The RGO-AuNPs composites exhibit tunable cytotoxicity and potent antibacterial activity.
• These multifunctional materials show potential for biomedical applications, including antimicrobial coatings and therapeutics.