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DNA-decorated graphene chemical sensors

DNA-decorated graphene chemical sensors. Brett Goldsmith , Ye Lu, Nicholas Kybert , A.T. Charlie Johnson University of Pennsylvania Department of Physics and Astronomy. Graphene Transistors. SiO 2. c. c. c. c. c. c. Silicon Gate. c. c. c. c. c. c. c. c. c. c. c. Vb. c. c.

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DNA-decorated graphene chemical sensors

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  1. DNA-decorated graphene chemical sensors Brett Goldsmith, Ye Lu, Nicholas Kybert, A.T. Charlie Johnson University of Pennsylvania Department of Physics and Astronomy

  2. Graphene Transistors SiO2 c c c c c c Silicon Gate c c c c c c c c c c c Vb c c c c c c c c c c c c c c c c c Vg c c c c c c c c c c c c c c c c c c c c c c c c c initial c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c

  3. Graphene Transistors Vb c c c c c c c c c c c c c c c c c c c c Vg c c c c c c c c c c c c c c Vb c c c c c c c c c c c c 400 C anneal c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c Vg c c c c c c c c c c c c c c c c c c c c c c c c clean initial c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c Yaping Dan, A.T.C. Johnson et al, Nano Letters, 2009 c c c c c c c c c c c c c c c c c c c c c c c c Ishigami et al. Nano Letters (2007)

  4. Effect of Cleaning on Sensing • Cleaning causes: • Reduction in carrier density here from 3.3×1012/cm2 to 6.2×1011/cm2 • Increase in mobility here from 1000 cm2/V-s to 2600 cm2/V-s • Decrease in chemical sensitivity Yaping Dan, A.T.C. Johnson et al, Nano Letters, 2009

  5. Why ssDNA? • Chemical sensing is moving beyond “single type” sensors – focus on useful diversity and “electronic nose” approaches • Diverse chemistry (e.g., 420 ~ 1012 sequences for 20-mer) • Existing literature on ssDNA functionalized sensors. mechanical electronic optical Zuniga C, et. al., APL. 2009 Staii C, A.T.C. Johnson et. al., Nano Lett., 2005 White J, et. al., PLoSBiol 2008

  6. DNA Deposition • 200 mg/mL single stranded DNA solution • non-covalent functionalization • graphene is exposed to DNA for 45 minutes • DNA code is used to alter the chemical properties of the applied bio-polymer 1mm Sequence 1: 5’ GAG TCT GTG GAG GAG GTA GTC 3’ Sequence 2: 5’ CTT CTG TCT TGA TGT TTG TCA AAC 3’

  7. DNA-graphene interaction • ssDNA deposition leads to • expected gate shift • lowered mobility c c c c c c c c c c c c c c c c c Vb c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c Vg c c c c c c c c c c c c clean ssDNA initial c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c c

  8. DNA-graphene interaction • ssDNA deposition leads to • expected gate shift • lowered mobility graphene modeling would predict around 1.5×1014 bases/cm2 at 100% coverage we measure an increase in doping of around 6.2×1011 /cm2 carriers direction is consistent with negatively charged adsorbates CNT Johnson, R. R.; Johnson, A. T. C., et. al., Nanoletters 2008

  9. Sensing Results - DMMP • no response with clean graphene • response with ssDNA is concentration dependent • response changes depending on sequence of applied ssDNA 2% 4% 6% 8% 10% 12% DMMP Sequence 1: 5’ GAG TCT GTG GAG GAG GTA GTC 3’ Sequence 2: 5’ CTT CTG TCT TGA TGT TTG TCA AAC 3’

  10. Chemically Gating in Two Directions 4% 6% 8% 10% 2% 4% 6% 8% 10% 12% Propionic Acid DMMP Chemical gating response, probably mediated by water – direction and magnitude is similar to ssDNA-CNT responses

  11. Similar Molecule Sensing sequence 2 2% 6% 9% 12% 15% sequence 1 2% 6% 15% 9% 12% • Changes in sequence show a dramatic ability to change chemical sensitivity • demonstrates differentiation between very similar chemicals

  12. Summary • Clean graphene makes a poor chemical sensor • Graphene can be easily functionalized with ssDNA, with a predictable gate shift • ssDNA-graphene devices show vastly improved chemical sensing over pristine graphene • Changing ssDNA sequence does alter chemical sensitivity of graphene

  13. Thank You Johnson Group UPenn Prof. A.T. Charlie Johnson Dr. ZhengtangLuo Dr. Brett Goldsmith Luke Somers Ye Lu Mitch Lerner Matthew Berck Dan Singer Nicholas Kybert Thomas Ly Jen Daily *Supported by the Intelligence Community Postdoctoral Fellowship Program, JSTO DTRA, The Nano/Bio Interface Center

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