Nanomaterials as electromagnetic sensors for tumour detection

Microwave (MW) imaging/sensing is a potential clinical diagnostic technique which exploits differences in the dielectric properties of tissues at MW frequencies. Notably, breast cancer detection has been identified as a key application for this modality; however, inherent contrast in tissue dielectric properties may not always be sufficient to allow imaging/sensing. Nanoparticles could provide the necessary enhancement, due to their effect on the dielectric properties of the target tissue and their ability to accumulate in tumours. This study aims to prepare novel zinc ferrites ZnFe₂O₄ nanoparticles and investigate their potential as contrast agents for MW imaging/sensing.

Zinc ferrite nanoparticles were synthesized by thermal decomopositon and phase transferred using a co-polymer to improve biocompatibility. Dielectric properties were evaluated using the co-axial probe technique, progressing to ex vivo and in vivo studies in a triple-negative breast cancer xenograft mouse model.

Tumours regions injected subcutaneously with nanoparticles in vivo showed an increased dielectric constant of up to 49% compared with approximately 3% ex vivo. Significant increases in conductivity were also observed indicating potential application of the particles as MW hyperthermia sensitizers.

Crucially, this study presents the first in vivo evaluation of nanoparticles as contrast agents for MW imaging/sensing. Observed increases in the dielectric properties highlight their potential to improve tumour detection using MW technologies.