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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.