Chemical and Biomolecular Engineering - Theses

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    Poly(methacrylic acid) hydrogel capsules as a platform for biomedical applications
    SHIMONI, OLGA ( 2012)
    The design and assembly of biocompatible nanoengineered carriers is of interest due to their potential applications in biotechnology as tools for catalysis and sensing, in biomedicine as systems for drug delivery, in diagnostics, and in vivo imaging. The layer-by-layer (LbL) technology is a prominent technique to design carrier systems for biomedical applications. In recent years, poly(methacrylic acid) hydrogel capsules (PMA HCs), based on disulfide-stabilized poly(methacrylic acid), have been fabricated from the LbL technique, and thoroughly studied to gain control over their stability, degradability and cargo release. These capsules are obtained by the sequential deposition of thiolated poly(methacrylic acid) (PMASH) and poly(N-vinylpyrrolidone) (PVPON) onto silica particles via hydrogen bonding. Upon controlled crosslinking and removal of the silica template, PVPON is released at physiological conditions due to the disrupted hydrogen bonding between PMASH and PVPON, which results in single-component PMA hydrogel capsules. This work provides an insight into designing a novel architecture and biofunctionalization of PMA HCs for enhanced and targeted drug delivery. Specifically, this research describes novel hydrogel capsule architectures, namely subcompartmentalized hydrogel capsules (SHCs), which are designed for potential applications in drug delivery and microencapsulated biocatalysis. Examples of SHCs with tens of subcompartments are demonstrated with their successful drug/cargo loading, as well as selective degradation of the SHC carrier and/or sub-units in response to multiple chemical stimuli. To develop a facile surface functionalization approach of the PMA hydrogel capsules, retention of PVPON was employed through modification of the polymer to obtain a bifunctional polymeric linker. The antibody-functionalized PMA/PVPON HCs demonstrate significantly enhanced cellular binding and internalization to specific cells, suggesting these capsules can specifically interact with cells through antibody/antigen recognition. To understand the impact of aspect ratio on cellular function, PMA HCs were prepared with various aspect ratios. Careful control over aspect ratio of the silica rods provided the ability to control the aspect ratio of the PMA HCs. Upon incubation of these capsules with living cells, varied behavior was observed, suggesting different mechanisms for their interactions with cells.