Size Control of Cu Nanoparticles in Ion-Exchanged Soda-Lime Glass by 6 MeV Electron Irradiation and Its Application in Biofilm Inhibition

ABSTRACT

A few soda-lime glass samples with a 1 cm² area and 0.1 cm thickness were dipped into a molten salt bath of copper sulfate and sodium sulfate in a molar ratio of 54:46 at 545°C for 10 min. These samples were irradiated with 6 MeV energy electrons in the fluence range from 10 × 10¹⁴ to 40 × 10¹⁴ electrons/cm² and annealed at 400°C. The optical properties and the corresponding induced effects were characterized by techniques such as ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The UV-Vis absorption spectra showed two peaks, one at 754 nm and other centered at 533 nm. The absorption peak at 754 nm was ascribed to Cu⁺² ions, and the one at 553 nm corresponded to the surface plasmon resonance (SPR) band of nanocrystalline copper clusters. The intensity and the full-width at half maximum (FWHM) of the optical absorption peaks increased with an increase in the electron fluence. The XRD spectra showed a peak at 2θ position of 43.19°, which corresponds to metal Cu(111) nanocrystalline planes of face-centered cubic. An SEM image of diffused copper nanoparticles showed an average size of ∼15 nm when the fluence was increased up to 40 × 10¹⁴ electrons/cm² and EDS showed the diffusion of copper into the soda-lime glass. About 70% and 80% biofilm reduction was observed with modified glass exposed to electron fluence. The modified glass prevented the growth of biofilms of a pathogenic bacterium Klebsiella pneumoniae to a considerable extent.

KEYWORDS:

• copper nanoparticles
• ion exchange
• electron irradiation
• K. pneumoniae