Molecular Systems Design & Engineering最新文献

An X-ray fluorescence spectrometer (XRF) combined with an energy dispersive spectrometer (EDS) offers a wealth of information about the mode of distribution in heterogeneous catalysis for platinum nanoparticles (Pt-NPs) encapsulated in MFI zeolite nanocrystallite aggregates, thus providing a promising probe of their local structure. In this paper, we hydrothermally synthesized a novel microsphere monomer containing encapsulated Pt ZSM-5 nanocrystalline aggregates with a diameter of 5–7 μm, in which the Pt content can be confirmed by direct detection with the difference in detection depths of XRF and EDS. Moreover, the package structure can limit the size of the metal Pt particles, improve the degree of metal dispersion, and obtain high propane conversion (45%) and propylene selectivity (63%) over the long term.

Materials with distinct stimulus-responsive properties hold potential as carriers in next-generation drug delivery systems. In this study, we propose the design and characterisation of a carrier that can stably administer drugs, regardless of external conditions, through a two-step reaction achieved by creating a composite of materials possessing photothermal and temperature-responsive (dual-stimuli) characteristics. This composite, a novel integration of photothermal liquid metals (LMs) responsive to near-infrared laser irradiation and a temperature-responsive carboxylated polylysine-based polyampholyte, marks a significant advancement in drug delivery technology. The temperature-responsive liquid–liquid phase separation behaviour of the polymer, crucial for drug release, is precisely controlled by adjusting the ratio and concentration of the polymer anions and cations. Moreover, the heat required for phase separation and compatibility with the polymer solution is modulated through nanoparticle formation of the photothermal LMs, along with variations in the irradiation time and intensity of near-infrared laser light. Our findings, corroborated through laser microscopy and cell toxicity tests, demonstrate that this composite can generate heat upon photo-stimulation and use this heat to induce phase separation. Additionally, unlike conventional temperature-responsive carriers, this composite concentrates drugs, likely due to enhanced electrostatic interactions between the polyampholyte and the drug. This research not only overcomes the challenges faced by traditional stimulus-responsive carriers, which are influenced by the surrounding physiological environment, but also demonstrates the potential of a two-step reaction approach to concentrate and deliver drugs effectively.

Almost all utilization of biocatalysis in the burgeoning field of synthetic biology requires not only enzymes but also that they function with peak efficiency, especially when paired with other enzymes in designer multistep cascades. This has driven concerted efforts into enhancing enzymatic performance by attaching them to macroscale scaffolding materials for display. Although providing for improved long-term stability, this attachment typically comes at the cost of decreased catalytic efficiency. However, an accumulating body of data has confirmed that attaching enzymes to various types of nanoparticle (NP) materials can often dramatically increase their catalytic efficiency. Many of the causative mechanisms that give rise to such enhancement remain mostly unknown but it is clear that the unique structured and interfacial environment that physically surrounds the NP material is a major contributor. In this review, we provide an updated and succinct overview of the current understanding and key factors that contribute to enzymatic enhancement by NP materials including the unique structured NP interfacial environment, NP surface chemistry and size, and the influence of bioconjugation chemistry along with enzyme mechanics. We then provide a detailed listing of examples where enzymes have displayed enhanced activity of some form when they are displayed on a NP as organized by material types such as semiconductor quantum dots, metallic NPs, DNA nanostructures, and other more non-specific and polymeric nanomaterials. This is followed by a description of what has been learned about enhancement from these examples. We conclude by discussing what more is needed for this phenomenon to be exploited and potentially translated in the design and engineering of far more complex molecular systems and downstream applications.

Despite the potential of Ru-based catalysts to achieve green sustainability in acetylene hydrochlorination, they are plagued by a lack of persistent active sites. Deep eutectic solvents (DESs), considered a novel type of ionic liquid (IL) analogue, can coordinate with metals and adsorb HCl. Hence, to investigate the role of DES in modifying Ru-based catalysts for acetylene hydrochlorination, a range of Ru-DES/AC catalysts were prepared and evaluated for their catalytic performance. The experimental results showed that the formation of DES from a hydrogen bond donor (HBD) and hydrogen bond acceptor (HBA) resulted in a more negative electrostatic potential (ESP) minima and stronger electron-donating ability. The interaction of DES with Ru precursors can effectively modulate the microchemical environment around the Ru active site and improve the dispersion of the active components, thereby boosting the activity of Ru-DES/AC catalysts. The addition of DES not only makes the Ru species more stable but also reduces the formation of coke deposition, thus enhancing the stability of the catalyst. Meanwhile, we found that the synergistic effect between HBD and HBA in DES on the performance enhancement of Ru-based catalysts is universal. Therefore, to scientifically design more efficient catalysts, we evaluated the potential descriptors of DES.

Selective and efficient removal of sulfate from aqueous solution having a high concentration of other competing ions is an important aspect of separation science technology and has attracted considerable attention from researchers to develop molecular systems to achieve this challenging goal. Selective sulfate separation from aqueous nuclear waste media with a high nitrate concentration and seawater with a high chloride concentration are the two main objectives to be accomplished along this line. Nuclear power plant-generated radioactive waste disposal and highly effective membrane-based seawater desalination processes require prior removal of corrosion-inducing hydrophilic sulfate ions from the aqueous media to avoid possible environmental risks and membrane blockage, respectively. Further, sulfate removal from highly acidic wastewater discharged from mining and metallurgical industrial operations needs to be seriously addressed to avoid irreversible damage to the aquatic environment. Therefore, to achieve selective sulfate separation from water, several hydrogen bond donor (HBD) macrocyclic and acyclic anion receptors having higher binding affinity for sulfate over other anions have been synthesized. The sulfate removal efficacy of anion receptors has been demonstrated by the industrially applicable liquid–liquid (solvent) extraction method and proof of concept technique involving the selective crystallization (precipitation) of a receptor–sulfate complex from aqueous solution. In this review, we provide the detailed development of sulfate-selective synthetic receptors and their application in effective sulfate separation from simulated wastewater media and seawater. Since the pioneering paper by Sessler and Moyer et al. (2007), significant progress has been made in this field, which needs to be thoroughly assessed and understood to deliver suitable chemical technology for selective sulfate separation.

Plastics are ubiquitous and essential to our society. Unfortunately, they contribute to environmental pollution due to their lack of degradation upon disposal. Here, we describe some model polymers that were used to demonstrate controlled degradation under environmental conditions (pH 7). The polymers were made from a 7 : 3 ratio of hydroquinone (HQA) and terephthalate (TPhA) alkyne derivatives with various amounts of polyethylene glycol (PEGAz) and acetal azides (AAz). Their structures were determined by ¹H NMR. The ratio of monomer units in the polymers was shown to be similar to the feed ratio. The polymers are amorphous with low glass transition temperatures (T_g). Furthermore, the polymer containing 1 : 1 ratio of PEG to acetal units was degraded in pH 5 and 7 buffer solutions over a 3 month period, whereas the polymer with only acetal group degraded at pH 5. Our results show that degradation can be controlled with different amounts of PEG and acetal groups.

Auxetic structures are unique with a negative Poisson's ratio. Unlike regular materials, they respond to external loading with simultaneous expansion or compression in all directions, rendering powerful properties advantageous in diverse applications from manufacturing to space engineering. The auxetic behaviors are determined by structural design and architecture. Such structures have been discovered in natural crystals and demonstrated synthetically with bulk materials. Recent development of DNA-based structures has pushed the unit cell size to the nanometer scale. DNA nanotechnology utilizes sequence complementarity between nucleotides. By combining sequence designs with programmable self-assembly, it is possible to construct complex structures with nanoscale accuracy and to perform dynamic reconfigurations. Herein, we report a novel design of auxetic nanostars with sliding behaviors using DNA origami. Our proposed structure, inspired by an Islamic pattern, demonstrates a unit cell with two distinct reconfigurations by programming directed sliding mechanisms. Compared to previous metamaterials, the DNA nanostars show an architecture with tunable auxetic properties for the first time. We envision that this strategy may form the basis of novel metastructures with adaptability and open new possibilities in bioengineering.