Alexa Fluor® Fluorescent Streptavidin Conjugates

Alexa Fluor® Fluorescent Streptavidin Conjugates

Life Technologies offers a broad range of Alexa Fluor® fluorescent streptavidin conjugates (Table 1 and Table 3) and avidin conjugates (Table 2) using the Molecular Probes® Alexa Fluor® dyes. These dyes represent a major breakthrough in the development of fluorescent labeling reagents and, without exception, produce the best and brightest conjugates we have ever tested. Benefits of the Alexa Fluor® dyes and their conjugates include exceptionally bright conjugates, excellent photostability, and a broad range of emission colors. These characteristics make Alexa Fluor® dyes the best choice for most imaging applications.

Table 1. Alexa Fluor® Fluorescent Streptavidin Conjugates

Streptavidin Conjugates   Ex (nm)* Em (nm)* Cat . No.  (Unit Size)
Alexa Fluor® 350 Streptavidin 346 442S11249 (1 mg)
Alexa Fluor® 405 Streptavidin 402 421S32351  (1 mg)
Alexa Fluor® 430 Streptavidin 434  539S11237  (1 mg)
Alexa Fluor® 488 Streptavidin 495 519

S11223 (1 mg)

S32354 (0.5 mL)

Alexa Fluor® 500 Streptavidin 503 525S32352  (1 mg)
Alexa Fluor® 514 Streptavidin 518 540S32353  (1 mg)
Alexa Fluor® 532 Streptavidin 530 554S11224  (1 mg)
Alexa Fluor® 555 Streptavidin 555 565

S21381 (1 mg)

S32355  (0.5 mL)
Alexa Fluor® 546 Streptavidin 556 573S11225 (1 mg)
Alexa Fluor® 568 Streptavidin578603S11226  (1 mg)
Alexa Fluor® 594 Streptavidin590617

S11227 (1 mg)

S32356  (0.5 mL)

Alexa Fluor® 610 Streptavidin612628S32359  (1 mg)
Alexa Fluor® 633 Streptavidin632647S21375  (1 mg)
Alexa Fluor® 635 Streptavidin633647S32364 (1 mg)
Alexa Fluor® 647 Streptavidin650668

S21374 (1 mg)

S32357 (0.5 mL)

Alexa Fluor® 660 Streptavidin663690S21377 (1 mg)
Alexa Fluor® 680 Streptavidin679702

S21378 (1 mg)

S32358 (0.5 mL)

Alexa Fluor® 700 Streptavidin702723S21383 (1 mg)
Alexa Fluor® 750 Streptavidin749775S21384   (1 mg)


*Approximate fluorescence excitation (Ex) an d emission (Em) maxima for conjugates, in nm.

Alexa Fluor® Streptavidin Fluorescent Conjugates in Action

Multicolor fluorescence microscopy analysis of muntjac fibroblasts. The actin cytoskeleton was labeled with biotin phalloidin and visualized using Alexa Fluor® 350 streptavidin. Mitochondria were stained with MitoTracker® Red CMXRos; the nucleus was labeled with an anti-phosphohistone primary antibody and visualized using Alexa Fluor® 500 goat anti–mouse IgG.


The cytoskeleton of a fixed and permeabilized bovine pulmonary artery endothelial cell. Tubulin was detected using mouse monoclonal anti–α-tubulin antibody and visualized with Alexa Fluor® 647 goat anti–mouse IgG antibody (pseudocolored magenta). Endogenous biotin in mitochondria was labeled with green-fluorescent Alexa Fluor® 488 streptavidin; DNA was stained with blue-fluorescent DAPI.
Streptavidn, Alexa Fluor® 488 and cytoskeleton

Table 2. Alexa Fluor® NeutrAvidin and Avidin Conjugates

Fluorescent  Conjugate  Ex (nm)* Em (nm)* Cat . No.
Alexa Fluor® 350  Neutravidin
 346
 442
A11236
Alexa Fluor® 488  Avidin
 495
 519
A21370

*Approximate fluorescence excitation (Ex) an d emission (Em) maxima for conjugates, in nm.

Alexa Fluor®–Phycobiliprotein Streptavidin Conjugates

Life Technologies™ offers fluorescent streptavidin conjugates of with tandem dyes R-PE and APC labeled with long-wavelength Alexa Fluor® dyes. Our tandem conjugates (Table 3) comprise a donor phycobiliprotein—R-PE or APC—conjugated to longer wavelength–emitting fluorescence acceptors. By the process of fluorescence resonance energy transfer (FRET), an energy transfer cascade is established wherein most of the light absorbed by the donor R-PE or APC results in fluorescence of the acceptor dye. This process can be quite efficient, resulting in almost total transfer of energy to the acceptor dye.

Table 3. Tandem Alexa Fluor®–Phycobiliprotein Streptavidin Conjugates

R-PE, B-PE, and Tandem–R-PE Conjugates

Streptavidin Conjugates   Ex (nm)* Em (nm)* Cat . No.  (Unit Size)
Alexa Fluor® 610–R-PE  Streptavidin
 496, 546, 565 †
630
S20982
Alexa Fluor® 647–R-PE  Streptavidin
 496, 546, 565 †
668
S20992
Alexa Fluor® 680–R-PE  Streptavidin
 496, 546, 565 † 
702
S20985
Alexa Fluor® 750–R-PE  Streptavidin
496, 546, 565 † 
771
S32363

APC and Tandem-APC Conjugates

Streptavidin Conjugates   Ex (nm)* Em (nm)* Cat . No.  (Unit Size)
Allophycocyanin (APC)  Streptavidin
 650
 660
S868, S32362 ‡
Alexa Fluor® 680–APC  Streptavidin
 650
 702
S21002
Alexa Fluor® 700–APC  Streptavidin
 650
 723
S21005
Alexa Fluor® 750–APC  Streptavidin
650
775
S21008

*Approximate fluorescence excitation (Ex) an d emission (Em) maxima for conjugates, in nm.

All-in-One Kits for Fluorescence Imaging

The Image-iT® FX Kits provide all of the dyes and reagents you need for optimal immunofluorescence imaging of fixed cells and tissue sections using Alexa Fluor® fluorescent streptavidin conjugates. Each kit includes:

  • Alexa Fluor® fluorescent streptavidin conjugates for superior photostability and brightness
  • ProLong® Gold antifade reagent for reduced photobleaching
  • Image-iT® FX signal enhancer for an improved signal-to-noise ratio

A pack of two CultureWell® (Grace Bio-Labs) chambered cover glasses is also included for convenient processing. Each Image-iT® FX Kit provides sufficient materials to perform 50–100 assays.

${comergentUrl}