4 research outputs found
In Situ Fibril Formation of ÎșâCasein by External Stimuli within Multilayer Thin Films
We
have developed the in situ fibrillation of Îș-casein, employed
as amyloid precursor, within multilayer films consisting of Îș-casein
and polyÂ(acrylic acid) (PAA) prepared by the layer-by-layer (LbL)
deposition. The fibrillation of Îș-casein within the multilayered
films is strongly dependent on the extent of intermolecular interactions
between Îș-casein and PAA. When films constructed initially at
pH 3 were heat treated at the same pH, Îș-casein did not transform
into fibrils. However, when the films were subjected to heat treatment
at pH 5, Îș-casein was transformed into fibrils within multilayer
films due to weakened intermolecular interactions between Îș-casein
and PAA. We also noted that the multilayer film was swollen at pH
5 by the charge imbalance within the film, which we believe gives
enough mobility for Îș-caseins to form fibrils with adjacent
Îș-caseins within the multilayer. The fibrils were found to be
uniformly distributed across the entire film thickness, and the aspect
ratio as well as the number density of fibrils increased as a function
of incubation time. The present study reveals a strategy to realize
in situ nanocomposites within LbL multilayer films simply by triggering
the formation of protein fibrils by controlling the intermolecular
interactions between amyloid precursors and polyelectrolytes (PEs)
ÎșâCasein-Based Hierarchical Suprastructures and Their Use for Selective Temporal and Spatial Control over Neuronal Differentiation
Functions are diversified by producing hierarchical structures
from a single raw material. Biologically compatible milk protein of
Îș-casein has been employed to fabricate higher-order suprastructures.
In the presence of dithiothreitol and heat treatment, Îș-casein
transforms into amyloid fibrils with distinctive morphology attributable
to mechanism-based fibrillar polymorphism. As the fibrils elongate
to yield high aspect ratio during high-temperature incubation, the
resulting fibrils laterally associate into the liquid crystalline
state by forming a two-dimensional fibrillar array. Following a desalting
process, the fibrillar arrays turn into a three-dimensional matrix
of hydrogel that could be selectively disintegrated by subsequent
salt treatment. The hydrogel was demonstrated to be a matrix capable
of exhibiting controlled release of bioactive substances like retinoic
acid, which led to temporal and spatial control over the differentiation
of neuronal cells. Therefore, the hierarchical suprastructure formation
derived from the single protein of Îș-casein producing one-dimensional
protein nanofibrils, a two-dimensional liquid crystalline state and
a three-dimensional hydrogel could be widely appreciated in various
areas of nanobiotechnology including drug delivery and tissue engineering
Controlled Charge Trapping and Retention in Large-Area Monodisperse Protein Metal-Nanoparticle Conjugates
Here,
we report on charge-retention transistors based on novel protein-mediated
Au nanoparticle (NP) arrays, with precise control over dimension and
distribution. Individual NPs are coated with alpha-synuclein, an amyloidogenic
protein responsible for Lewy body formation in Parkinsonâs
disease. Subsequently, a monolayer of protein-NP conjugates is successfully
created via a simple and scalable solution deposition to function
as distributed nanoscale capacitors. Controllability over the film
structure translates into the tunability of the electrical performance;
pentacene-based organic transistors feature widely varying programmability
and relaxation dynamics, providing versatility for various unconventional
memory applications
High-Density Single-Layer Coating of Gold Nanoparticles onto Multiple Substrates by Using an Intrinsically Disordered Protein of 뱉Synuclein for Nanoapplications
Functional
graffiti of nanoparticles onto target surface is an
important issue in the development of nanodevices. A general strategy
has been introduced here to decorate chemically diverse substrates
with gold nanoparticles (AuNPs) in the form of a close-packed single
layer by using an omni-adhesive protein of α-synuclein (αS)
as conjugated with the particles. Since the adsorption was highly
sensitive to pH, the amino acid sequence of αS exposed from
the conjugates and its conformationally disordered state capable of
exhibiting structural plasticity are considered to be responsible
for the single-layer coating over diverse surfaces. Merited by the
simple solution-based adsorption procedure, the particles have been
imprinted to various geometric shapes in 2-D and physically inaccessible
surfaces of 3-D objects. The αS-encapsulated AuNPs to form a
high-density single-layer coat has been employed in the development
of nonvolatile memory, fule-cell, solar-cell, and cell-culture platform,
where the outlying αS has played versatile roles such as a dielectric
layer for charge retention, a sacrificial layer to expose AuNPs for
chemical catalysis, a reaction center for silicification, and biointerface
for cell attachment, respectively. Multiple utilizations of the αS-based
hybrid NPs, therefore, could offer great versatility to fabricate
a variety of NP-integrated advanced materials which would serve as
an indispensable component for widespread applications of high-performance
nanodevices