Facile synthesis of Au@Mn3O4 magneto-plasmonic nanoflowers for T1-weighted magnetic resonance imaging and photothermal therapy of cancer

Abstract

The integration of advanced diagnostic contrast agents with versatile therapeutic drugs is an effective method for cancer treatment. However, combining various biocompatible theranostic modalities into a single platform at the nanoscale is a challenging assignment. In this work, we report a simple chemical synthetic route for producing a homogeneous hybrid nanoflower shaped morphology based on Au@Mn₃O₄ magneto-plasmonic nanomaterials. The synthetic mechanism of the nanoflowers is well-matched with the heteroepitaxial growth phenomena by which the nano-petals of Mn₃O₄ generated on the surface of the Au core. The food and drug administration (FDA) in the USA approved the use of triblock polymer Pluronic F-127 to enhance the biocompatibility of Au@Mn₃O₄ hybrid nanoflowers. The prepared hybrid nanoflowers produce a significant photothermal heating effect with a thermal transduction efficiency of 38%, comparable to the nanorods and nanoparticles of gold (Au). The hybrid junction reveals promising optical and magnetic properties and the prepared Au@Mn₃O₄ nanoflowers not only exhibit strong near-infrared (NIR) absorption to produce excellent photothermal efficacy under irradiation with an 808 nm NIR laser, but also demonstrate a significant T₁-weighted magnetic resonance (MR) image enhancement in vitro and in vivo. The histopathology assessments indicate only negligible toxicity of the nanoflowers to major organs. Therefore, the hybrid Au@Mn₃O₄ nanoflowers exhibit great potential in T₁-weighted MR-imaging and photothermal therapy, opening up new possibilities for synthesizing novel bio-compatible, homogeneous, and shape controllable nanostructures with multifunctional applications.