DNA conductivity DNA DNA Dr Barton DNA C
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.
• DNA conductivity ? ? – Biology – Electronic industry – Nanotechnology • May be ………………. – Work faster – Fit into smaller spaces – Less power – Produce less heat
DNA 的 潛在用途 Y. Ito, E. Fukusaki / Journal of Molecular Catalysis B: Enzymatic 28 (2004) 155– 166
DNA: From Living Cells to Electronic Hardware adenine (A) thymine (T) guanine (G) cytosine (C) 3. 4Å A=T G ≡C 2 nm
3. 4Å R. G. Endres et al. , "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76: 195 -214, 2004.
• DNA is a – Nonconductor ? – Semiconductor ? – Conductor ? – Superconductor ?
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.
DNA structure L. Stryer, 1995, Stryer’s Biochemistry, 4 th ed
DNA structure A B Z Helical sense Right handed Left handed Diameter ~2. 6 nm ~2. 0 nm ~1. 8 nm Base pairs per helical turn 11 10 12(6 dimers) Helical twist per base pair 33° 36° 60° (per dimer) Helix pitch(rise per turn) 2. 8 nm 3. 4 nm 4. 5 nm Helix rise per base pair 0. 26 nm 0. 34 nm 0. 37 nm Base tilt normal to the helix axia 20° 6° 7° Major groove Narrow and deep Wide and deep Flat Minnor groove Wide and shallow Narrow and deep
R. G. Endres et al. , "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76: 195 -214, 2004.
Porath, D. ; Bezryadin, A. ; De Vries, S. ; Dekker, C. Direct Measurement of Electrical Transport through. DNAMolecules. Nature 2000, 403, 635– 638.
Fink, H. W. ; Sch€onenberger, C. Electrical Conduction through DNA Molecules. Nature 1999, 398, 407– 410.
Hopping mechanism http: //www. chemsoc. org/ chembytes/ezine/2000/ giese_jul 00. htm 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
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.
The nature of DNA’s intrinsic conductance properties remains highly controversial. R. G. Endres et al. , "Colloquium: The quest for high-conductance DNA, " REVIEWS OF MODERN PHYSICS, 76: 195 -214, 2004.
Direct measurement of DNA conductivity SH SH
Result- Program design
Result • 菌種 : 藍色鏈黴菌 • 符合長度 • GC Space 3 mer 7 kb 以上 • GC Space 2 mer 3 kb~4 kb
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 SH SH X Restriction SH SH X Ligation SH SH SH X X X SH Bam. HI cutting site Bgl. II cutting site X Mutant site SH SH
PCR • Use 5’- thiol modified primer Digest and ligation • For GC 之間 2 AT – 3000~4000 bp – PCR : primer with Bam. HI site – Ligation
Result - microelectrode
電極間僅一條DNA分子連接 RH 75%,30℃ RH 30~50%, 30℃ 空白電極 3. 07 E-12 (A) 電流值(X) 8. 41 E-13 (A) 3. 77 E-14 (A) 步驟 2之 4. 65 E-12 (A) 電流值(Y) 8. 31 E-13 (A) 9. 14 E-14 (A) Y-X -0. 1 E-13 (A) 5. 37 E-14 (A) Data 1 -1 RH 95%,30℃ 1. 58 E-12 (A)
電極間DNA為束狀結構(續) Data 2 -2 RH 95%,30℃ RH 75%,30℃ RH 30~50%, 30℃ 空白電極 電流值(X) 2. 05 E-11 (A) 6. 77 E-12 (A) 1. 48 E-13 (A) 步驟 2之電 4. 88 E-10 (A) 流值(Y) 5. 10 E-12 (A) 4. 12 E-14 (A) Y-X -1. 67 E-12 (A) -1. 07 E-13 (A) 4. 68 E-10 (A)
THE END
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