Cream

[gpmatthews]

I thought I'd posted these a little while back, but apparently not... anyway, having seen http://www.photomacrography.net/forum/v ... hp?t=27288 posted by Olympusman, where he had recovered the active ingredients from an ointment, I thought it might be interesting to show a cream (in this case a cetrimide cream), but rather than showing the drug, illustrate the cream structure as a dispersed system (all photomicrographs using Zeiss Standard Microscope with Zeiss 25/0.45 plan achromat):


Simple Darkground



Oblique Rheinberg



Crossed polars

The first two images show oily droplets dispersed in the cream aqueous phase and are much as you might expect from a dispersion of droplets, but the third image shows additionally the presence of a surfactant used to keep the oily phase dispersed and physically stable. This gives a liquid crystal-like structure to the continuous aqueous phase with surfactant molecules arranged radially around the droplets of the dispersed oily phase. This alignment gives rise to characteristic dark cross extinctions in polarised light:


Oil in water dispersions
- after Klein, K. (2002) Liquid crystals and emulsions: a wonderful marriage. Chapter 26, p. 265-269. In: Skin Barrier: Chemistry of Delivery Systems, http://www.alluredbooks.com/sample_page ... t_ch26.pdf

Also see Microscopy of Medical Materials, Matthews, G.P., The Quekett Journal of Microscopy 42, 281-290

[allmicroscope]

Great Photos, gpmatthews!

[zzffnn]

Graham, thank you for the fascinating photos!

As a pharmacist and amateur microscopist, I am also highly interested in your manuscript, would you please kindly forward me a cope at zzffnn at hotmail dot com (I tried but could not find a copy online) . I am only asking for it for personal use. Thank you!

[gpmatthews]

zzffnn - copy in the e-post!

[zzffnn]

Thank you so much Graham. The email got blocked by my email box. But I found it.