4 research outputs found
Early transcriptomic response of mouse adrenal gland and Y-1 cells to dexamethasone
Glucocorticoids have short- and long-term effects on adrenal gland function and development. RNA sequencing (RNA-seq) was performed to identify early transcriptomic responses to the synthetic glucocorticoid, dexamethasone (Dex), in vitro and in vivo. In total, 1711 genes were differentially expressed in the adrenal glands of the 1-h Dex-treated mice. Among them, only 113 were also considered differentially expressed genes (DEGs) in murine adrenocortical Y-1 cells treated with Dex for 1 h. Gene ontology analysis showed that the upregulated DEGs in the adrenal gland of the 1-h Dex-treated mice were highly associated with the development of neuronal cells, suggesting the adrenal medulla had a rapid response to Dex. Interestingly, only 4.3% of Dex-responsive genes in the Y-1 cell line under Dex treatment for 1 h were differentially expressed under Dex treatment for 24 h. The heatmaps revealed that most early responsive DEGs in Y-1 cells during 1 h of treatment exhibited a transient response. The expression of these genes under treatment for 24 h returned to basal levels similar to that during control treatment. In summary, this research compared the rapid transcriptomic effects of Dex stimulation in vivo and in vitro. Notably, adrenocortical Y-1 cells had a transient early response to Dex treatment. Furthermore, the DEGs had a minimal overlap in the 1-h Dex-treated group in vivo and in vitro
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Tunable Dopants with Intrinsic Counterion Separation Reveal the Effects of Electron Affinity on Dopant Intercalation and Free Carrier Production in Sequentially Doped Conjugated Polymer Films
Carrier mobility in doped conjugated polymers is limited by Coulomb interactions with dopant counterions. This complicates studying the effect of the dopant's oxidation potential on carrier generation because different dopants have different Coulomb interactions with polarons on the polymer backbone. Here, dodecaborane (DDB)-based dopants are used, which electrostatically shield counterions from carriers and have tunable redox potentials at constant size and shape. DDB dopants produce mobile carriers due to spatial separation of the counterion, and those with greater energetic offsets produce more carriers. Neutron reflectometry indicates that dopant infiltration into conjugated polymer films is redox-potential-driven. Remarkably, X-ray scattering shows that despite their large 2-nm size, DDBs intercalate into the crystalline polymer lamellae like small molecules, indicating that this is the preferred location for dopants of any size. These findings elucidate why doping conjugated polymers usually produces integer, rather than partial charge transfer: dopant counterions effectively intercalate into the lamellae, far from the polarons on the polymer backbone. Finally, it is shown that the IR spectrum provides a simple way to determine polaron mobility. Overall, higher oxidation potentials lead to higher doping efficiencies, with values reaching 100% for driving forces sufficient to dope poorly crystalline regions of the film
Designing Amphiphilic Conjugated Polyelectrolytes for Self-Assembly into Straight-Chain Rod-like Micelles
Semiconducting polymers are a versatile class of materials
that
are used in many (opto)electronic applications, including organic
photovoltaics. However, they are inherently disordered and suffer
from poor conductivities due to bends and kinks in the polymer chains
along the conjugated backbone, as well as disorder at grain boundaries.
In an effort to reduce polymer disorder, we developed a method to
straighten polymer chains by creating amphiphilic conjugated polyelectrolytes
(CPEs) that self-assemble in water into worm-like micelles. The present
work refines our design rules for self-assembly of CPEs. We present
the synthesis and characterization of a straight, micelle-forming
polymer, a derivative of poly(cyclopentadithiophene-alt-thiophene) (PCT) bearing two ammonium-charged groups per cyclopentadithiophene
unit. Solution-phase self-assembly of PCT into micelles is observed
by both small-angle X-ray scattering (SAXS) and cryo-electron microscopy
(cryo-EM), while detailed SAXS fitting allows for characterization
of intra-micellar interactions and inter-micelle aggregation. We find
that PCT displays significant chain straightening thanks to the lack
of steric hindrance between its alternating cyclopentadithiophene
and thiophene subunits, which increases the propensity for the polymer
to self-assemble into straight rod-like micelles. This work extends
the availability of micelle-forming semiconducting polymers and points
to further enhancements that can be made to obtain homogeneous nanostructured
polymer assemblies based on cylindrical micelles