Superparamagnetic nanosystems based on iron oxide nanoparticles & mesoporous silica: synthesis & evaluation of their magnetic, relaxometric and biocompatability properties

Abstract

Mesoporous silica has attracted attention in recent years due to its high surface area, tunable ordered narrow pores and easily modifiable functional groups. In the present work, iron oxide nanoparticles (Fe₂O₃) were incorporated into the pores and surface of mesoporous SBA–15 (Santa Barbara Amorphous) via a thermal pre-synthesis method. The textural and surface properties were characterized using electron microscopy, X-ray diffraction and nitrogen adsorption–desorption analysis. Due to a reduction in thermal pressure during the synthesis, the textural property of the magnetic silica remained highly ordered. The superparamagnetic property of the synthesized material was confirmed using SQUID–VSM. Cell viability studies were carried out with MC3T3 fibroblast cell lines in the presence and absence of magnetic silica and our results showed no significant change in the cell viability between the concentration range of 31.3 μg mL⁻¹ and 250 μg mL⁻¹. The magnetic resonance properties of the iron oxide doped mesoporous silica was determined using MRI and showed excellent longitudinal (R₁) and transverse relaxivities (R₂) with an R₂/R₁ ratio close to 1, indicating the potential of this material as a magnetic contrast agent.