Dye another day

My research requires me to stain coconut tissues to locate oil globules in them. This should give me a map of what I'm trying to extract from where.

I thought I can get away with just mixing Nile Red or Sudan Black with distilled water. At least I found out that the specification is correct. Both of these are insoluble. These powder stain would just float in water regardless of physical mixing.

I had no choice but to proceed to the Food Microbiology to try my hand, or eyes, at the microscope which I call electronic. I have to fit into the schedule of my supervisor, Laleh Loghavi, PhD student from Iran and a senior member of our Food Engineering laboratory.

The microscope is not an electron microscope. I am calling it electronic because it can function as brightfield, fluorescent and confocal through a remote computer control. It can capture both still and video image.

Confocal microscope

This is my first time to see an Olympus microscope. Most scopes are Nikon, which is a heavyweight in the camera industry. Olympus can be considered a leader only in the dustproof, waterproof category, but that should be another story.

I tried viewing an unstained coconut tissue, both cross and longitudinal sections. I was expecting to see just plain white, as what I've seen before through a brightfield microscope. To my surprise, it stained itself with a bluish hue. I know buko juice would stain that way but I didn't see something like that in my previous attempt. The minor difference this time is that I refrigerated my sample. Anyway, I was able to get a better picture of the cross section. Although I wasn't able to mark oil globules in the tissue, I was already satisfied with my microscopy attempt yesterday. At least, I saw the cell wall which closely resemble my reference image, and I got the appropriate viewing settings in terms of distance, magnification and ISO value.

Cross-section of unstained coconut tissue

This afternoon, I tried concocting my own solution of lipid stains from Nile Red and Sudan Black. I started with a small volume for each, this time using an acetone as solvent. I bought a nail polish remover from CVS. This should be the same as acetone although the extra scent must've been added knowing that it is intended for beauty parlor use.


I don't have any dilution reference for Sudan Black using acetone so I tried to match it with my index information for Nile Red. The latter comes in a tiny bottle, at 100 mg. It has been successfully used as a lipid marker at 0.4 g/L solution. So, I was expecting Nile Red to be stronger than Sudan Black which comes in bigger bottle and greater quantity (10 g, I guess). I was surprised I had to pour at least 6 times more acetone to even see significant dissolution of Sudan Black.

Dye materials

An extra good news today, I received approval from Dr. Wayne Armstrong to use his stained coconut tissue image. Well, I have been communicating with some people including reference persons from the Philippines (like Philippine Coconut Authority) and I didn't receive any reply. At least, with Dr. Armstrong's quick response, my hope was revived that there are some other people who's willing to share something.

Hopefully, I can squeeze into the microscopy schedule soon to see if my dye solutions work or if I need to adjust the concentration for any of them.

Whatever it takes to stain and locate the oil molecules in coconut tissue, I'm willing to dye another day.

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written and posted 06.14.07, istoriami.