Download DNA Length Dependence on Laser Tube Separation

DNA Length Dependence on Laser Tube Separation
(GT)10-LaCNT
Abs
M11
b10
d6
e4
Absorbance (a.u.)
ssDNA-LaCNT (starting sample)
c4
d11
(GT)20-LaCNT
400
400
600
800
Wavelength (nm)
1000
1200
600
800
1000
1200
1400
1600
Wavelength (nm)
No metallic enrichment for (GT)20
Shorter DNA sequence produces a much more effective
metal/semiconductor separation.
• smaller helical pitch
• larger difference in net effective linear charge density
~ 14 nm
DNA Helical Wrap
Roll up
2p (D + 1 nm)
DNA wrapping helix
For a 1 nm SWNT, ~ 20 mer is needed to wrap a full turn.
Total possible sequences: 420
Full of potential, but a search strategy is needed
Sequence Expansion
As a way to effectively cover the sequence parameter
space. It is also a natural extension of our previous work.
1st order expansion (mononucleotide repeat):
M20 , where M = G, or A, or T, or C; total sequences = 4
2nd order expansion (di-nucleotide repeat):
(D1D2)10 , where Di = G, or A, or T, or C; total sequences = 16
3rd order expansion (tri-nucleotide repeat):
(T1T2T3)7 , where Ti = G, or A, or T, or C; total sequences = 64
4th order expansion (quadr-nucleotide repeat):
(Q1Q2Q3Q4)5 , where Qi = G, or A, or T, or C; total sequences = 256
.
.
.
Tri-nucleotide repeat
For tri-nucleotide repeat sequences,
a 30-mer is used to disperse HiPco
tubes.
Quadr--nucleotide repeat
Chirality Enrichment in HiPco
(TCG)10-HiPco (starting sample)
b4
b11
c2
Abs
(8,6) tubes elute
at early fractions
along with metallic
tubes.
(8, 6)
400
600
800
1000
Wavelength (nm)
1200
Chirality Enrichment in HiPco
(TCC)10-HiPco (starting sample)
Abs
b2
b6
b9
(9,1)
Also found in (CCA)10
and (TGA)10 wrapped
HiPco fractions.
400
600
800
1000
Wavelength (nm)
1200
Chirality Enrichment from CoMoCAT
5.00E-013
PL intensities @ 660 nm Excitation
(TCC)10-CoMoCAT
a13
c3
4.00E-013
a13
3.00E-013
2.00E-013
1.00E-013
Abs
0.00E+000
800
900
1000
1100
1200
1300
1400
1500
Wavelength (nm)
(9, 1) d ~ 0.757 nm
PL intensities @ 660 nm Excitation
4.00E-012
(6, 5) d ~ 0.757 nm
400
600
800
1000
1200
3.50E-012
3.00E-012
2.50E-012
2.00E-012
1.50E-012
1.00E-012
5.00E-013
0.00E+000
Wavelength (nm)
-5.00E-013
800
900
1000
1100
1200
1300
Wavelength (nm)
Chirality separation among nanotubes of very similar diameter.
The ability to extract a very minor species from a mixture.
1400
1500
1600
1600
Metal Enrichment in HiPco
ssDNA-HiPco
(TTC)10-HiPco metallic fraction
Abs
(TTA)10-HiPco metallic fraction
400
600
800
1000
Wavelength (nm)
1200
•
T rich sequences can
enrich metallic tubes,
e.g. (TTA)10, (TTC)10
•
Metallic tubes elute at
early fractions.
Metal/Semiconductor Separation of Laser Tubes
0.9
M22
Metallic LaCNT
Semiconducting LaCNT
(TTC)10-LaCNT (starting sample)
M11
S22
PL Intensities @ 827 nm Excitation
6.00E-013
Abs
0.6
0.3
4.00E-013
semiconducting fraction
metallic fraction
2.00E-013
0.00E+000
1000
1200
1400
Emission Wavelength (nm)
S33
400
600
800
1000
Wavelength (nm)
1200
Laser Tube Dispersion
(GT)30-LaCNT
(GTT)20-LaCNT
Abs
(GTT)6-LaCNT
400
600
800
1000
Wavelength (nm)
1200
• DNA Sequence
dependence
• DNA Length
dependence
Can DNA separate SWNTs of large diameters?
(TTA)10-LaCNT
a12
a14
b2
b6
0.4
0.3
Abs
(TTA)6-LaCNT
M22
Abs
M11
0.2
400
600
800
1000
1200
Wavelength (nm)
(15,0) d ~ 1.19
0.1
400
600
800
Wavelength (nm)
1000
• Tuning ssDNA sequence
• Reducing ssDNA Length
Summary
• Lots of interesting sequences from the trinucleotide repeat studies for
metal/semiconductor separation and chirality
enrichment.
• A few quadr-nucleotide repeat sequences (0,1
and 2 purines) give some metal/semiconductor
separation, but the overall performance is not as
exciting.
• Unexpected DNA length dependence on the
laser tube separation. Shorter is better.
• By tuning the DNA sequence and length,
purification of nanotube with specific electronic
type and chirality can be achieved.