Customize your panel with Flexi-Fluor antibodies.


Our Flexi-Fluor products provide flow cytometry users with even greater flexibility in panel design. Flexi-Fluors are a made-to-order, rapid alternative to traditional custom products that expand antibody-fluorophore options beyond our off-the-shelf catalog of 30,000 reagents. Every Flexi-Fluor product is created by our team of experts and manufactured to the same high-quality standards you’ve trusted for over 20 years. Accelerate your next breakthrough with these customized reagents.

Flexi-Fluor™ Features


  • Faster turnaround than traditional custom orders, typically within 2-3 weeks for domestic orders.
  • Reliable, high-quality antibodies produced through our rigorous and regulated manufacturing systems.
  • Unique antibody-dye combinations with initial fluorophore offerings of Spark Blue™ 550, Spark Blue™ 574, and Spark Red™ 718.
  • Convenient 50 μg sizes.


Learn About the Dyes


Our Flexi-Fluor conjugates are currently offered in three formats: Spark Blue™ 550, Spark Blue™ 574, and Spark Red™ 718. These dyes belong to the Spark family of synthetic fluorophores and are advantageous due to their high conjugation efficiency and lot-to-lot consistency. Visit our Spark Dyes webpage to learn more about these dyes and how to incorporate them into your multicolor panels.


Additional Services


For guidance on selecting products or designing your panel, contact Technical Services or your local application scientist to learn more. Our panel building consultations are always free-of-charge and provided by experienced scientists with extensive backgrounds in multicolor panel design.


If you need an antibody-dye combination that is not available as a Flexi-Fluor or regular catalog product, contact our Custom Solutions team. We will work with you to build the ideal reagent for your multicolor flow cytometry panel.



What are Flexi-Fluors?

Flexi-Fluors are rapidly made-to-order conjugated antibodies. The technology, manufacturing processes, and specifications used to create Flexi-Fluors are the same as our regular catalog products. However, the optimal concentration and performance of each Flexi-Fluor must be determined by the customer. 


How quickly will I receive my order?

We aim to ship Flexi-Fluors within 2-3 weeks of receipt of your order. However, depending on your location, shipping times may vary. 


How are Flexi-Fluors different from regular catalog products?

Flexi-Fluors are made on demand, specifically for you. Flexi-Fluors are manufactured using the same high-quality standards, and specifications as other catalog products. For faster delivery, Flexi-Fluors are not tested by flow cytometry to determine optimal concentrations or evaluate performance. This testing needs to be performed by the customer.


How do I determine the optimal concentration for using my Flexi-Fluor? How should I titrate my antibody?

Flexi-Fluors are provided at a standard 0.2 mg/mL concentration. We recommend that you titrate your antibody to determine the optimal concentration to use for your application. For many flow cytometry applications, conjugated antibodies perform well at concentrations ranging from 0.03 to 1.0 µg per million cells in 100 µL volume. We recommend that you test a range of concentrations starting from 10 µg/mL. 


For example, make five 1:1 serial dilutions of your 0.2 mg/mL antibody.  Add 5 µL of each dilution (including the undiluted antibody) to 100 µL of cells (at 107 cells/ml) to test six concentrations - 1.0, 0.5, 0.25, 0.125, 0.06, and 0.03 µg per million cells in 100 µL volume. Compare staining patterns or create a titration curve using the MFI or staining index to determine the optimal concentration. 


I can’t find the antibody-dye combination that I need. When will it be available? 

We continuously update our catalog, introducing scores of new products every month. Please get in touch with our Technical Service team for an update on new products or recommendations for suitable alternatives to complete your panel. Or contact Custom Solutions to inquire about our affordable custom conjugation services. 


I need help to validate the performance of my Flexi-Fluor. Who should I contact?

Please get in touch with Technical Service for assistance. 


Can I order more than 50 μg of a Flexi-Fluor?

Yes, you can order multiple vials of the same Flexi-Fluor products.  We cannot guarantee, however, that these vials will be bottled from the same lot. For bulk single-lot orders, contact our Custom Solutions team.


What is the expiration date of my Flexi-Fluor?

Expiration dates can be found on the vial label or by using our CoA lookup tool


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