Chirality Enriched (12,1) and (11,3) Single-Walled Carbon Nanotubes for Biological Imaging

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 in vivo 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.

Fluorescent chemical probes for accurate tumor diagnosis and targeting therapy

“…In vivo NIR imaging was achieved over a period of 24 h. The fluorescence emission that lies in the first near-infrared window (NIR-I; 650-900 nm) is far superior to visible wavelengths, but a fluorophore that emits within the second nearinfrared window (NIR-II; 1000-1700 nm) exhibits a greater improvement in imaging quality, such as decreased tissue autofluorescence, reduced photon scattering, and low levels of photon absorption. [63][64][65][66] However, NIR-II fluorophores are often constrained by slow metabolism and long retention in the reticuloendothelial system. Hong et al synthesized a soluble NIR-II emitting probe (5) for imaging the mouse lymphatic vasculature and sentinel lymphatic mapping near the tumor.…”

Biological imaging without autofluorescence in the second near-infrared region

“…Recently, we, along with other researchers, discovered that fluorescence imaging in the second near-infrared region (NIR-II, 1,000-1,700 nm) is advantageous compared to that in the visible and traditional near-infrared regions with wavelengths less than 900 nm [15][16][17][18][19][20][21][22]. The NIR-II region affords higher spatial resolution at deeper tissue penetration depths owing to reduced photon scattering at longer wavelengths [15][16][17][18][19][20][21][22] as scattering of photons scales as λ -α (α = 0.…”

“…The NIR-II region affords higher spatial resolution at deeper tissue penetration depths owing to reduced photon scattering at longer wavelengths [15][16][17][18][19][20][21][22] as scattering of photons scales as λ -α (α = 0. [23].…”

Competitive Binding in Mixed Surfactant Systems for Single-Walled Carbon Nanotube Separation

“…20 The improved efficiency driven by the homogeneous electronic structure was corroborated by the Arnold group with a demonstration of a near single chirality (7,5) photovoltaic. 26 Among the several methods that exist to separate carbon nanotubes, advances in the gel-based separation, 1,2,[11][12][13][14][15][16][17][18][19][20][21][22][23]31,32 and more recently a two-phase method pioneered by the Zheng group, 9 seem to provide a promising path toward enabling industrial scale separations. Additional work by the Pang group has made significant advances in achieving a high dispersion of (6,5) SWNTs using π-conjugated polymers and helically binding polymers for length-specific SWNT fractions.…”