ja8b10688_si_003.pdf (881.92 kB)
Self-Assembling Micelles Based on an Intrinsically Disordered Protein Domain
journal contribution
posted on 2019-02-11, 00:00 authored by Sarah
H. Klass, Matthew J. Smith, Tahoe A. Fiala, Jess P. Lee, Anthony O. Omole, Bong-Gyoon Han, Kenneth H. Downing, Sanjay Kumar, Matthew B. FrancisThe self-assembly of micellar structures
from diblock polymers
that contain hydrophilic and hydrophobic domains has been of great
interest for the encapsulation of drugs and other hydrophobic molecules.
While most commercially used surfactants are derived from hydrocarbon
sources, there have been recent efforts to replace these with biodegradable,
nontoxic, biologically synthesized alternatives. Previous examples
have primarily examined naturally occurring self-assembling proteins,
such as silk and elastin-like sequences. Herein, we describe a new
series of fusion proteins that have been developed to self-assemble
spontaneously into stable micelles that are 27 nm in diameter after
enzymatic cleavage of a solubilizing protein tag. The sequences of
the proteins are based on a human intrinsically disordered protein,
which has been appended with a hydrophobic segment. The micelles were
found to form across a broad range of pH, ionic strength, and temperature
conditions, with critical micelle concentration (CMC) values in the
low micromolar range, 3 orders of magnitude lower than the CMC of
commonly used surfactant sodium dodecyl sulfate (SDS). The reported
micelles were found to solubilize hydrophobic metal complexes and
organic molecules, suggesting their potential suitability for catalysis
and drug delivery applications. Furthermore, the inherent flexibility
in the design of these protein sequences enables the encoding of additional
functionalities for many future applications. Overall, this work represents
a new biomolecular alternative to traditional surfactants that are
based on nonrenewable and poorly biodegradable hydrocarbon sources.