The fabrication of biodegradable nanospheres from novel hydroxalkanoates for the delivery of actives of pharmaceutical and agricultural interest

This work describes the fabrication of nanospheres from a range of novel polyhydroxyalkanoates supplied by Monsanto, St Louis, Missouri, USA for the delivery of selected actives of both pharmaceutical and agricultural interest. Initial evaluation of established microsphere and nanosphere fabrication techniques resulted in the adoption and optimisation of a double sonication solvent evaporation method involving the synperonic surfactant F68. Nanospheres could be consistently generated with this method. Studies on the incorporation and release of the surrogate protein Bovine Serum Albumin V demonstrated that BSA could be loaded with between 10-40% w/w BSA without nanosphere destabilisation. BSA release from nanospheres into Hanks Balanced Salts Solution, pH 7.4, could be monitored for up to 28 days at 37°C. The incorporation and release of the Monsanto actives - the insecticide Admire® ({ 1-[(6-chloro-3-pyridinyl)methyIJ-N-nitro-2-imidazolidinimine}) and the plant growth hormone potassium salt Gibberellic acid (GA3K) from physico-chemically characterised polymer nanospheres was monitored for up to 37 days and 28 days respectively, at both 4°C and 23°C. Release data was subsequently fitted to established kinetic models to elaborate the possible mechanisms of release of actives from the nanospheres. The exposure of unloaded nanospheres to a range of physiological media and rural rainwater has been used to investigate the role polymer biodegradation by enzymatic and chemical means might play in the in vivo release of actives and agricultural applications. The potential environmental biodegradation of Monsanto polymers has been investigated using a composting study (International Standard ISO/FDIS 14855) in which the ultimate aerobic biodegradation of the polymers has been monitored by the analysis of evolved carbon dioxide. These studies demonstrated the potential of the polymers for use in the environment, for example as a pesticide delivery system.

Insect pest control research : the analysis of historical trends with special reference to scientometric analysis

The thesis investigates the value of quantitative analyses for historical studies of science through an examination of research trends in insect pest control, or economic entomology. Reviews are made of quantitative studies of science, and historical studies of pest control. The methodological strengths and weaknesses of bibliometric techniques are examined in a special chapter; techniques examined include productivity studies such as paper counts, and relational techniques such as co-citation and co-word analysis. Insect pest control is described. This includes a discussion of the socio-economic basis of the concept of `pest'; a series of classifications of pest control techniques are provided and analysed with respect to their utility for scientometric studies. The chemical and biological approaches to control are discussed as scientific and technological paradigms. Three case studies of research trends in economic entomology are provided. First a scientometric analysis of samples of chemical control and biological control papers; providing quantitative data on institutional, financial, national, and journal structures associated with pest control research fields. Second, a content analysis of a core journal, the Journal of Economic Entomology, over a period of 1910-1985; this identifies the main research innovations and trends, in particular the changing balance between chemical and biological control. Third, an analysis of historical research trends in insecticide research; this shows the rise, maturity and decline of research of many groups of compounds. These are supplemented by a collection of seven papers on scientometric studies of pest control and quantitative techniques for analysing science.