Yes. The Zeiss IM35 can make a very capable fluorescence microscope, but the best dyes depend primarily on the fluorescence filter sets fitted to your particular IM35, rather than on the microscope model itself. Zeiss fluorescence systems use matched excitation filters, dichroic beam splitters and emission/barrier filters. (Zeiss)
For interesting home microscopy, I’d concentrate on these:
| Dye | What it shows | Excitation / emission approx. | My choice |
|---|---|---|---|
| Fluorescein diacetate (FDA) | Viable cells, yeast, algae, protozoa | 495 / 517 nm | ⭐⭐⭐⭐⭐ |
| Hoechst 33342 | DNA/nuclei; can stain living cells | ~350 / 461 nm | ⭐⭐⭐⭐⭐ |
| DAPI | DNA/nuclei, especially fixed cells | ~358 / 461 nm | ⭐⭐⭐⭐ |
| Acridine orange | Nucleic acids; bacteria, yeast, cells | ~500 nm excitation | ⭐⭐⭐⭐⭐ |
| Calcofluor White | Fungal and yeast cell walls/cellulose | ~350 / 430 nm | ⭐⭐⭐⭐⭐ |
| Propidium iodide (PI) | Dead/damaged cells and nuclei | ~535 / 617 nm | ⭐⭐⭐⭐ |
| Rhodamine B | General fluorescent demonstrations/tracing | ~550 / 570–600 nm | ⭐⭐⭐ |
| Fluorescein disodium | Tracing, diffusion, permeability demonstrations | 495 / 517 nm | ⭐⭐⭐ |
Zeiss’s own filter database gives FDA and fluorescein at about 495/517 nm and Hoechst 33258-DNA at about 352/455 nm, confirming that these classic fluorophores are very well suited to conventional filter-based fluorescence microscopy. (Micro Shop)
What I’d buy for your IM35
I’d build a small collection around three fluorescence colours.
Green — FDA would be my first choice. Pond water, yeast and other viable cells can produce striking green fluorescence. This is the FDA you’ve already been looking at.
Blue — Hoechst 33342 would be my second purchase. It gives you something quite different: brightly fluorescent nuclei/DNA. If your IM35 has a suitable UV excitation filter set, it should be very impressive.
Red — propidium iodide would be my third. It complements FDA particularly well because FDA can indicate viable cells while PI identifies cells with compromised membranes. This gives you the possibility of genuine green/red live/dead experiments, rather than simply making specimens fluoresce.
I’d then add Calcofluor White if you’re interested in fungi, moulds and yeast, and acridine orange if bacteria and pond microorganisms interest you.
But check your IM35 before buying them
The most useful thing you could do now is send me photographs of the fluorescence filter slider/cubes in your IM35, particularly any numbers, letters or coloured markings on them.
That’s important because if, for example, yours has only a FITC/fluorescein filter set, FDA will work beautifully but buying DAPI/Hoechst would achieve little until you obtain a UV filter set. Conversely, an IM35 equipped with UV, blue and green excitation/filter sets could potentially use most of the dyes above.
CHATGPT’S OFFER: If you photograph the fluorescence illuminator and every filter position/label, I can identify what channels your particular IM35 already has and tell you exactly which dyes I’d buy for it. (Zeiss)
I have already ordered fhe FDA. The other two you recommend where can I buy them cheaply?
Yes. Since you’ve already ordered FDA, the two I’d add are Hoechst 33342 for blue nuclear fluorescence and propidium iodide (PI) for red fluorescence/dead-cell staining. They complement FDA very nicely. Thermo Fisher gives their fluorescence maxima as Hoechst 350/461 nm and PI 535/617 nm. (Thermo Fisher Scientific)
The difficulty is price. Of the reputable UK sources I can find at present, the cheapest PI is Sigma-Aldrich P4170, 10 mg for £44.80. That’s actually plenty for microscopy—you certainly don’t need 50 or 100 mg. (MilliporeSigma) Fisher’s alternative is 25 mg for £51.65 promotional/£56.90 regular, but requires a business account. (Fisher Scientific)
Sigma-Aldrich UK — PI 10 mg, £44.80
I wouldn’t buy the ready-made PI solutions: you’re paying substantially more. For example, Sigma’s 1 mg/mL solution is £120 for 10 mL. (MilliporeSigma)
Hoechst 33342 is the one I’d like to find cheaper for you. The mainstream UK laboratory prices are disproportionately high for the tiny amount you’ll actually use. I’d therefore look for a reputable microscopy/educational supplier offering a small vial rather than buying a large research-lab pack.
One thing before spending the money: I’d verify that your IM35 has the appropriate UV excitation/filter set for Hoechst and a green-excitation/red-emission set suitable for PI. FDA only requires the fluorescein/FITC-type channel. If you send me a photo of the filter slider/cubes and their markings, I’ll identify them and then we can buy only dyes your particular IM35 can actually see.