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4-Acetamido-4'-((iodoacetyl)amino)Stilbene-2,2'-Disulfonic Acid, Disodium Salt (Invitrogen™)

The iodoacetamide derivative of stilbene (4-acetamido-4'-((iodoacetyl) amino)stilbene-2,2'-disulfonic acid, disodium salt) is readily conjugated to thiols. The combination of high polarity and membrane impermeability makes this polysulfonated dye useful for determining whether thiol-containing proteins and polypeptide chains are exposed at the extracellular or cytoplsamic membrane surface. Stilbene protein adducts are charged and can be detected by gel or capillary electrophoresis.

4-Acetamido-4'-Maleimidylstilbene-2,2'-Disulfonic Acid, Disodium Salt (Invitrogen™)

Our 4-acetamido-4'-maleimidylstilbene-2,2'- disulfonic acid is a thiol-reactive reagent that is water soluble, with high polarity and membrane impermeability. This polysulfonated dye is useful for determining whether thiol-containing proteins and polypeptide chains are exposed at the extracellular or cytoplasmic membrane surface.

Rhodamine Green™ Carboxylic Acid, Succinimidyl Ester, Hydrochloride (5(6)-CR 110, SE), mixed isomers (Invitrogen™)

This mixed isomer preparation of the amine-reactive Rhodamine Green carboxylic acid, succinimidyl ester yields bright and photostable conjugates. Rhodamine Green dye—labeled probes have been frequently used for Fluorescence Correlation Spectroscopy (FCS).

Rhodamine Green™-X, Succinimidyl Ester, Hydrochloride, mixed isomers (Invitrogen™)

The thiol-reactive Rhodamine Green®-X, succinimidyl ester can be used to create green-fluorescent bioconjugates with excitation/emission maxima ~502/527 nm. This dye is the nonsulfonated analog of the Alexa Fluor® 488 dye.

Qtracker™ 565 Vascular Labels (Invitrogen™)

Qtracker® non-targeted quantum dots are designed to be injected into the tail vein of mice for the study of vascular structure using small animal in vivo imaging (SAIVI) techniques. These nanocrystals exhibit intense fluorescence with red-shifted emission for increased tissue penetration, and have a PEG surface coating specially developed to minimize nonspecific interactions and reduce immune response by the tissue. Because the PEG surface coating does not contain reactive functional groups, the Qtracker® non-targeted quantum dots are retained in circulation longer and can be imaged for up to 3 hours with a single injection or for longer periods of time with additional injections.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Key Attributes:

Qtracker® 565 label has Ex/Em (405-525/565) nm
Designed for small animal in vivo imaging
Introduced via tail vein injection, can be imaged for up to 3 hours after injection
Available in four colors—565 nm, 655 nm, 705 nm, or 800 nm emission

Read more about SAIVI and about applications for Qdot® nanocrystals.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

Rhodamine Red™-X, Succinimidyl Ester, 5-isomer (Invitrogen™)

The amine-reactive Rhodamine Red™-X, succinimidyl ester can be used to create red-fluorescent bioconjugates with excitation/emission maxima ~560/580 nm. This reactive dye contains an additional seven-atom aminohexanoyl spacer ("X") between the fluorophore and the succinimidyl ester group. This spacer helps to separate the fluorophore from its point of attachment, potentially reducing the interaction of the fluorophore with the biomolecule to which it is conjugated.

ATTO-TAG™ FQ Derivatization Reagent (FQ; 3-(2-Furoyl)quinoline-2-Carboxaldehyde) (Invitrogen™)

The ATTO-TAG FQ reagent allows the ultrasensitive detection of primary amines. This reagent is available as a standalone product or as a component of an amine-derivatization kit (A-2334). Because ATTO-TAG FQ is nonfluorescent in the unreacted state and reacts specifically with amines to form highly fluorescent conjugates, it is particularly well-suited to the derivatization of peptides, amino acids, aminated sugars and other amine-containing molecules for detection by capillary electrophoresis with laser-induced fluorescence (LIF). Recently, researchers described a simple method in which the ATTO-TAG FQ reagent was used to derivatize very dilute solutions (10-8 M) of peptides.

pHrodo™ iFL Green STP Ester (amine-reactive) (Invitrogen™)

The amine-reactive pH-sensitive pHrodo iFL Green STP Ester dye is an improved version of pHrodo Green dye optimized for the creation of bioconjugates to be used in the study of antibody internalization, endocytosis, and phagocytosis. pHrodo iFL Green dye dramatically increases fluorescence as the pH of its surroundings become more acidic. It is more soluble than the original pHrodo Green dye, making it more useful for the labeling of antibodies that may otherwise precipitate out of solution during conjugation.

• Use pH-sensitive pHrodo iFL Green STP Ester to make pH-sensitive bioconjugates of your choice
• Get faster, more accurate results than with any other endocytosis or phagocytosis assay—no need for wash steps or quenchers
• Multiplex with red fluorescent markers such as RFP, pHrodo iFL Red STP, and many others

The increase in fluorescence of pHrodo iFL Green dye as the pH changes from basic to acidic correlates with the acidification of intracellular vesicles, making it a valuable tool for the study of endocytosis or phagocytosis and their regulation by environmental factors, drugs, or pathogens. The spectral properties of pHrodo iFL Green dye make it useful for multi-color experiments. pHrodo iFL Green dye can be detected using most standard green-fluorescent filter sets and has been validated for use in a variety of applications, including flow cytometry, fluorescent microscopy, and high content screening (HCS). The lack of fluorescence of pHrodo iFL Green dye in a typical extracellular environment eliminates the need for wash steps or quencher dyes in the experimental workflow.

pHrodo iFL Green STP Ester is an amine-reactive dye that can be used to make pHrodo iFL Green STP bioconjugates in aqueous buffer. The STP ester will react with primary amines on a protein, cell, or virus to create a stable conjugate that can be used in live cell assays or stored for later use.

DACM, N-(7-Dimethylamino-4-Methylcoumarin-3-yl))Maleimide (Invitrogen™)

The thiol reactive coumarin, DACM can be used to create blue-fluorescent bioconjugates. When compared with AMCA conjugates, conjugates of the UV light-excitable 7-dialkylaminocoumarin fluorophore have slightly longer-wavelength emission spectra (~470 nm). The unreacted reagent is nonfluorescent and can also be used to quantitate free thiols.

CellTrace™ Calcein Green, AM - Special Packaging (Invitrogen™)

CellTrace calcein green AM is a cell-permeant dye that can be used to determine cell viability in most eukaryotic cells. In live cells the nonfluorescent CellTrace calcein green AM is converted to a green-fluorescent calcein after intracellular esterases remove the acetoxymethyl (AM) esters. This dye is also available as 1 mg of the solid (C-1430) and resuspended in DMSO (C-3099). For a longer wavelength version of this dye, check out our CellTrace calcein red-orange AM (C-34851).

Qtracker™ 705 Vascular Labels (Invitrogen™)

Qtracker® non-targeted quantum dots are designed to be injected into the tail vein of mice for the study of vascular structure using small animal in vivo imaging (SAIVI) techniques. These nanocrystals exhibit intense fluorescence with red-shifted emission for increased tissue penetration, and have a PEG surface coating specially developed to minimize nonspecific interactions and reduce immune response by the tissue. Because the PEG surface coating does not contain reactive functional groups, the Qtracker® non-targeted quantum dots are retained in circulation longer and can be imaged for up to 3 hours with a single injection or for longer periods of time with additional injections.

Need a different emission spectrum or longer tracking? View our other mammalian cell tracking products.

Key Attributes:

Qtracker® 705 label has Ex/Em (405-665/705) nm
Designed for small animal in vivo imaging
Introduced via tail vein injection, can be imaged for up to 3 hours after injection
Available in four colors—565 nm, 655 nm, 705 nm, or 800 nm emission

Read more about SAIVI and about applications for Qdot® nanocrystals.

For Research Use Only. Not intended for any animal or human therapeutic or diagnostic use.

SAMSA Fluorescein, 5-((2-(and-3)-S-(acetylmercapto) succinoyl) amino) Fluorescein, mixed isomers (Invitrogen™)

SAMSA fluorescein is a useful reagent for forming fluorescent protein conjugates and for assaying maleimide and iodoacetamide moieties on proteins with fluorescein. SAMSA fluorescein is activated with base to remove the acetyl protecting group, thereby generating a thiol-containing fluorescein.

Molecular Probes® Cell Imaging Kit (Invitrogen™)

Fluorescence imaging protocols are sometimes complicated and tedious, with more time spent preparing samples and reagents than acquiring images and data. To help researchers focus more on biology and get results faster, we have developed a set of imaging reagents that emphasize user friendliness and workflow convenience.

The Molecular Probes® Cell Imaging Kit contains the following products:

NucBlue™ Live ReadyProbes™ Reagent (Cat. No. R37605)
NucRed™ Live 647 ReadyProbes™ Reagent (Cat. No. R37106)
ReadyProbes™ Cell Viability Imaging Kit, Blue/Green (Cat. No. R37609)
Goat Anti-Rabbit IgG (H+L) Secondary Antibody, Alexa Fluor™ 594 conjugate (Cat. No. R37117)
Goat Anti-Mouse lgG Secondary Antibody, Alexa Fluor™ 488 conjugate (Cat. No. R37120)
Image-iT™ FX Signal Enhancer ReadyProbes™ Reagent (Cat. No. R37107)

5-ROX, SE (5-Carboxy-X-Rhodamine, Succinimidyl Ester), single isomer (Invitrogen™)

The isomeric 5-ROX, SE is an amine-reactive form of carboxy-X-rhodamine and is widely used for oligonucleotide labeling and automated DNA sequencing applications.

SiteClick™ Qdot™ 625 Antibody Labeling Kit (Invitrogen™)

Create a perfectly labeled antibody with the SiteClick™ Qdot® 625 Antibody Labeling Kit. This kit replaces the conventional Qdot® 625 Antibody Conjugation Kit (A10197). Unlike the conventional amine-thiol crosslinker method, SiteClick™ labeling specifically attaches the label to the heavy chains of an IgG antibody, ensuring that the antigen-binding domains remain available for binding to your antigen target. This site selectivity is achieved by targeting the carbohydrate domains present on essentially all IgG antibodies regardless of isotype and host species. In addition, no harsh reduction steps are required, and the labeling is consistent and reproducible each time it is performed. Depending upon the label, the resulting SiteClick™ -labeled antibody can be used in flow cytometry, fluorescence imaging, or Western blot detection.

Important Features of the SiteClick™ Qdot® 625 Antibody Labeling Kit:

• Contains everything required to label 100 µg of IgG antibody
• Easy to follow step-by-step protocol
• Highly efficient, site-specific, reproducible labeling chemistry results in high quality antibody conjugate.
• Qdot® 625 labels can be used in confocal or traditional fluorescence microscopy.
• In flow cytometry, Qdot® 625 can be excited by the 488 nm line of the argon-ion laser, or alternatively via excitation at 405 nm. This is true of all Qdot® fluorophores.

Qdot® Fluorophores are Our Brightest Labels
Antibody conjugates made with Qdot® fluorophores produce fluorescence output that surpasses that of traditional organic dyes. Paired with the correct optical filters, Qdot® nanocrystals are as much as 50 times brighter. Read more about Qdot® nanocrystals or review additional product details in Qdot® Nanocrystals—Section 6.6 in the Molecular Probes® Handbook.

Learn More About Protein and Antibody Labeling
We offer a wide selection of Molecular Probes® antibody and protein labeling kits (see Antibody Labeling from A to Z). To learn more about our various kits, read Kits for Labeling Proteins and Nucleic Acids—Section 1.2 in the Molecular Probes® Handbook.

Custom SiteClick™ Antibody Labeling Services
If you have an antibody that is considered "difficult to label" or has lost activity after labeling using a conventional method, please contact our custom service representatives to determine whether the SiteClick™ Antibody Labeling Service would be right for your antibody. We offer complete custom SiteClick™ antibody labeling services with the option of multiple detection molecules including biotin, Alexa Fluor® dyes, Qdot® fluorophores, R-PE, and others.