To evaluate the morphological stability of the hybrid bicelles in air, we observed the dried specimen prepared on a mica substrate using atomic force microscopy (AFM). The hybrid bicelles clearly maintained their discoid structure in a dry environment (Fig. 4a), whereas conventional phospho- lipid bicelles of DPPC/2 (7 : 2) were readily ruptured to form ambiguous aggregates (Fig. 4b). Since the coefficient of variation (CV) on the diameter of hybrid bicelles was small (9.0% for 40 samples), it is evident that mono-disperse discoid particles were produced. The thickness of the hybrid bicelles (5.0