Chitosan/copper nanocomposites: Correlation between electrical and antibacterial properties

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Chitosan (CS) is a versatile biopolymer with potential in biomedical applications.
• Copper nanoparticles (CuNPs) exhibit potent antibacterial properties.
• Developing effective and safe nanocomposites requires understanding property correlations.

Purpose of the Study:

• To investigate the relationship between electrical and antibacterial properties of CS/CuNPs.
• To determine the minimum effective CuNPs concentration in a CS matrix.
• To explore the potential for creating non-toxic nanocomposites for biomedical use.

Main Methods:

• Synthesis and characterization of CS/CuNPs using UV-vis, TEM, XRD, FTIR, and XPS.
• Measurement of DC electrical conductivity to identify the percolation threshold.
• Antibacterial assays against Gram-positive bacteria.

Main Results:

• Formation of polygonal metallic CuNPs (30-50 nm) confirmed.
• Chelation mechanism between CS and CuNPs identified.
• Electrical percolation threshold observed at approximately 0.143% CuNPs concentration.
• Maximum antibacterial activity achieved below the electrical percolation threshold.

Conclusions:

• Antibacterial activity correlates with electron transfer between bacteria and CuNPs.
• Optimal antibacterial efficacy is achieved at extremely low, sub-percolation CuNPs concentrations.
• These findings support the design of safer, low-concentration CS/CuNPs for biomedical applications.