Publications
9 results found
Leese HS, Govada L, Saridakis E, et al., 2016, Reductively PEGylated carbon nanomaterials andtheir use to nucleate 3D protein crystals:a comparison of dimensionality, Chemical Science, Vol: 7, Pages: 2916-2923, ISSN: 2041-6539
A range of carbon nanomaterials, with varying dimensionality, were dispersed by a non-damaging and versatile chemical reduction route, and subsequently grafted by reaction with methoxy polyethylene glycol (mPEG) monobromides. The use of carbon nanomaterials with different geometries provides both a systematic comparison of surface modification chemistry and the opportunity to study factors affecting specific applications. Multi-walled carbon nanotubes, single-walled carbon nanotubes, graphite nanoplatelets, exfoliated few layer graphite and carbon black were functionalized with mPEG-Br, yielding grafting ratios relative to the nanocarbon framework between ca. 7 and 135 wt%; the products were characterised by Raman spectroscopy, TGA-MS, and electron microscopy. The functionalized materials were tested as nucleants by subjecting them to rigorous protein crystallization studies. Sparsely functionalized flat sheet geometries proved exceptionally effective at inducing crystallization of six proteins. This new class of nucleant, based on PEG grafted graphene-related materials, can be widely applied to promote the growth of 3D crystals suitable for X-ray crystallography. The association of the protein ferritin with functionalized exfoliated few layer graphite was directly visualized by transmission electron microscopy, illustrating the formation of ordered clusters of protein molecules critical to successful nucleation.
Mattia D, Leese H, Calabrò F, 2016, Electro-osmotic flow enhancement in carbon nanotube membranes, Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 374, Pages: 20150268-20150268, ISSN: 1364-503X
<jats:p> In this work, experimental evidence of the presence of electro-osmotic flow (EOF) in carbon nanotube membranes with diameters close to or in the region of electrical double layer overlap is presented for two different electrolytes for the first time. No EOF in this region should be present according to the simplified theoretical framework commonly used for EOF in micrometre-sized channels. The simplifying assumptions concern primarily the electrolyte charge density structure, based on the Poisson–Boltzmann (P-B) equation. Here, a numerical analysis of the solutions for the simplified case and for the nonlinear and the linearized P-B equations is compared with experimental data. Results show that the simplified solution produces a significant deviation from experimental data, whereas the linearized solution of the P-B equation can be adopted with little error compared with the full P-B case. This work opens the way to using electro-osmotic pumping in a wide range of applications, from membrane-based ultrafiltration and nanofiltration (as a more efficient alternative to mechanical pumping at the nanoscale) to further miniaturization of lab-on-a-chip devices at the nanoscale for <jats:italic>in vivo</jats:italic> implantation. </jats:p>
Chayen N, shaffer, govada, et al., 2016, Exploring Carbon Nanomaterial Diversity for Nucleation of Protein Crystals, Scientific Reports, Vol: 6, ISSN: 2045-2322
Controlling crystal nucleation is a crucial step in obtaining high quality protein crystals for structure determination by X-ray crystallography. Carbon nanomaterials (CNMs) including carbon nanotubes, graphene oxide, and carbon black provide a range of surface topographies, porosities and length scales; functionalisation with two different approaches, gas phase radical grafting and liquid phase reductive grafting, provide routes to a range of oligomer functionalised products. These grafted materials, combined with a range of controls, were used in a large-scale assessment of the effectiveness for protein crystal nucleation of 20 different carbon nanomaterials on five proteins. This study has allowed a direct comparison of the key characteristics of carbon-based nucleants: appropriate surface chemistry, porosity and/or roughness are required. The most effective solid system tested in this study, carbon black nanoparticles functionalised with poly(ethylene glycol) methyl ether of mean molecular weight 5000, provides a novel highly effective nucleant, that was able to induce crystal nucleation of four out of the five proteins tested at metastable conditions.
Mattia D, Leese H, Lee KP, 2015, Carbon nanotube membranes: From flow enhancement to permeability, Journal of Membrane Science, Vol: 475, Pages: 266-272, ISSN: 0376-7388
Mattia D, Leese H, 2014, Controlled hydrothermal pore reduction in anodic alumina membranes, Nanoscale, Vol: 6, Pages: 13952-13957, ISSN: 2040-3364
Leese H, Mattia D, 2014, Electroosmotic flow in nanoporous membranes in the region of electric double layer overlap, Microfluidics and Nanofluidics, Vol: 16, Pages: 711-719, ISSN: 1613-4982
Wu C, Leese HS, Mattia D, et al., 2013, Study of Fluid and Transport Properties of Porous Anodic Aluminum Membranes by Dynamic Atomic Force Microscopy, LANGMUIR, Vol: 29, Pages: 8969-8977, ISSN: 0743-7463
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Leese H, Bhurtun V, Lee KP, et al., 2013, Wetting behaviour of hydrophilic and hydrophobic nanostructured porous anodic alumina, Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol: 420, Pages: 53-58, ISSN: 0927-7757
Lee KP, Leese H, Mattia D, 2012, Water flow enhancement in hydrophilic nanochannels, Nanoscale, Vol: 4, Pages: 2621-2621, ISSN: 2040-3364
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