Combining Aminocyanine Dyes with Polyamide Dendrons: A Promising Strategy for Imaging in the Near‐Infrared Region

Abstract

Cyanine dyes are known for their fluorescence in the near-IR (NIR) region, which is desirable for biological applications. We report the synthesis of a series of aminocyanine dyes containing terminal functional groups such as acid, azide, and cyclooctyne groups for further functionalization through, for example, click chemistry. These aminocyanine dyes can be attached to polyfunctional dendrons by copper-catalyzed azide alkyne cycloaddition (CuAAC), strain-promoted azide alkyne cycloaddition (SPAAC), peptide coupling, or direct S(NR)1 reactions. The resulting dendron-dye conjugates were obtained in high yields and displayed high chemical stability and photostability. The optical properties of the new compounds were studied by UV/Vis and fluorescence spectroscopy. All compounds show large Stokes shifts and strong fluorescence in the NIR region with high quantum yields, which are optimal properties for in vivo optical imaging.

Generation 3 PAMAM dendrimer TAMRA conjugates containing precise dye/dendrimer ratios

“…Many groups have explored strategies to improve the control over fluorophore/dendrimer ratios since the relatively lower polydispersity index (PDI) of dendrimers and/or synthetic methodologies make this class of scaffold attractive for addressing the challenges [7–14]. Approaches include dye encapsulation [12–14], employing the core of the dendrimer as the dye [11], and convergent synthesis starting with the dye [8,9]. All of these approaches have particular advantages and limitations.…”

Lipo‐Poly(L‐histidine) Hybrid Materials with pH‐Sensitivity, Intracellular Delivery Efficiency, and Intrinsic Targetability to Cancer Cells

“…Compared to the 1 H NMR calculation of , in all cases, the GPC data showed a difference between the two MWs, presumably due to the polystyrene standards used for molecular weight calibration . In order to facilitate the dye conjugation, IR‐820 dye was initially reacted with aminocaproic acid in the presence of a base in dimethylformamide (DMF), and the resulting product was treated with DPPE–p(His) in the presence of N ‐hydroxysuccinimide (NHS) to give the NIR prodrug (see Figure S2 in the Supporting Information for UV/vis absorption spectra) …”

Disulfide Cross‐Linked Polypeptide Nanogel Conjugated with a Fluorescent Probe as a Potential Image‐Guided Drug‐Delivery Agent

“…Click chemistry has been widely adopted to prepare various polymer–polymer or polymer–small molecule conjugates because of its excellent efficiency 28. It should be noted that because of the cyanine dye's tendency to coordinate with copper ions,29 an excess amount of PMDETA (2 equiv. to CuBr) was used to ensure a complete coordination of the Cu + ion before the addition of the alkyne cyanine.…”