A nitrobenzofuran-conjugated phosphatidylcholine (C12-NBD-PC) as a stain for membrane lamellae for both microscopic imaging and spectrofluorimetry

The use of C12-nitrobenzofuran-conjugated phosphatidylcholine (NBD-PC) for staining intracellular lipid in the form of membrane lamellae present in cultured cell monolayers, which recently was reported by Kasahara et al., is summarized and commented on. This is the first report of this fluorochrome's application as a "dye" rather than as a fluorescent lipid analogue. Analysis using the log P parameter suggests that the observed efficacy of the C12 form, compared to the non-staining character of the C6 form, may be attributed to insufficient partitioning of the latter into lipid. Confusion of the terms "dye" or "stain" and "fluorescent lipid analogue" in the current literature is addressed here. Optical and other physicochemical properties of the stain useful for practical laboratory purposes are summarized from various sources.