Fluorescent organic dyes that absorb and emit in the near-infrared (NIR, 700–1000 nm) and shortwave infrared (SWIR, 1000–1700 nm) regions have the potential to produce noninvasive high-contrast biological images and videos. BODIPY dyes are well known for their high quantum yields in the visible energy region. To tune these chromophores to the NIR region, fused nitrogen-based heterocyclic indolizine donors were added to a BODIPY scaffold. The indolizine BODIPY dyes were synthesized via microwave-assisted Knoevenagel condensation with indolizine aldehydes. The non-protonated dyes showed NIR absorption and emission at longer wavelengths than an aniline benchmark. Protonation of the dyes produced a dramatic 0.35 eV bathochromic shift (230 nm shift from 797 nm to 1027 nm) to give a SWIR absorption and emission (λmaxemis = 1061 nm). Deprotonation demonstrates that material emission is reversibly switchable between the NIR and SWIR.
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Ultra‐Bright Near‐Infrared Sulfonate‐Indolizine Cyanine‐ and Squaraine‐Albumin Chaperones: Record Quantum Yields and Applications
The design of bright, high quantum yield (QY) materials in the near‐infrared (NIR) spectral region in water remains a significant challenge. A series of cyanine and squaraine dyes varying water solubilizing groups and heterocycles are studied to probe the interactions of these groups with albumin in water. Unprecedented, ′ultra‐bright′ emission in water is observed for a sulfonate indolizine squaraine dye (61.1 % QY) and a sulfonate indolizine cyanine dye (46.7 % QY) at NIR wavelengths of >700 nm and >800 nm, respectively. The dyes presented herein have a lower limit of detection than the most sensitive dyes known in the NIR region for albumin detection by at least an order of magnitude, which enables more sensitive diagnostic testing. Additionally, biotinylated human serum albumin complexed with the dyes reported herein was observed to function as an immunohistochemical reagent enabling high resolution imaging of cellular α‐tubulin at low dye concentrations.
more » « less- Award ID(s):
- 1757220
- PAR ID:
- 10371631
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- ChemPhotoChem
- Volume:
- 6
- Issue:
- 9
- ISSN:
- 2367-0932
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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