Tailoring Aqueous Dispersibility and Biofunctionalization of Carbon Nanotubes Using Maleimide-Containing Clickable Polymers

Functionalization of carbon nanotubes (CNTs) using functional polymers can enhance their properties by enabling conjugation of functional molecules, apart from just providing them with enhanced solubilization. A family of amphiphilic copolymers bearing the maleimide functional groups as side chain residues has been synthesized, and their stacking and further functionalization are explored. While copolymers composed of hydrophilic poly(ethylene glycol) and hydrophobic maleimide groups provide the CNTs with solubilization, subsequent functionalization of the maleimide group with hydrophilic peptides leads to a loss of the stabilizing interaction. A maleimide-containing copolymer containing a pyrene group at the chain end allows both solubilization and further functionalization while retaining the polymeric layer on the CNT. Polymers are synthesized using controlled radical polymerization and characterized using H NMR and gel permeation chromatography, and the functionalization of the obtained CNT-stacked composites is investigated using Fourier transform infrared and thermogravimetric analyses. Importantly, this strategy provides access to CNTs modified with bioactive peptides that provides a cytocompatible interface with an enhanced cellular interaction, making these carbon materials viable candidates for biological interfacing.