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Silica nanoparticles are commonly integrated within polymeric matrices to form composite materials, due to their non-toxic nature, chemical resistance and physical properties. Polymer-silica colloidal nanocomposites are the most studied class of hybrid nanoparticles and their applications can be tailored based on synthetic approaches. The aims of this work were to prepare polymer-silica colloidal nanocomposites via a combination of reversible deactivation radical polymerization, self-assembly and sol-gel chemistry. This approach enabled the preparation of hybrid nanoparticles with controllable shape and size. The influences of compositional design (e.g. block copolymer architecture), solvent and initiating systems were also studied. Firstly, polymer nanoparticles were prepared by Polymerization-Induced Self-Assembly (PISA) in ethanol where the solvophilic block was an alkoxysilane-functional methacrylate. Spherical nanoparticles and polymeric vesicles were successfully prepared. A solid silica shell was successfully grown from the particle surface via subsequent hydrolysis and condensation of tetraethyl orthosilicate. Secondly, block copolymer self-assembly was studied where the alkoxysilane functionality was present in the core-forming block. This approach was not viable by aqueous PISA emulsion polymerization. A solvent-mediated self-assembly approach was thus adopted, yielding spherical nanoparticles in water, and a mixture of spheres and vesicles in n-hexane. Finally, the reactivity of alkoxysilane-functional methacrylates was exploited to prepare triblock copolymers as surfactants where the interfacial block could be crosslinked via hydrolysis and condensation. Triblock copolymers were either formed separately (and used to stabilize oil-in-water miniemulsions) or in-situ via the PISA method. The encapsulation of Nile Red in the particle core was achieved in parallel with self-assembly and the retention rate was improved through interfacial crosslinking.

Antigen-specific multifunctional T cells that secrete interferon-γ, interleukin-2 and tumour necrosis factor-α simultaneously after activation are important for the control of many infections. It is unclear if these CD8(+) T cells are at an early or late stage of differentiation and whether telomere erosion restricts their replicative capacity. We developed a multi-parameter flow cytometric method for investigating the relationship between differentiation (CD45RA and CD27 surface phenotype), function (cytokine production) and replicative capacity (telomere length) in individual cytomegalovirus (CMV) antigen-specific CD8(+) T cells. This involves surface and intracellular cell staining coupled to fluorescence in situ hybridization to detect telomeres (flow-FISH). The end-stage/senescent CD8(+) CD45RA(+) CD27(-) T-cell subset increases significantly during ageing and this is exaggerated in CMV immune-responsive subjects. However, these end-stage cells do not have the shortest telomeres, implicating additional non-telomere-related mechanisms in inducing their senescence. The telomere lengths in total and CMV (NLV)-specific CD8(+) T cells in all four subsets defined by CD45RA and CD27 expression were significantly shorter in old compared with young individuals in both a Caucasian and an Asian cohort. Following stimulation by anti-CD3 or NLV peptide, similar proportions of triple-cytokine-producing cells are found in CD8(+) T cells at all stages of differentiation in both age groups. Furthermore, these multi-functional cells had intermediate telomere lengths compared with cells producing only one or two cytokines after activation. Therefore, global and CMV (NLV)-specific CD8(+) T cells that secrete interferon-γ, interleukin-2 and tumour necrosis factor-α are at an intermediate stage of differentiation and are not restricted by excessive telomere erosion.