3 research outputs found
Structural Determinants of Chirally Selective Transport of Amino Acids through the α‑Hemolysin Protein Nanopores of Free-Standing Planar Lipid Membranes
Despite the importance of the enantioselective
transport
of amino
acids through transmembrane protein nanopores from fundamental and
practical perspectives, little has been explored to date. Here, we
study the transport of amino acids through α-hemolysin (αHL)
protein pores incorporated into a free-standing lipid membrane. By
measuring the transport of 13 different amino acids through the αHL
pores, we discover that the molecular size of the amino acids and
their capability to form hydrogen bonds with the pore surface determine
the chiral selectivity. Molecular dynamics simulations corroborate
our findings by revealing the enantioselective molecular-level interactions
between the amino acid enantiomers and the αHL pore. Our work
is the first to present the determinants for chiral selectivity using
αHL protein as a molecular filter
Flash-Thermal Shock Synthesis of Single Atoms in Ambient Air
Single-atom catalysts feature interesting catalytic activity
toward
applications that rely on surface reactions such as electrochemical
energy storage, catalysis, and gas sensors. However, conventional
synthetic approaches for such catalysts require extended periods of
high-temperature annealing in vacuum systems, limiting their throughput
and increasing their production cost. Herein, we report an ultrafast
flash-thermal shock (FTS)-induced annealing technique (temperature
> 2850 °C, 5 K/s) that operates in an ambient-air environment to prepare
single-atom-stabilized N-doped graphene. Melamine is utilized as an
N-doping source to provide thermodynamically favorable metal–nitrogen
bonding sites, resulting in a uniform and high-density atomic distribution
of single metal atoms. To demonstrate the practical utility of the
single-atom-stabilized N-doped graphene produced by the FTS method,
we showcased their chemiresistive gas sensing capabilities and electrocatalytic
activities. Overall, the air-ambient, ultrafast, and versatile (e.g.,
Co, Ni, Pt, and Co–Ni dual metal) FTS method provides a general
route for high-throughput, large area, and vacuum-free manufacturing
of single-atom catalysts
Rational Design of Aminopolymer for Selective Discrimination of Acidic Air Pollutants
Strong
acidic gases such as CO<sub>2</sub>, SO<sub>2</sub>, and
NO<sub>2</sub> are harsh air pollutants with major human health threatening
factors, and as such, developing new tools to monitor and to quickly
sense these gases is critically required. However, it is difficult
to selectively detect the acidic air pollutants with single channel
material due to the similar chemistry shared by acidic molecules.
In this work, three acidic gases (i.e., CO<sub>2</sub>, SO<sub>2</sub>, and NO<sub>2</sub>) are selectively discriminated using single
channel material with precise moiety design. By changing the composition
ratio of primary (1°), secondary (2°), and tertiary (3°)
amines of polyethylenimine (PEI) on CNT channels, unprecedented high
selectivity between CO<sub>2</sub> and SO<sub>2</sub> is achieved.
Using in situ FT-IR characterizations, the distinct adsorption phenomenon
of acidic gases on each amine moiety is precisely demonstrated. Our
approach is the first attempt at controlling gas adsorption selectivity
of solid-state sensor via modulating chemical moiety level within
the single channel material. In addition, discrimination of CO<sub>2</sub>, SO<sub>2</sub>, and NO<sub>2</sub> with the single channel
material solid-state sensor is first reported. We believe that this
approach can greatly enhance air pollution tracking systems for strong
acidic pollutants and thus aid future studies on selective solid-state
gas sensors