Chirality Enriched (12,1)\nand (11,3) Single-Walled\nCarbon Nanotubes for Biological Imaging

Abstract

The intrinsic band gap photoluminescence of semiconducting\nsingle-walled\ncarbon nanotubes (SWNTs) makes them promising biological imaging probes\nin the second near-infrared (NIR-II, 1.0–1.4 μm) window.\nThus far, SWNTs used for biological applications have been a complex\nmixture of metallic and semiconducting species with random chiralities,\npreventing simultaneous resonant excitation of all semiconducting\nnanotubes and emission at a single well-defined wavelength. Here,\nwe developed a simple gel filtration method to enrich semiconducting\n(12,1) and (11,3) SWNTs with identical resonance absorption at ∼808\nnm and emission near ∼1200 nm. The chirality sorted SWNTs showed\n∼5-fold higher photoluminescence intensity under resonant excitation\nof 808 nm than unsorted SWNTs on a per-mass basis. Real-time <i>in vivo</i> video imaging of whole mouse body and tumor vessels\nwas achieved using a ∼6-fold lower injected dose of (12,1)\nand (11,3) SWNTs (∼3 μg per mouse or ∼0.16 mg/kg\nof body weight vs 1.0 mg/kg for unsorted SWNTs) than a previous heterogeneous\nmixture, demonstrating the first resonantly excited and chirality\nseparated SWNTs for biological imaging.