Hi, I am Ben and I am undertaking PhD in DNP enhanced NMR spectroscopy at the University of Nottingham.
Having completed my undergraduate MSci course here at Nottingham, I proceeded to hang around for a few more years. Moving slightly north to the Magnetic Resonance Centre.
Dynamic nuclear polarisation can be used to substantially enhance the nuclear spin polarisation. This technique dramatically improves the sensitivity of NMR spectroscopy experiments. The high signal intensity makes it possible to avoid long averaging.
Instead, the spectral signature of the sample can frequently be acquired in a single excitation. Information about dynamic molecular processes within the sample can be obtained by a sequential acquistion of data using small flip angle rf pulses. To improve the temporal resolution a novel strategy based on muli-channel detection will be implemented on a dedicated DNP MR spectrometer.
This will involve the testing and optimisation of a probehead with 6 rf micro-coils, the development of shimming protocols to generate high field homogeneity, the design of sample injection devices and the integration of this strategy with the existing hardware for rapid sample transfer in a dual iso-centre magnet. Experimental protocols will be developed to maximise the DNP induced signal on molecules with biological relevance and time resolved acquisition data will be acquired and analysed with novel schemes, avoiding the conventional Fourier transformation.
Current state of project
Over the course of my project, we have managed to produce a robust and reliable peice of apparatus. The dual core system has been heavily modified and refined to increase the efficiency of the dissolution process. The dissolution DNP procedure has seen SNR enhancements of around 6000 be realised. We have also seen such enhancements on fast relaxing spin species such as labelled carbons in methyl groups. Results such as this would not be possible on slower systems.
We are now looking into applications for the system including interaction between cell wall pentapeptide and anti-biotic compounds such as Vancomycin. Progress has also been made with the custom made Bruker Six channel flow probe. I have produced a robust shimming algorithm based on the traditional Simplex topological search algorithm. This has so far produced line widths on the order of 8 to 15Hz for all of the channels. While this is not impressive in comparison to hi-resolution single channel probes, it seems to be the best comprimise for a probe with such a geometry.
I have also been investigating the use of the six coil probe for the measurement of reaction kinetics. This has initially involved the use of a small mixing vessel to produce a fluid flod that is an anolog of a simple two site exchange chemical reaction. Initial tests show that six coil probe could become invaluable in testing extremely fast reactions using hyperpolarised NMR.