Nano-probe™ technology applications

One other application where Nano-probe technology excels relative to conventional tube or flow NMR probe formats is in the area of heterogeneous samples. One of the early applications demonstrated for the Nano-probe was the acquisition of NMR spectral data for chemically modified polymer beads used in solid-phase-assisted peptide synthesis and related chemical transformations.21 23 When chemically modified beads are interrogated in a conventional NMR sample tube, the resin bead behaves as an insoluble material and at best very broad and poorly resolved spectra may be recorded. In contrast, when the same beads are placed in a Nano-probe and spun at several kHz at the magic angle, there is sufficient solvation of the pendant chemical moiety and the linker to resin bead nucleus to allow the modified portion to behave as if it is in pseudo solution, which allows reasonable NMR spectra to be recorded. Various factors affect the quality of the NMR data that can be obtained for the pendant molecule, which include the tether length and the solvent used for the measurement.23 There have been a diverse assortment of applications of Nano-probe applications reported in the literature that are discussed in further detail in Section 6.3. 

The only natural product application of Nano-probe technology of which the author is aware in 1998 was the report of the isolation and unambiguous synthesis of cryptolepinone (33) by Bierer and co-workers.201... 

Only two reported applications of Nano-probe technology appeared in 2002. The first was a report detailing the solution of the 3D structure of small scorpion toxins present in nano-molar amounts in venom by Delepierre.216 The other report by Wang et a I.2 1 reviewed the application combined application of LC-NMR and Nano-probe technologies for the analysis of mixtures of natural products. 

Several applications of 3 mm micro-NMR probe technology were reported in 1994. The first utilized both a 3 mm micro-inverse probe as well as a heteronuclear Nano-probe to acquire the NMR data necessary for the characterization of a 30 pg (0.07 pmol) metabolite sample.59 Following the acquisition of a 13C reference spectrum using a heteronuclear Nano-probe the 40 pL sample from the nano-cell was quantitatively transferred to a 3 mm NMR tube and diluted to a total sample... 

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