Fabrication of high-capacity biomolecular carriers from dispersible single-walled carbon nanotube-polymer composites.

One of the most interesting applications for carbon nanotubes is as a support material for bioanalytical devices. In this work, we successfully used an ultraviolet light initiated "graft from" polymerization method to fabricate polymer functionalized carbon nanotubes (PFCNTs) with pendant chains of various functionalities, including poly(ethylene glycol) chains to boost dispersibility and pendant epoxy groups for protein conjugate sites. A model enzyme, alkaline phosphatase, was used to study biomolecule loading efficiency as well as the retention of enzyme activity. Samples with various ratios of the two monomers were fabricated to optimize their use in aqueous environments, and an optimal composition was determined. This method allows the enhancement of enzyme loading amount while retaining high enzyme activity. The morphology of the carbon nanotubes were characterized by STEM and AFM before and after functionalization. In addition, the resulting PFCNTs were analyzed by FT-IR, TGA, and XPS.