Peptide Nanotubes: Simple Separation Using Size-Exclusion Columns and Use as Templates for Fabricating One-Dimensional Single Chains of Au Nanoparticles
✍ Scribed by X. Gao; R. Djalali; A. Haboosheh; J. Samson; N. Nuraje; H. Matsui
- Publisher
- John Wiley and Sons
- Year
- 2005
- Tongue
- English
- Weight
- 301 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0935-9648
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✦ Synopsis
perature for 10 min. The DTT was removed by extraction with 400 lL ethylacetate. The resulting aqueous solution was diluted to create a 1 lM solution in 1 M potassium phosphate buffer pH 7.0. The DNA linker solution was mixed with a 1 lM solution of 6-mercapto-1-hexanol in 1 M potassium phosphate buffer pH 7.0 at a given molar percentage to give solutions that were 1 lM in total thiol, of which 0, 10, 20 and 100 % of the thiol content was 1. Hereafter, those solutions are denoted as 0 %, 10 %, 20 %, and 100 % solution, respectively.
A gold-coated cantilever was immersed in 100 % solution overnight. The cantilever was then rinsed with deionized water and immediately immersed in a 1 lM solution of 6-mercapto-1-hexanol overnight. The cantilever was then rinsed with deionized water and absolute ethanol. A couple of droplets of each co-deposition solution were placed on an individual quadrant of the patterned substrate and kept overnight in 100 % humidity. The 100 % quadrant was rinsed with deionized water and then immersed in a 1 lM solution of 6-mercapto-1-hexanol overnight to backfill the quadrant. The surface was then rinsed with deionized water and ethanol and dried under a flow of nitrogen. For the 100 % quadrant, the surface density of 1 was determined by washing off a fluorescently tagged complementary sequence on an identically treated but larger (2 cm by 2 cm) gold surface.
Gold Pattern Height and Unbinding-Force Measurements: Heights of gold patterns were measured in solution at room temperature using tapping-mode AFM (Nanoscope III, Digital Instruments), on which a commercially available Si 3 N 3 cantilever and the immobilized surface were mounted. The force measurements were carried out with the functionalized cantilever (spring constant after thiol immobilization determined to be 0.133 pN m ±1 by thermal fluctuations) [14]. The threshold was set to 10 nm, delay to 0 s, scan rate to 1 Hz, and ramp size to 1 lm. The force measurements were repeated 50±100 times for every set of conditions. In trials, no statistically significant difference in average pull-off force was observed between the first 50 and all 100 measurements.