Designed peptide surfactants offer a number of
advanced properties over conventional petrochemical surfactants,
including biocompatibility, sustainability, and tailorability of the
chemical and physical properties through peptide design. Their
biocompatibility and degradability make them attractive for various
applications, particularly for food and pharmaceutical applications.
In this work, two new peptide surfactants derived from an
amphiphilic peptide surfactant (AM1) were designed (AM-S and
C8-AM) to better understand links between structure, interfacial
activity, and emulsification. Based on AM1, which has an interfacial
α-helical structure, AM-S and C8-AM were designed to have two
modules, tha... More
Designed peptide surfactants offer a number of
advanced properties over conventional petrochemical surfactants,
including biocompatibility, sustainability, and tailorability of the
chemical and physical properties through peptide design. Their
biocompatibility and degradability make them attractive for various
applications, particularly for food and pharmaceutical applications.
In this work, two new peptide surfactants derived from an
amphiphilic peptide surfactant (AM1) were designed (AM-S and
C8-AM) to better understand links between structure, interfacial
activity, and emulsification. Based on AM1, which has an interfacial
α-helical structure, AM-S and C8-AM were designed to have two
modules, that is, the α-helical AM1 module and an additional
hydrophobic moiety to provide for better anchoring at the oil−
water interface. Both AM-S and C8-AM at low bulk concentration of 20 μM were able to adsorb rapidly at the oil−water interface
and reduced interfacial tension to equilibrium values of 17.0 and 8.4 mN/m within 400 s, respectively. Their relatively quick
adsorption kinetics allowed the formation of nanoemulsions with smaller droplet sizes and narrower size distribution. AM-S and
C8-AM at 800 μM bulk concentration could make nanoemulsions of average diameters 180 and 147 nm, respectively, by simple
sonication. With respect to the long-term stability, a minimum peptide concentration of 400 μM for AM-S and a lower
concentration of 100 μM for C8-AM were demonstrated to effectively stabilize nanoemulsions over 3 weeks. Compared to AM1,
the AM-S nanoemulsion retained its stimuli-responsive function triggered by metal ions, whereas the C8-AM nanoemulsions did
not respond to the stimuli as efficiently as AM-S because of the strong anchoring ability of the hydrophobic C8 module. The twomodule design of AM-S and C8-AM represents a new strategy in tuning the surface activity of peptide surfactants, offering useful
information and guidance of future designs.
