Novel molecular architectures for “multicolor” magnetic resonance imaging

Luminescent materials with their rich color palettes have revolutionized the field of bioimaging through the ability to distinguish between spectrally resolved colors and, thus, to map the complexity of biological systems. Yet, advanced solutions to overcome the restricted tissue penetration of light are still needed to allow in vivo mapping of tissue multiplexity in both health and disease. Among the diverse capabilities and many advantages of MRI, the ability to encode specific frequencies of imaging agents and, by that, to allow pseudo-color display of MRI maps, is unique. Here, I summarize our recently developed molecular probes that are capable of generating artificial MR-based colors. To this end, the use of nanofabrication, supramolecular chemistry, and protein engineering approaches to generate novel molecular formulations (inorganic nanocrystals, supramolecular assemblies, and enzyme/substrate pairs) as MRI sensors with unique multicolor display characteristics is reviewed.