High Specific Reaction Research Articles

Signature of click chemistry in exosome modification for cancer therapeutic

AbstractExosomes, small extracellular vesicles secreted by cells, have gained attention as potential therapeutic agents due to their natural ability to deliver biomolecules and traverse biological barriers. However, their limited targeting specificity and payload capacity necessitate modifications for improved therapeutic efficacy. Click chemistry, known for its high specificity, efficiency, and mild reaction conditions, offers an innovative solution for modifying exosomal surfaces. This technique enables precise attachment of targeting ligands, imaging agents, and therapeutic molecules, enhancing the targeting, delivery, and overall effectiveness of exosome‐based therapies. By addressing cancer heterogeneity, click chemistry‐modified exosomes can target diverse cancer cell populations within tumors, improving treatment specificity and reducing drug resistance. The development of copper‐free click chemistry, such as strain‐promoted azide‐alkyne cycloaddition (SPAAC), minimizes toxicity, ensuring biocompatibility and safety. As research progresses, this approach holds great promise for personalized and effective cancer treatment, paving the way for next‐generation therapeutics and diagnostics.

Rapid and multi-target genotyping of Helicobacter pylori with digital microfluidics

Helicobacter pylori (H. pylori) infection correlates closely with gastric diseases such as gastritis, ulcers, and cancer, influencing more than half of the world's population. Establishing a rapid, precise, and automated platform for H. pylori diagnosis is an urgent clinical need and would significantly benefit therapeutic intervention. Recombinase polymerase amplification (RPA)-CRISPR recently emerged as a promising molecular diagnostic assay due to its rapid detection capability, high specificity, and mild reaction conditions. In this work, we adapted the RPA-CRISPR assay on a digital microfluidics (DMF) system for automated H. pylori detection and genotyping. The system can achieve multi-target parallel detection of H. pylori nucleotide conservative genes (ureB) and virulence genes (cagA and vacA) across different samples within 30 min, exhibiting a detection limit of 10 copies/rxn and no false positives. We further conducted tests on 80 clinical saliva samples and compared the results with those derived from real-time quantitative polymerase chain reaction, demonstrating 100% diagnostic sensitivity and specificity for the RPA-CRISPR/DMF method. By automating the assay process on a single chip, the DMF system can significantly reduce the usage of reagents and samples, minimize the cross-contamination effect, and shorten the reaction time, with the additional benefit of losing the chance of experiment failure/inconsistency due to manual operations. The DMF system together with the RPA-CRISPR assay can be used for early detection and genotyping of H. pylori with high sensitivity and specificity, and has the potential to become a universal molecular diagnostic platform.

Improving the efficiency of using tractors by equipping the drive wheels with a built-in differential

.Relevance. The efficiency of the use of agricultural wheel units, the process of interaction of the wheel mover with the support surface is influenced by structural parameters, the properties of the support surface and the tire tread, the ratio of vertical load and longitudinal pushing force. In order to reduce wheel slipping, a built-in differential with an off-center application of external knobs and a driving torque is proposedMethods. For a quantitative and qualitative description of the operation of the wheel, methods of analytical, comparative, information-logical and system analysis of factors that have a causal relationship with the performance of mobile units, wheel propellers were used. The analysis of the propeller operation was carried out by the methods of theoretical mechanics on the provisions of the theory of rolling of a deformable wheel on a deformable supporting surface. The subject of the study is a two-stage process of interaction between the surface and the drive wheel during acceleration. At the first stage, the sprung mass of the tractor moves with a stationary wheel rim within its radius. At the second stage, the movement of the tractor masses occurs with a rotating wheel, the wheel gear operates in differential mode, preventing its external slip.Results. The wheel differential contributes to maintaining the maximum value of the friction coefficient and the rational ratio of the driving moment and the moment of resistance to rolling. The use of a built-in differential in wheel propellers is a promising option for their improvement, it helps to maintain a high specific longitudinal reaction, preventing slipping and, thereby, destruction of the soil structure. As a result, the productivity of wheeled mobile units increases, fuel consumption and tire wear decrease, soil compaction decreases.

Construction of copper-manganese based aminoclays with significant laccase-like activity and its prominent degradation performance towards bisphenol A

In recent years, nanozymes have become promising alternatives to natural enzymes owing to their high catalytic efficiency, substrate specificity, and mild reaction conditions. The catalytic performance of nanozymes can be further improved by doping heterogeneous metals to provide high redox potentials. However, nanozymes for the degradation of endocrine-disrupting chemicals (EDCs) have been scarcely studied, and the degradation mechanisms remain unclear. Herein, a series of aminoclays (ACs) containing various metal dopants were prepared and employed for the degradation of phenolic compounds. The as-synthesized ACs with a Cu-Mn molar ratio of 1:7 (CuMnAC-1–7) showed excellent stability and superior activity for oxidizing bisphenol A (BPA) than natural laccases owing to the electron transport between Cu2+/Cu+ and Mn4+/Mn3+ in the nanozyme. The catalytic oxidation process of BPA consists of a non-free radical pathway mediated by Mn3+, as well as a free radical pathway facilitated by superoxide radicals (O2·-) and singlet oxygen (1O2). Specifically, Mn3+ deprived the electrons of the BPA benzene ring to form phenolic hydroxyl radicals, which were then polymerized to BPA dimers. Cu+ in the structure reduced Mn4+ to Mn3+, accelerating the electron deprivation of BPA and promoting the polymerization reaction. Finally, the high-charge-density region on the dimeric benzene ring tended to lose electrons and form free radicals, facilitating the polymerization into trimers and tetramers. The CuMnAC-1–7 could remove 95% of BPA at a concentration of 200 mg/L within 1 h under acidic conditions. This study provides a new strategy to design high-performance laccase nanozymes for EDCs degradation.

Design of new, efficient, and suitable electrode material through interconnection of ZIF-67 by polyaniline nanotube on graphene flakes for supercapacitors

Metal-organic frameworks (MOFs) have been given more significant consideration in energy storage systems due to their high specific surface areas, mesoporous structures, and numerous reaction sites. To introduce additional conductive pathways and facilitate fast charge transfer, MOFs can be integrated with suitable conducting agents. In this study, we report the preparation of a novel Graphene@ZIF-67/polyaniline nanotube (PANI-NT) composite by using an easy stirring and sonication approach at room temperature. ZIF-67 rhombic dodecahedron structures are interconnected through PANI-NTs and deposited on the graphene flakes. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis have confirmed such individual morphology. This composite by the high surface area of 961.53 m2 g−1 exhibits a high specific capacitance of 20416.70 mF g−1 at a current density of 0.05 mA cm−2. This is due to a quick permeation of ions, easy forwarding of electrons, and excellent cooperation between the ingredients of the composite that result in reversible redox interactions. Moreover, the electrode material possesses 75% specific capacitance retention after 3000 cycles indicate good reversibility and cyclic stableness. The prepared Graphene@ZIF-67/PANI-NT composite can render outstanding electrochemical performance and is properly candidate for supercapacitors application.

Homochiral Metal-Organic Framework Based Mixed Matrix Membrane for Chiral Resolution.

Efficient separation of enantiomers is critical in the chemical, pharmaceutical, and food industries. However, conventional separation methods, such as chromatography, crystallization, and enzymatic kinetic resolution, require high energy costs and specific reaction conditions for the efficient purification of one enantiomer. In contrast, membrane-based processes are continuous processes performed with less energy than conventional separation processes. Enantioselective polymer membranes have been developed for the chiral resolution of pharmaceuticals; however, it is difficult to generate sufficient enantiomeric excess (ee) with polymer membranes. In this work, a homochiral filler of L-His-ZIF-8 was synthesized by the ligand substitution method and mixed with polyamide(imide) (i.e., Torlon®) to fabricate an enantioselective mixed-matrix membrane (MMM). The enantio-selective separation of R-1-phenylethanol over S-1-phenylethanol was demonstrated with a 25 wt% loaded L-His-ZIF-8/Torlon® MMM in an organic solvent nanofiltration (OSN) mode.

Constructing MnO2 alpha/amorphous heterophase junction by mechanochemically induced phase transformation for formaldehyde oxidation

Construction of heterophase junction has emerged as an effective approach for boosting the catalytic performance of diverse photoelectrocatalysts and electrocatalysts. But its potential in remediation of formaldehyde (HCHO) pollution was scarcely investigated. Herein, we report the fabrication, catalytic properties, and mechanistic study of α/A-MnO2 heterophase junction catalyst for HCHO oxidation. Our study found that mechanically milling δ-MnO2 could readily induce an δ to α phase transformation via an intermediate amorphous phase, thus providing a simple method for construction of MnO2 heterophase junction. The α/A-MnO2 catalyst prepared under the optimal condition exhibited an exceptionally high area specific reaction rate of 0.21 μmol m−2 min−1 at 80 °C and excellent stability towards HCHO oxidation, outperforming most reported MnO2-based catalysts. Based on the in situ diffused reflectance infrared Fourier transform spectroscopy and on-line gas chromatography analyses, a possible mechanism was put forward to describe the synergistic catalysis effect between α-MnO2 and amorphous MnO2.

DNA-Templated Bioorthogonal Reactions via Catalytic Hairpin Assembly for Precise RNA Imaging in Live Cells.

There has been a significant interest in developing proximity-induced bioorthogonal reactions for nucleic acid detection and imaging, owing to their high specificity and tunable reaction kinetics. Herein, we reported the first design of a fluorogenic sensor by coupling a bioorthogonal reaction with a DNA cascade circuit for precise RNA imaging in live cells. Two DNA hairpin probes bearing tetrazines or vinyl ether caged fluorophores were designed and synthesized. Upon target mRNA triggering catalytic hairpin assembly, the chemical reaction partners were brought in a spatial proximity to yield high effective concentrations, which dramatically facilitated the bioorthogonal reaction efficiency to unmask the vinyl ether group to activate fluorescence. The proposed fluorogenic sensor was demonstrated to have a high signal-to-noise ratio up to ∼30 fold and enabled the sensitive detection of target mRNA with a detection limit of 4.6 pM. Importantly, the fluorogenic sensor presented low background signals in biological environments due to the unique "click to release" feature, avoiding false positive results caused by unspecific degradation. We also showed that the fluorogenic sensor could accurately image mRNA in live cells and distinguish the relative mRNA expression levels in both tumor and normal cells. Benefiting from these significant advantages, our method provides a useful tool for basic studies of bioorthogonal chemistry and early clinical diagnosis.

Novel Nb26Mo4O77 rod-like nanoparticles anode with enhanced electrochemical performances for lithium-ion batteries

As a branch of intercalation type niobium-based anodes for lithium-ion batteries, Nb26Mo4O77 samples are synthesized by hydrothermal and solid-state method, respectively, while the structure and lithium-ion storage characteristics are studied in depth. Nb26Mo4O77 belongs to a monoclinic phase with ordered intergrowth ReO3 structure, which is constructed by a mixture of (Nb/Mo)O6 octahedra blocks of 3 × 4 × ∞ and 4 × 4 × ∞ occurring in alternate sequence and linked by MoO4 tetrahedra, favoring to the structural stability during the rapid lithium-ion deintercalation. Compared to agglomerated Nb26Mo4O77 microparticles synthesized via solid-state process, rod-like nanoparticles synthesized by hydrothermal method with the high specific surface area and reaction reactivity exhibit an improved initial coulombic efficiency (89.3%), notable cyclability (203 mAh g−1 after 503 cycles at 0.5 C), significant intercalation pseudocapacitive contribution (82.2% at 0.9 mV s−1) and increased rate capability (107 mAh g−1 at 10 C). These results provide some new supplements for the improvement of niobium-based anodes.

Engineering oxygen vacancies via amorphization in conjunction with W-doping as an approach to boosting catalytic properties of Pt/Fe-W-O for formaldehyde oxidation

Engineering functional defects in support materials has gained ever-increasing attention as a novel approach to boosting the catalytic performance of oxide-supported catalysts. Herein, we demonstrate the feasibility of engineering oxygen vacancy in iron oxide through amorphization in conjunction with foreign cation doping and elucidate the important role of support functionality in the catalytic oxidation of formaldehyde (HCHO). A supported Pt catalyst on Fe-W-O amorphous nanosheets (denoted as Pt/a-Fe-W-O) was synthesized using a one-step solvothermal method. This simple method allowed us to simultaneously create abundant oxygen vacancies in the substrate and to ensure uniform dispersion of tiny Pt nanoparticles with an average diameter of 1.4 nm on the high-surface-area substrate. This renders an increased possibility of Pt/O-vacancy coexistence in close proximity, which synergistically boosts the formation of active oxygen and surface hydroxyl species. Consequently, the Pt/a-Fe-W-O catalyst with an optimal W/Fe molar ratio of 0.08:1 and a 1.51 wt% Pt loading exhibited a high specific reaction rate of 68.3 μmol gPt−1 s−1 and excellent stability during 24 h continuous test, outperforming most existing HCHO oxidation catalysts. Our study highlights the importance of functional oxygen defects in construction of synergistic active sites for promoting the reactions requiring multiple active species.

Insight into the Maturation Process of the Nitrile Hydratase Active Site

Nitrile hydratases (NHases) are metalloenzymes that catalyze stereo and regio-specific hydration of nitriles to their corresponding higher value amides under ambient conditions and physiological pH. NHase has acquired substantial interest as a biocatalyst in preparative organic chemistry industries due to its advantages over the chemical catalysis such as zero byproduct formation, high specificity, higher yield, recycling ability, and mild reaction conditions. The metal ion is coordinated by three cysteine sulfur atoms, two amide nitrogen atoms (from the backbone of the amino acid chain), and a water molecule. Two of the active site cysteine ligands at the equatorial plane have post-translationally oxidized into cysteine sulfinic acid (Cys-SO2H) and cysteine sulfenic acid (Cys-SOH) which are essential for the catalysis of nitrile hydration. The metal binding motif of all Nitrile hydratases (NHases, EC 4.2.1.84) is highly conserved within a single amino acid sequence (CXXCSCX) in the α-subunit. Accordingly an eight amino acid peptide (VCTLCSCY), based on the metal binding motif of the Co-type NHase from Pseudonocardia thermophilia (PtNHase) was synthesized and shown to coordinate Fe(II) under anaerobic conditions. Parallel-mode EPR data on the mononuclear Fe(II)-peptide complex confirmed an integer-spin signal at g' ~ 9, suggesting an S = 2 system (D = 0.29 cm-1, E/D = 0.14, sD = 1.2 GHz, sE = 200 MHz). Exposure to air yielded a transient high-spin EPR signal most consistent with an intermediate/admixed S = 3/2 spin-state, while the integer-spin signal was extinguished. Prolonged exposure to air resulted in the observation of EPR signals at g = 2.04, 2.16, and 2.20, consistent with the formation of a low-spin Fe(III)-peptide complex that is remarkably similar to the NHase from Rhodococcus equi TG328-2 (ReNHase); however, these signals only account for ~8% of the total spins in the sample. These data indicate a progression for iron oxidation in NHases that proceeds from a reduced high-spin to an oxidized-high-spin followed by formation of an oxidized low-spin iron center, something that heretofore has not been observed.

Rod-like Nb14Mo3O44 nanoparticles fabricated by a facile solvothermal method as novel anode for lithium-ion batteries

The niobium molybdenum oxide Nb14Mo3O44 nanoparticles are synthesized by a convenient solvothermal method and explored as new anodes for lithium-ion batteries. Nb14Mo3O44, which belongs to tetragonal structure that consists of 4 × 4 × ∞ NbO6 octahedra-blocks linked by MoO4 tetrahedra, generates stable structure for the efficient Li+ de/intercalation. Compared with the agglomerated microparticles obtained by solid-state reaction, Nb14Mo3O44 nanoparticles demonstrate a higher initial coulombic efficiency (90.6%), better cycle property (218 mAh g−1 after 503 cycles at 0.5 C) and improved rate capability (74 mAh g−1 at 20 C), benefiting from nanoparticles possessed rather high specific surface area and reaction reactivity. This work provides a current supplement for intercalation-type Nb-M-O compounds anodes.

Bromide–acetate co-mediated high-power density rechargeable aqueous zinc–manganese dioxide batteries

A new bromide-acetate co-mediated multicomponent metal-ion aqueous electrolyte was for the first time developed to achieve a high specific capacity two-electron transfer reaction between Mn2+ and MnO2 with extremely fast reaction kinetics.

Revealing the structure design of alloyed based electrodes for alkali metal ion batteries with in situ TEM

With the guidance of in situ TEM, the high energy density alloyed based anode materials can be realized optimization structure design, thus obtaining excellent electrochemical performances in storing metal ions. Alloyed based anode materials with high theoretical specific capacity and low reaction potential are considered to be highly potential high-energy density anode materials for alkali metal ion batteries (AMIBs). Thus, the design of alloyed based materials with high electrochemical performance has attracted great attention. Among the numerous characterization methods for guiding electrode materials design, in situ transmission electron microscopy (TEM) gradually plays an irreplaceable role due to its high temporal and spatial resolution in directly observing the change of morphology, crystal structure and element evolutions. Herein, we reviewed the two current research hotspots and mainly focused on the structure design of alloyed based electrode material under the guidance of in situ TEM. Specifically, various nanostructure designs of alloyed based electrode materials with guidance of in situ TEM were employed to solve the key scientific issues of the violent volume change during alloying/dealloying processes for enhanced electrochemical performances. Mainly through introducing buffer space in the electrode material to reduce volume change to improve structural stability, including porous structure (0D), nanotube structure (1D), simple hollow structure, yolk-shell structure and some hybrid hollow structures (3D). Furthermore, the direct guidance of in situ TEM is expected for creating new opportunities to next-generation electrode material design for AMIBs.

Development and applications of inverse-electron-demand Diels-Alder reaction in bioorthogonal chemistry

Inverse-electron-demand Diels-Alder (IEDDA) reaction has become the most attractive bioorthogonal reaction due to its advantages of good biocompatibility, high reaction specificity and fast reaction kinetics. Therefore, extensive studies have been conducted in terms of reaction mechanism, reactants synthesis, chemistry optimization, biological applications, etc ., for IEDDA ligation and cleavage reactions respectively. In this review, first of all, we introduce the development and optimizations of the IEDDA reaction, followed by its biological applications including biomolecules labeling, protein manipulation, activation, drug delivery, pharmacokinetics study, prodrug releasing, siRNA activation and solid phase RNA purification. At last, we envision that further studies and applications of the IEDDA reaction are in demand, and expect that by exploring more optimized reaction pairs and wider biological applications, the research area of bioorthogonal chemistry would rush into a new era.

Ultrasmall SnO2 nanocrystals with adjustable density embedded in N-doped hollow mesoporous carbon spheres as anode for Li+/Na+ batteries

SnO2 has been widely studied in lithium-ion batteries (LIBs) because of its high theoretical specific capacity and reversible alloying reaction. Herein, we reported a novel strategy of confinement growth to implant nano-sized SnO2 crystals into N-doped hollow mesoporous carbon spheres (NHMCS) to form SnO2@NHMCS composite with unique nanoscale voids. The nanocrystals (~ 5 nm) decrease the required activation energy for redox reactions, and the carbon shell of NHMCS improves the conductivity and structural stability. It is worth noting that this method can effectively control the filling degree of ultrasmall nanocrystals in NHMCS and adjust the nanosize of voids between nanocrystals and NHMCS. When SnO2@NHMCS is evaluated as an anode material for LIBs, it is proved to exhibit high reversible capacity and stable cycling performance, which is attributted to the appropriate content of active components and the ample buffer space for conversion reaction of SnO2 and alloying reaction of Sn. It also shows excellent electrochemical property as anode material for sodium-ion batteries.

Incorporating nitrogen defects into novel few-layer carbon nitride nanosheets for enhanced photocatalytic H2 production

Carbon nitride nanosheets have shown a great promise for photocatalytic water splitting among numerous photocatalysts due to the versatile advantages. The crucial issues of the weak visible-light absorption and the separation of photo-generated carrier remain a matter of serious concern. Herein, we report a facile calcination-solvothermal-calcination method to prepare nitrogen-deficient carbon nitride nanosheets (DCNS) for the first time, which leads to the simultaneous introduction of nitrogen defects and formation of a fragmented few-layer nanosheet structure. The fragmented few-layer nanosheet structure is known to possess a high specific surface area and abundant interfacial reaction sites, contributing to the rapid consumption of photo-generated carrier. The nitrogen defects are responsible for further boosting the photocatalytic performance by regulating the band structure and optical properties as well as improving the separation efficiency of photo-generated carrier. The optimized DCNS-120 delivers a superior H2 production rate of 5375 μmol·g−1·h−1, considerably higher than that of bulk carbon nitride (164 μmol·g−1·h−1). We anticipate that this work may pave a new pathway to engineering carbon nitride with a matched structure to achieve the desired efficient photocatalytic H2 production under visible-light irradiation.

Experimental study on the optimisation of azo-dyes removal by photo-electrochemical oxidation with TiO2 nanotubes

An experimental investigation is here presented on the photo-electrochemical removal of Methyl Orange (MO), selected as a model of the organic dyes, contained in wastewaters. The process is carried out in an electrochemical flow reactor, in which titania nanotubular electrode is irradiated with a simulated solar light. Design of Experiments (DOE) technique is used to plan the experimental campaign and investigate on the single and combined effects of applied current, electrolyte flow rate, and initial MO concentration, on the specific reaction rate. The results of the DOE analysis, also combined with the study of the distribution of the intermediate products, confirm a reaction mechanism mediated by OH radicals; high applied current and low reactant concentration resulted as favourable conditions to achieve high specific reaction rate of color removal.

Nb <sub>14</sub>Mo <sub>3</sub>O <sub>44</sub> Nanoparticles Fabricated by a Facile Solvothermal Method as Novel Anode for Lithium-Ion Batteries

The niobium molybdenum oxide Nb14Mo3O44 nanoparticles are synthesized by a convenient solvothermal method and explored as new anodes for lithium-ion batteries.Nb14Mo3O44 , which belongs to tetragonal structure that consists of 4×4×∞ NbO 6 octahedra-blocks linked by MoO 4 tetrahedra, generates stable structure for the efficient Li + de/intercalation. Compared with the agglomerated microparticles obtained by solid-state reaction, Nb14Mo3O44nanoparticles demonstrate a higher initial coulombic efficiency ( 90.6 %), better cycle property (218 mAh g -1 after 503 cycles at 0.5 C) and improved rate capability (74 mAh g -1 at 20 C), benefiting from nanoparticles possessed rather high specific surface area and reaction reactivity.

Feasibility Study of Tissue Transglutaminase for Self-Catalytic Cross-Linking of Self-Assembled Collagen Fibril Hydrogel and Its Promising Application in Wound Healing Promotion.

Collagen-based bio-hydrogels are undoubtedly a hot spot in the development of biological dressings for wound healing promotion. Herein, glutamine transaminase (TGase), a biological nontoxic cross-linker with high specific activity and reaction rate under mild conditions, was utilized for the self-catalytic cross-linking of the regenerated collagen (COL) fibril hydrogel fabricated through a molecular self-assembly method. The results showed that the natural triple helical conformation of COL remained completely integrated after self-catalytic cross-linking TGase, which was definitively the fundamental for maintaining its superior bioactivity. It was worth noting that TGase could promote the self-assembly process of COL building blocks into a higher order D-period cross-striated structure. Also, the reconstructed TGase cross-linked COL fibrils exhibited a higher degree of interfiber entanglements with more straight and longer fibrils. Meanwhile, the thermal stability of COL was significantly improved after introducing TGase. Besides, the cytocompatibility analysis suggested that the regenerated COL fibril hydrogel showed excellent cell growth activity and proliferation ability when the dosage of TGase is less than 40 U/g. Further, animal experiments indicated that the targeted COL fibril hydrogel could significantly promote skin wound healing, exhibiting better capacity of skin tissue for regeneration than the COL hydrogel untreated as expected. Therefore, the reconstructed TGase cross-linked COL fibril hydrogel could serve as a novel soft material for wound healing promotion.