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Title: Spheres on sphere silica particles : mechanism and modification
Author: Hayes, Richard
ISNI:       0000 0004 6059 3784
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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One of the current challenges in chromatography is the fast separation of large biomolecules. The demand for this is huge in pharmaceutical and biological research. To meet this challenge a new type of porous, large pore support material is required. A new, unique type of silica support, named spheres on sphere (SOS) silica, has recently been discovered which may meet these demands. SOS particles are produced via a one-pot synthesis and are comprised of a nanoparticle shell surrounding a larger core microsphere. High performance liquid chromatography (HPLC) columns packed with such particles have shown remarkably fast separation of proteins. These new particles show high potential as a revolutionary HPLC technology compared to widely used core-shell silica particles, which are prepared by a tedious layer by layer procedure and suffer with the issue of poor mass transfer for large analytes. This thesis outlines the experimental work undertaken to develop SOS particles which are specifically designed for the separation of proteins and large molecules using HPLC. The synthesis method has been optimised to achieve particles with a complete, densely packed, single-layer shell and a diameter suitable for use in HPLC. Additionally, a narrow particle size distribution is achieved, removing the need for a time-consuming and wasteful classification process. The suitability of microwave irradiation for the surface functionalisation of silica materials has been investigated. This includes the development of a bonding method for SOS particles which is shown to be highly reproducible and capable of providing comparable bonding density to conventional reflux heating methods. The use of microwave heating also results in significantly shorter reaction times and lower power consumption compared to commonly used equipment such as hot plates or heating mantles. Following surface functionalisation, the performance of HPLC columns packed with SOS particles have been assessed in both isocratic and gradient elution mode. Parameters such as column permeability, total porosity and impedance have been determined in isocratic mode, which allows direct comparison with other column packing materials. In gradient elution mode the SOS columns have been used for the analysis and separation of a wide range of peptides and proteins. Excellent performance has been obtained using the SOS material where fast gradient analysis is applied, in some cases outperforming a commercial core-shell column specifically designed for protein analysis.
Supervisor: Zhang, H. ; Myers, P. Sponsor: Engineering and Physical Sciences Research Council ; Thermo Fisher Scientific
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral