Gold nanoparticles immobilized on halloysite nanotubes for spatially-temporally localized photohyperthermia

Abstract Halloysite nanotubes (HNTs) with immobilized gold (Au) nanoparticles (NPs) were explored to enhance photoheating of aqueous media under excitation by continuous wave (CW) and nanosecond pulsed lasers with wavelengths close to the plasmonic resonance of Au-NPs. The structure and plasmonic properties of HNTs/Au-NP nanocomposites were analyzed by means of the transmission electron microscopy and optical spectroscopy. A remarkable photothermal effect with initial temperature growth of about 0.5 °C/min was observed for HNTs/Au-NPs’ aqueous suspension under relatively low excitation intensity, while the same photoexcitation of bare HNTs’ aqueous suspension did not result in any noticeable heating. In vitro experiments with Paramecium caudatum unicellular organisms have revealed a strong suppression of the cell viability after photoexcitation. While the average photoheating effect did not exceed 3–4 °C, the cell viability was decreased multifold, especially for the pulsed photoexcitation. The experimental results are explained by the spatially and temporally localized photohyperthermia in the vicinity of Au-NPs. The observed photoheating of HNTs/Au-NP nanocomposite is promising for applications in antibacterial treatment and targeted cancer therapy.