Iodine-stabilized Cu nanoparticle chitosan composite for antibacterial applications

Area of Science:

• Materials Science
• Nanotechnology
• Microbiology

Background:

• Copper nanoparticles (Cu NPs) possess antimicrobial properties but suffer from instability in ambient conditions.
• Chitosan (CS) is a biocompatible polymer with inherent antimicrobial potential.
• Stabilizing Cu NPs is crucial for developing effective antimicrobial materials.

Purpose of the Study:

• To synthesize and characterize a novel composite of Cu NPs and CS stabilized with molecular iodine.
• To evaluate the antimicrobial activity of the iodinated CS-Cu NP composite against Gram-negative and Gram-positive bacteria.
• To elucidate the mechanism of bactericidal action of the developed composite.

Main Methods:

• Synthesis of Cu NPs within a CS matrix using CuSO(4) and hydrazine.
• Stabilization of Cu NPs by introducing molecular iodine post-synthesis.
• Characterization of Cu NPs size (8±4 nm) and composite stability.
• Antibacterial assays including Minimum Inhibitory Concentration (MIC) determination against Escherichia coli and Bacillus cereus.
• Zeta potential measurements and electron microscopy for interaction studies.
• Flow cytometry to assess bacterial cell membrane integrity.

Main Results:

• A stable iodinated CS-Cu NP composite was successfully synthesized.
• The composite demonstrated significant antibacterial activity, with a low MIC (130.8 μg/mL, containing 21.5 μg/mL Cu NPs) against E. coli.
• Zeta potential and electron microscopy confirmed the attachment of the composite to bacterial cell walls.
• Irreversible membrane damage leading to bacterial cell death was observed.

Conclusions:

• The iodinated CS-Cu NP composite offers enhanced stability and potent antimicrobial efficacy compared to previously reported Cu NPs.
• The composite exerts its bactericidal effect by damaging the bacterial cell membrane.
• This novel material holds promise for applications in combating bacterial infections.