Characterisation of ZnO NPs as contrast agents for MWI

This study presents the examination of zinc oxide (ZnO) nanoparticles (NPs) as potential contrast agents for microwave imaging (MWI). Polyethylene Glycol (PEG) with varying molecular weights (Mw) have been used to coat NPs. Characterisation of the colloidal dispersions have been recorded using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Ultraviolet-Visible spectroscopy (UV-Vis). The dielectric characterisation of the aqueous colloidal suspensions was recorded over the microwave frequency range between 1-4 GHz, to assess effective contrast for microwave breast imaging applications. Our data shows zinc oxide NPs increase dielectric constant compared to the background medium. The PEGylation process further improved the suspension stability, which was confirmed by DLS and UV-Vis. ZnO-PEG achieved a significant increase in the dielectric constant and the increase was dependent on the different molecular weights of PEG.