NMR spectroscopy of single sub-nL ova with inductive ultra-compact single-chip probes

Nuclear magnetic resonance (NMR) spectroscopy enables non-invasive chemical studies of intact living matter. However, the use of NMR at the volume scale typical of microorganisms is hindered by sensitivity limitations, and experiments on single intact organisms have so far been limited to entities having volumes larger than 5 nL. Here we show NMR spectroscopy experiments conducted on single intact ova of 0.1 and 0.5 nL (i.e. 10 to 50 times smaller than previously achieved), thereby reaching the relevant volume scale where life development begins for a broad variety of organisms, humans included. Performing experiments with inductive ultra-compact (1 mm²) single-chip NMR probes, consisting of a low noise transceiver and a multilayer 150 μm planar microcoil, we demonstrate that the achieved limit of detection (about 5 pmol of ¹H nuclei) is sufficient to detect endogenous compounds. Our findings suggest that single-chip probes are promising candidates to enable NMR-based study and selection of microscopic entities at biologically relevant volume scales.