3 research outputs found
Highly Selective and Stable Carbon Dioxide Uptake in Polyindole-Derived Microporous Carbon Materials
Adsorption
with solid sorbents is considered to be one of the most
promising methods for the capture of carbon dioxide (CO<sub>2</sub>) from power plant flue gases. In this study, microporous carbon
materials used for CO<sub>2</sub> capture were synthesized by the
chemical activation of polyindole nanofibers (PIF) at temperatures
from 500 to 800 °C using KOH, which resulted in nitrogen (N)-doped
carbon materials. The N-doped carbon materials were found to be microporous
with an optimal adsorption pore size for CO<sub>2</sub> of 0.6 nm
and a maximum (Brunauer–Emmett–Teller) BET surface area
of 1185 m<sup>2</sup> g<sup>–1</sup>. The PIF activated at
600 °C (PIF6) has a surface area of 527 m<sup>2</sup> g<sup>–1</sup> and a maximum CO<sub>2</sub> storage capacity of 3.2 mmol g<sup>–1</sup> at 25 °C and 1 bar. This high CO<sub>2</sub> uptake is attributed to its highly microporous character and optimum
N content. Additionally, PIF6 material displays a high CO<sub>2</sub> uptake at low pressure (1.81 mmol g<sup>–1</sup> at 0.2 bar
and 25 °C), which is the best low pressure CO<sub>2</sub> uptake
reported for carbon-based materials. The adsorption capacity of this
material remained remarkably stable even after 10 cycles. The isosteric
heat of adsorption was calculated to be in the range of 42.7–24.1
kJ mol<sup>–1</sup>. Besides the excellent CO<sub>2</sub> uptake
and stability, PIF6 also exhibits high selectivity values for CO<sub>2</sub> over N<sub>2</sub>, CH<sub>4</sub>, and H<sub>2</sub> of
58.9, 12.3, and 101.1 at 25 °C, respectively, and these values
are significantly higher than reported values
Precise Tuning of Cationic Cyclophanes toward Highly Selective Fluorogenic Recognition of Specific Biophosphate Anions
Cationic cyclophanes
with bridging and spacer groups possess well-organized
semirigid cavities and are able to encapsulate and stabilize anionic
species through diverse molecular interactions. We highlight the precise
tuning of functionalized cyclophanes toward selective recognition
of AMP, GTP, and pyrophosphate (PPi) using fluorescence, NMR spectroscopy,
and density functional theory (DFT)
Accelerated Bone Regeneration by Two-Photon Photoactivated Carbon Nitride Nanosheets
Human bone marrow-derived mesenchymal
stem cells (hBMSCs) present
promising opportunities for therapeutic medicine. Carbon derivatives
showed only marginal enhancement in stem cell differentiation toward
bone formation. Here we report that red-light absorbing carbon nitride
(C<sub>3</sub>N<sub>4</sub>) sheets lead to remarkable proliferation
and osteogenic differentiation by runt-related transcription factor
2 (Runx2) activation, a key transcription factor associated with osteoblast
differentiation. Accordingly, highly effective hBMSCs-driven mice
bone regeneration under red light is achieved (91% recovery after
4 weeks compared to 36% recovery in the standard control group in
phosphate-buffered saline without red light). This fast bone regeneration
is attributed to the deep penetration strength of red light into cellular
membranes <i>via</i> tissue and the resulting efficient
cell stimulation by enhanced photocurrent upon two-photon excitation
of C<sub>3</sub>N<sub>4</sub> sheets near cells. Given that the photoinduced
charge transfer can increase cytosolic Ca<sup>2+</sup> accumulation,
this increase would promote nucleotide synthesis and cellular proliferation/differentiation.
The cell stimulation enhances hBMSC differentiation toward bone formation,
demonstrating the therapeutic potential of near-infrared two-photon
absorption of C<sub>3</sub>N<sub>4</sub> sheets in bone regeneration
and fracture healing