The influence of systematic structure alterations on the photophysical properties and conjugation characteristics of asymmetric cyanine 5 dyes

Abstract

The light spectrum above 650 nm allows for good tissue penetration depths, far-red and nearinfrared fluorescent dyes are therefore popular fluorophores applied in (bio)medical diagnostics, including image-guided surgery. However, near-infrared fluorescent dyes often suffer from instability and limited brightness, two important features that, together with the labelling efficiency (e.g., non-one-or di-conjugated products) and serum-dye interactions are key elements that drive in vivo characteristics. Due to the fact that stability and brightness of far-red fluorophores are often superior over near-infrared dyes, interest in the use of dyes such as Cy5 is increasing. As there are clear indications that the influence of the chemical structure on the (photo)physical properties of a dye is dye-structure-dependent, the (photo)physical properties of ten structural variants of asymmetrical Cy5-(R1)R2-(R3)COOH (R representing the varied substituents) were extensively studied, While stacking in solution was not induced in most of the Cy5 far-red fluorophores, multimers and 2 stacking characteristics were observed in protein conjugates. And although all dye variants were shown to be stable towards photobleaching, clear differences in brightness and serum interactions were found. Combined, these findings indicate that the chemical substituents prominently influence the photophysical properties of Cy5 dyes, a feature that should be considered when using fluorescent dyes in future tracer development.

Computational and experimental data on electrostatic density and stacking tendency of asymmetric cyanine 5 dyes

“…Synthesis of compound 2 – 11 was performed according to previous reports [1]. Absorbance spectra were measured with the Ultrospec 3000 UV–Visible spectrophotometer (Pharmacia Biotech) according to previously described methods [1].…”

“…Absorbance spectra were measured with the Ultrospec 3000 UV–Visible spectrophotometer (Pharmacia Biotech) according to previously described methods [1].…”

“…1. These structural analogues were analyzed to determine whether molecular substituents on the fluorophore influences their utility as an imaging label [1].…”

“…Previous reports describe the stacking of methylene blue ( 1 ) [1] and this dye is therefore not included in this Data in Brief. The absorption spectra were assessed at concentrations ranging from 0.3 to 100.0 µM as the stacking characteristic of a dye is concentration-dependent.…”

“…The influence of systematic structure alterations on the photophysical properties and conjugation characteristics of asymmetric cyanine 5 dyes. Dyes and Pigments.2018152:19–28 [1]…”