Aqueous synthesis of polyhedral “brick-like” iron oxide nanoparticles for hyperthermia and T₂MRI contrast enhancement

Abstract

A low temperature, aqueous synthesis of polyhedral iron oxide nanoparticles (IONPs) is presented. The modification of the co-precipitation hydrolysis method with Triton X surfactants results in the formation of crystalline polyhedral particles. The particles are herein termed iron oxide “nanobricks” (IONBs) as the variety of particles made are all variations on a simple “brick-like” rhombohedral shape as evaluated by TEM. These IONBs can be easily coated with hydrophilic silane ligands, allowing them to be dispersed in aqueous media. The dispersed particles are investigated for potential applications as hyperthermia and T2 MRI contrast agents. The results demonstrate that the IONBs perform better than comparable spherical IONPs in both applications, and show r2 values amongst the highest for iron oxide based materials reported in the literature.

Synthesis, characterization, and evaluation of PEGylated first-row transition metal ferrite nanoparticles as T2contrast agents for high-field MRI

“…9), we believe further improvements are possible by, e.g., templating directional growth to form morphological variations like octapods, 23 bricks, 24 or whiskers; 25 or subjecting them to controlled aggregation and/or self-assembly, which are known to lead to higher contrasting abilities.…”

Metal‐Based Nanoparticle Magnetic Resonance Imaging Contrast Agents: Classifications, Issues, and Countermeasures toward their Clinical Translation

“…Studies have disclosed that non‐spherical nanocrystals have higher relaxivities than spherical ones in the presence of external magnetic fields, attributable to their notable effective radii. [ 22a,138 ] On this premise, interesting morphologies such as tripod SPIOs, [ 139 ] iron oxide nanobricks (IONBs), [ 140 ] and the like for tumor imaging [ 141 ] have been reported.…”

Synthesis of Distinct Iron Oxide Nanomaterial Shapes Using Lyotropic Liquid Crystal Solvents

“… Transmission electron microscopy (TEM) images of previously synthesized IO nanostructures: ( A ) polyhedral nanobricks prepared by co-precipitation of Fe(III)- and Fe(II)-precursors (2:1 ratio) in the LLC phases (lamellar and hexagonal columnar) of Triton X-100 or Triton X-45 in H 2 O [ 46 ]. Using TEM tomography the height of the nanobricks was determined to be ~5 nm.…”

“…Reproduced from Ref. [ 46 ] with permission from The Royal Society of Chemistry; ( B ) Large nanosheets (lateral dimensions up to several micron) prepared in the Col h LLC phase formed by Triton X-100 in water using the reduction/hydrolysis method feature heights of 5 or 10 nm (inset shows higher resolution) [ 47 ]. Reproduced from Ref.…”

“…Spherical (diameter: 10 nm) and brick-shaped IO NPs (polyhedral bricks with 10 nm × 15 nm × 5 nm; w × d × h ) were synthesized with identical negatively charged surface EDTS coating (EDTS = N -(trimethoxysilylpropyl) ethylenediaminetriacetate trisodium salt; with a ζ-potential around −40 mV). These nanobricks were synthesized using Triton X surfactants in the hexagonal columnar or lamellar lyotropic liquid crystal (LLC) phase ( Figure 1 A) [ 46 ]. The nanobricks showed a significantly greater uptake profile in endothelial cells compared to the IO nanospheres.…”