Near-Infrared Confocal Imaging of Single-Walled Carbon Nanotube Uptake in Bacterial Cells

Abstract

The distinctive properties of single-walled carbon nanotubes (SWCNTs) have inspired the development of innovative applications in the field of cell nanobiotechnology. Most studies to date have focused on eukaryotic cells capable of internalizing SWCNTs functionalized with a variety of non-covalent wrappings. However, the effect of SWCNT functionalization on transport across the thick cell wall of prokaryotes remains unexplored. In this study, we explore the uptake of SWCNTs in Gram-negative cyanobacteria and demonstrate selective internalization of SWCNTs decorated with charged protein wrappings. The functionalized SWCNTs are shown to traverse the outer cell wall of both filamentous and unicellular strains of cyanobacteria, independent of whether the strain is naturally competent for DNA uptake, with adsorption and internalization rate constants of kads = (9.08 ± 0.16) x 10-8 s-1 and kin = (1.466 ± 0.011) x 10-4 s-1, respectively. A custom-built, spinning disc confocal microscope was used for the first time to directly image near-infrared (NIR) SWCNT fluorescence within cells, revealing a highly inhomogeneous distribution of SWCNTs that is otherwise overlooked using conventional NIR widefield imaging. The nanobionic cells show sustained photosynthetic activity and growth, offering a powerful avenue for engineering photosynthetic organisms with augmented and even inherited nanobionic capabilities.