Clusters of Superparamagnetic Iron Oxide Nanoparticles Encapsulated in a Hydrogel: A Particle Architecture Generating a Synergistic Enhancement of the T₂ Relaxation

Abstract

Clusters of iron oxide nanoparticles encapsulated in a pH-responsive hydrogel are synthesized and studied for their ability to alter the T 2 -relaxivity of protons. Encapsulation of the clusters with the hydrophilic coating is shown to enhance the transverse relaxation rate by up to 85% compared to clusters with no coating. With the use of pH-sensitive hydrogel, difficulties inherent in comparing particle samples are eliminated and a clear increase in relaxivity as the coating swells is demonstrated. Agreement with Monte Carlo simulations indicates that the lower diffusivity of water inside the coating and near the particle surface leads to the enhancement. This demonstration of a surface-active particle structure opens new possibilities in using similar structures for nanoparticle-based diagnostics using magnetic resonance imaging.

Incorporation of Conductive Materials into Hydrogels for Tissue Engineering Applications

“…By functionalizing nanoparticle surfaces, the interaction between a polymer and nanoparticles can be strengthened [11][12][13]. Various types of metal nanoparticles have been used in the production of nanocomposite hydrogels in the field of biomaterials including gold [14], silver [15] and other noble metal nanoparticles, while metal oxide nanoparticles such as iron oxide [16] and zirconia [17] have also been used. Since metal and metal oxide nanoparticles possess the desired electrical conductivity, magnetic properties, and antibacterial properties, nanocomposite hydrogels that contain metal or metal oxide nanoparticles are widely used in conductive scaffolds, electronic switches, actuators, and sensors [18][19][20][21].…”

Microstructure Effects on the Water Oxidation Activity of Co3O4/Porous Silica Nanocomposites

“…70 A polymer-coated Fe 2 O 3 composite shows enhanced T 2 shortening near the particle surface. 71 Naturally, this shortening of the T 2 suggests that the magnetic Co 3 O 4 core has a much larger influence on helping relax those protons that can get closer to the magnetic surface. It follows that thicker silica shells should increasingly separate and minimize the magnetic screening of protons by the magnetic Co 3 O 4 core.…”

Catechol-derivatized poly(vinyl alcohol) as a coating molecule for magnetic nanoclusters

“…It is known that iron oxide clusters present peculiar magnetic properties [16,18] For example, the net magnetization is higher for SPION clusters than for individual SPIONs [4,18,19], which offers enormous potential in therapeutics [4], magnetic resonance imaging (MRI [16,19,20] and hyperthermia [9,21]. However, obtaining these constructs necessitates a bottom-up approach and control of the synthetic pathways and materials at a basic level, making the chemical aspects critical to creating future nanomaterials for application-oriented purposes.…”