As the “engines of life”, proteins play the most dynamic and diverse roles among all macromolecules in the body. Owing to their high specificity and potency, more than 130 proteins or peptides therapeutics have been developed for clinical use, and many more are being developed. Despite their tremendous promises, effective delivery of protein therapeutics to achieve the maximum efficacy needs to overcome three major barriers, which are associated with the delivery of therapeutics to the target organs, entrance of the therapeutics to the tissues, and entrance of the therapeutics to the cells. The inability to overcome such barriers may result in rapid loss of the activity, fast clearance and undesirable tissue biodistribution of the therapeutic proteins. Engineering nanocarriers for escorting therapeutic proteins into their specified destination has thus generated considerable interests.
In this dissertation, a delivery strategy employing polymeric nanocapsules for efficient extracellular and intracellular protein delivery is described. As an extension, zwitterionic polymer-based biosensors with effective protein immobilization and enhanced properties are also discussed. This dissertation work can be briefly outlined into three topics below:
1) Oxalate oxidase (OxO) was encapsulated within a thin layer of zwitterionic polymer shell via aqueous free-radical polymerization for the treatment of hyperoxaluria. As-synthesized OxO nanocapsules exhibited enhanced bioactivity, prolonged blood circulation half-life and reduced immunogenicity. This design enables systemic delivery of therapeutic enzymes for various applications.
2) The transcription activator-like effector nucleases (TALEN) were encapsulated. The shell properties were judiciously modulated to be cationic and acid-labile, which facilitates cellular uptake and subsequent cargo release. TALEN pairs recognizing the TAR region of HIV LTRs were delivered through this platform to induce robust excision of HIV-1 provirus in a variety of human cell lines, especially the primary T cell lines. This work provides useful suggestions for the research and development of anti-HIV therapies.
3) Zwitterionic polymers bearing amine groups were developed to facilitate the enzyme immobilization on chitosan-coated electrode for choline sensing. Such zwitterionic coating brought in sensors with improved enzyme loading, sensitivity and detection limit.
In summary, this research utilizes the nanocapsule platform to overcome different delivery barriers to realize specific delivery goals. The zwitterionic polymers can be used to prepare biosensors with enhanced properties.