Thermal response of CuO/polydopamine nanospheres under NIR laser irradiation

Abstract

Composite nanostructures with enhanced photothermal conversion (PTC) play an important role in near infrared (NIR) light-mediated photothermal therapy (PTT) and cancer theranostic applications. However, the diversity and multiplicity of assembled components in a single nanostructured particle produce complexity, so the integrated effects of such a formulation product are difficult to predict and control. In this study, novel composite nanospheres were synthesized by combining only two components with inherent multifunctional properties, i.e., small copper oxide nanoparticles (CuO-NPs) and polydopamine (PDA). The CuO-NPs embedded PDA nanospheres (CuO/PDA-NS) were subjected to material analysis demonstrating strong chelating interactions between the catechol groups of PDA and CuO-NPs surface. This behavior apparently suppresses the release of the embedded CuO-NPs in water, consequently giving the composite nanospheres remarkable stability in aqueous solution (19% copper release in 78 days, pH 7.2). The heating efficiency of CuO/PDA-NS versus water was found to be 66%, which is significantly higher than the heating efficiency of CuO-NPs and PDA-NS (i.e., 50% and 55%, respectively). Additionally, CuO/PDA-NS showed a good thermal stability after consecutive NIR irradiations. Taken together, these results confirm that CuO/PDA-NS exhibit an enhanced thermal effect under NIR laser irradiation, which is expected to lead to great advantages in the treatment of cancer diseases with a minimally invasive approach.