| AVS 54th International Symposium | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS1+BI-WeA |
| Session: | Biological and Molecular Applications of Nanoscale Structures |
| Presenter: | Y.-J. Oh, University of New Mexico |
| Authors: | Y.-J. Oh, University of New Mexico D. Bottenus, Washington State University D.N. Petsev, University of New Mexico C.F. Ivory, Washington State University S.R.J. Brueck, University of New Mexico G.P. Lopez, University of New Mexico S.M. Han, University of New Mexico |
| Correspondent: | Click to Email |
We have studied field-effect-transistor (FET) flow control and separation of proteins in a parallel array of nanochannels (100 nm W ×500 nm D), using scanning laser confocal fluorescence microscopy (SL-CFM) and multiple internal reflection Fourier transform infrared spectroscopy (MIR-FTIRS). For fluidic FET, a DC potential is applied to the gate surrounding an isolated mid-section of the channels under longitudinal electric field along the nanochannels. The gate potential controls the surface charge on SiO2 channel walls and therefore the ξ-potential. Depending on the polarity and magnitude, the gate potential can accelerate, decelerate, or reverse the flow of proteins. We also analyze a pH shift in the nanochannels according to the surface charge modulation and longitudinal electrical field, using Fluorescein as a pH indicator. Our MIR-FTIR analysis shows that Fluorescein dye molecules are hydrogenated and dehydrogenated in response to the gate bias and subsequent pH shift. We demonstrate that the pH shift affects the FET flow control with SL-CFM analysis. A nanochannel device containing multiple gates is used to improve the controllability of protein flow and to introduce a pH gradient along the channels for isoelectric focusing. A different potential is applied to each gate to differentially control the surface charge on the SiO2 channel walls and to create a pH gradient along the channels. We also generate a pH gradient along the nanochannels, induced by controlled water electrolysis under longitudinal electrical field. The control and separation of proteins, which have different isoelectric points (pI), by the pH gradient along the nanochannels as a function of gate bias and longitudinal electrical field will be further discussed in this presentation.