6 Perspective
Organic dyes and inorganic particles in NIR-II range emission have been designed
and synthesized. To expand and accelerate the applications of NIR-II imaging from
experimental animal models to clinical translatability and applicability, in particular,
for the understanding of design and synthesis mechanism and pathways in living
organisms, several key points should be noted.
1. NIR-II imaging clinical translation: Preclinical research is the first step on the way
to translate NIR-II imaging techniques into clinic. Conventional NIR-I dye ICG
has been demonstrated to be capable for NIR-II imaging, which makes quick
clinical translation of NIR-II imaging highly feasible. However, the
photostability, NIR-II efficiency, in vivo pharmacokinetics, as well as the
targeting specificity should be optimized before the clinical application. In
addition, how to via chemical functionalize the ICG structure leading to emission
peak red shift into NIR-II region will be great significance. Moreover,
bioconjugation ICG to targeting ligands will be the highly useful visualization
of specific structures during cancer screening or image-guided surgery.
2. Design and synthesis of new NIR-II fluorophores: High quantum yield,
physiochemical stability, photostability, and non-biotoxicity are the first several
important criteria to be considered for designing new generation of NIR-II
fluorophores. In addition, the direct synthesis of NIR-II fluorophores with
targeting group rather than post-synthetic surface targeting modifications is
more effective in improving therapeutic efficacy. Synthesis of biodegradable
NIR-II fluorophores should be encouraged. The biological use of these NIR-II
fluorophores was only recently reported, and further improvements are required,
including their synthesis process according to the FDA’s current GMP
regulations.
3. Multimodal imaging: The NIR-II penetration depth is still limited in 10 mm.
Combining with other imaging mobility is an alternative method to achieve
higher-resolution images. Considering PET can be used in preoperative imaging,
⁄
ä
Fig. 22 (continued) and NIR-IIb windows. Scale bars: 40 μm. (k) Noninvasive, high-resolution
NIR-IIa fluorescence imaging of mouse brain vasculature from low magnification to high magnification of cerebral vascular image taken at the depth of 2.6 mm. (l) Bright-field/NIR-II fluorescence
(green) overlaid images showing a healthy mouse liver (top) and a mouse liver with inflammation
(bottom), with clear quenching of the NIR-II fluorescence due to inflammation. (a, b) Reprinted
(adapted) with permission from Ref. [27], Copyright 2012, American Chemical Society. (c–f)
Reprinted (adapted) with permission from Ref. [28], Copyright 2011, National Academy of
Sciences. (g) Reprinted (adapted) with permission from Ref. [29], Copyright 2012, Nature Publishing Group. (h) Reprinted (adapted) with permission from Ref. [31], Copyright 2016, Nature
Publishing Group. (i, j) Reprinted (adapted) with permission from Ref. [32], Copyright 2015,
Wiley-VCH Verlag GmbH & Co. KGaA. (k) Reprinted (adapted) with permission from Ref. [30],
Copyright 2014, Nature Publishing Group. (l) Reprinted (adapted) with permission from Ref. [33],
Copyright 2013, Nature Publishing Group
Advancements of Second Near-Infrared Biological Window Fluorophores:. . .
115
Organic dyes and inorganic particles in NIR-II range emission have been designed
and synthesized. To expand and accelerate the applications of NIR-II imaging from
experimental animal models to clinical translatability and applicability, in particular,
for the understanding of design and synthesis mechanism and pathways in living
organisms, several key points should be noted.
1. NIR-II imaging clinical translation: Preclinical research is the first step on the way
to translate NIR-II imaging techniques into clinic. Conventional NIR-I dye ICG
has been demonstrated to be capable for NIR-II imaging, which makes quick
clinical translation of NIR-II imaging highly feasible. However, the
photostability, NIR-II efficiency, in vivo pharmacokinetics, as well as the
targeting specificity should be optimized before the clinical application. In
addition, how to via chemical functionalize the ICG structure leading to emission
peak red shift into NIR-II region will be great significance. Moreover,
bioconjugation ICG to targeting ligands will be the highly useful visualization
of specific structures during cancer screening or image-guided surgery.
2. Design and synthesis of new NIR-II fluorophores: High quantum yield,
physiochemical stability, photostability, and non-biotoxicity are the first several
important criteria to be considered for designing new generation of NIR-II
fluorophores. In addition, the direct synthesis of NIR-II fluorophores with
targeting group rather than post-synthetic surface targeting modifications is
more effective in improving therapeutic efficacy. Synthesis of biodegradable
NIR-II fluorophores should be encouraged. The biological use of these NIR-II
fluorophores was only recently reported, and further improvements are required,
including their synthesis process according to the FDA’s current GMP
regulations.
3. Multimodal imaging: The NIR-II penetration depth is still limited in 10 mm.
Combining with other imaging mobility is an alternative method to achieve
higher-resolution images. Considering PET can be used in preoperative imaging,
⁄
ä
Fig. 22 (continued) and NIR-IIb windows. Scale bars: 40 μm. (k) Noninvasive, high-resolution
NIR-IIa fluorescence imaging of mouse brain vasculature from low magnification to high magnification of cerebral vascular image taken at the depth of 2.6 mm. (l) Bright-field/NIR-II fluorescence
(green) overlaid images showing a healthy mouse liver (top) and a mouse liver with inflammation
(bottom), with clear quenching of the NIR-II fluorescence due to inflammation. (a, b) Reprinted
(adapted) with permission from Ref. [27], Copyright 2012, American Chemical Society. (c–f)
Reprinted (adapted) with permission from Ref. [28], Copyright 2011, National Academy of
Sciences. (g) Reprinted (adapted) with permission from Ref. [29], Copyright 2012, Nature Publishing Group. (h) Reprinted (adapted) with permission from Ref. [31], Copyright 2016, Nature
Publishing Group. (i, j) Reprinted (adapted) with permission from Ref. [32], Copyright 2015,
Wiley-VCH Verlag GmbH & Co. KGaA. (k) Reprinted (adapted) with permission from Ref. [30],
Copyright 2014, Nature Publishing Group. (l) Reprinted (adapted) with permission from Ref. [33],
Copyright 2013, Nature Publishing Group
Advancements of Second Near-Infrared Biological Window Fluorophores:. . .
115