Biomolecule Exchange Dynamics on Carbon Nanotubes Via Multiplexed Fluorophore Quenching

Abstract

Adsorption of biomolecules on single-walled carbon nanotubes (SWCNTs) has enabled developments in molecular sensing, in vivo imaging, and gene delivery applications.1,2 This noncovalent functionalization of SWCNTs 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, 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 biomolecule binding and unbinding processes on SWCNTs are important contributors to the success of SWCNT-based technologies. Understanding this binding process is especially important for intended uses of functionalized SWCNTs in biological environments, where native biomolecules such as proteins compete with the original biomolecule to occupy the SWCNT surface. Such biofouling of the SWCNT surface disrupts the intended functionality of the nanoparticle and can further lead to adverse biocompatibility outcomes.We present a generalizable method to study the corona exchange dynamics between solution-phase and corona-phase biomolecules on SWCNTs in real-time.3 This approach exploits the quenching property of fluorophores proximal to the SWCNT surface to monitor ligand binding and unbinding events. Real-time tracking of 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 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.Beyene, A. G. et al. Imaging striatal dopamine release using a nongenetically encoded near infrared fluorescent catecholamine nanosensor. Science Advances 5, eaaw3108 (2019).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. Figure 1