(22g) Understanding Corona Exchange Dynamics on Carbon Nanotubes with Multiplexed Fluorescence Monitoring

Adsorption of polymers on single-walled carbon nanotubes (SWCNTs) has enabled developments in molecular sensing, in vivo imaging, and gene delivery applications.^1,2 Noncovalent functionalization of SWCNTs with polymers preserves the pristine SWCNT atomic structure, thus retaining the intrinsic near-infrared fluorescence for sensing or imaging functions, and offers a reversible binding mode for cargo delivery. However, noncovalent biomolecule adsorption is an inherently dynamic process, where exchange occurs between molecules in the bulk solution and molecules on the nanoparticle surface, into what is known as the corona phase. The nature, strength, and kinetics of both the polymer binding and unbinding processes on SWCNTs are important contributors to the success of polymer-SWCNT based technologies. Understanding this binding process is especially important for intended uses of functionalized SWCNTs in biological environments, where native biomolecules compete with the original polymer to occupy the SWCNT surface. Binding of proteins and other biomolecules to the SWCNT disrupts the intended functionality of the nanoparticle and can further lead to adverse biocompatibility outcomes.

We present an assay to study the corona exchange dynamics between solution-phase and corona-phase polymers on SWCNTs.³ This assay exploits the quenching property of fluorophores proximal to the SWCNT surface to monitor ligand binding and unbinding events. Real-time tracking of polymer adsorption and desorption events on the SWCNT surface are conducted with systematic variation of the molecular entities and solution conditions, with a specific focus on DNA (as the sensing moiety) and protein (as the biofouling agent). Binding profiles are extracted from the experimental assay and used to inform a kinetic model of the system. The work presented herein develops an understanding of the fundamental corona exchange mechanism and provides insight into performance of these designed SWCNT-based systems in biologically relevant, protein-rich conditions.

References

1. Demirer, G. S. et al. High aspect ratio nanomaterials enable delivery of functional genetic material without DNA integration in mature plants. Nature Nanotechnology 1 (2019) doi:10.1038/s41565-019-0382-5.
2. Beyene, A. G. et al. Imaging striatal dopamine release using a nongenetically encoded near infrared fluorescent catecholamine nanosensor. Science Advances 5, eaaw3108 (2019).
3. Pinals, R. L., Yang, D., Lui, A., Cao, W. & Landry, M. P. Corona Exchange Dynamics on Carbon Nanotubes by Multiplexed Fluorescence Monitoring. J. Am. Chem. Soc. (2019) doi:10.1021/jacs.9b09617.