Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (4): 722-728.doi: 10.3866/PKU.WHXB201503031

• SOFT MATTER • Previous Articles     Next Articles

Self-Assembly and Acid-Responsive Behavior of Three Amphiphilic Peptides

LIANG Ju1, LAI Dan-Yu1, WU Wen-Lan2, LI Guo-Zhi1, LI Jun-Bo1, FANG Cai-Lin1   

  1. 1 Chemical Engineering and Pharmaceutics School, Henan University of Science and Technology, Luoyang 471023, Henan Province, P. R. China;
    2 Medical School, Henan University of Science and Technology, Luoyang 471023, Henan Province, P. R. China
  • Received:2014-10-16 Revised:2015-03-02 Published:2015-04-03
  • Contact: LIANG Ju
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (51403055).


Three amphiphilic peptides containing KKGRGDS as hydrophilic heads and VVVVVV, C12, and FAFAFA as hydrophobic tails (VVVVVVKKGRGDS (AP1), C12KKGRGDS (AP2), FAFAFAKKGRGDS (AP3)) were designed and prepared using the standard solid-phase peptide synthesis (SPPS) technique. Three peptides assembled into spherical micelles under neutral conditions (pH 7.0) with a size of ~30 nm determined by transmission electron microscope (TEM). Dynamic light scattering (DLS) tests showed that their size distributions were uniform and narrow. In dilute hydrochloric acid (pH 5.0), peptide AP1 presented a sharp aciddependent demicellization transition, with no assembled particles found by TEM and no DLS peak in the range 1-1000 nm. However, the micellar structures of the amphiphilic peptides AP2 and AP3 did not disappear at pH 5.0. TEM results showed that AP2 assembly appeared through aggregation and the shape of AP3 micellar particles became non-spherical or irregular. AP2 assembly at pH 5.0 showed a multiple peak distribution and AP3 assembly showed a broad peak distribution in DLS, consistent with the TEM results. The changes in secondary structures of amphiphilic peptides AP1, AP2, and AP3 at pH 7.0 and 5.0 were confirmed by circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopy. We then selected curcumin as a model drug to investigate the drug-loading capacity and in vitro release behavior of peptide AP1 micelles. As a result, AP1 is expected to comprise an ideal acid-responsive drug carrier for the intelligent delivery of anticancer drugs. The differences between AP1, AP2, and AP3 assembly behaviors in neutral and acidic conditions provide a novel and effective approach for regulating self-assembly of peptides. AP1 is expected to offer an ideal pH-responsive functional material.

Key words: Self-assembly, Nano-sized micelle, Acid-sensitive material, Circular dichroism, Fourier transform infrared spectroscopy, Secondary structure of peptide


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