In this report, we prepared a porous Si nanoparticle with a pore morphology that facilitates the proximal loading and alignment of magnetite nanoparticles. We characterized the composite materials using superconducting quantum interference device magnetometry, dynamic light scattering, transmission electron microscopy, and MRI. The in vitro
cytotoxicity of the composite materials was tested using cell viability assays on human liver cancer cells and rat
hepatocytes. An in vivo analysis using a hepatocellular carcinoma (HCC) Sprague Dawley rat model was used to determine the biodistribution properties of the material, while naïve Sprague Dawley rats were used to determine the
pharmocokinetic properties of the nanomaterials. The composite material reported here demonstrates an injectable nanomaterial that exploits the dipolar coupling of superparamagnetic nanoparticles trapped within a secondary inorganic
matrix to yield significantly enhanced MRI contrast. This preparation successfully avoids agglomeration issues that plague larger ferromagnetic systems. A Fe<sub>3</sub>O<sub>4</sub>:pSi composite formulation consisting of 25% by mass Fe<sub>3</sub>O<sub>4</sub> yields an maximal T2* value of 556 mM Fe<sup>−1</sup> s<sup>−1</sup>. No cellular (HepG2 or rat hepatocyte cells) or in vivo (rat) toxicity was
observed with the formulation, which degrades and is eliminated after 4–8 h in vivo. The ability to tailor the magnetic
properties of such materials may be useful for in vivo imaging, magnetic hyperthermia, or drug-delivery applications.