18 research outputs found
Nanopatterned Protein Films Directed by Ionic Complexation with Water-Soluble Diblock Copolymers
The use of ionic interactions to direct both protein
templating
and block copolymer self-assembly into nanopatterned films with only
aqueous processing conditions is demonstrated using block copolymers
containing both thermally responsive and pH responsive blocks. Controlled
reversible addition–fragmentation chain-transfer (RAFT) polymerization
is employed to synthesize polyÂ(<i>N</i>-isopropylacrylamide-<i>b</i>-2-(dimethylamino)Âethyl acrylate) (PNIPAM-<i>b</i>-PDMAEA) diblock copolymers. The pH-dependent ionic complexation
between the fluorescent protein, mCherry, and the ionic PDMAEA block
is established using dynamic light scattering (DLS) and UV–vis
spectroscopy. DLS shows that the size of the resulting coacervate
micelles depends strongly on pH, while UV–vis spectroscopy
shows a correlation between the protein’s absorption maximum
and the ionic microenvironment. Zeta potential measurements clearly
indicate the ionic nature of the complex-forming interactions. Spin-casting
was used to prepare nanostructured films from the protein–block
copolymer coacervates. After film formation, the lower critical solution
temperature (LCST) of the PNIPAM blocks allows the nanomaterial to
be effectively immobilized in aqueous environments at physiological
temperatures, enabling potential use as a controlled protein release
material or polymer matrix for protein immobilization. At pH 9.2 and
7.8, the release rates are at least 10 times faster than that at pH
6.4 due to weaker interaction between protein and PNIPAM-<i>b</i>-PDMAEA (PND) diblock copolymer. Because of the ionic environment
in which protein is confined, the majority of the protein (80%) remains
active, independent of pH, even after having been dehydrated in vacuum
and confined in the films
Salami-like Electrospun Si Nanoparticle-ITO Composite Nanofibers with Internal Conductive Pathways for use as Anodes for Li-Ion Batteries
We report novel salami-like core–sheath
composites consisting
of Si nanoparticle assemblies coated with indium tin oxide (ITO) sheath
layers that are synthesized via coelectrospinning. Core–sheath
structured Si nanoparticles (NPs) in static ITO allow robust microstructures
to accommodate for mechanical stress induced by the repeated cyclical
volume changes of Si NPs. Conductive ITO sheaths can provide bulk
conduction paths for electrons. Distinct Si NP-based core structures,
in which the ITO phase coexists uniformly with electrochemically active
Si NPs, are capable of facilitating rapid charge transfer as well.
These engineered composites enabled the production of high-performance
anodes with an excellent capacity retention of 95.5% (677 and 1523
mAh g<sup>–1,</sup> which are based on the total weight of
Si-ITO fibers and Si NPs only, respectively), and an outstanding rate
capability with a retention of 75.3% from 1 to 12 C. The cycling performance
and rate capability of core–sheath-structured Si NP-ITO are
characterized in terms of charge-transfer kinetics
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 treatment on mitochondrial morphology in 3T3-L1 cells after differentiation.
<p>(A) DsRed2-Mito-expressing 3T3-L1 cells treated with 1 μg/mL insulin for 6 days with or without 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 after MDI treatment for 48 h. Mitochondrial morphology was determined by confocal microscopy. (B) Graph showing average mitochondrial length. (C) Graph indicating mitochondrial morphology. Data in the bar graphs represent the means ± SEM of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001 compared with untreated or insulin-treated cells. <sup>##</sup>p < 0.01, <sup>###</sup>p < 0.001 compared with untreated cells.</p
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 on lipid accumulation in 3T3-L1 cells during adipogenesis.
<p>3T3-L1 adipocytes were pretreated with 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 for 30 min and then with insulin during adipogenesis. (A) Accumulated lipid was stained with Oil Red O reagent and quantified by absorbance at 490 nm (B). Data in the bar graph represent the means ± SEM of three independent experiments. *p < 0.05, ***p < 0.001, compared with untreated or insulin-treated cells. <sup>###</sup>p<0.001, compared with insulin-treated cells.</p
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 treatment on antioxidant related genes in 3T3-L1 cells after differentiation.
<p>(A) 3T3-L1 adipocytes were pretreated with 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 for 30 min and then with insulin during adipogenesis. Cells were lysed and proteins were subjected to Western blot analysis analysis with the indicated antibodies; antioxidant genes (Prx1, Prx2, Prx3, Prx5, SOD1, and SOD2). Data in the bar graph represent the means ± SEM of three independent experiments. * p< 0.05, ** p< 0.01, *** p< 0.001, compared with not treated cell. # p< 0.05, ## p< 0.01, ### p< 0.001, compared with insulin-treated cell.</p
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 treatment on intracellular and mitochondrial ROS production in 3T3-L1 cells after differentiation.
<p>(A) 3T3-L1 adipocytes were pretreated with 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 for 30 min and then with insulin during adipogenesis. After 8 days of the initiation of differentiation, cells were used in CM-H<sub>2</sub>DCF-DA (A, B) and Mito-SOX (A, C) stained assays. Data in the bar graphs represent the means ± SEM of three independent experiments. ***p < 0.001 compared with untreated or insulin-treated cells.</p
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 on mitochondrial dynamics-related genes in 3T3-L1 cells after differentiation.
<p>3T3-L1 adipocytes were pretreated with 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 for 30 min and then with insulin during adipogenesis. Cells were lysed and proteins were subjected to western blot analysis with the indicated antibodies: mitochondrial dynamics-related genes (OPA1, Mfn1, Mfn2, p-Drp1 (Ser616), and Drp1). Data in the bar graphs represent the means ± SEM of three independent experiments. **p < 0.01, ***p < 0.001, compared with untreated cells. <sup>#</sup>p < 0.05, <sup>##</sup>p < 0.01, <sup>###</sup>p < 0.001 compared with insulin-treated cells.</p
Effect of N-acetyl cysteine (Nac), Mito-TEMPO, and Mdivi-1 on the expression of adipogenic related genes in 3T3-L1 cells after differentiation.
<p>3T3-L1 adipocytes were pretreated with 10 mM Nac, 200 μM Mito-TEMPO, or 50 μM Mdivi-1 for 30 min and then with insulin during adipogenesis. Cells were lysed and proteins were subjected to western blot analysis with the indicated antibodies: adipogenic genes (PPARγ, C/EBPα, p-AKT, AKT, GLUT4, and aP2). Data in the bar graphs represent the means ± SEM of three independent experiments. *p < 0.05, **p < 0.01, ***p < 0.001, compared with untreated cells. <sup>#</sup>p < 0.05, <sup>##</sup>p < 0.01, <sup>###</sup>p < 0.001 compared with insulin-treated cells.</p
Tuning the “Roadblock” Effect in Kinesin-Based Transport
Major efforts are underway to harness motor proteins
for technical
applications. Yet how to best attach cargo to microtubules that serve
as kinesin-driven “molecular shuttles” without compromising
transport performance remains challenging. Furthermore, microtubule-associated
proteins (MAPs) can block motor protein-powered transport in neurons,
which can lead to neurodegenerative diseases. Again it is unclear
how different physical roadblock parameters interfere with the stepping
motion of kinesins. Here, we employ a series of MAPs, tailored (strept)Âavidins,
and DNA as model roadblocks and determine how their geometrical, nanomechanical,
and electrochemical properties can reduce kinesin-mediated transport.
Our results provide insights into kinesin transport regulation and
might facilitate the choice of appropriate cargo linkers for motor
protein-driven transport devices
Tuning the “Roadblock” Effect in Kinesin-Based Transport
Major efforts are underway to harness motor proteins
for technical
applications. Yet how to best attach cargo to microtubules that serve
as kinesin-driven “molecular shuttles” without compromising
transport performance remains challenging. Furthermore, microtubule-associated
proteins (MAPs) can block motor protein-powered transport in neurons,
which can lead to neurodegenerative diseases. Again it is unclear
how different physical roadblock parameters interfere with the stepping
motion of kinesins. Here, we employ a series of MAPs, tailored (strept)Âavidins,
and DNA as model roadblocks and determine how their geometrical, nanomechanical,
and electrochemical properties can reduce kinesin-mediated transport.
Our results provide insights into kinesin transport regulation and
might facilitate the choice of appropriate cargo linkers for motor
protein-driven transport devices