# Beads emitting in the blue (ex 405, em 420-480) or far-red (ex 640, em \>=660), with size below 0.5uM

**URL:** <https://forum.microlist.org/t/beads-emitting-in-the-blue-ex-405-em-420-480-or-far-red-ex-640-em-660-with-size-below-0-5um/2147>\
**Category:** Probes & Prep\
**Created:** [May 4, 2023, 12:51pm UTC](https://forum.microlist.org/t/beads-emitting-in-the-blue-ex-405-em-420-480-or-far-red-ex-640-em-660-with-size-below-0-5um/2147 "2023-05-04T12:51:33Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lgelman](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.microlist.org/lgelman/32/303_2.png) [@lgelman](https://forum.microlist.org/u/lgelman)\
**Post date:** [May 4, 2023, 12:51pm UTC](https://forum.microlist.org/t/beads-emitting-in-the-blue-ex-405-em-420-480-or-far-red-ex-640-em-660-with-size-below-0-5um/2147/1 "2023-05-04T12:51:33Z")

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Hi everybody,

We are looking for beads (max size 0.5uM) to discriminate under a fluorescent microscope active vs. moulting C. elegans worms (the active ones will eat the beads in the medium together with the bacteria and the beads will be visible in the gut of the worms).  
There is a publication with the beads referenced just below, but there spectra is too much overlapping with our fluorophores:  
[https://www.sigmaaldrich.com/CH/de/product/sigma/l3280](https://www.sigmaaldrich.com/CH/de/product/sigma/l3280)

Do you know any alternative in the blue or far-red range? Invitrogen sells 175nm beads in this range, I just fear they are too small and/or not bright enough for our imaging conditions (imaging with 20x/0.8 air objective).

Thanks in advance for your help,

Cheers,

Laurent.

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**Author:** ![Hazen\_Babcock](https://sea2.discourse-cdn.com/flex020/user_avatar/forum.microlist.org/hazen_babcock/32/281_2.png) [@Hazen\_Babcock](https://forum.microlist.org/u/Hazen_Babcock)\
**Post date:** [May 4, 2023, 10:54pm UTC](https://forum.microlist.org/t/beads-emitting-in-the-blue-ex-405-em-420-480-or-far-red-ex-640-em-660-with-size-below-0-5um/2147/2 "2023-05-04T22:54:43Z")

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Maybe look at Bangs Labs?

> **[Fluorescent Microspheres | Bangs Laboratories, Inc.](https://www.bangslabs.com/products/fluorescent-microspheres)**
>
> Fluorescent microspheres are a mainstay in diagnostics and life sciences research, finding use as fluorescent markers, assay substrates, and instrument standards. In order to meet the unique performance criteria required of microparticles in these...

They have fluorescent beads that might work for your application, 0.5um “Flash Red”?