Preliminary Research on SDS/DNA-CNT Exchange

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Preliminary Research on SDS/DNA-CNT Exchange

• Daniel Roxbury
• Advisor Anand Jagota

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Objectives

• Use the reaction
• DNA-CNT SDS --gt SDS-CNT DNA
• to show the binding strengths of DNA-CNT
  hybrids in solution
• Apply an array-based model to show dependence on
  DNA sequence

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Starting Sample

• Poly (GT)30 ssDNA dispersed HiPCO nanotubes
• Run through Size Exclusion Chromatography (SEC)
• Remove amorphous carbon
• Remove free DNA
• A3 through A6 samples used for experiment

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DNA-CNT Spectrum
992 nm
280 nm
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Preliminary Experiment

• Mix DNA-CNT sample with excess surfactant, SDS
• 1 SDS solution
• Sonicate at 8W for one hour
• Observe any shifts in peaks described previously

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SDS Sonication Spectra
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Observations

• Sonicating with SDS produces a 7 nm blue shift
  in the 992 peak
• Sonicating w/o SDS, results in a 6 nm red shift
• Both shifts produce a broadened peak

985
998
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Observations (contd)

• Qualitatively, appears to be increased absorbance
  at the free DNA peak
• Sonication alone displaced the bound DNA, but SDS
  increased the effect

280 nm
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Additionally..

• Upon letting the SDS-sonicated sample sit for a
  20hr period, a back-shift in the 985 peak was
  observed

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Langmuir Modeling

• 1-Component Adsorption (DNA on CNT)

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Langmuir Modeling

• 2-Component Modeling (SDS DNA)

Where p SDS q DNA
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Future Work

• Ultimately, it is desired to confine this
  experiment to an array of bound ssDNA
• Many thousands of DNA sequences could be tested
  at a single time
• DNA-CNT binding strengths could then be determined

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Thank you

• Suggestions Welcomed