Abstract
Aqueous formulations are essential components of personal care products such as shampoos, creams and gels for pharmaceutical products and paints and drilling lubricants. The majority of these products mainly contain polymeric thickeners or additives such as surfactants to modify their rheology. These materials are however derived from non-renewable resources. TEMPO-oxidised cellulose nanofibrils (TOCN) could provide a desired alternative for such thickeners. TOCN is a nontoxic, renewable and non-irritating material which gels aqueous and alcohol based formulations and forms films on surfaces, such as skin. This also offers opportunities in delivery of active pharmaceutical compounds via the skin. The previous studies suggested that even at low concentrations of additives (surfactants and salts) TOCN could form shear thinning gels. However, this mechanism is not fully understood. It is thought that it is mainly due to the charge shielding effect and depletion flocculation mechanism. The aim of this work was to further our understanding on this mechanism.TOCN gels in the presence of low molecular weight alcohols (methanol, ethanol and propan-1-ol) and TOCN films were developed in an attempt to understand the interaction between these additives and TOCN in a formulation and once applied to the skin. The work included many advanced techniques including small angle X-ray and neutron scattering and reflectivity. The transdermal delivery of ibuprofen across the skin/membrane from TOCN gels as well as the commercial gels was investigated for the final part of this study. This work involved determining the amount of drug penetrated across the skin/membrane using Franz diffusion cells and tape-stripping method.
Overall, the thesis has provided an insight on the changes of the fibril aggregation in different alcohol systems and the interaction of TOCN with the surfactants and salts. Due to its ability to thicken formulations, TOCN may be of use in many applications including personal care products and alcohol sanitisers. This role could also be extended for use in pharmaceutical gel formulations for transdermal drug delivery.
| Date of Award | 22 Jun 2015 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Karen Edler (Supervisor), Janet Scott (Supervisor), Richard Guy (Supervisor) & Gianfranco Unali (Supervisor) |