Molecular Systems Design & Engineering最新文献

In recent years, nanocellulose has emerged as a sustainable and environmentally friendly alternative to traditional petroleum-derived structural polymers. Sourced either from plants, algae, or bacteria, nanocellulose can be processed into colloid, gel, film and fiber forms. However, the required fundamental understanding of process parameters that govern the morphology and structure–property relationships of nanocellulose systems, from colloidal suspensions to bulk materials, has not been developed and generalized for all forms of cellulose. This further hinders the more widespread adoption of this biopolymer in applications. Our study investigates the dispersion of cellulose nanofibers (CNFs) produced by a bacterial–yeast co-culture, in solvents, highlighting the role of thermodynamic interactions in influencing their colloidal behavior. By adjusting Hansen solubility parameters, we controlled the thermodynamic relationship between CNFs and solvents across various concentrations, studying the dilute to semi-dilute regimes. Rheological measurements revealed that the threshold at which a concentration-based regime transition occurs is distinctly solvent-dependent. Complementing rheological analysis with small angle X-ray scattering and zeta potential measurements, our findings reveal that enhancing CNF–solvent interactions increases excluded volume in the dilute regime, emphasizing the importance of the balance between fiber–fiber and fiber–solvent interactions. Moreover, we investigated the transition from colloidal to solid state by creating films from dispersions with varying interaction parameters in semi-dilute regimes. Through mechanical testing and scanning electron microscopy imaging of the fracture surfaces, we highlight the significance of electrokinetic effects in such transitions, as dispersions with higher electrokinetic stabilization gave rise to stronger and tougher films despite having less favorable thermodynamic interaction parameters. Our work provides insights into the thermodynamic and electrokinetic interplay that governs bacterial CNF dispersion, offering a foundation for future application and a deeper understanding of nanocellulose's colloidal and structure-property relationships.

In the current research, we have unveiled an advanced technique termed the quantitative read-across structure–activity relationship (q-RASAR) framework to harness the power of machine learning (ML) for significantly enhancing the precision of predictions related to blood–brain barrier (BBB) permeability. It is important to emphasize that the central objective of this study is not to introduce an additional model for predicting BBB permeability. Instead, our focus is on highlighting the improvement in quantitatively predicting the BBB permeability of organic compounds by utilizing the q-RASAR approach. This innovative methodology strives to enhance the precision of evaluating neuropharmacological implications and streamline the drug development process. In this investigation, we developed a machine learning (ML)-based q-RASAR PLS regression model using a large dataset comprising 1012 diverse classes of heterocyclic and aromatic compounds, obtained from the freely accessible B3DB database (accessible at https://github.com/theochem/B3DB) to predict BBB permeability during the lead discovery phase for central nervous system (CNS) drugs. The model's predictive capability underwent validation using two external sets, encompassing a total of 1 130 315 compounds, including synthetic compounds and natural products (NPs) for data gap filling and other two external sets comprising 116 drug-like/drug compounds from the FDA and ChEMBL databases to assess the model's reliability against the reported BBB permeability values. This study aimed to bridge the data gap by employing a predictive regression model to estimate the BBB permeability for both synthetic compounds and natural products (NPs). To further enhance predictability, we have developed various other ML-based q-RASAR models. The insights from the developed model highlight the pivotal roles played by hydrophobicity, electronic effects, degree of ionization, and steric factors as essential features facilitating the traversal of the blood–brain barrier. This research not only advances our understanding of the molecular determinants influencing the permeability of central nervous system drugs but also establishes a versatile computational platform for the rapid assessment of diverse compounds, facilitating informed decision-making in the realms of drug development and design.

Bioink in three-dimensional (3D) bioprinting of biomimetic tissue scaffolds has emerged as a key factor for the success of tissue engineering and regenerative medicine. The bioinks used for extrusion 3D bioprinting have hydrogel matrices with different kinds of polymeric biomaterials such as proteins, peptides, polysaccharides, hydrophilic synthetic polymers, and others. Natural polysaccharides such as alginate, chitosan, and hyaluronic acid have garnered significant attention as bioink materials due to their excellent biocompatibility, extracellular matrix mimetic properties, biodegradability, injectability, bioprintablilty and structural versatility among their many advantages, even though many research groups focus on the study of protein-based bioinks to utilize their high potential of cell adhesiveness. This review encompasses recent advancements of polysaccharide-based hydrogels and bioinks for bioengineered tissue regeneration and reconstruction, especially by focusing on fabrication of multilayered complex structures for biomimetic tissue engineering applications.

Eighteen boron subphthalocyanines (BsubPcs) axial derivatives were synthesized through axial exchange reactions with Br-BsubPc under relatively mild conditions to systematically study the influence of a structurally diverse array of axial group derivatives on the physical properties of the BsubPcs. The photophysical and electrochemical properties of BsubPcs were investigated through solution-state UV-vis absorbance and fluorescence spectroscopy, relative fluorescence quantum yield (QY), cyclic voltammetry (CV), and differential pulse voltammetry (DPV), as these properties are crucial for the application of BsubPcs in the field of organic electronics. The impact of the axial groups on photophysical properties was evaluated by taking measurements in both toluene and α,α,α-trifluorotoluene as the solvent, and referencing QY to two compounds. The axial group has a minimal impact on the absorbance and fluorescence peak shifts, with α,α,α-trifluorotoluene causing a slight blueshift. The axial group had a significant impact on QY, with values ranging from <1% to >70%, and the majority falling in the 30–60% range, depending on the experimental conditions. Although the trends remained consistent, the solvent and reference compound both had notable impacts on QY. CV revealed some BsubPcs have one reversible reduction and one irreversible or quasi-reversible oxidation, others displayed unique reversibility and/or additional redox processes. The axial groups also influenced the redox potentials, with first oxidation potentials spanning a 194 mV range and first reduction potentials covering a 266 mV range. Electron-withdrawing or electron-donating axial groups impacted the redox behaviour of BsubPcs, suggesting an electronic connection between the axial group and the BsubPc core occurs. This study leads to insights into the axial substituents that should be targeted to be used for other peripherally functionalized BsubPc derivatives for further studies.

Copper(I) thiocyanate (CuSCN) has emerged as an excellent hole-transporting semiconductor with applications spanning across electronic and optoelectronic fields. The coordination chemistry of CuSCN allows for extensive structural versatility via ligand modification. In particular, CuSCN modified with pyridine (Py) derivatives can produce novel two-dimensional (2D) structures of the Cu–SCN network while also allowing for the tuning of electronic properties by changing the substituent group on Py. However, obtaining phase-pure 2D structures remains a challenge as the conventional method often yields mixed products of varying stoichiometry having different structures. In this work, we have developed a synthetic method that reliably produces phase pure [Cu(SCN)(3-XPy)]_n complexes (X = OMe, H, Br, and Cl) in a 1 : 1 : 1 ratio all with confirmed 2D structures. The single crystal structure of [Cu(SCN)(3-OMePy)]_n is also reported herein and compared with the reported structures of the other three compounds. Complexes with X = OMe and H show similar structures, in which the 2D layers are analogous to the buckled 2D sheets of silicene or blue phosphorene. On the other hand, for complexes with X = Br and Cl, their rippled 2D structures resemble the puckered 2D sheets found in black phosphorene. The variation of the electron-withdrawing ability of the substituent group is found to systematically shift the electronic energy levels and band gaps of the complexes, allowing the 2D CuSCN-based materials to display optical absorptions and emissions in the visible range. In addition, first-principles calculations reveal that the drastic change in the electronic levels is a result of the emergence of the Py ligand electronic states below the SCN states. This work demonstrates that the structural, electronic, and optical properties of 2D Cu–SCN networks can be systematically tailored through ligand modification.

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.