Design of AIEgens for near-infrared IIb imaging through structural modulation at molecular and morphological levels

Li, Yuanyuan; Cai, Zhaochong; Liu, Shunjie; Zhang, Haoke; Wong, Ting Hei; Lam, Jacky W. Y.; Kwok, Ryan T. K.; Qian, Jun; Tang, Ben Zhong

doi:10.1038/s41467-020-15095-1

Cited by 319 publications

(175 citation statements)

References 63 publications

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“…The fluorescence quenching of D–A–D chromophores in water is associated with the formation of the dark TICT state, in which intramolecular rotation results in nonradiative deactivation of the excited state. 102 TICT is governed by a driving force, which depends on solvent polarity, steric hindrance, and the electron-donating strength of the donor groups. Restricting molecular rotation or encapsulating the molecule into a nanomicelle to prevent water contact can straightforwardly produce a brilliant increase in fluorescent brightness.…”

Section: Nir-ii Linear Emission For Deep-tissue Bioimagingmentioning

confidence: 99%

“…Furthermore, the small bowel diverticula (∼1 mm) could be observed under 5 mm tissue penetration with an SBR of 2.7 ( Figure 4 h). 102 Such distortion not only prevents intermolecular interactions but also provides certain spatial isolation of the molecules in aggregates to promote the intramolecular rotation of triphenylamine units, which were conducive to the formation of the TICT state.…”

Section: Nir-ii Linear Emission For Deep-tissue Bioimagingmentioning

confidence: 99%

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Molecular Fluorophores for Deep-Tissue Bioimaging

2020

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Fluorescence imaging has made tremendous inroads toward understanding the complexity of biological systems, but in vivo deep-tissue imaging remains a great challenge due to the optical opacity of biological tissue. Recent improvements in laser and detector manufacturing have allowed the expansion of nonlinear and linear fluorescence imaging to the underexplored “tissue-transparent” second near-infrared (NIR-II; 1000–1700 nm) window, opening up new opportunities for optical access deep inside opaque tissue. Molecular fluorophores have historically played a major role in fluorescence bioimaging. It is increasingly important to design new molecular fluorophores to fully unlock the potential of NIR-II imaging techniques. In this outlook, we give an overview of the novel molecular fluorophores developed for deep-tissue bioimaging in the past five years and discuss their pros and cons in applications. Guidelines for designing new molecular fluorophores with the desirable properties are also provided.

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Section: Nir-ii Linear Emission For Deep-tissue Bioimagingmentioning

confidence: 99%

Section: Nir-ii Linear Emission For Deep-tissue Bioimagingmentioning

confidence: 99%

Molecular Fluorophores for Deep-Tissue Bioimaging

2020

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“…In order to fabricate NIR absorbing or emitting materials, several strategies are generally applied to tune the energy gap in these materials. They involve the extension of the length of π-conjugation in unsaturated molecules 13 and the introduction of metal centers into coordination compounds 8 , as well as the association of electron-donor and acceptor units in molecular materials 14 , 15 . Moreover, two-photon absorption (TPA) materials, through the absorption of two photons simultaneously, are capable of converting the excitation wavelengths from the visible to the NIR region.…”

Section: Introductionmentioning

confidence: 99%

Two-photon excited deep-red and near-infrared emissive organic co-crystals

Wang

et al. 2020

Nat Commun

118

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Two-photon excited near-infrared fluorescence materials have garnered considerable attention because of their superior optical penetration, higher spatial resolution, and lower optical scattering compared with other optical materials. Herein, a convenient and efficient supramolecular approach is used to synthesize a two-photon excited near-infrared emissive co-crystalline material. A naphthalenediimide-based triangular macrocycle and coronene form selectively two co-crystals. The triangle-shaped co-crystal emits deep-red fluorescence, while the quadrangle-shaped co-crystal displays deep-red and near-infrared emission centered on 668 nm, which represents a 162 nm red-shift compared with its precursors. Benefiting from intermolecular charge transfer interactions, the two co-crystals possess higher calculated two-photon absorption cross-sections than those of their individual constituents. Their two-photon absorption bands reach into the NIR-II region of the electromagnetic spectrum. The quadrangle-shaped co-crystal constitutes a unique material that exhibits two-photon absorption and near-infrared emission simultaneously. This co-crystallization strategy holds considerable promise for the future design and synthesis of more advanced optical materials.

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“…Traditionally, most NIR-II fluorophores are derived from D-A-D structures. In these molecules, benzobisthiadiazole (BBTD) is often employed as strong acceptors, whose stabilized quinoidal structure can redshift the emission to the NIR-II region [ [45] , [46] , [47] ]. Electron donors play decisive roles in the fluorescence properties of D-A-D fluorophores.…”

Section: Resultsmentioning

confidence: 99%

A two-in-one Janus NIR-II AIEgen with balanced absorption and emission for image-guided precision surgery

Liu

Zhang

et al. 2021

Materials Today Bio

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Fluorescence imaging in the near-infrared II (NIR-II, 1000–1700 nm) region opens up new avenues for biological systems due to suppressed scattering and low autofluorescence at longer-wavelength photons. Nonetheless, the development of organic NIR-II fluorophores is still limited mainly due to the shortage of efficient molecular design strategy. Herein, we propose an approach of designing Janus NIR-II fluorophores by introducing electronic donors with distinct properties into one molecule. As a proof-of-concept, fluorescent dye 2 TT- m, o C6B with both twisted and planar electronic donors displayed balanced absorption and emission which were absent in its parent compound. The key design strategy for Janus molecule is that it combines the merits of intense absorption from planar architecture and high fluorescence quantum yield from twisted motif. The resulting 2 TT- m, o C6B nanoparticles exhibit a high molar absorptivity of 1.12 ⨯10 4 M −1 cm −1 at 808 nm and a NIR-II quantum yield of 3.7%, displaying a typical aggregation-induced emission (AIE) attribute. The highly bright and stable 2 TT- m, o C6B nanoparticles assured NIR-II image-guided cancer surgery to resect submillimeter tumor nodules. The present study may inspire further development of molecular design philosophy for highly bright NIR-II fluorophores for biomedical applications.

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Design of AIEgens for near-infrared IIb imaging through structural modulation at molecular and morphological levels

Cited by 319 publications

References 63 publications

Molecular Fluorophores for Deep-Tissue Bioimaging

Molecular Fluorophores for Deep-Tissue Bioimaging

Two-photon excited deep-red and near-infrared emissive organic co-crystals

A two-in-one Janus NIR-II AIEgen with balanced absorption and emission for image-guided precision surgery

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