Promotional price valid on web orders only. Your contract pricing may differ. Interested in signing up for a dedicated account number?
Learn More

Invitrogen™ Alexa Fluor™ 430 NHS Ester (Succinimidyl Ester)

Used for stable signal generation in imaging and flow cytometry, Alexa Fluor™ 430 dye is water soluble and pH-insensitive from pH 4 to pH 10.

Supplier:  Invitrogen™ A10169


Catalog No. A10169

Add to Cart



In addition to reactive dye formulations, Invitrogen offers Alexa Fluor™ 430 dye conjugated to a variety of antibodies, peptides, proteins, tracers, and amplification substrates optimized for cellular labeling and detection.

The NHS ester (or succinimidyl ester) of Alexa Fluor™ 430 is the most popular tool for conjugating this dye to a protein or antibody. NHS esters can be used to label to the primary amines (R-NH2) of proteins, amine-modified oligonucleotides, and other amine-containing molecules. The resulting Alexa Fluor™ conjugate will exhibit brighter fluorescence and greater photostability than the conjugates of other spectrally similar fluorophores.

Detailed information about this AlexaFluor™ NHS ester:

Fluorophore label: Alexa Fluor™ 430 dye

Reactive group: NHS ester

Reactivity: Primary amines on proteins and ligands, amine-modified oligonucleotides

Ex/Em of the conjugate: 430/545 nm

Extinction coefficient: 15,000 cm-1M-1

Molecular weight: 701.8

Typical Conjugation Reaction

Conjugate amine-reactive reagents with virtually any protein or peptide (the provided protocol is optimized for IgG antibodies). You can scale the reaction for any amount of protein, but the concentration of the protein should be at least 2 mg/mL for optimal results. We recommend trying three different degrees of labeling, using three different molar ratios of the reactive reagent to protein.

The Alexa Fluor™ NHS ester is typically dissolved in high-quality anhydrous dimethylformamide (DMF) or dimethylsulfoxide (DMSO) (D12345), and the reaction is carried out in 0.1–0.2 M sodium bicarbonate buffer, pH 8.3, at room temperature for 1 hour. Because the pKa of the terminal amine is lower than that of the lysine epsilon-amino group, you may achieve more selective labeling of the amine terminus using a buffer closer to neutral pH.

Conjugate Purification

Labeled antibodies are typically separated from free Alexa Fluor™ dye using a gel filtration column, such as Sephadex™ G-25, BioGel™ P-30, or equivalent. For much larger or smaller proteins, select a gel filtration media with an appropriate molecular weight cut-off or purify by dialysis. We offer several purification kits optimized for different quantities of antibody conjugate:

Antibody Conjugate Purification Kit for 0.5-1 mg A33086)

Antibody Conjugate Purification Kit for 20-50 μg (A33087)

Antibody Conjugate Purification kit for 50-100 μg (A33088)

Learn More About Protein and Antibody Labeling

Invitrogen offers a wide selection of Molecular Probes™ antibody and protein labeling kits to fit your starting material and your experimental setup.



Store in freezer (-5 to -30°C) and protect from light.
Room Temperature
Alexa Fluor™ 430
Alexa Fluor™
Active Ester, Succinimidyl Ester
Alexa Fluor


Product Certifications


Provide Content Correction

The Fisher Scientific Encompass Program offers items which are not part of our distribution portfolio. These products typically do not have pictures or detailed descriptions. However, we are committed to improving your shopping experience. Please use the form below to provide feedback related to the content on this product.

Product Title

By clicking Submit, you acknowledge that you may be contacted by Fisher Scientific in regards to the feedback you have provided in this form. We will not share your information for any other purposes. All contact information provided shall also be maintained in accordance with our Privacy Policy.

Cancel Submit

For Research Use Only. Not for use in diagnostic procedures.