Сolloidal probe based on iron(III)-doped calcium phytate nanoparticles for 31P NMR monitoring of bacterial siderophores

Abstract A conceptually new class of probes was developed for detection of bacterial siderophores (BSPs), important determinants of virulence and pathogenicity, using 31P nuclear magnetic resonance (31P NMR). These probes are based on biodegradable nontoxic nanoparticles of calcium phytate (CaIP6), which possess measurable signal on 31P NMR spectra. The nanoparticles were doped with paramagnetic Fe3+ ions broadening the magnetic resonance signal of 31P. Therefore, the nanoparticles were not detectable by 31P NMR in the environment not containing BSPs, however, in the presence of BSPs, the Fe3+ ion is released from the nanoparticles, and the 31P NMR signal become detectable. In vitro demonstration of this Fe3+ release was performed with BSP deferoxamine (DFO), exhibiting a complete depletion of Fe3+ within 2 h for the nanoparticles containing 17.7 mol% Fe (III). The Fe3+ depletion was accompanied with a restoration of 31P NMR signal.