Single Molecule Bioelectronics and Their Application to Amplification-Free Measurement of DNA Lengths
- Biosensors (Basel). 2016 Jun 24;6(3):29. doi: 10.3390/bios6030029.
- 1. Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA.
- 2. Department of Physics, Polatlı Faculty of Science and Arts, Gazi University, Polatlı 06900, Turkey.
- 3. Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA.
- 4. Department of Physics, North Dakota State University, Fargo, ND 58108, USA.
- 5. Department of Chemistry, University of California at Irvine, Irvine, CA 92697, USA. [email protected].
- 6. Department of Molecular Biology and Biochemistry, University of California at Irvine, Irvine, CA 92697, USA. [email protected].
- 7. Department of Physics and Astronomy, University of California at Irvine, Irvine, CA 92697, USA. [email protected].
As biosensing devices shrink smaller and smaller, they approach a scale in which single molecule electronic sensing becomes possible. Here, we review the operation of single-enzyme transistors made using single-walled carbon nanotubes. These novel hybrid devices transduce the motions and catalytic activity of a single protein into an electronic signal for real-time monitoring of the protein's activity. Analysis of these electronic signals reveals new insights into enzyme function and proves the electronic technique to be complementary to other single-molecule methods based on fluorescence. As one example of the nanocircuit technique, we have studied the Klenow Fragment (KF) of DNA Polymerase I as it catalytically processes single-stranded DNA templates. The fidelity of DNA Polymerases makes them a key component in many DNA Sequencing techniques, and here we demonstrate that KF nanocircuits readily resolve DNA polymerization with single-base sensitivity. Consequently, template lengths can be directly counted from electronic recordings of KF's base-by-base activity. After measuring as few as 20 copies, the template length can be determined with <1 base pair resolution, and different template lengths can be identified and enumerated in solutions containing template mixtures.