PAMAM structure-based multifunctional fluorescent conjugates for improved fluorescent labelling of biomacromolecules.

Area of Science:

• Bioconjugation Chemistry
• Fluorescence Imaging
• Medicinal Chemistry

Background:

• Fluorescent probes are crucial for visualizing cellular structures and functions in biological and medicinal applications.
• High fluorescence signal intensity is vital for accurate investigations, but achieving this often compromises the carrier's structural integrity.
• Polyvalent molecules capable of hosting multiple dyes are desirable for intense signals without significant structural damage.

Purpose of the Study:

• To synthesize and characterize novel fluorescent dye oligomers based on polyamidoamine (PAMAM) dendrimers.
• To evaluate the fluorescence properties and reactivity of various dye-dendrimer conjugates.
• To demonstrate the applicability of these dye multimers for labeling large biomolecules like antibodies.

Main Methods:

• Synthesis of PAMAM dendrimers using an improved protocol for homogeneous scaffolds with numerous conjugation sites.
• Coupling of diverse fluorescent dyes (dansyl, NBD, coumarin-343, fluorescein, sulforhodamine B2) to the dendrimer scaffolds.
• Characterization of dye oligomers and conjugation of a dansylated dendrimer to an anti-EGFR antibody (hMAb425) for functional assessment.

Main Results:

• The improved PAMAM dendrimer synthesis yielded scaffolds with up to 128 conjugation sites.
• Among the investigated dye oligomers, only dansylated dendrimers exhibited significantly enhanced fluorescence signals.
• The conjugate of a 16-dye dansylated dendrimer with hMAb425 showed preserved immunoreactivity of 54%.

Conclusions:

• Dansylated PAMAM dendrimers are effective for creating highly fluorescent dye multimers.
• These dye oligomers enable efficient labeling of proteins and large molecules, leading to high contrast in fluorescence applications.
• The developed dye multimers show promise for advanced biological imaging and diagnostics.