Hyperpolarized Porous Silicon Nanoparticles: Potential Theragnostic Material for Si-29 Magnetic Resonance Imaging

Abstract

Porous silicon nanoparticles have recently garnered attention as potentially-promising biomedical platforms for drug delivery and medical diagnostics. Here, we demonstrate porous silicon nanoparticles as contrast agents for Si-29 magnetic resonance imaging. Size-controlled porous silicon nanoparticles were synthesized by magnesiothermic reduction of silica nanoparticles and were surface activated for further functionalization. Particles were hyperpolarized via dynamic nuclear polarization to enhance their Si-29 MR signals; the particles demonstrated long Si-29 spin-lattice relaxation (T-1) times (approximate to 25mins), which suggests potential applicability for medical imaging. Furthermore, Si-29 hyperpolarization levels were sufficient to allow Si-29 MRI in phantoms. These results underscore the potential of porous silicon nanoparticles that, when combined with hyperpolarized magnetic resonance imaging, can be a powerful theragnostic deep tissue imaging platform to interrogate various biomolecular processes invivo.