High performance in vivo near-IR (>1 μm) imaging and photothermal cancer therapy with carbon nanotubes

TLDR

Short single‑walled carbon nanotubes (SWNTs) functionalized by PEGylated phospholipids are biologically non‑toxic, long‑circulating nanomaterials with intrinsic near‑infrared photoluminescence, characteristic Raman spectra, and strong optical absorbance in the NIR. This work demonstrates the first dual application of intravenously injected SWNTs as photoluminescent agents for in vivo tumor imaging in the 1.0–1.4 µm emission region and as 808 nm absorbers and heaters for photothermal tumor elimination at the lowest reported injected dose (70 µg SWNT/mouse, 3.6 mg/kg) and laser power (0.6 W/cm²). The authors injected PEGylated SWNTs intravenously, used them for NIR photoluminescent imaging in the 1.0–1.4 µm range, applied 808 nm laser irradiation for photothermal ablation, and compared their performance to gold nanorods at higher doses. Ex vivo Raman imaging confirmed tumor‑localized SWNTs, and treated mice showed complete tumor eradication without toxicity for over six months, achieving superior efficacy at tenfold lower doses and laser powers than gold nanorods, underscoring the advantages of biocompatible SWNTs for combined imaging and therapy.

Abstract

Short single-walled carbon nanotubes (SWNTs) functionalized by PEGylated phospholipids are biologically non-toxic and long-circulating nanomaterials with intrinsic near infrared photoluminescence (NIR PL), characteristic Raman spectra, and strong optical absorbance in the near infrared (NIR). This work demonstrates the first dual application of intravenously injected SWNTs as photoluminescent agents for in vivo tumor imaging in the 1.0–1.4 μm emission region and as NIR absorbers and heaters at 808 nm for photothermal tumor elimination at the lowest injected dose (70 μg of SWNT/mouse, equivalent to 3.6 mg/kg) and laser irradiation power (0.6 W/cm2) reported to date. Ex vivo resonance Raman imaging revealed the SWNT distribution within tumors at a high spatial resolution. Complete tumor elimination was achieved for large numbers of photothermally treated mice without any toxic side effects after more than six months post-treatment. Further, side-by-side experiments were carried out to compare the performance of SWNTs and gold nanorods (AuNRs) at an injected dose of 700 μg of AuNR/mouse (equivalent to 35 mg/kg) in NIR photothermal ablation of tumors in vivo. Highly effective tumor elimination with SWNTs was achieved at 10 times lower injected doses and lower irradiation powers than for AuNRs. These results suggest there are significant benefits of utilizing the intrinsic properties of biocompatible SWNTs for combined cancer imaging and therapy.