Author ORCID Identifier


Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)



First Advisor

Gangli Wang


Crystallization of biomacromolecules, a crucial solute-to-solid phase transition, presents technical challenges but is of immense importance for structural determination and pharmaceutical applications. A significant obstacle in traditional experimental methodologies, which are generally trial-and-error and ensemble-based, is characterizing and controlling the asynchronous and dynamic nucleation process. This dissertation introduces a novel single-entity method, named the Nanoscale Actively Controlled method (NanoAC), capable of synthesizing protein crystals one at a time under active control to achieve superior crystal quality. NanoAC utilizes unique ion transport properties arising from nanoconfinement effects in single nanopipettes to spatiotemporally tailor the kinetics and thermodynamics of supersaturation. The method integrates optical and electroanalytical techniques for real-time monitoring, providing feedback for actively controlling phase transitions at the nanoscale interface. Using the protein lysozyme as a prototype, electrical and optical signatures for nucleation are established, enabling the quantification of early-stage kinetics. By tailoring the rate of subsequent crystal growth, the X-ray diffraction quality is significantly improved to atomic resolution, and the crystal habits are regulated. Additionally, this dissertation explores fundamental ion transport behaviors through single nanopipettes, with a focus on negative differential resistance as a new principle for designing advanced logic functions and capabilities in iontronics, neuromorphic computing, and broadly defined processes of ion transport separation, energy harvesting, storage, and conversion.


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