The objective of this proposal is to develop a system that can perform in situ and on demand detection of surface charge of single cells. To achieve this objective we will fabricate a nanomechanical system with a controlled amount of charge at its tip. Upon an electrostatic interaction with a cell, the structure will deflect in a manner that is proportional to the surface charge of the cell. Since the interaction could potentially have other constituents such as Van der Waals and hydration forces, these effects will be deconvoluted by varying the amount of charge on the cantilever, and hence only measuring the electrostatic interactions. The PI will investigate the extent of surface charge density on a number of cancer cell lines and compare the results with normal cells. He will also weigh the individual cells using the same electromechanical system and investigate the correlation between surface charge and mass density. Intellectual Merit: Investigation of electrical properties of cells has been important for a long time. Recent studies show that cancer researchers are increasingly interested in correlating phenotype with electrical properties. Here the PI proposes a system that can interrogate a particular cell identified by the user on demand under the microscope. In addition, the system can be used to hover above a group of cells immobilized on a surface or interrogate a section of a larger tissue sample. The versatility of the system also allows it to serve as a mass sensor. Hence, the cells interrogated for their electrical properties can be grabbed by a micro-tweezer and placed on the tip of the electromechanical system for on demand weighing, allowing correlation of electrical properties with mass density. Broader Impacts: Cells have an enormous amount of information packed within their intracellular organelles that code for the gene products expressed on the cell surface membrane and the structures in the cell periphery. Membranes and membrane surfaces have attracted the attention of many scientists for centuries. The cell surface membrane is involved in a wide variety of interactions of the cell with its environment, which are of considerable interest in health and disease. The system proposed here can be extremely useful not only in studying electrical surface properties of a wide variety of cells but also performing these studies under a wide range of conditions. If successful, the project could make a broad impact in cancer research by in situ electrical analysis of particular cells. The PI will choose his PhD student from a minority student body. Prof. Savran teaches courses related to systems and measurements to engineering students. He frequently integrates interdisciplinary examples into an otherwise traditional curriculum. The findings of this study will also be shared with undergraduate students and used as examples in class, in homework and projects.
