To extend the application range of L-asparaginase in food pre-processing, the thermostability improvement of the enzyme is essential. Herein, two non-conserved cysteine residues with easily oxidized ...free sulfhydryl groups, Cys8 and Cys283, of Acinetobacter soli L-asparaginase (AsA) were screened out via consensus design. After saturation mutagenesis and combinatorial mutation, the mutant C8Y/C283Q with highly improved thermostability was obtained with a half-life of 361.6 min at 40 °C, an over 34-fold increase compared with that of the wild-type. Its melting temperature (Tsub.m) value reaches 62.3 °C, which is 7.1 °C higher than that of the wild-type. Molecular dynamics simulation and structure analysis revealed the formation of new hydrogen bonds of Gln283 and the aromatic interaction of Tyr8 formed with adjacent residues, resulting in enhanced thermostability. The improvement in the thermostability of L-asparaginase could efficiently enhance its effect on acrylamide inhibition; the contents of acrylamide in potato chips were efficiently reduced by 86.50% after a mutant C8Y/C283Q treatment, which was significantly higher than the 59.05% reduction after the AsA wild-type treatment. In addition, the investigation of the mechanism behind the enhanced thermostability of AsA could further direct the modification of L-asparaginases for expanding their clinical and industrial applications.
Nuclear quantum effects influence the structure and dynamics of hydrogen-bonded systems, such as water, which impacts their observed properties with widely varying magnitudes. This review highlights ...the recent significant developments in the experiment, theory, and simulation of nuclear quantum effects in water. Novel experimental techniques, such as deep inelastic neutron scattering, now provide a detailed view of the role of nuclear quantum effects in water’s properties. These have been combined with theoretical developments such as the introduction of the principle of competing quantum effects that allows the subtle interplay of water’s quantum effects and their manifestation in experimental observables to be explained. We discuss how this principle has recently been used to explain the apparent dichotomy in water’s isotope effects, which can range from very large to almost nonexistent depending on the property and conditions. We then review the latest major developments in simulation algorithms and theory that have enabled the efficient inclusion of nuclear quantum effects in molecular simulations, permitting their combination with on-the-fly evaluation of the potential energy surface using electronic structure theory. Finally, we identify current challenges and future opportunities in this area of research.
Recently, flexible capacitive pressure sensors have received significant attention in the field of wearable electronics. The high sensitivity over a wide linear range combined with long-term ...durability is a critical requirement for the fabrication of reliable pressure sensors for versatile applications. Herein, we propose a special approach to enhance the sensitivity and linearity range of a capacitive pressure sensor by fabricating a hybrid ionic nanofibrous membrane as a sensing layer composed of Ti3C2T x MXene and an ionic salt of lithium sulfonamides in a poly(vinyl alcohol) elastomer matrix. The reversible ion pumping triggered by a hydrogen bond in the hybrid sensing layer leads to high sensitivities of 5.5 and 1.5 kPa–1 in the wide linear ranges of 0–30 and 30–250 kPa, respectively, and a fast response time of 70.4 ms. In addition, the fabricated sensor exhibits a minimum detection limit of 2 Pa and high durability over 20 000 continuous cycles even under a high pressure of 45 kPa. These results indicate that the proposed sensor can be potentially used in mobile medical monitoring devices and next-generation artificial e-skin.
The intramolecular hydrogen bond (intra‐HB) is one of the best‐known examples of non‐covalent interactions in molecules. Among the different types of intramolecular hydrogen bonding, the NH⋅⋅⋅O ...hydrogen bond in amino‐alcohols and amino‐ethers is one of the weakest. In contrast to the strong OH⋅⋅⋅N intramolecular hydrogen bond, the strength of the NH⋅⋅⋅O bond can hardly be measured with conventional spectroscopic methods, even for simple amino‐alcohols, since the band belonging to the NH⋅⋅⋅O conformer merges with the free OH band. In this work, we developed a combination of G4 calculations, and a method based on experimental vaporization enthalpies to determine the NH⋅⋅⋅O hydrogen bonding strength. The archetypal compounds for this study are 2‐amino‐1‐ethanol and 3‐amino‐1‐propanol as well as their respective methoxy analogs. Based on these molecules, different series were studied to investigate various factors influencing NH⋅⋅⋅O intra‐HB strength. In the first series, the influence of alkylation near the hydroxy or methoxy group and the amino group in sterically hindered aminoalcohols was examined. In the second series, the influence of alkylation of the amino‐group was investigated. In the third series, the effect of extending the alkyl chain between functional groups was studied.
The strength of NH⋅⋅⋅O bond in three series of amino‐alcohols characterized by branching, mono‐alkylation of the amino group, or increased chain length between the functional groups, was evaluated by a combination of quantum chemistry and a method based on experimental vaporization enthalpies. It was observed that moderate tertiary branching at the H‐acceptor or at the H‐donor side has only a marginal effect on the NH⋅⋅⋅O hydrogen bond strength so that it remains in the range of −4 kJ⋅mol−1 to −6 kJ⋅mol−1.
Self-healing soft electronic and robotic devices can, like human skin, recover autonomously from damage. While current devices use a single type of dynamic polymer for all functional layers to ensure ...strong interlayer adhesion, this approach requires manual layer alignment. In this study, we used two dynamic polymers, which have immiscible backbones but identical dynamic bonds, to maintain interlayer adhesion while enabling autonomous realignment during healing. These dynamic polymers exhibit a weakly interpenetrating and adhesive interface, whose width is tunable. When multilayered polymer films are misaligned after damage, these structures autonomously realign during healing to minimize interfacial free energy. We fabricated devices with conductive, dielectric, and magnetic particles that functionally heal after damage, enabling thin-film pressure sensors, magnetically assembled soft robots, and underwater circuit assembly.
Deep eutectic solvents (DESs) as the novel kind of green solvents have been received widespread attention. After the addition of molecular solvents, a pseudo-binary system is set up with the ...advantages such as low cost. A kind of DES (1TEAB: 3EG) was prepared and confirmed, and it is mixed with acetonitrile, ethanol and water. Their density, surface tension and refractive index of the DES and its corresponding pseudo-binary mixtures are explored in depth. In addition to the excess molar volumes, the partial molar volumes, partial molar volume at infinite dilution and their excess molar volumes are also investigated. The molar Gibbs free energy and the corresponding molar surface enthalpy could be deduced from the improved EÓ§tvÓ§s equation. It is suggested that the molar Gibbs free energy model is fit for that of DES and its pseudo-binary systems. In addition, the surface tension deviations and refractive index deviations are figured out. This illustrates that there are fairly strong interactions between DES (1TEAB: 3EG) and molecular solvents, which could attribute to mainly two sides: H-bonding and structural effect. Besides, refractive properties such as the molar refraction and free volume are advised that there are ion-dipole interactions between DES and molecular solvents.
Pressure-adapted organisms are able to survive in the depths of the ocean because of trimethylamine N-oxide-assisted hydrogen bonding between water molecules.
Metal-organic gels (MOGs) emerged as a novel class of functional soft materials in which the scaffolding framework is fabricated by metal-ligand coordination in combination with other supramolecular ...interactions (for example, hydrogen bonding or π-π stacking). Through the combination of organic and inorganic (metal/metal-oxo clusters) building blocks, significant steps forward have been made in the development of new electrochemical sensors, superhydrophobic materials and ion storage devices, among others. These leaps forward are to some extend induced by the intrinsic hierarchical microporous/mesoporous pore structure of these metal-organic materials. Within this review we give an overview of recent developments of this growing field. First, we shed light onto the parallels to the well-established field of conventional gels and outline similarities and differences. Afterwards, we classify different types of MOGs according to their architectural/structural nature: (1) pristine MOGs, (2) hybrid MOGs, (3) crosslinking-based MOGs and (4) MOG-derived materials. Furthermore, we look at the different properties of MOGs and the requirements for the preparation of spatially patterned macro-structured MOGs by emerging additive manufacturing technologies. Moreover, different potential fields of application for MOGs and MOG derived materials are critically evaluated and potential improvements and pitfalls in comparison to traditional gel-based materials are given. Finally, a comprehensive outlook into future directions for the development of MOGs is provided.
This review summarizes recent progress in the development and applications of metal-organic gels (MOGs) and their hybrids and derivatives dividing them into subclasses and discussing their synthesis, design and structure-property relationship.
We report that the use of a hydrogen-bonded pyrimidine-macrocycle complex can efficiently facilitate the threading of two bispyridinium ethylenes into four rings, as evidenced by X-ray ...crystallography of its precursor, offering a rare example of a doubly threaded 6rotaxane in 91% yield. The unusual architecture is found to be stable with no dethreading despite the large ring size of the macrocycle with respect to the stopper.
This study reveals that a hydrogen-bonded pyrimidine-macrocycle complex can efficiently thread two bispyridinium ethylenes into four rings yielding a rare, stable doubly threaded 6rotaxane in 91% yield.
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