Search Results (154)

5-Hydroxymethylfurfural (HMF) is a versatile platform molecule with the potential to replace many fossil fuel derivatives. It can be obtained through the dehydration of carbohydrates. In this study, we present a simple and cost-effective microwave-assisted method for producing HMF. This method involves the use of readily available sucrose as a substrate and glucose-derived bifunctional hydrochars as carbocatalysts. These catalysts were produced via hydrothermal carbonisation using thiourea and urea as nitrogen and sulphur sources, respectively, to introduce Brønsted acidic and basic sites into the materials. Using a microwave reactor, we found that the S, N-doped hydrochars were active in sucrose dehydration in water. Catalytic results showed that HMF yield depended on the balance between acidic and basic sites as well as the types of S and N species present on the surfaces of these hydrochars. The best-performing catalyst achieved an encouraging HMF yield of 37%. The potential of N, S-co-doped biochar as a green solid catalyst for various biorefinery processes was demonstrated. A simple kinetic model was developed to elucidate the kinetics of the main reaction pathways of this cascade process, showing a very good fit with the experimental results. The calculated rate constants revealed that reactions with a 5% sucrose loading exhibited significantly higher fructose dehydration rates and produced fewer side products than reactions using a more diluted substrate. No isomerisation of glucose into fructose was observed in an air atmosphere. On the contrary, a limited rate of isomerisation of glucose into fructose was recorded in an oxygen atmosphere. Therefore, efforts should focus on achieving a high glucose-to-fructose isomerisation rate (an intermediate reaction step) to improve HMF selectivity by reducing humin formation. Full article

The large portion of the eukaryotic genomes was considered non-functional and called the “dark matter” of the genome, now appearing as regulatory hubs coding for RNAs without the potential for making proteins, known as non-coding RNA. Long non-coding RNA (lncRNA) is defined as functional RNA molecules having lengths larger than 200 nucleotides without the potential for coding for proteins. Thousands of lncRNAs are identified in different plants and animals. LncRNAs are characterized by a low abundance, fewer exons than mRNA, tissue-specific expression, and low sequence conservation compared to protein-coding genes (PCGs). LncRNAs, like PCGs, are regulated by promoters and enhancers with characteristic chromatin signatures, DNA methylation, multiple exons, introns, and alternate splicing. LncRNAs interact with DNA, mRNA, microRNA, and proteins, including chromatin/histone modifiers, transcription factors/repressors, epigenetic regulators, spliceosomal, and RNA-binding proteins. Recent observations indicate that lncRNAs code for small peptides, also called micropeptides (<100 amino acids), and are involved in the development and growth of plants, suggesting the bi-functional activities of lncRNAs. LncRNAs have emerged as the major regulators of diverse functions, principally by altering the transcription of target genes. LncRNAs are involved in plant growth, development, immune responses, and various physiological processes. Abiotic, biotic, nutrient, and other environmental stresses alter the expressions of numerous lncRNAs. Understanding the mechanisms of actions of lncRNAs opens up the possibility of improving agronomic traits by manipulating lncRNAs. However, further studies are required in order to find the interactions among the deregulated lncRNAs and validate the findings from high-throughput studies to harness their potential in crop improvement. Full article

A polyoxometalate-based metal–organic complex with the ability to treat pollutants in water was obtained under hydrothermal conditions, namely [Ni(H₂L)(HL)₂](PMo₁₂O₄₀)·3H₃O·4H₂O (1) (H₂L = 4,4′-(1H,1′H-[2,2′-biimidazole]-1,1′-diyl)dibenzoicacid). Structural analysis reveals that the [Ni(H₂L)(HL)₂] units are interconnected into a 2D layer via hydrogen bonds between adjacent carboxyl groups and water molecules of crystallization. [PMo₁₂O₄₀]³⁻ anions are embedded within the larger pores of the layer and are connected to the adjacent layers through hydrogen bonds, ultimately expanding the structure into a 3D supramolecular architecture. The intermolecular interactions were studied via Hirshfeld surface (HS) analysis. Electrochemical performance tests reveal that 1 exhibits electrocatalytic activity toward the oxidation and reduction of diverse pollutants in water, including NO₂⁻, Cr(VI), BrO₃⁻, Fe(III), and ascorbic acid (AA). Additionally, it can also serve as an amperometric sensor for the detection of BrO₃⁻ and Cr(VI). Photocatalytic studies reveal that compound 1 functions as a bifunctional photocatalyst, which not only achieves efficient degradation of organic dyes but also demonstrates remarkable reduction efficiency for toxic Cr(VI). Compound 1 demonstrates significant potential for practical water remediation applications. Full article

Biomass, as a renewable carbon resource, holds broad application prospects. Among various bio-based platform molecules, furan derivatives play a significant role in green chemical production. Notably, the conversion of 2-methylfuran (2-MF) to 3-acetyl-1-propanol (3-AP) over bifunctional catalysts has attracted considerable interest. In this study, a Pd@PHZSM-5 catalyst was prepared by encapsulating Pd nanoparticles within P-doped HZSM-5 for 2-MF conversion. The encapsulation improved Pd dispersion and metal–acid synergy, enhancing both catalytic activity and 3-AP selectivity. Additionally, phosphorus doping increased HZSM-5 crystallinity, resulting in excellent stability. This work provides a feasible strategy for optimizing metal–acid cooperation, offering theoretical guidance for bifunctional catalysis and biomass valorization. Full article

This study describes the development of catalytic surface immobilizing dopamine via cross-linking or tyrosinase through covalent bonds on an electrografted screen-printed carbon electrode with a 4-nitrobenzenediazonium ion. A simple electrochemical reduction approach was used to covalently graft aryldiazonium ions onto the surface of commercial electrodes. After functionalization with aminophenyl groups, dopamine, an important neurotransmitter, was immobilized by imine bond formation using glutaraldehyde as a bifunctional cross-linking molecule. The presence of immobilized dopamine was confirmed by cyclic voltammetry following the electrochemical response of the hydroquinone/quinone redox process from catechol functionalities on the surface, which are responsible for the catalytic activity. In addition, the surface was also characterized by cyclic voltammetry using the redox probe, [Fe(CN)₆]^3−/4−, obtaining a signal approximately 14 times higher than that of a bare electrode, achieving a dynamic concentration range spanning three orders of magnitude. Remarkable sensitivity was also obtained by combining the electrografting, in situ diazotation, to generate grafted aryl diazonium ions on the surface, and coupling reaction to anchor the tyrosinase enzyme to the electrode surface. The response of the TYR-biosensor towards catechol, using the redox probe as mediator, was 10 times higher than that obtained with the dopamine modified catalytic surface. These modified surfaces offer promising alternatives for the voltammetric quantification of catechol in environmental fields. Full article

Chemical recycling of plastic waste, especially polyolefins, into valuable liquid fuels is of considerable significance to address the serious issues raised by their threat on environmental and human health. Nevertheless, the construction of efficient and economically viable catalytic systems remains a significant hurdle. Herein, we developed an efficient bifunctional catalyst system comprising γ-Al₂O₃-supported ruthenium nanoparticles (Ru/γ-Al₂O₃) and β-zeolite for the conversion of polyolefins into gasoline-range hydrocarbons. A yield of C_5–12 paraffins up to 73.4% can be obtained with polyethene as the reactant at 250 °C in hydrogen. The Ru sites primarily activate the initial cleavage of C–H bonds of polymer towards the formation of olefin intermediates, which subsequently go through further cracking and isomerization over the acid sites in β-zeolite. Employing in situ infrared spectroscopy and probe–molecule model reactions, our investigation reveals that the optimized proportion and spatial distribution of the dual catalytic sites are pivotal in the tandem conversion process. This optimization synergistically regulates the cracking kinetics and accelerates intermediate transfer, thereby minimizing the production of side C_1–4 hydrocarbons resulting from over-cracking at the Ru sites and enhancing the yield of liquid fuels. This research contributes novel insights into catalyst design for the chemical upgrading of polyolefins into valuable chemicals, advancing the field of plastic waste recycling and sustainable chemical production. Full article

Considering the issues of significant ammonia volatilization loss and toxic gas emission associated with the conventional ammonia leaching method used in the resource utilization of cobalt-rich alloy slag, a novel approach involving selective complexation leaching of cobalt in an alkaline histidine solution has been proposed. Under conditions of 35 °C temperature, a molar ratio of histidine to cobalt of 1.5, pH of 8, a leaching period of 12 h, and a stirring speed of 300 rpm, the cobalt leaching rate from cobalt-rich alloy slag exceeds 95%. In contrast, the leaching rates for impurity metals such as iron, lead, and copper remain below 3%, demonstrating outstanding leaching selectivity. Leaching kinetics calculations indicate that the rate-controlling step is chemical reaction control, with an apparent activation energy of 64.32 kJ/mol. Through the use of FTIR and XPS characterization techniques, it has been confirmed that histidine molecules form a stable complex with cobalt ions via the dual coordination of the carboxyl (COO⁻) and amino (-NH₂) groups. This distinctive bifunctional synergistic coordination mechanism markedly enhances leaching selectivity and reaction efficiency. Full article

There is relatively little research on cyclic amphiphilic block polymers, having both hydrophilic and hydrophobic segments placed in the ring and thus resulting in a higher degree of topological restriction, as drug vehicles. Cyclic amphiphilic binary block polymer is synthesized by the click coupling reaction of bimolecular homodifunctional precursors. The results indicate that cyclization between linear polymer precursors is successful if the trace linear by-products generated are ignored, which also suggests that the small molecule bifunctional terminating agent applied in traditional bimolecular homodifunctional ring-closure process can be extended to large molecule. Moreover, the study on the self-assembly behavior of polymers shows that, compared with linear counterparts, the stability and drug loading capacity of micelles based on the resultant cyclic polymer are not significantly improved due to the influence of topological structure and linear impurities. Nevertheless, drug loaded micelles formed by the obtained cyclic polymers still exhibit superior cellular uptake ability. It can be seen that topological effects do play an irreplaceable role in the application performance of polymers. Therefore, the construction and synthesis of cyclic and its derivative polymers with moderate topological confinement and high purity may be a key direction for future exploration of polymer drug delivery carriers. Full article

Soluble epoxide hydrolase (sEH) is a bifunctional enzyme with epoxide hydrolase activity in the C-terminal domain (C-EH) and lipid phosphate phosphatase activity in the N-terminal domain (N-phos). The C-EH hydrolyzes bioactive epoxy fatty acids such as epoxyeicosatrienoic acid (EET). The N-phos hydrolyzes lipid phosphomonesters, including the signaling molecules of lysophosphatidic acid (LPA). Here, we report that the C-EH and N-phos are reciprocally regulated by their respective substrates. Full-length sEH (sEH-FL) showed positive cooperativity toward the substrate for each domain. Similar cooperativity was found when truncated enzymes having only C- and N-terminal domains, sEH-C and sEH-N, respectively, were used, suggesting an intra-domain nature of the cooperativity. In addition, the N-phos substrate LPA inhibited C-EH activity in sEH-FL and sEH-C equally. Similarly, the C-EH substrate EET inhibited N-phos activity. Structural and kinetic data suggest the presence of allosteric sites in each domain of the sEH enzyme, which share the binding of LPA and EET. Thus, each of the two sEH activities is regulated by a substrate of its own and by that of the other domain. This mechanism may explain why sEH has evolved to have two different enzyme activities, which possibly allows sEH to balance the metabolism of bioactive lipids. Full article

Among the most selective catalytic systems for the hydroisomerization of C₁₆₊ n-paraffins, catalytic systems based on SAPO-11 are quite promising. In order to increase the activity and selectivity of these bifunctional catalysts, it is necessary to reduce the diffusion restrictions for the reacting molecules and their products in the microporous structure of SAPO-11 by reducing the crystal size. To solve this problem, we have studied the influence of different templates (diethylamine, dipropylamine, diisopropylamine, and dibutylamine) on the physicochemical properties of reaction gels and SAPO-11 silicoaluminophosphates during their crystallization. Using XRD, SEM, and NMR techniques, we found that regardless of the template used, the reaction gel after the aging process at 90 °C is an AlPO₄·2H₂O hydroaluminophosphate. At the same time, the nature of the template affects the morphology and crystal sizes of the intermediate alumophosphate, AlPO₄·2H₂O, and the molecular sieves, SAPO-11. The acidic properties and the porous structure characteristics of SAPO-11 are also affected by the template. A template was proposed to enable the synthesis of nanoscale SAPO-11 crystals. The influence of the morphology and crystal size of SAPO-11 on the catalytic properties of a bifunctional catalyst based on SAPO-11 in the hydroisomerization of hexadecane was investigated. Full article

The disorder and heterogeneity of low-molecular-weight amyloid-beta oligomers (AβOs) underlie their participation in multiple modes of cellular dysfunction associated with the etiology of Alzheimer’s disease (AD). The lack of specified conformational states in these species complicates efforts to select or design small molecules to targeting discrete pathogenic states. Furthermore, targeting AβOs alone may be therapeutically insufficient, as AD progresses as a multifactorial, self-amplifying cascade. To address these challenges, we have screened the activity of seven new candidates that serve as Paramagnetic Amyloid Ligand (PAL) candidates. PALs are bifunctional small molecules that both remodel the AβO structure and localize a potent antioxidant that mimics the activity of SOD within live cells. The candidates are built from either a stilbene or curcumin scaffold with nitroxyl moiety to serve as catalytic antioxidants. Measurements of PAL AβO binding and remolding along with assessments of bioactivity allow for the extraction of useful SAR information from screening data. One candidate (HO-4450; PMT-307), with a six-membered nitroxyl ring attached to a stilbene ring, displays the highest potency in protecting against cell-derived Aβ. A preliminary low-dose evaluation in AD model mice provides evidence of modest treatment effects by HO-4450. The results for the curcumin PALs demonstrate that the retention of the native curcumin phenolic groups is advantageous to the design of the hybrid PAL candidates. Finally, the PAL remodeling of AβO secondary structures shows a reasonable correlation between a candidate’s bioactivity and its ability to reduce the fraction of antiparallel β-strand. Full article

Small bifunctional molecules are attractive for use as models in different areas of knowledge. How can their functional groups interact in solids? This is important to know for the prediction of the physical and chemical properties of the materials based on them. In this study, two new hydrogen-bonded organic frameworks (HOFs) based on sterically demanding molecular compounds, bis(1-hydroxy-2-methylpropane-2-aminium) sulfate (1) and 2-methyl-4-oxopentan-2-aminium hydrogen ethanedioate hydrate (2), were synthesized and fully characterized by means of FTIR and NMR spectroscopies, as well as by X-ray powder diffraction and thermogravimetric analyses. Their molecular and crystal structures were established through single-crystal X-ray diffraction analysis. It was shown that both compounds have a layered structure due to the formation of a 2D hydrogen-bonding network, the layers being linked by systematically arranged Van der Waals contacts between the methyl groups of organic cations. To unveil some dependencies between the chemical nature of bifunctional molecules and their solid structure, Hirschfeld surface (HS) analysis was carried out for HOFs 1, 2, and their known congeners 1-hydroxy-2-methylpropan-2-aminium hemicarbonate (3) and 1-hydroxy-2-methylpropan-2-aminium (1-hydroxy-2-methylpropan-2-yl) carbamate (4). HS was performed to quantify and visualize the close intermolecular atomic contacts in the crystal structures. It is clearly seen that H–H contacts make the highest contributions to the amino alcohol based compounds 1, 3 and 4, with a maximal value of 65.2% for compound 3 having CO₃²⁻ as a counterion. A slightly lower contribution of H–H contacts (64.4%) was found for compound 4, in which the anionic part is represented by 1-hydroxy-2-methylpropan-2-yl carbamate. The significant contribution of the H–H contacts in the bifunctional moieties is due to the presence of a quaternary carbon atom with a short three-carbon chain. Full article

Inhalable formulations with cyclodextrins (CDs) as solubility and absorption enhancers show promise for pulmonary delivery. Thiolated hydroxypropyl-β-cyclodextrin (HP-β-CD-SH) has mucoadhesive properties, enhancing drug absorption. Moreover, it has self-aggregation capability, which could further improve absorption and drug stability, as well as reduce irritation. This study aims to stabilize CD nanoaggregates using bifunctional cross-linkers and evaluate their benefits for lung drug delivery compared to pristine HP-β-CD-SH. Methods: The effectiveness of cross-linked HP-β-CD-SH nanoparticles (HP-β-CD-SH-NP) was compared to transient nanoaggregates in enhancing the activity of dexamethasone (DMS) and olive leaf extracts (OLE). DMS, a poorly soluble drug commonly used in lung treatments, and OLE, known for its antioxidant properties, were chosen. Drug-loaded HP-β-CD-SH-NP were prepared and nebulized onto a lung epithelial Air–Liquid Interface (ALI) model, assessing drug permeation and activity. Results: HP-β-CD-SH with 25% thiolation was synthesized via microwave reaction, forming 150 nm nanoaggregates and stabilized 400 nm HP-β-CD-SH-NP. All carriers showed good complexing ability with DMS and OLE and were biocompatible in the lung ALI model. HP-β-CD-SH promoted DMS absorption, while stabilized HP-β-CD-SH-NP protected against oxidative stress. Conclusion: HP-β-CD-SH is promising for lung delivery, especially as stabilized nanoaggregates, offering versatile administration for labile molecules like natural extracts. Full article

The extensive use of plastics has led to a significant environmental threat due to the generation of waste plastic, which has shown significant challenges during recycling. The catalytic hydrocracking route, however, is viewed as a key strategy to manage this fossil-fuel-derived waste into plastic-derived fuels with lower carbon emissions. Despite numerous efforts to identify an effective bi-functional catalyst, especially metal-loaded zeolites, the high-performing zeolite for hydrocracking plastics has yet to be synthesized. This is due to the microporous nature of zeolite, which results in the diffusional limitations of bulkier polymer molecules entering the structure and reducing the overall cracking of plastic and catalyst cycle time. These constraints can be overcome by developing hierarchical zeolites that feature shorter diffusion paths and larger pore sizes, facilitating the movement of bulky polymer molecules. However, if the hierarchical modification process of zeolites is not controlled, it can lead to the synthesis of hierarchical zeolites with compromised functionality or structural integrity, resulting in reduced conversion for the hydrocracking of plastics. Therefore, we provide an overview of various methods for synthesizing hierarchical zeolites, emphasizing significant advancements over the past two decades in developing innovative strategies to introduce additional pore systems. However, the objective of this review is to study the various synthesis approaches based on their effectiveness while developing a clear link between the optimized preparation methods and the structure-activity relationship of the resulting hierarchical zeolites used for the hydrocracking of plastics. Full article