Preparation of Multilayer Capsules for Enzymatic Reactions

Date

2024-9-6

Author

Alemdar, Cemre

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This thesis study aimed preparation of stimuli-responsive polymer nano- and micro reactors for enzymatic reactions. For the fabrication of nanoreactors, three model enzymes, Candida antarctica lipase B (CAL B), glucose oxidase (GOx), and horseradish peroxidase (HRP) were separately encapsulated into polymersomes that were obtained through self-assembly of poly(2-isopropyl-2-oxazoline)-b-poly(2-phenyl-2-oxazoline)-b-poly(2-isopropyl-2-oxazoline) (PiPOX-b-PPhOX-b-PiPOX) using double emulsion method. The enzyme loaded polymersomes had temperature responsive PiPOX inner/outer corona and PPhOX-membrane. Enzymatic reactions were performed separately in GOx-loaded, HRP-loaded, and CAL B-loaded polymersomes (polymersome-GOx, polymersome-HRP, and polymersome-CAL B, respectively). A two-enzyme cascade reaction was performed in a mixture of polymersome-GOx and polymersome-HRP. However, no product formation was observed in the three-enzyme cascade reaction involving polymersome-GOx, polymersome-HRP, and polymersome-CAL B. For the fabrication of microreactors, hollow polymer capsules were prepared using polymersome-GOx, polymersome-HRP, and pH-responsive Tannic Acid as building blocks to construct compartmentalized multilayers through layer-by-layer (LbL) self-assembly technique, followed by dissolution of the core. Only polymersome-GOx containing hollow capsules performed enzymatic reactions. The effects of pH and temperature on enzymatic activity were compared between polymersome-GOx and hollow capsules. Increasing the temperature from 25 °C to 37 °C enhanced reaction rates in both, with a slightly greater increase in polymersomes. The reaction rate was faster at pH 5.5 than pH 7.4, with a more pronounced effect in capsules. Cytotoxicity experiments on HeLa cells showed no significant decrease in cell viability with either polymersome-GOx or hollow capsules. Polymersome-GOx was internalized by HeLa cells, whereas only a few hollow capsules interacted with the cell membrane.

Subject Keywords

Layer-by-layer Self-assembly, Polymer Microcapsule, pH-responsive, Temperature-responsive, Enzymatic Reactions

URI

https://hdl.handle.net/11511/111418

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Graduate School of Natural and Applied Sciences, Thesis