Certainly. If you’re experimenting with fluorescence microscopy, I’d choose the stain according to what you want to see rather than buying fluorescein disodium first.
| What you want to examine | Good fluorescent stain | Appearance |
|---|---|---|
| Living cells / viability | Fluorescein diacetate (FDA) | Bright green |
| Nuclei / DNA | DAPI | Blue |
| Nuclei in living cells | Hoechst 33342 | Blue |
| Dead cells | Propidium iodide (PI) | Red |
| Bacteria, yeast, protozoa | Acridine orange | Green/orange-red |
| Fungi / fungal cell walls | Calcofluor White | Bright blue |
| General tracer / fluid movement | Fluorescein disodium | Green |
| Plants | Often no stain needed | Strong natural autofluorescence |
What I’d buy first
For interesting amateur microscopy, fluorescein diacetate (FDA) would be much more useful than fluorescein disodium. FDA itself is non-fluorescent and membrane-permeable. Living cells take it up and intracellular esterases convert it to fluorescent fluorescein, so viable cells glow green. (MilliporeSigma)
A particularly nice experiment is FDA + propidium iodide: viable cells fluoresce green while membrane-compromised/dead cells take up PI and fluoresce red. This combination has long been used for microscopy-based viability assessment. (PubMed)
For a modern viability assay, calcein-AM is arguably even better because fluorescein can leak from cells; Thermo Fisher notes that calcein-AM and related dyes are now generally preferred for this purpose. (Thermo Fisher Scientific)
For easily obtained specimens such as pond water, yeast, onion/plant material and fungi, I’d start with FDA + DAPI/Hoechst, and add Calcofluor White if fungi interest you.
One important consideration is your microscope’s excitation source and filter cubes.
UK suppliers do sell these flourescent stains, although many professional suppliers require an account.
- Fluorescein diacetate (FDA) — Fisher Scientific UK lists 5 g, 97%, product 11475927, specifically described for staining living cells green. Unfortunately that particular pack is currently shown as unavailable/discontinued. (Fisher Scientific)
- Hoechst 33342 — Fisher Scientific UK has several versions. A 5 mL, 20 mM solution is about £120.65 and currently listed in stock, although Fisher requires a business account. (Fisher Scientific)
- DAPI — Fisher has 10 mg packs, but they’re expensive (about £241) and require a business account. (Fisher Scientific)
For home/amateur microscopy, those quantities and prices are excessive—you only need tiny amounts.
I can search specifically for UK sellers who will sell small quantities to private individuals, preferably £5–£30 per stain. That would be much more suitable for your microscopy.
Yes. I found a particularly good UK option for fluorescein diacetate (FDA):
Apollo Scientific UK – Fluorescein diacetate — 5 g for £34, currently shown in UK stock with roughly one-week lead time. Apollo Scientific is based in Manchester. (Apollo Scientific)
For comparison, Sigma-Aldrich/Merck – Fluorescein diacetate lists 5 g at £81.20, so Apollo is substantially cheaper. (MilliporeSigma)
For your microscopy, FDA would be my first purchase if you’re interested in pond organisms, yeast and other living cells: cellular esterases convert it into fluorescent fluorescein, causing viable cells with intact membranes to fluoresce green. (MilliporeSigma)
I haven’t yet found comparably inexpensive small UK retail quantities of DAPI/Hoechst or Calcofluor White; the mainstream laboratory suppliers tend to sell them at fairly high prices.
One caution: 5 g of FDA is an enormous amount for microscopy. I’d much rather find you 100–500 mg for £10–20 if possible. I can search UK chemical and amateur-microscopy suppliers specifically for those tiny quantities.
HOW DO YOU MAKE UP FDA?
If you mean the fluorescein diacetate (FDA) for fluorescence microscopy, you normally don’t make it up directly in water because FDA has poor aqueous solubility. A concentrated stock is usually prepared in acetone or DMSO, then diluted into water/buffer immediately before use.
For simple amateur microscopy, a convenient approach is a 5 mg/mL stock: dissolve 50 mg FDA in 10 mL acetone (or 5 mg in 1 mL). Keep the stock tightly closed, protected from light and cool. Then make a fresh working solution by adding a small amount of stock to your aqueous specimen. For example, 10 µL of 5 mg/mL stock into 1 mL of specimen gives approximately 50 µg/mL FDA.
The best working concentration depends considerably on the specimen—yeast, pond organisms, plant cells, etc.—and FDA fluorescence develops as viable cells hydrolyse it to fluorescein.
HOW LONG IS THE SHELF LIFE OF FDA?
If you mean fluorescein diacetate (FDA) dry powder, it can have a fairly long shelf life if stored correctly.
Keep the dry powder tightly sealed, dry and protected from light, preferably at 2–8 °C. Some manufacturers specify refrigerated storage, and the manufacturer’s expiry date on the container should take precedence.
As a practical rule, unopened dry FDA can often remain usable for several years under appropriate storage. Once opened, moisture and repeated warming/cooling become more important concerns than simple age.
For microscopy, I’d therefore keep most of your 5 g as dry powder and only prepare a small stock solution—perhaps 5–10 mL at a time. That will preserve the bulk material much better than making the whole quantity into solution.
If you’d like, I can also check the specific shelf life and storage instructions for the £34 Apollo Scientific 5-g FDA we found.
I checked the specific Apollo Scientific product (BIF4105, CAS 596-09-8).
Apollo currently sells 5 g for £34, and its certificate describes it as a faint-yellow powder. (Apollo Scientific)
The important point is that Apollo does not publish a fixed shelf-life/expiry period on the online product information or SDS that I could find. So I wouldn’t claim, for example, that their particular bottle is guaranteed for 2 or 5 years.
For the same chemical, Merck/Calbiochem specifies:
- Dry powder: 2–8 °C
- Protect from light
- Freezing is acceptable.
- Solutions are unstable and should be prepared just before use. (MilliporeSigma)
So if you buy the Apollo 5-g bottle, I’d keep it dry, tightly sealed and in the refrigerator at 2–8 °C, preferably inside an opaque/amber secondary container. Don’t make the whole 5 g into solution.
Given how tiny the quantities needed for microscopy are, 5 g should potentially provide you with years of experiments, subject to the batch expiry/COA.
You can also ask Apollo for the batch-specific Certificate of Analysis, which their product page explicitly offers. (Apollo Scientific)
Apollo Scientific – Fluorescein diacetate 5 g, £34