A new conjugate technology that provides higher signal to noise ratios for fluorescent imaging and western blotting

Invitrogen Alexa Fluor Plus secondary antibodies represent an advancement in fluorescent conjugate technology, designed to provide brighter signal, enhanced sensitivity, and minimal cross-reactivity in a variety of applications.

Obtain superior images with Alexa Fluor Plus secondary antibodies. Make your low-abundance targets visible, spend less time optimizing, and make every one of your precious samples count. Alexa Fluor Plus secondary antibodies have up to 4.2 times higher signal to noise in IF/ICC imaging and up to 5.8 times higher signal to noise ratio in western fluorescent blotting while having lower cross-reactivity compared to leading Alexa Fluor secondary antibodies, providing you with higher sensitivity and better signal-to-noise ratios for your critical experiments.

The development of Alexa Fluor Plus secondary antibodies is supported by two decades of our industry-leading research and experience with fluorescent probe technologies. With over 30,000 publications citing their use in research, Alexa Fluor secondary antibodies are the trusted name in fluorescent applications.

Features of Alexa Fluor Plus secondary antibodies

  • Higher signal-to-noise ratio, enabling detection of low-abundance targets
    • Up to 4.2 times higher to signal noise in IF/ICC imaging
    • Up to 5.8 times higher signal to noise in western fluorescent blotting
  • Enhanced sensitivity and greater range of linear detection

Alexa Fluor Plus 488 allows you to see greater detail and shows higher signal-to-noise – secondary  antibody conjugates of Alexa Fluor 488 (left) vs. Alexa Fluor Plus 488 (right). Immunofluorescent analysis of β-III tubulin in E18 Sprague Dawley primary cortical neuronal cells. The cells were fixed with 4% formaldehyde for 15 min, permeabilized with 0.25% Triton™ X-100 detergent in PBS for 10 min, and blocked with 3% BSA in PBS for 30 min at RT. Cells were stained with a β-III tubulin mouse monoclonal antibody (Cat. No. MA1-118) at a dilution of 1:200 in 3% BSA in PBS for 1 hr at RT, and then incubated with either Alexa Fluor 488 goat anti-mouse IgG secondary antibody (Cat. No. A-11029) or Alexa Fluor Plus 488 goat anti-mouse IgG secondary antibody (Cat. No. A32723) at a dilution of 1:1,000 for 1 hr at RT. Nuclei were stained with Hoechst 33342 stain (Cat. No. H3570). The image contains overlay of neuronal tubulin (green) and nuclei (blue). Images were taken on a Zeiss LSM 710 confocal microscope at 40x magnification.


Alexa Fluor Plus 555 enables detection of low abundant targets, showing higher signal-to-noise – secondary antibody conjugates of Alexa Fluor 555 (left) vs. Alexa Fluor Plus 555 (right). Immunofluorescent analysis of β-III tubulin in E18 Sprague Dawley primary cortical neuronal cells. The cells were fixed with 4% formaldehyde for 15 min, permeabilized with 0.25% Triton X-100 detergent in PBS for 10 min, and blocked with 3% BSA in PBS for 30 min at RT. Cells were stained with a β-III tubulin mouse monoclonal antibody (Cat. No. MA1-118) at a dilution of 1:200 in 3% BSA in PBS for 1 hr at RT, and then incubated with either Alexa Fluor 555 goat anti-mouse IgG secondary antibody (Cat. No. A-21424) or Alexa Fluor Plus 555 goat anti-mouse IgG secondary antibody (Cat. No. A32727) at a dilution of 1:1,000 for 1 hr at RT. Nuclei were stained with Hoechst 33342 stain (Cat. No. H3570). The image contains overlay of neuronal tubulin (orange) and nuclei (blue). Images were taken on a Zeiss LSM 710 confocal microscope at 40x magnification.


Alexa Fluor Plus 647 allows you to see a brighter signal over the noise – secondary antibody conjugates of Alexa Fluor 647 (left) vs. Alexa Fluor Plus 647 (right). Immunofluorescent analysis of β-III tubulin in E18 Sprague Dawley primary cortical neuronal cells. The cells were fixed with 4% formaldehyde for 15 min, permeabilized with 0.25% Triton™ X-100 detergent in PBS for 10 min, and blocked with 3% BSA in PBS for 30 min at RT. Cells were stained with a β-III tubulin mouse monoclonal antibody (Cat. No. MA1-118) at a dilution of 1:200 in 3% BSA in PBS for 1 hr at RT, and then incubated with either Alexa Fluor 647 goat anti-mouse IgG secondary antibody (Cat. No. A21235) or Alexa Fluor Plus 647 goat anti-mouse IgG secondary antibody (Cat. No. A32728) at a dilution of 1:1,000 for 1 hr at RT. Nuclei were stained with Hoechst 33342 stain (Cat. No. H3570). The image contains overlay of neuronal tubulin (pink) and nuclei (blue). Images were taken on a Zeiss LSM 710 confocal microscope at 40x magnification.


Alexa Fluor Plus 800 shows more bands at lower dilutions, providing greater sensitivity and range of detection – secondary antibody conjugates of Alexa Fluor Plus 800 goat anti-rabbit (top) vs. competitor (bottom). Western blot analysis of heat shock protein 90 (Hsp90) and histone deacetylase 1 (HDAC1) was performed by loading 3-fold serial dilutions of A431 whole cell lysate (starting at 15 µg) and 2 µL of the Thermo Scientific PageRuler Prestained NIR Protein Ladder (Cat. No. 26635) per well onto a 4-20% Tris-HCl polyacrylamide gel. Proteins were transferred to nitrocellulose membranes (Cat. No. 88018) and blocked with fluorescence blocker for 30 min. Membranes were probed with a Hsp90 polyclonal antibody (Cat. No. PA3-013) at a dilution of 1:5,000 and an HDAC1 polyclonal antibody (Cat. No. PA1-1110) at a dilution of 1:5,000 overnight at 4°C on a rocking platform, washed with TBST, and probed with either Alexa Fluor Plus 800 goat anti-rabbit IgG (Cat. No. A32735) at a dilution of 1:40,000 or another supplier’s goat anti-rabbit 800 IgG conjugate at dilution of 1:15,000 for 45 minutes. Blots were imaged on an infrared fluorescence imaging system.


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Compare the technology

See how Alexa Fluor Plus secondary antibody conjugates compare to original Alexa Fluor and classical dye secondary antibody conjugates.

  Classical fluorophore
conjugates
Alexa Fluor
conjugates
Alexa Fluor Plus
conjugates
What are they? Affordable, traditional dyes conjugated to secondary antibodies Bright and stable industry-leading dyes conjugated to secondary antibodies Innovative, proprietary dyes conjugated to highly cross-adsorbed secondary antibodies
Signal-to-noise ratio Low Medium High
Photostability Varying levels of photostability, depending on dye Photostable Photostable
Specificity Various options available Various options available Highly specific, low cross-reactivity (highly cross-adsorbed)
Sensitivity and brightness Lower sensitivity and brightness compared to leading Alexa Fluor conjugates Widely recognized standard for brightness and sensitivity Improved sensitivity and brightness over leading Alexa Fluor conjugates in IF/ICC imaging and fluorescent western blotting
Research areas Designed for detection of high-abundance targets in research areas with easy-to-obtain samples Designed for detection of medium- to high-abundance targets in most research areas Designed for detection of low-abundance targets in research areas with hard-to-obtain samples, e.g., neuroscience
Range of linear detection Low Medium High

New packaging helps save time and space

  • Storage made easier—the new vials have flagless labels. No more struggling to wrap the flag around the vial to fit it into racks or centrifuges.
  • Identifying made easier—vials have colored caps corresponding to the Alexa Fluor Plus dye of the secondary antibody conjugate. If you are looking for an Alexa Fluor Plus 488 antibody, just look for the green cap.
  • Easier to see how much antibody you have left—vials are clear so you can easily see the volume remaining. No need to pipette from an opaque or solid-colored vial just to estimate how much antibody remains.