Design and optimization of high-sensitivity probes for improved limits of detection in protein nuclear magnetic resonance spectroscopy

Nuclear magnetic resonance (NMR) spectroscopy is a powerful tool widely used in structural analysis of biological macromolecules at atomic resolution. Inherently, this advanced experimental technique has a poor limit of detection (LOD). Even though great technological progress has been made during recent years, this fundamental issue still limits its further application in many areas, especially in protein NMR, where there exist serious limitations on the sample mass, concentration, and NMR throughput.; The signal-to-noise ratio (SNR) is a central concept in the improvement of NMR LODs. The LOD, in terms of sample volume, relates to the NMR sensitivity and the instrumentation design parameters through the spectral SNR. This indicates the significance of probe design optimization in LOD improvement. Sensitivity analysis of the probe design gives the theoretical fundamentals to optimize radiofrequency (RF) design in terms of the lowest LOD in protein NMR.; Two high-sensitivity, solenoid, multiple-resonance probes were developed in this thesis work. The RF design was optimized according to theoretical sensitivity analysis and experimental results. It was found that the coil configuration plays the most important role in the LOD improvement. HSQC experiments on lab-fabricated protein samples, IA-3 and Ubiquitin, were used to test the probe performance. A spectral comparison was made with a commercial 5-mm triple resonance probe. An improved LOD was shown from the spectral results.; The application of wavelet analysis in the NMR spectroscopy was also investigated in this study. A basic wavelet denoising method was employed to process two-dimensional NMR data. It was shown that the LOD could be further improved if such a postprocessing method was used with the probe design improvement.