Experimental investigation of photothermal conversion and thermal conductivity of broadband absorbing gold nanoblackbodies and graphene oxide nanoparticles for plasmonic photothermal cancer therapy

The choice of nanomaterial is crucial for achieving desired thermal ablation of a tumors, considering nanoparticle dose/concentration and near-infrared (NIR) irradiation parameters during plasmonic photothermal therapy (PPTT). Most studies prioritize use of nanoparticles with high photothermal conversion efficiency (η) for PPTT without emphasizing the thermal conductivity (κ) within a solid tumor. Herein, two broadband absorbing nanoparticles, i.e., gold nanoblackbodies (AuNBs) and graphene oxide (GO) nanoparticles, are compared for η under similar NIR irradiation and nanoparticles dose. Further, the effect of photothermal conversion and κ are studied through tumor-tissue mimicking phantoms mimicking invasive ductal carcinoma embedded with nanoparticles, surrounded by normal tissue region. Under similar conditions, η is higher in AuNBs (73.2%) than GO nanoparticles (63.7%), while κ of GO nanoparticles embedded phantom (0.62 W/mK) surpasses AuNBs embedded phantom (0.59 W/mK) by 5.08%. Photothermal response through tumor-tissue mimicking phantoms shows that GO nanoparticles achieve higher temperatures within the entire tumor region than AuNBs due to their high κ, despite having lower η. This finding suggests that η is not the sole parameter, and it is the coupled effect of η and κ for the choice/suitability of a nanoparticle to attain desired temperatures throughout the tumor for PPTT.