Chirality Enriched (12,1)
and (11,3) Single-Walled
Carbon Nanotubes for Biological Imaging
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Abstract
The intrinsic band gap photoluminescence of semiconducting
single-walled
carbon nanotubes (SWNTs) makes them promising biological imaging probes
in the second near-infrared (NIR-II, 1.0–1.4 μm) window.
Thus far, SWNTs used for biological applications have been a complex
mixture of metallic and semiconducting species with random chiralities,
preventing simultaneous resonant excitation of all semiconducting
nanotubes and emission at a single well-defined wavelength. Here,
we developed a simple gel filtration method to enrich semiconducting
(12,1) and (11,3) SWNTs with identical resonance absorption at ∼808
nm and emission near ∼1200 nm. The chirality sorted SWNTs showed
∼5-fold higher photoluminescence intensity under resonant excitation
of 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
was achieved using a ∼6-fold lower injected dose of (12,1)
and (11,3) SWNTs (∼3 μg per mouse or ∼0.16 mg/kg
of body weight vs 1.0 mg/kg for unsorted SWNTs) than a previous heterogeneous
mixture, demonstrating the first resonantly excited and chirality
separated SWNTs for biological imaging