Multimodal 19F NMR Dopamine Detection and Imaging with a Nanoparticle‐Based Displacement Assay

Nanoconjugates composed of gold nanoparticles (core diameter=1.9 nm) coated with thioundecyl‐d‐glucopyranosides and fluorinated phenylboronic acids can detect diol‐containing derivatives by means of 19F NMR spectroscopic analysis. The spectra of nanoconjugate solutions display broad signals due to the fast relaxation of the 19F nuclei caused by nanoparticle grafting. When dopamine is added, the formation of a boronate ester between the analyte and the fluorinated boronic acid causes the release of the latter in solution and consequent sharpening of the NMR signals. Dopamine can be selectively detected through magnetic resonance imaging (MRI) and NMR spectroscopic analysis with respect to glucose and galactose with a detection limit of 20 μm. The chemical shift of the released ester is diagnostic of the recognized analyte. Consequently, the sensor also enables the simultaneous detection of different analytes.