Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Jin He

First Advisor's Committee Title

Major Professor

Second Advisor's Name

Wenzhi Li

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Prem P Chapagain

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Joong-Ho Moon

Fourth Advisor's Committee Title

Committee member


SPM, SICM, Live Cell Imaging, Single cell Study, Extracellular potentail imaging, nanoelectrode, nanopipette, nanopore, nanoparticle accumulation, potential sensing, multimode sensing

Date of Defense



Most biological experiments are performed on an ensemble of cells under the assumption that all cells are identical. However, recent evidence from single cells studies reveals that this assumption is incorrect. Individual cells within the same generation may differ dramatically, and these differences have important consequences for the health and function of the entire living body. I have used Scanning Ion Conductance Microscopy (SICM) for imaging and analysis of topographical change of single cell membrane, which is difficult to be revealed by optical microscopes. Morphological change in the fixed and live HeLa cell membrane during endocytosis of conjugated polymer nanoparticles was studied. Results demonstrated SICM is a powerful tool to study the interaction between nanoparticle and cell membrane during internalization of nanoparticles through the membrane. This research can improve our fundamental understanding of cellular behavior and will be helpful for drug delivery applications.

Based on conventional SICM, we have developed a novel method to simultaneous map the topography and potential distributions of the single living cells membranes. At the first step, multifunctional nanopipettes (nanopore/nanoelectrode) have been fabricated and characterized. To demonstrate the potential sensing capability and understand the mechanism, I measured the ionic current and local electric potential change during translocation of 40 nm charged gold nanoparticles. Our results reveal the capability of the multifunctional probe for the highly sensitive detection of the ionic current and local electrical potential changes during the translocation of the charged entity through the nanopore. From the potential change, we revealed the dynamic assembly of GNPs before entering the nanopore. The experimental results are also nicely explained by the finite element method based numerical simulation results.

At the second step, I have measured the surface potential of living cell membrane at selected locations. Very recently, I have obtained results to show that we can map the extracellular membrane potential distribution of the complicated living cell membrane with sub-micron spatial resolution.This new imaging technique can help biologist to explore the extracellular potential distribution of varieties of cells quantitatively.These studies will have impacts on several biomedical applications such as regenerative repair and cancer treatment.






Rights Statement

Rights Statement

In Copyright. URI:
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).