(405b) Probing Peptoid-Carbon Nanotube Coatings for Biological Imaging

Single-walled carbon nanotubes (SWNT) have emerged as ideal candidates for biological imaging due to their tissue-transparent near-infrared fluorescence, and infinite photobleaching lifetimes.¹ However, the hydrophobic surfaces of SWNT require ligand functionalization or polymer encapsulation to promote aqueous colloidal stability for use in biological environments. We introduce peptoids, N-substituted glycine polymers, as easily synthesized programmable polymers with a large monomer space and that are less susceptible to proteolytic degradation than peptide or protein polymers.² We show that peptoids can be used as a novel carbon nanotube coating by pinning peptoid polymers to the SWNT surface through pi-pi and electrostatic interactions. Herein, we identify the stabilizing interactions of peptoids on SWNT surfaces. We probe the effect of peptoid polymer length, hydrophilicity, initial dispersion conditions, and ionic buffer conditions on the resulting colloidal stability of peptoid-SWNT conjugates. These findings allow us to stabilize carbon nanotubes with rationally designed peptoid polymers and enable us to effectively use peptoid-based SWNT coatings for biological imaging.

1. Zhang, J. et al. Molecular recognition using corona phase complexes made of synthetic polymers adsorbed on carbon nanotubes. Nat. Nanotechnol. 8, 959–68 (2013).
2. Nam, K. T. et al. Free-floating ultrathin two-dimensional crystals from sequence-specific peptoid polymers. Nat. Mater. 9, 454–60 (2010).