Invited Presentation: SWCNT-Based Fluorescent Immunoprobes for Short-Wave Infrared Cancer Detection

One of the most unusual properties of semiconducting single-walled carbon nanotubes (SWCNT) is the emission of distinct fluorescence peaks at short-wave infrared (SWIR) wavelengths that depend on specific nanotube structure, or (n,m) indices. This emission is promising for biological marker applications because the peaks are spectrally sharp and distinguishable, they fall in a spectral region of very low autofluorescence backgrounds, and the nanotubes are highly resistant to photobleaching. In order to exploit these properties, we are conjugating structure-sorted SWCNTs to antibodies to make novel fluorescent immunoprobes. Our initial approach has involved covalent linkage of generic IgG antibodies to the polyethylene glycol sidearm of a phospholipid surfactant used to noncovalently coat surfaces of individual SWCNTs. We have optimized our protocols by SWIR fluorescence imaging of flow cytometry beads linked to Protein G to capture the SWCNT-antibody conjugates. Studies to generate similar probes against important cancer biomarkers, such as the CA125 (MUC16), a 1.5mD heavily glycosylated mucin that is displayed on the surface of ovarian cancer cells, are in progress. We will describe results of experiments linking the OC125 antibody, which detects an epitope on the CA125 molecule, to (n,m)-sorted SWCNT samples followed by detection of CA125 on cultured ovarian cancer cells.