Interaction between a self-assembling peptide and hydrophobic compounds.

The formation of colloidal suspension of a hydrophobic model compound, pyrene, with self-assembling peptide RAD16-I initially demonstrated the hydrophobic interaction between RAD16-I and hydrophobic compounds. The interaction between RAD16-I and pyrene in water was further investigated by using fluorescence spectroscopy and atomic force microscopy (AFM). It was observed that the fluorescence intensities of pyrene in aqueous RAD16-I solutions increased with the increase of RAD16-I at pyrene concentration of 0.1 microM, and the I(1)/I(3) and I(1)/I(5) ratios of the emission spectra decreased as the RAD16-I concentration increased. Fluorescence results and differences in AFM images of RAD16-I aggregates with and without pyrene suggested that pyrene preferentially resided in non-polar microenvironments of RAD16-I due to the hydrophobic interaction between RAD16-I and pyrene. The potential of RAD16-I as a carrier for hydrophobic drugs was revealed with the property of pyrene transferring from the suspensions into egg phosphatidylcholine vesicles. This study gives an insight into exploitation of self-assembling peptides for encapsulation of hydrophobic compounds.