Rational Design of Protein-loaded Polymeric nanoparticles: A Computational and Experimental Approach
Nyambura, Christopher Wanjohi
MetadataShow full item record
Enzymes are a class of macromolecules that can catalyze a wide range of chemical reactions. Enzymes are critical in the function of complex biological processes and more recently, industrial processes that result in high-value products and services. Their large and complex structure, when compared to small molecules, allows for unique chemistries to occur, due to highly specific binding of substrates within the reaction site and subsequent conversion to products with high regio- and/or chemo-selectivity. However, the environment in which enzymes execute their function must be tailored to ensure preservation of protein structure and easy access to substrates. For therapeutic drug delivery, toxic side-effects such as protease recognition and development of neutralizing antibodies can occur when administrating a therapeutic enzyme in free form; hence, their targeted delivery is necessary to ensure high patient compliance and to reduce healthcare costs associated with medical care. Polymer nanoparticles (PNPs) can potentially address issues observed in enzymatic drug delivery due to their high surface area, ability to encapsulate a wide range of proteins, and ability to tailor the nanocarrier surface to minimize non-specific interactions. Nevertheless, ensuring high enzymatic loading while preserving protein activity when formulating protein-loaded PNPs remains a difficult task, due to a poor understanding of molecular-level mechanisms that allow for high encapsulation efficiencies and desirable PNP characteristics such as monodispersity, near neutral surface charge, and small size. To aid in the rational design of enzyme-loaded PNPs, Molecular Dynamics provides a way to probe key interactions, in atomistic detail, that are present at many points during nanoparticle formulation, resulting in better methodologies for making highly effective nanocarriers. In this dissertation, I elucidated structure and dynamics of the poly(lactic-co-glycolic acid)–polyethylene glycol (PLGA-PEG) copolymer and its homopolymer constituents in solvents commonly used to form core-shell PNPs, resulting in key insights that are necessary to control polymer chain rigidity and shape. Next, I examined the role of polymer extension on protein-polymer interactions prior to and during formation of PLGA-PEG nanoparticles, to better understand how the choice of solvent could impact enzymatic loading. Lastly, I employed hydrophobic-ion pairing to reduce the hydrophilic nature of catalase to drive increased encapsulation within PLGA-PEG nanoparticles. This work demonstrates the advantages of using both computational and experimental tools to develop and rationally design enzyme-loaded PNPs.
- Chemical engineering