Neil H. Thomson

Bio: Neil H. Thomson is an academic researcher from University of Leeds. The author has contributed to research in topics: RNA polymerase & DNA. The author has an hindex of 38, co-authored 79 publications receiving 6143 citations. Previous affiliations of Neil H. Thomson include École Polytechnique Fédérale de Lausanne & St James's University Hospital.

Mechanical properties of carbon nanotubes

Abstract: A variety of outstanding experimental results on the elucidation of the elastic properties of carbon nanotubes are fast appearing. These are based mainly on the techniques of high-resolution transmission electron microscopy (HRTEM) and atomic force microscopy (AFM) to determine the Young’s moduli of single-wall nanotube bundles and multi-walled nanotubes, prepared by a number of methods. These results are confirming the theoretical predictions that carbon nanotubes have high strength plus extraordinary flexibility and resilience. As well as summarising the most notable achievements of theory and experiment in the last few years, this paper explains the properties of nanotubes in the wider context of materials science and highlights the contribution of our research group in this rapidly expanding field. A deeper understanding of the relationship between the structural order of the nanotubes and their mechanical properties will be necessary for the development of carbon-nanotube-based composites. Our research to date illustrates a qualitative relationship between the Young’s modulus of a nanotube and the amount of disorder in the atomic structure of the walls. Other exciting results indicate that composites will benefit from the exceptional mechanical properties of carbon nanotubes, but that the major outstanding problem of load transfer efficiency must be overcome before suitable engineering materials can be produced.

Short cantilevers for atomic force microscopy

Abstract: We have designed and tested a family of silicon nitride cantilevers ranging in length from 23 to 203 μm. For each, we measured the frequency spectrum of thermal motion in air and water. Spring constants derived from thermal motion data agreed fairly well with the added mass method; these and the resonant frequencies showed the expected increase with decreasing cantilever length. The effective cantilever density (calculated from the resonant frequencies) was 5.0 g/cm3, substantially affected by the mass of the reflective gold coating. In water, resonant frequencies were 2 to 5 times lower and damping was 9 to 24 times higher than in air. Thermal motion at the resonant frequency, a measure of noise in tapping mode atomic force microscopy, decreased about two orders of magnitude from the longest to the shortest cantilever. The advantages of the high resonant frequency and low noise of a short (30 μm) cantilever were demonstrated in tapping mode imaging of a protein sample in buffer. Low‐noise images were tak...

Escherichia coli RNA Polymerase Activity Observed Using Atomic Force Microscopy

Abstract: Fluid tapping-mode atomic force microscopy (AFM) was used to observe Escherichia coli RNA polymerase (RNAP) transcribing two different linear double-stranded (ds) DNA templates The transcription process was detected by observing the translocation of the DNA template by RNAP on addition of ribonucleoside 5‘-triphosphates (NTPs) in sequential AFM images Stalled ternary complexes of RNAP, dsDNA and nascent RNA were adsorbed onto a mica surface and imaged under continuously flowing buffer On introduction of all four NTPs, we observed some DNA molecules being pulled through the RNAP, some dissociating from the RNAP and others which did not move relative to the RNAP The transcription rates were observed to be approximately 05−2 bases/s at our NTP concentrations, approximately 5 μM The RNA transcripts were not unambiguously imaged in fluid However, in experiments using a small single-stranded (ss) circular DNA template, known as a rolling circle, transcripts up to 1 or 2 microns long could be observed wit

Protein Misfolding, Functional Amyloid, and Human Disease

Abstract: Peptides or proteins convert under some conditions from their soluble forms into highly ordered fibrillar aggregates. Such transitions can give rise to pathological conditions ranging from neurodegenerative disorders to systemic amyloidoses. In this review, we identify the diseases known to be associated with formation of fibrillar aggregates and the specific peptides and proteins involved in each case. We describe, in addition, that living organisms can take advantage of the inherent ability of proteins to form such structures to generate novel and diverse biological functions. We review recent advances toward the elucidation of the structures of amyloid fibrils and the mechanisms of their formation at a molecular level. Finally, we discuss the relative importance of the common main-chain and side-chain interactions in determining the propensities of proteins to aggregate and describe some of the evidence that the oligomeric fibril precursors are the primary origins of pathological behavior.

Nanoparticles, Proteins, and Nucleic Acids: Biotechnology Meets Materials Science

Abstract: Based on fundamental chemistry, biotechnology and materials science have developed over the past three decades into today's powerful disciplines which allow the engineering of advanced technical devices and the industrial production of active substances for pharmaceutical and biomedical applications. This review is focused on current approaches emerging at the intersection of materials research, nanosciences, and molecular biotechnology. This novel and highly interdisciplinary field of chemistry is closely associated with both the physical and chemical properties of organic and inorganic nanoparticles, as well as to the various aspects of molecular cloning, recombinant DNA and protein technology, and immunology. Evolutionary optimized biomolecules such as nucleic acids, proteins, and supramolecular complexes of these components, are utilized in the production of nanostructured and mesoscopic architectures from organic and inorganic materials. The highly developed instruments and techniques of today's materials research are used for basic and applied studies of fundamental biological processes.