Near-Infrared Emitting Poly(amidoamine) Dendrimers with an Anthraquinone Core toward Versatile Non-Invasive Biological Imaging

Biomacromolecules. 2022 Mar 14;23(3):1392-1402. doi: 10.1021/acs.biomac.1c01604. Epub 2022 Mar 2.

Abstract

Today, there is a very strong demand for versatile near-infrared (NIR) imaging agents suitable for non-invasive optical imaging in living organisms (in vivo imaging). Here, we created a family of NIR-emitting macromolecules that take advantage of the unique structure of dendrimers. In contrast to existing fluorescent dendrimers bearing fluorophores at their periphery or in their cavities, a NIR fluorescent structure is incorporated into the core of the dendrimer. Using the poly(amidoamine) dendrimer structure, we want to promote the biocompatibility of the NIR-emissive system and to have functional groups available at the periphery to obtain specific biological functionalities such as the ability to deliver drugs or for targeting a biological location. We report here the divergent synthesis and characterization by NMR and mass spectrometries of poly(amidoamine) dendrimers derived from the fluorescent NIR-emitting anthraquinone core (AQ-PAMAF). AQ-PAMAFs ranging from the generation -0.5 up to 3 were synthesized with a good level of control resulting in homogeneous and complete dendrimers. Absorption, excitation, and emission spectra, as well as quantum yields, of AQ-PAMAFs have been determined in aqueous solutions and compared with the corresponding properties of the AQ-core. It has been demonstrated that the absorption bands of AQ-PAMAFs range from UV to 750 nm while emission is observed in the range of 650-950 nm. Fluorescence macroscopy experiments confirmed that the NIR signal of AQ-PAMAFs can be detected with a satisfactory signal-to-noise ratio in aqueous solution, in blood, and through 1 mm thick tissue-mimicking phantom. The results show that our approach is highly promising for the design of an unprecedented generation of versatile NIR-emitting agents.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthraquinones
  • Dendrimers* / chemistry
  • Fluorescent Dyes / chemistry
  • Polyamines / chemistry
  • Water

Substances

  • Anthraquinones
  • Dendrimers
  • Fluorescent Dyes
  • Poly(amidoamine)
  • Polyamines
  • Water