3 research outputs found
Molecular Dynamics Simulation of the Oil Sequestration Properties of a Nonionic Rhamnolipid
A detailed molecular
dynamics simulation study is presented on
the behavior of aggregates composed of the nonionic monorhamnolipid
α-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate
(Rha-C10-C10) and decane in bulk water. A graph theoretical approach
was utilized to characterize the size and composition of the many
aggregates generated in our simulations. Overall, we observe that
the formation of oil in Rha-C10-C10 aggregates is a favorable process.
Detailed analysis on the surfactant/oil aggregate shows that larger
aggregates are stable. The shape and size of the aggregates are widely
distributed, with the majority of the aggregates preferring ellipsoidal
or cylindrical structures. Irrespective of the decane concentration
in the system, we did not observe free decane in any of the simulations.
Further insights into the binding energy of decane were carried out
using free-energy perturbation calculations. The results showed that
the trapped decane molecules provide stability to the Rha-C10-C10
aggregates of size <i>N</i> = 50 which are shown to be unstable
in our previous study and allow for the growth of larger aggregates
than pure Rha-C10-C10 in water. The density profile plots show that
decane molecules encapsulated inside the aggregate preferred to remain
closer to the center of mass. This study points to the feasibility
of using this biosurfactant as an environmental remediation agent
Structural Properties of Nonionic Monorhamnolipid Aggregates in Water Studied by Classical Molecular Dynamics Simulations
Molecular dynamics simulations were
carried out to investigate
the structure and stabilizing factors of aggregates of the nonionic
form of the most common congener of monorhamnolipids, α-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate
(Rha-C10-C10), in water. Aggregates of size ranging from 5 to 810
monomers were observed in the simulation forming spherical and ellipsoidal
structures, a torus-like structure, and a unilamellar vesicle. The
effects of the hydrophobic chain conformation and alignment in the
aggregate, role of monomer···monomer and monomer···water
H-bonds, and conformations of monomers in the aggregate were studied
in detail. The unilamellar vesicle is highly stable due to the presence
of isolated water molecules inside the core adding to the binding
energy. Dissociation of a monomer from a larger micellar aggregate
is relatively easy compared to that from smaller aggregates as seen
from potential of mean force calculations. This analysis also shows
that monomers are held more strongly in aggregates of Rha-C10-C10
than the widely used surfactant sodium dodecyl sulfate. Comparisons
between the aggregation behavior of nonionic and anionic forms of
Rha-C10-C10 are presented
Molecular Dynamics Simulation of the Oil Sequestration Properties of a Nonionic Rhamnolipid
A detailed molecular
dynamics simulation study is presented on
the behavior of aggregates composed of the nonionic monorhamnolipid
α-rhamnopyranosyl-β-hydroxydecanoyl-β-hydroxydecanoate
(Rha-C10-C10) and decane in bulk water. A graph theoretical approach
was utilized to characterize the size and composition of the many
aggregates generated in our simulations. Overall, we observe that
the formation of oil in Rha-C10-C10 aggregates is a favorable process.
Detailed analysis on the surfactant/oil aggregate shows that larger
aggregates are stable. The shape and size of the aggregates are widely
distributed, with the majority of the aggregates preferring ellipsoidal
or cylindrical structures. Irrespective of the decane concentration
in the system, we did not observe free decane in any of the simulations.
Further insights into the binding energy of decane were carried out
using free-energy perturbation calculations. The results showed that
the trapped decane molecules provide stability to the Rha-C10-C10
aggregates of size <i>N</i> = 50 which are shown to be unstable
in our previous study and allow for the growth of larger aggregates
than pure Rha-C10-C10 in water. The density profile plots show that
decane molecules encapsulated inside the aggregate preferred to remain
closer to the center of mass. This study points to the feasibility
of using this biosurfactant as an environmental remediation agent