Furan Donor for NIR-II Molecular Fluorophores with Enhanced Bioimaging Performance

Abstract

The second near-infrared (NIR-II, 1,000 to 1,700 nm) molecular fluorophores containing donor–acceptor–donor conjugated backbone have attracted substantial attention due to their outstanding advantages, such as stable emission and facilely tuned photophysical properties. However, it is still challenging for them to simultaneously achieve high brightness and red-shifted absorption and emission. Herein, furan is adopted as the D unit to construct NIR-II fluorophores, demonstrating red shift of absorption, enhanced absorption coefficient, and fluorescent quantum yield when compared with the generally used thiophene counterparts. The high brightness and desirable pharmacokinetics of the optimized fluorophore, IR-FFCHP, endows improved performance for angiography and tumor-targeting imaging. Furthermore, dual-NIR-II imaging of tumor and sentinel lymph nodes (LNs) has been achieved with IR-FFCHP and PbS/CdS quantum dots, enabling the in vivo imaging navigated LN surgery in tumor-bearing mice. This work demonstrates the potential of furan for constructing bright NIR-II fluorophores for biological imaging.

Boosting Luminescence Efficiency of Near-Infrared-II Aggregation-Induced Emission Luminogens via a Mash-Up Strategy of π-Extension and Deuteration for Dual-Model Image-Guided Surgery

“…As presented in Figure d–f, after intravenous injection of NDA-PDTPE NPs, the PA signal and fluorescence intensity of tumor sites gradually intensified as time elapsed, which met the prerequisite of surgical excision. Sentinel LNs were the principal pathway in tumor metastasis, which was closely related to tumor prognosis, tumor staging, and treatment decision . Thus, visualizing the metastasis of the tumor in sentinel LNs during tumor surgery is crucial.…”

2, 1, 3‐Benzothiadiazole Derivative Small Molecule Fluorophores for NIR‐II Bioimaging

“…However, most S-D-A-D-S structure fluorophores that use alkyl thiophene as donor will result in hypsochromic shifted spectra. [11b,40] To solve this problem, Liang et al [41] started to use furan as the donor, IR-FFC8 constructed by n-octyl modified furan donor and IR-FFCH constructed by 2-cyclohexylmethyl modified furan donor were designed in 2023. Compared with thiophene, furan has a stronger electron donating ability and a smaller oxygen atom size, which allows the molecule to have a stronger ICT effect and less skeletal distortion, bringing about a bathochromic-shift and intensive absorption properties.…”

“…Meanwhile, high-performance imaging is of great help to the surgical treatment of tumors. Liang et al [41] designed the S-D-A-D-S structured fluorescent molecular IR-FFCHP with a QY 7.3% for in vivo whole-body angiography and imaging-guided tumor surgery treatment in mice (Figure 9c). IR-FFCHP performs well in both angiography and tumor imaging due to its low biotoxicity, high brightness, and long circulation time in mice.…”

“…Adapted under the terms of the CC‐BY license. [ 41 ] Copyright 2023, American Association for the Advancement of Science.…”

Brightness Strategies toward NIR-II Emissive Conjugated Materials: Molecular Design, Application, and Future Prospects

“…Ma et al used donor PDOTs to replace EDOTs to achieve weaker effects on backbone distortion, maintaining the ICT effect . Subsequently, the ability of shielding units to improve the brightness of NIR-II emissive conjugated materials was reported. − Dai’s group employed two 9,9′-dialkyl-substituted fluorene molecules as shielding units and designed the material IR-FEP based on a conjugated skeleton. IR-FEP had a greater QY (2%, solvent: H 2 O) and ε (5.69 × 10 3 L mol –1 cm –1 ) than IR-BBEP (QY = 0.4%, ε = 4.1 × 10 3 L mol –1 cm –1 , solvent: H 2 O) without shielding units (Figure ).…”