Multispectral MR imaging and sensing using shaped nanoparticles
The idea that size and shape can determine color is well known in optics-based quantum dot and plasmonic nanoparticle fields. But what about in the radio-frequency (RF) portion of the spectrum? This chapter reviews recent work on specially shaped magnetic nanostructures that shift the nuclear magnetic resonance (NMR) frequency of surrounding water, effectively using shape to control the RF "color" of an NMR signal. Operational principles behind these RF analogs to multicolor optical nanoparticles are explained, showing how particle shape can add new multispectral content to magnetic resonance imaging (MRI) and comparing these shaped nanoparticles to conventional MRI contrast agents. Magnetic structures that can dynamically vary their shape in response to local conditions are also discussed and their potential as NMR-readable RF "colorimetric" nanoprobes considered.
Design and Applications of Nanoparticles in Biomedical Imaging