| AVS 54th International Symposium | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS1+BI-WeA |
| Session: | Biological and Molecular Applications of Nanoscale Structures |
| Presenter: | V.R. Dukkipati, University of Michigan |
| Authors: | V.R. Dukkipati, University of Michigan S.W. Pang, University of Michigan |
| Correspondent: | Click to Email |
Nanofluidic systems are useful in the studies of single-molecule DNA-protein interactions, nanofluidics, and polymer dynamics. DNA is a flexible polymer with a large aspect ratio of 2 nm in width and length in the order of the micrometers. Due to its unique properties, it is ideally suited for investigations using nanofluidic systems for both biological and mechanical characteristics. We present an integrated nanofluidic system, which is applied to study DNA-protein interactions and DNA-force dynamics. In this system, electrodes are integrated in sealed Si nanochannels by PMMA bonding. Cr/Au electrodes are patterned on a 100 µm thick glass followed by PMMA coating and patterning to expose the electrodes. The 100 µm thick glass allows high resolution imaging of DNA at single molecule level. Si nanochannels varying from 350-500 nm in width are sealed with electrodes using PMMA bonding. A 150 µm wide, 1 µm deep microchannel is connected to each of the fluidic ports as an interface to the nanochannels. The microchannel allows the DNA molecules from the inlet port to have an easy access to the nanochannels. The DNA molecules are pumped into the nanochannel array using both hydrodynamic force and electric field. Using the hydrodynamic force, the DNA molecules near the inlet are pumped by evaporation from the outlet port, which is open to atmosphere. Using 100-300 KHz electric field generated by ac voltage applied across the electrodes integrated in the microchannel, the DNA molecules are driven from the microchannel into the nanochannel array. The linear motion generated by the electric field causes the DNA molecules to move in the nanochannels with velocity varying from 5-40 µm/s. This corresponds to a viscous drag force of 0.04-3.80 pN acting on the DNA molecules, assuming the values of viscosity of the water and the radius of the DNA molecules of 0.5 µm in nanochannels. The nanofluidic system is also used to immobilize and stretch T2-DNA molecules using the protein assisted DNA immobilization (PADI) technique. 350 nm wide and 100 nm deep channels are used to immobilize and stretch λ-DNA molecules up to 12 µm long. Further studies will be conducted on the influence of multiple sources of electric field on DNAs in nanochannels.