Description 16-Doxyl-stearic acid methyl ester has been employed as spin label:to investigate the changes within the lipid double layer of liposomal membranesto measure the bacterial membrane fluidity by electron spin resonanceSpin label reagent useful for the study of membrane fluidity by electron spin resonance spectrophotometry. Description 16-Doxyl-stearic acid methyl ester has been employed as spin label:to investigate the changes within the lipid double layer of liposomal membranesto measure the bacterial membrane fluidity by electron spin resonanceSpin label reagent useful for the study of membrane fluidity by electron spin resonance spectrophotometry.