Fig. 2.
Characterization of the amidophospholipid vesicular architecture. (A) TEM image of negatively stained vesicular structures formed by spontaneous de novo NCL-based synthesis of phospholipid 3. (Scale bar, 100 nm.) (B) Fluorescence microscopy image demonstrating the in situ encapsulation of HPTS within membrane vesicles during de novo synthesis of phospholipid 3. (Scale bar, 10 µm.) (C) Anisotropy of DPH as a function of temperature within membranes formed from phospholipid 3 (×) and 5 (•). A sudden change in the slope of the anisotropy indicates a transition from a gel to liquid-crystalline phase. The melting temperature of the lipid chains in membranes formed from 5 was detected at 270 K, comparable to the transition temperature of analogous POPC membranes. In contrast, within the temperatures tested (263–283 K), a phase transition was not detected in membranes formed from 3, as predicted by comparing to analogous DOPC membranes (Tc = 256 K). The unitless anisotropy ratio (R) is a measure of the acyl packing of the bilayer, with higher values indicating a more ordered membrane.