Fluorescent-Labeled Peptides

Fluorescent-labeled peptides are a class of bioactive peptides covalently conjugated with fluorescent moieties, enabling molecular-level visualization with high sensitivity, safety, and cost-effectiveness. The principle relies on the fact that fluorophores contain conjugated double-bond systems that, upon excitation by ultraviolet or violet-blue light, return from an excited state to the ground state while releasing photons, thereby generating detectable fluorescence signals.

1. Key Features and Advantages

High sensitivity: Capable of detecting molecules at very low concentrations for precise imaging.

Non-radioactive and safe: No radioactive contamination, ensuring safe experimental operations.

Cost-effective: More economical compared with radioactive labeling or advanced imaging technologies.

2.Selection of Fluorophores

In vitro studies: Fluorophores with emission wavelengths of 400–600 nm (e.g., AMC, FITC, TAMRA) are widely applied in cell-based or protein-based assays.

In vivo imaging: Fluorophores with emission wavelengths of 650–900 nm (e.g., ICG, Cy5.5, Nile Blue) provide strong tissue penetration and low background interference.

3. Applications of Fluorescent-Labeled Peptides

3.1 Peptide Synthesis and Labeling

Fluorophores are typically conjugated to the N-terminus or C-terminus of peptides via covalent bonds to preserve biological activity. For long-chain peptides, FRET (Förster Resonance Energy Transfer) donor–acceptor pairs can be introduced within the sequence to investigate protein–protein interactions.

3.2 Application of FRET Technology

FRET technology enables the study of intermolecular interactions through non-radiative energy transfer between donor and acceptor fluorophores. FRET efficiency is inversely proportional to the sixth power of the donor–acceptor distance, allowing precise monitoring of protein–protein interactions, enzymatic activity, and molecular dynamics.

3.3 In vitro and In vivo Imaging

In vitro imaging: Confocal and fluorescence microscopy with labeled peptides allows efficient investigation of intracellular molecular targets and biological processes.

In vivo imaging: Fluorescent-labeled peptides enable real-time imaging in living organisms, applied in angiography, tumor imaging, and other biomedical fields, supporting precision medicine and personalized therapeutic strategies.

4.Common Fluorescent Modifications for Peptides

Name	Excitation (nm)	Emission (nm)	Emission Color
7-Methoxycoumarin-4-acetic acid	328	393	Blue
FITC-Ahx	494	521	Green
FAM	495	520	Green
Cy3	555	570	Yellow
5-Carboxytetramethylrhodamine (TMR)	542	568	Orange
Cy5	646	662	Red
Cy5.5	673	707	Near-infrared
Cy7	750	773	Near-infrared

5.Representative FRET Pairs

Donor	Ex (nm)	Em (nm)	Acceptor	Ex (nm)	Em (nm)
Cy2	490	510	Cy3	555	570
FITC	494	521	TRITC	557	576
FAM	495	520	Cy3	555	570
FAM	495	520	Texas Red	589	615
FAM	495	520	Cy5	646	662
Cy3	555	570	Cy5	646	662
EDANS	335	493	DABCYL	453	-
Glu(EDANS)-NH2	335	493	DABCYL	453	-
MCA	328	393	DNP	348	-
Abz	330	420	DNP	348	-
Abz	330	420	Tyr (3-NO2)	360	-

6. Quotation and Ordering

Detailed workflows, technical specifications, and quotation information for customized fluorescent peptide services are available on our official website. Professional technical support will be provided to meet your research needs.

Aladdin: https://www.aladdinsci.com/