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DNA conductivity

DNA conductivity. 侯劭毅. DNA 能不能導電 ?. 在 DNA 分子中一個電子的轉移反應 , 螢光將會熄滅 , Dr. Barton 認為此反應代表了電子在 DNA 中傳遞。. C.J. Murphy et al., "Long-range photoinduced electron transfer through a DNA helix, " Science, 262:1025-9, 1993. Dandliker, P. J., R. E. Holmlin, and J. K. Barton, 1997, Science 275 , 1465.

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DNA conductivity

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  1. DNA conductivity 侯劭毅

  2. DNA 能不能導電? 在DNA分子中一個電子的轉移反應,螢光將會熄滅, Dr. Barton 認為此反應代表了電子在DNA中傳遞。 C.J. Murphy et al., "Long-range photoinduced electron transfer through a DNA helix, " Science, 262:1025-9, 1993.

  3. Dandliker, P. J., R. E. Holmlin, and J. K. Barton, 1997, Science 275, 1465.

  4. DNA conductivity ?? • Biology • Electronic industry • Nanotechnology • May be ………………. • Work faster • Fit into smaller spaces • Less power • Produce less heat

  5. DNA 的 潛在用途 Y. Ito, E. Fukusaki / Journal of Molecular Catalysis B: Enzymatic 28 (2004) 155–166

  6. DNA: From Living Cells to Electronic Hardware • adenine (A) • thymine (T)guanine (G) • cytosine (C) 3.4Å A=T G ≡C 2nm

  7. 3.4Å R.G. Endres et al., "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76:195-214, 2004.

  8. DNA is a • Nonconductor ? • Semiconductor ? • Conductor ? • Superconductor ?

  9. Braun et al. 以λDNA進行導電度之量測,其研究結果顯示DNA並無導電能力。 E. Braun, "DNA-templated assembly and electrode attachment of a conducting silver wire," Nature, 391:775-8, 1998.

  10. DNA structure L. Stryer, 1995,Stryer’s Biochemistry, 4th ed

  11. DNA structure

  12. R.G. Endres et al., "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76:195-214, 2004.

  13. Porath, D.; Bezryadin, A.; De Vries, S.; Dekker, C. Direct Measurement of Electrical Transport throughDNAMolecules. Nature 2000, 403, 635–638.

  14. Fink, H.W.; Sch€onenberger, C. Electrical Conduction through DNA Molecules. Nature 1999, 398, 407–410.

  15. Hopping mechanism • Bernd Giese提出長距離的電子傳遞藉由一個多步驟的跳躍機構。電子可以個別的跳躍從一個鹼基到另一個,並允許長距離的傳遞。然而,並非全部的鹼基都有相同的良好結果,只有guanine(G)可以提供藉由電子傳遞的明確電荷移動,以Marcus有關長距離的電子傳遞理論推斷電子只能傳遞10到15Å ,以DNA分子的兩個鹼基對間的垂直距離是3.4Å約等於2-3bps。 ket=(4π2/h)H2DA(4πλkBT)-1/2exp[-(ΔG-λ)2/4λkBT] B. Giese et al., "On the mechanism of long-range electron transfer through DNA, " Angewandte Chemie International Edition, 38:996-8, April 1999.

  16. Hopping mechanism Giese et al., “Direct observation of hole transfer through DNA by hopping between adenine bases and by tunnelling” NATURE VOL 412, pp 318-320, 2001 http://www.chemsoc.org/ chembytes/ezine/2000/ giese_jul00.htm

  17. Hopping mechanism B. Giese et al., "Long-distance charge transport through DNA.An extended hopping model," Pure Appl. Chem., Vol. 73, No. 3, pp. 449–453, 2001.

  18. The nature of DNA’s intrinsic conductanceproperties remains highly controversial. R.G. Endres et al., "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76:195-214, 2004.

  19. SH SH Direct measurement of DNA conductivity

  20. 實驗方法 尋找目標片段 目標片段之製備 微電極製作 將DNA固定於電極上 量測電流值 AFM or SEM觀測 程式設計

  21. Result- Program design

  22. Result • 菌種 : 藍色鏈黴菌 • 符合長度 • GC Space 3 mer • 7kb 以上 • GC Space 2 mer • 3kb~4kb

  23. SH SH X Restriction SH SH X Ligation SH SH SH SH X SH X X SH BamHI cutting site BglII cutting site X Mutant site 實驗流程-Restriction & Ligation 利用在引子上設計點突變的 方式，研究在DNA內僅有一 GC鹼基對間，間隔2或3個AT 鹼基對之間的差別

  24. Digest and ligation PCR • For GC 之間2 AT • 3000~4000bp • PCR : primer with BamHI site • Ligation • Use 5’- thiol modified primer

  25. Result - microelectrode

  26. 實驗結果-電阻係數計算及比較 *此處計算為假設僅一條DNA片段連接於電極間

  27. 電極間僅一條DNA分子連接

  28. 電極間DNA為束狀結構(續)

  29. THE END

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