1. Preliminary Research on SDS/DNA-CNT Exchange
Daniel Roxbury
Advisor: Anand Jagota

2. Objectives Use the reaction: DNA-CNT + SDS --> 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

3. 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

4. DNA-CNT Spectrum
992 nm
280 nm

5. 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

6. SDS Sonication Spectra

7. 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

8. Observations (cont’d)
Qualitatively, appears to be increased absorbance at the free DNA peak
Sonication alone displaced the bound DNA, but SDS increased the effect
280 nm

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

10. Langmuir Modeling
1-Component Adsorption (DNA on CNT)

11. Langmuir Modeling 2-Component Modeling (SDS & DNA) Where: p = SDS
q = DNA

12. 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

13. Thank you
Suggestions Welcomed