Intracellular Localization of DNA-Wrapped Single-Walled Carbon Nanotube Sensors for Nitric Oxide Detection in Triple-Negative Breast Cancer Cells.

Spatiotemporal sensors capable of monitoring analyte activity in subcellular compartments of cells are critical to advancing our understanding of complex disease progression. Nitric oxide (NO) plays a key role in tumor progression, yet its precise function remains unclear due to its bimodal effect, which is influenced by its subcellular distribution. Factors such as membrane permeability, NO reactivity, and redox states of intracellular compartments may determine whether NO promotes or suppresses tumor growth. Current sensors are limited in providing spatial and temporal information about NO in live cells. Single-walled carbon nanotubes (SWNT), specifically (6,5) SWNT functionalized with (AT)15 DNA, have demonstrated potential for intracellular NO detection, but their organelle-specific localization and stability are unknown. In this study, we investigated the subcellular distribution, stability, and retention of (AT)15 SWNT sensors in triple-negative breast cancer cells to assess their suitability for long-term intracellular NO sensing. Fluorescence and hyperspectral microscopies were used to examine the localization of the SWNT sensors within the live cells. Our findings reveal that SWNT sensors have an initial higher colocalization with mitochondria followed by a time-dependent translocation to lysosomes. They do not alter basic cell functions, and they remain stable over time. These factors make (AT)15 SWNT ideal for studies elucidating the bimodal effects of NO in cancer progression, particularly by providing insights into organelle-specific NO dynamics.