Modulating the fluorescence spectra of single-walled carbon nanotubes by tailored enzyme-responsive polymer-dendron wrapping.

The unique optical property of single-walled carbon nanotubes (SWCNTs) to fluoresce in the near-infrared (NIR) range, where optical interference from biological tissues is minimum, makes them particularly attractive for various biomedical applications.¹ However, due to their high hydrophobicity, non-covalent functionalization with amphiphilic molecules is required for suspending SWCNTs in an aqueous media. Herein, we designed polymer-dendron hybrids composed of hydrophobic dendrons and hydrophilic polyethylene glycol (PEG) polymer as tunable amphiphiles for coating SWCNTs. These PEG-dendron-wrapped-SWCNTs can be used in biomedical applications such as optical sensing as they are biocompatible with the aqueous environment.

Considering how minor structural changes in the polymeric amphiphiles were previously shown to affect their self-assembly into micelles and enzymatic degradation rate,² we synthesized four PEG-dendron hybrids which differ in the hydrophobicity of their enzymatically degradable end-groups. Using these highly modular and tuneable enzyme-responsive amphiphilic PEG-dendron hybrids as wrapping agents, we demonstrate the ability to translate the enzymatic response of the amphiphiles into changes in the unique spectral properties of the SWCNTs. ³

1. J. Pan, F. Li, and Jong Hyun Choi. Single-walled carbon nanotubes as optical probes for bio-sensing and imaging. J. Mater. Chem. B. 2017, 5, 6511—6522.

2. M. Segal, R. Avinery, M. Buzhor, R. Shaharabani, A. J. Harnoy, E. Tirosh, R. Beck, and R. J. Amir. Molecular precision and enzymatic degradation: From readily to undegradable polymeric micelles by minor structural changes. J. Am. Chem. Soc. 2017, 139, 803–810.

3. V. Wulf, G. Slor, P. Rathee, R. J. Amir, and G. Bisker (2021). Dendron-Polymer hybrids as tailorable coronae of single-walled carbon nanotube. ChemRxiv. Preprint. https://doi.org/10.26434/chemrxiv.14452785.v1.