The self-assemblies of OA-Gly-OH, OA-Phe-OH, and OA-Thr-OH are prepared by simply dissolving them in 0.6 M pH 10 Na2CO3 buffer solution respectively. The TEM sample were prepared by depositing 10 μL of 100 mM OA-Gly-OH, OA-Thr-OH, and OA-Phe-OH buffer solution onto copper grids (200-mesh carbon support film, TED Pella, Inc.) and incubate for 1 minute. Excess solution was removed by gently wicking it away with filter paper and then leave copper grids to dry. All TEM analyses were conducted using an LVEM5 Benchtop Electron Microscope with 5kV accelerating voltage (Delong Instruments).