A small-molecule dye for NIR-II imaging

Abstract

Fluorescent imaging of biological systems in the second near-infrared window (NIR-II) can probe tissue at centimetre depths and achieve micrometre-scale resolution at depths of millimetres. Unfortunately, all current NIR-II fluorophores are excreted slowly and are largely retained within the reticuloendothelial system, making clinical translation nearly impossible. Here, we report a rapidly excreted NIR-II fluorophore (∼90% excreted through the kidneys within 24 h) based on a synthetic 970-Da organic molecule (CH1055). The fluorophore outperformed indocyanine green (ICG)-a clinically approved NIR-I dye-in resolving mouse lymphatic vasculature and sentinel lymphatic mapping near a tumour. High levels of uptake of PEGylated-CH1055 dye were observed in brain tumours in mice, suggesting that the dye was detected at a depth of ∼4 mm. The CH1055 dye also allowed targeted molecular imaging of tumours in vivo when conjugated with anti-EGFR Affibody. Moreover, a superior tumour-to-background signal ratio allowed precise image-guided tumour-removal surgery.

Layer-by-layer assembled fluorescent probes in the second near-infrared window for systemic delivery and detection of ovarian cancer

“…2F). Based on previous reports (24,25), it is thought that QDs (∼6 nm), first encapsulated in amphiphilic PAA, can diffuse out of the LbL film and eventually be cleared via the renal system (26,27). Finally, the LbL dye complex presented an unusual fluorescence profile of the organs, in which the fluorescence intensity peaked at ∼24 h postinjection (Fig.…”

Fluorescent chemical probes for accurate tumor diagnosis and targeting therapy

“…Hong et al synthesized a soluble NIR-II emitting probe (5) for imaging the mouse lymphatic vasculature and sentinel lymphatic mapping near the tumor. 66 The fluorescent signal in 4T1 xenograft tumors was observed within 10 min after intradermal injection of 5-PEG. The probe 5-PEG was excreted through the kidneys within 24 h. Dye 5 also allowed targeted imaging of tumors in vivo when conjugated with an antiepidermal growth factor receptor (EGFR) antibody.…”

“…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.…”

Shortwave infrared fluorescence imaging with the clinically approved near-infrared dye indocyanine green

“…Increasing the quantum yield, functionality, and biocompatibility of SWIR fluorophores is an active focus of emerging research studies (24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41).…”