Developing Cytometries for Carbon Nanotube Fluorophores

Semiconducting single-wall carbon nanotubes (SWCNTs) have been demonstrated to be promising in vivo diagnostic probes due to their unique fluorescent properties in the short-wave infrared (SWIR), which ranges from 900 to 1,700 nm. The development of in vivo diagnostic modalities using SWCNT-based fluorescent probes will require fundamental studies of these probes in the cellular level, where many advanced bioanalytical tools need to be utilized for understanding their efficacies, side effects and many other metabolic and pathologic issues. Therefore, expanding the standard fluorescent-based analytical instruments from the visible to the SWIR range is necessary. In this work, we introduce SWIR-based flow and image cytometries for the cellular studies using racemic (6,5). We treated ssDNA-coated (6,5) with pre-incubated RAW macrophages and collected these treated cells for cytometric measurements. The absolute mass of the (6,5) in the cells was deduced and the detection limits of both systems were found to be in the level of femtograms of (6,5) per cell within a reasonable time of measurements. We will also conduct multi-channel measurements by combining the SWIR and visible channels for correlating SWCNT dose and cellular responses. We hope our study will fulfil this missing SWIR bioanalytical tool for SWCNT applications in the physiological systems.