Anisotropic nanoparticles from polymer self-assembly and phase separation for biomedical applications

Four types of complex polymeric nanoparticles have been developed and investigated for their use in biomedical applications such as drug delivery, pH sensing and self-propulsion. Each type of nanoparticle was synthesised using a combination of controlled radical polymerisation, polymer self-assembly, polymer phase separation and gold nanoparticle preparation and conjugation. Polymers were characterised using gel permeation chromatography (GPC) and nuclear magnetic resonance (NMR) spectroscopy and synthesis was optimised to produce monomodal, low dispersity polymers. Assembled nanoparticles were characterised using a range of advanced techniques, including dynamic light scattering (DLS) and transmission electron microscopy (TEM). Patchy micelles were prepared from the aqueous assembly of pH responsive (poly (oligo(ethylene glycol)methyl ether methacrylate)-b-(2-(diisopropyl amino)ethyl methacrylate)-b-(2-(methacryloyloxy)ethyl phosphorylcholine) (POEGMA-PDPA-PMPC) ABC block copolymers and characterised using selective phosphotungstic acid staining, which revealed phase separation in the corona of the micelles. The micelles were confirmed to be biocompatible and exhibited different drug encapsulation and release properties compared to homogenous micelles. Triblock copolymer coated spherical gold nanoparticles were prepared and found to exhibit low protein fouling, good biocompatibility and triggered doxorubicin release. Cell studies revealed they were more effective at killing cancer cells than doxorubicin controls. Triblock copolymer coated anisotropic gold nanoparticles (nanotriangles and nanohelices), were prepared successfully despite challenges relating to the instability of the structures, and the use of these nanoparticles for pH sensing was investigated. Phase separation of various homopolymers on the surface of gold nanoparticles was investigated and characterised with selectively stained TEM. Enzymes were successfully conjugated and self-diffusiophoresis behaviour of these nanoparticles was investigated