Donor Engineering for NIR-II Molecular Fluorophores with Enhanced Fluorescent Performance

Area of Science:

• Organic Chemistry
• Biomedical Imaging
• Materials Science

Background:

• Organic fluorophores are crucial for biological imaging in visible and first near-infrared (NIR-I) ranges.
• Limited fluorescence quantum yields (QYs) hinder the application of organic fluorophores in the second near-infrared window (NIR-II, 1000-1700 nm).

Purpose of the Study:

• To engineer high-performance organic fluorophores for enhanced NIR-II biological imaging.
• To address the limitations of low QYs in existing NIR-II fluorophores through molecular design.

Main Methods:

• Molecular engineering of donor units within a shielding unit-donor(s)-acceptor-donor(s)-shielding unit structure.
• Introduction of thiophene and alkyl thiophene as donor units to increase conjugation length and red-shift emission.
• Synthesis and characterization of the novel fluorophore IR-FTAP.

Main Results:

• The developed fluorophore IR-FTAP exhibits fluorescence emission at 1048 nm with a QY of 5.3% in aqueous solutions.
• This QY is among the highest reported for molecular NIR-II fluorophores.
• IR-FTAP demonstrated superior temporal and spatial resolutions in NIR-II imaging of mouse hindlimb vasculature.

Conclusions:

• Molecular engineering of donor units is an effective strategy to develop high-performance NIR-II fluorophores.
• The novel IR-FTAP fluorophore shows significant potential for advanced biological imaging in the NIR-II window.
• This advancement could lead to improved diagnostic and research capabilities in preclinical studies.