Click Chemistry of Organic Color Center-Tailored Carbon Nanotubes

Single-wall carbon nanotubes (SWCNTs) can be used as versatile near-infrared (NIR) fluorescent probes for biological applications, such as biosensing and imaging. The use of click and bioorthogonal chemistry can open many possibilities for tailoring the SWCNT surface with a diverse range of biological functionalities for targeted biomedical applications. This work focuses on using organic color center (OCC)-tailored SWCNTs with specific functional groups as a material foundation for click chemistry. Specifically, we performed the isolation of pure-chirality (6,5) SWCNTs, the creation of fluorescent quantum defects (i.e., OCC) on (6,5) SWCNTs using aryl diazonium chemistry, and the copper-catalyzed azide-alkyne cycloaddition click chemistry. The newly formed defect-state emission peak, that is red-shifted compared to the pristine emission peak, confirmed the creation of fluorescent quantum defects on SWCNTs. Following the membrane filtration to remove the excess diazonium, CuSO₄, THPTA and varying [aryl azide]: [defect] molar ratios were mixed for reaction at various time periods. The vis-NIR absorption and fluorescence of samples were characterized using the NS3 NanoSpectralyzer. Our preliminary findings show a possible azide-alkyne cycloaddition reaction, providing potential for versatile surface functionalization of SWCNTs for biosensing, early diagnostics, and bioimaging applications.