Peptidomimetic Modified Heptamethine Cyanine Dyes for Enhanced Bioimaging Targetability: A Molecular Interaction Study on Bovine Serum Albumin and Human Parvalbumin

Cyanine dyes have found great applications in bioimaging
due to
their NIR-emitting capabilities. In this work, six heptamethine cyanine
dyes (TEA1–6) were designed, synthesized, and
photophysically studied. While they had strong absorption, their fluorescence
was quenched in aqueous solutions. The dyes incorporated amide linkages
and amino acid moieties, intended to mimic the peptide bonds to potentially
improve biological interactions. This hypothesis was tested by examining
the potential interactions between the dyes and two common biological
proteins, bovine serum albumin (BSA) and human parvalbumin (HPA).
Interestingly, the dyes’ nonfluorescent behavior in aqueous
solutions was reversed upon the addition of the proteins BSA or HPA.
This was hypothesized to be due to the binding interactions with these
proteins and the disruption of the aggregates formed in aqueous solutions.
These findings showed that peptide-like substituents could help promote
protein recognition and open the horizon for more implementation in
biomedical applications