Single-walled carbon nanotubes separation and redox chemistry and their applications for optical biosensing and scaffold materials

Single-walled carbon nanotubes (SWNTs) have drawn great attention worldwide for their unique electronic, mechanical and optical properties. This dissertation details studies of some of the most important areas including: (1) Single-stranded DNA (ssDNA) assisted separation of SWNTs using high performance liquid chromatography; (2) Optical sensitivity and kinetic studies of redox reaction of ssDNA functionalized SWNTs with hydrogen peroxide (H2O2); (3) Effects of Ag+ on the redox reaction of ssDNA-encased SWNTs with hydrogen peroxide; (4) Single-walled carbon nanotube based optical sensors for DNA detection; and (5) SWNTs as scaffolds for promoting stem cell differentiation into bone forming cells.;By using size-exclusion chromatography (SEC) and ion-exchange chromatography (IEC) for ssDNA assisted SWNT separations, enrichment for nanotubes of a few single types, including (6, 5), (8, 4), and (10, 5) nanotubes has been demonstrated. The redox reaction and the reaction kinetics of ssDNA functionalized SWNT hybrids with H2O2 under different environments including different buffer constituents and transition metal ions have been studied for developing optical sensors for H2O2 detection with a detection limit determined to be 0.28 ppm. The reaction between ssDNA-SWNTs and H2O2 has been found to be pH and buffer dependent, and can be affected by Ag+ ions which play a dual role in the reaction. By taking advantage of SWNT's unique near infrared optical properties and Raman features, SWNT-based optical DNA detection schemes have been developed for breast cancer diagnostics. With their robust mechanical properties and rich surface chemistry, it has been demonstrated that SWNTs are a promising scaffold material for promoting stem cell differentiation.