Drug delivery systems are used to transport a cargo to a specific location in the body, allowing targeted control over the biodistribution of their cargo. This is particularly useful when targeting spatially confined diseases such as tumours, where action of the therapeutic agent should be localised rather than systemic. Existing approaches respond either to endogenous or exogenous stimuli to trigger the release of therapeutic cargos, however, there are limited examples where on-off control of cargo release is possible. Artificial molecular photoswitches have emerged as a promising handle for the incorporation of light controlled, on-off switchable release of therapeutic cargos which could find applications both in vivo and in vitro. However, a key challenge is the design of materials which are compatible in aqueous environments and can utilise visible light.

The work presented in this thesis describes a method for the translation of the photoswitching properties of donor-acceptor Stenhouse adducts (DASAs) from the molecular level into bulk, photo-active hydrogels. DASAs were randomly copolymerised into the hydrophobic block of amphiphilic poly(ethylene glycol)-b-(poly(hexamethyl acrylate) which was posteriorly self-assembled into polymersomes. The compatibility of these polymersomes with free radical photopolymerisation was then investigated as a basis for the direct fabrication of stimuli-responsive hydrogels which can be fabricated by 3D printing. Finally, these hydrogels were used to demonstrate release of a model therapeutic cargo in response to irradiation with visible light.

Overall, this work presents a method for fabrication of photo-active hydrogels via 3D printing of multi-arm PEG acrylate hydrogels which encapsulate DASA-functionalised polymersomes. These polymersomes were demonstrated as a useful tool for light-controlled, on-off switchable drug release and could contribute a useful basis for the further development of systems for the modulation of bulk properties in hydrogels in response to stimulation with visible light.