Exploiting Protein Cage Dynamics to Engineer Active Nanostructures

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Exploiting Protein Cage Dynamics to Engineer
Active Nanostructures
Brian Bothner, Trevor Douglas, Ives U Idzerda,
and Mark J Young 2007 NIRT Montana State
University, Bozeman MT
The focus of this Montana State University (MSU)
NIRT is the development of protein cage
architectures as size and shape constrained
templates for nanomaterials synthesis. A
deepening understanding of these systems has led
to an appreciation that protein cage dynamics
plays an important role in the overall properties
of the nanomaterials. The central focus of this
NIRT proposal is to examine how particle
confinement and protein cage dynamics at active
interfaces controls nanomaterials synthesis and
material functionality. The long-term goal is to
use this knowledge to guide the development of a
new generation of active and responsive
nanomaterials.
Hard-soft composite material
CCMV (soft)
MoS2 (hard)
TEM of MoS2 mineralized CCMV
The biological world is increasingly recognized
as an important inspiration and source of raw
materials for nanomaterials fabrication. The high
fidelity of biological materials is made possible
through hierarchical assembly mediated by
molecular interactions that span the molecular to
macroscopic length scales. From the nanomaterials
point of view, a truly unique aspect of
biological systems is that they are both active
and responsive to their environments. It is this
aspect around which the proposed NIRT is
centered.
Viruses are perhaps the most elegant example of
highly evolved, finely tuned, biological
nanomaterials able to respond to changes in their
environment. The essential nature of all viruses
is to recognize and infect a host cell,
replicate, selectively package its nucleic acid
cargo, and exit the cell. In the process, viruses
have evolved to move through a broad range of
chemical environments. Viruses demonstrate a
remarkable plasticity in their metastable
structure and dynamics including coordinated
assembly/disassembly and site-specific delivery
of cargo molecules.
Unmodified CCMV
Modified CCMV
Programmed cage aggregation on a targeted
surface. Staphylococcus aureus cells that has
been specifically targeted with chemically
modified CCMV cages.
Three active interfaces can be manipulated, both
chemically and genetically, in all the protein
cage architectures in this proposed study. These
include the exterior surface, the interior
surface, and the interface between the subunits
that comprise the protein cage architecture
DPS 6 nm interior diameter
The project is divided into three integrated
components Active Interfaces, Cage Dynamics, and
Confinement. Active Interfaces is focused on
directing interactions for defined chemical
synthesis using hard-soft interfaces,
particle-surface interactions and controlled
hierarchical assembly. Cage Dynamics is centered
around understanding and directing inherent and
engineered cage dynamics to control material
confinement, directed self-assembly, and
particle-particle interactions. The Confinement
thrust integrates the Active Interfaces and Cage
Dynamics to explore their consequences on the
physical properties of individual and collections
of particles. This highly interdisciplinary
approach is a platform for the training of
graduate (and undergraduate) students, the
development of public outreach, and education all
of which are integrated with the research
efforts.
Ferritin 8 nm interior diameter
Active control of surface anisotropy. Confinement
of mineralized particles in protein cages
modifies the behavior of the surface spins by
reducing the surface anisotropy. This directly
affects the surface spin configuration, greatly
enhancing the overall moment of the nanoparticle.
Control would allow us to turn on and off
catalytic activity, substantially reduce particle
magnetic moment for new sensor applications, and
modify optical properties. As an example,
magnetic nanoparticle sensor applications
typically rely on the attachment or detachment of
the particle. By using active control of the
surface anisotropy, the particle can remain
attached, but the particle moment can be reduced
by 80 which would essentially remove the
magnetic signal.
Cowpea chlorotic mottle virus (CCMV)
24 nm interior diameter
Heat shock protein 8 nm interior diameter
Sulfolobus Turreted Icosahedral virus
We have developed a protein cage toolbox that
spans a wide-range of sizes. The stability and
dynamics of the cages are highly variable and can
be modified to tune functionality.