Photothermally Active Upconversion Core–Shell NaGdF₄:Yb:Tm@Cu Nanostructures: Synthesis and Theranostic Properties

Abstract

Near infrared (NIR) active nanostructures with applications in imaging and therapy have attracted significant attention in cancer diagnosis and treatment. NIR active structures can provide molecular images, penetrating from deep within tissue with high resolution. In addition, particles with photothermal properties can lead to a new era of cancer diagnostics. The first synthesis of core–shell NaGdF4:Yb:Tm@Cu (NGF@Cu) nanostructures is reported. NGF@Cu particles have molecular imaging and photothermal activation properties owing to an upconverting core and metallic shell. The upconversion core means that cancer cell location can be recognized and the Cu‐based photothermal therapy is subsequently able to disrupt the cells. NGF@Cu characterization studies, including scanning tunneling electron microscopy and energy dispersive X‐ray spectroscopy mapping, confirm the core–shell structure with Cu as the shell. This study demonstrates the use of a single nanostructure for diagnosis in the NIR therapeutic window (650–1400 nm) and photothermal therapy, with a core–shell particle efficiency of ≈36.3%.