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Title: Assessing the relationship between nanoparticle physicochemical characteristics and biological interactions : optimisation of in vitro techniques and protocols
Author: David, Christopher A. W.
ISNI:       0000 0004 6422 5081
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2016
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The development and implementation of nanomaterials for a variety of clinical applications is increasing as their utility in improving healthcare is demonstrated. However, consideration must be given to appropriate pre-clinical testing to fully translate these materials into clinical use. A library of 22 nanomaterials, both commercially available and those developed in-house, were subject to an assay cascade forming the basis of a preclinical in vitro assessment which utilised a broad and widely accessible range of techniques. The library comprised numerous material classes; metallic (gold, silver, iron oxide, titanium dioxide, zinc oxide), non-metal (silica), and polymeric (polystyrene, liposome, emulsion, polydendron), varying in manufacturer stated particle size, charge, and functionalization. Chapter 2 details characterisation of the size and zeta potential of the nanomaterial library in biologically relevant matrices. When combined with information provided by the manufacturers regarding stabilisation and surface functionalization, where available, these measures allowed associations to be made between nanoparticle physicochemical characteristics and the biological effects observed in subsequent chapters. Inherent optical properties of the nanomaterials in biologically relevant matrices and sample sterility were assessed in order to gain indication of any potential incompatibility with subsequent assays. The haemocompatibility of nanomaterials is of primary concern in their application as nanomedicines, especially those administered intravenously. The work presented in Chapter 3 assessed the haemolytic potential of a subset of nanomaterials. All nanomaterial treatments were found to result in a lower level of complement activation compared to untreated cells, and cases of prolongation or reduction in plasma coagulation times via the extrinsic, intrinsic, and common pathways were observed. In Chapter 4 the impact of nanomaterials on pro-inflammatory and antiin ammatory cytokine secretion by primary immune cells demonstrated. Endotoxin was shown to exacerbate the inflammatory responses toward tested nanoparticles. Further to this; the inhibitory effects of polystyrene nanoparticles to caspase-1 activity described in the literature was confirmed. Proliferation in primary human leukocytes was shown to be significantly affected by certain nanomaterials where particular variants of silver and silica nanoparticles had antiproliferative and proliferation effects, respectively. The work presented in Chapter 5 describes the development and utilisation of screening methodologies to investigate the influence of nanomaterials on reactive oxygen species generation, reduced glutathione and autophagy. Trends have been observed within assays e.g. the reduction in levels of autophagy appears to be linked with surface charge of the nanomaterials with the most negative having the greatest effect. Chapter 6 details the application of methods optimised throughout the thesis to perform a preclinical assessment on a novel class of polymeric nanomaterial termed polydendrons. It was found that variants composed of a higher ratio of novel G2' initiator demonstrated less immunogenic potential than those with an equal ratio to PEG. Given the heterogeneity of engineered nanomaterials in terms of composition, coatings, particle characteristics and functionalization, the identification of particle characteristics that influence biological interactions will enable the rational design of future nanomaterials. The work presented in this thesis has found associations between nanoparticle characteristics and biological effects. These included concentration-dependent correlations between zeta potential and reactive oxygen species generation, and nanoparticle size and autophagic impact. Additionally, the need for thorough physicochemical characterisation, to generate as many parameters as possible for determining structure-activity relationships, has been presented. The methodologies used, and developed, throughout this thesis will aid future preclinical characterisation of novel nanomaterials.
Supervisor: Liptrott, N. ; Owen, A. ; Rannard, S. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral