Enhanced Magneto-Optical Properties of Au–Fe₃O₄ Heterodimer Nanoparticles Synthesized With Triiron Dodecacarbonyl

This study presents a pioneering and efficient method for synthesizing Au–Fe3O4 heterodimer nanoparticles (NPs) with enhanced magneto-optical properties via a thermal decomposition route. By utilizing triiron dodecacarbonyl (Fe3(CO)12) as a safer alternative to the commonly used toxic iron pentacarbonyl (Fe(CO)5), a near 100% production yield was achieved through optimization of the molar ratio of Au seeds to Fe3(CO)12 (0.6:2.0 m mol) and reflux time (60 min). The resulting heterodimer NPs exhibited a medium diameter of $d_{0} = 6.89$ nm for the Au component and $d_{0} = 14.51$ nm for the Fe3O4 component, with the Au seeds having a diameter of $d_{0} = 4.22$ nm. These NPs displayed remarkable magneto-optical properties, including high magnetization (Ms = 72.6 emu/g-Fe3O4 at 300K) and a distinct plasmon resonance band at 553 nm. This band experienced a 42 nm red shift compared to pure Au NPs, attributed to electron transfer at the interface between Au and Fe3O4. The lattice match between the materials suggests epitaxial growth of Fe3O4 onto the Au surface, enhancing the stability of heterodimer NPs. The use of triiron dodecacarbonyl as a precursor in the synthesis of these high-quality Au–Fe3O4 NPs highlights their significant potential for magnetic-plasmonic bio-applications.

I. Introduction

Cancer represents a pervasive global health challenge, necessitating continual advancements in therapeutic modalities [1]. In response, theranostic applications have emerged as a promising approach, seamlessly integrating diagnostic and therapeutic components to provide comprehensive cancer management [2], [3], [4]. Of particular interest are multicompartment nanoparticles (NPs), incorporating magnetic and plasmonic constituents such as gold and iron oxide [5], [6], [7], [8]. Iron oxide facilitates magnetic resonance imaging, while gold enables X-ray attenuation and optical imaging, thereby affording versatile bioimaging and targeted drug delivery strategies. Moreover, these NPs hold the potential for combined magnetic hyperthermia and photothermal therapy, presenting a multifaceted approach to cancer treatment [9], [10]. Within the landscape of NP architectures, heterodimer, and core-shell structures have garnered considerable attention due to their promising applications.