An adaptive and label-free colorimetric assay for EDTA using copper(II)-aptamer complexes as soft nanozymes.

The development of molecular clamps as drugs

Bis-tren (tren = tris(2-aminoethyl)amine) azacryptands were previously studied profoundly for the coordination of two +II metals and subsequent binding of substrates within their cavity. Likewise, cryptates including metals in different oxidations states were reported with the rather unstable hexa-imine analogues but also revealed only little stability. In this work, we report the synthesis of an asymmetric hexa-amine cryptand analogue by selectively exchanging three of the secondary amines of one binding site with sulphur atoms. We show that the presence of two distinct binding sites allows for the selective formation of stable dinuclear complexes of metals with different oxidation numbers and present the formation of distinct CuICoII, CuINiII and CuICuIII cryptates.

Peroxymonosulfate activation by brownmillerite-type oxide Ca2Co2O5 for efficient degradation of pollutants via direct electron transfer and radical pathways

The use of antibody fragments for crystallization and structure determinations.

Adenosine triphosphate (ATP) is produced mainly in the mitochondrion, and its primary task is to function as a ubiquitous energy currency to meet the cellular metabolic demands in biological system...

Coordination Number Regulation of Molybdenum Single-Atom Nanozyme Peroxidase-like Specificity

Facile access and switchability between multiple oxidation states are key properties of many catalytic applications and spintronic devices yet poorly understood due to inherent complications arising from isolating a redox system in multiple oxidation states without drastic structural changes. Here, we present the first isolable, free fluoflavine (flv) radical flv(1-•) as a bottleable potassium compound, [K(crypt-222)](flv•), 1, and a new series of organometallic rare earth complexes [(Cp*2Y)2(μ-flvz)]X, (where Cp* = pentamethylcyclopentadienyl, X = [Al(OC{CF3}3)4]- (z = -1), 2; X = 0 (z = -2), 3; [K(crypt-222)]+ (z = -3), 4) comprising the flv ligand in three different oxidation states, two of which are paramagnetic flv1-• and flv3-•. Excitingly, 1, 2, and 4 constitute the first isolable flv1-• and flv3-• radical complexes and, to date, the only isolated flv radicals of any oxidation state. All compounds are accessible in good crystalline yields and were unambiguously characterized via single-crystal X-ray diffraction analysis, cyclic voltammetry, IR-, UV-vis, and variable-temperature EPR spectroscopy. Remarkably, the EPR spectra for 1, 2, and 4 are distinct and a testament to stronger spin delocalization onto the metal centers as a function of higher charge on the flv radical. In-depth analysis of the electron- and spin density via density functional theory (DFT) calculations utilizing NLMO, QTAIM, and spin density topology analysis confirmed the fundamental interplay of metal coordination, ligand oxidation state, aromaticity, covalency, and spin density transfer, which may serve as blueprints for the development of future spintronic devices, single-molecule magnets, and quantum information science at large.

The study and development of present and future processes for the treatment/recycling of spent nuclear fuels require many steps, from design in the laboratory to setting up on an industrial scale. In all of these steps, analysis and instrumentation are key points. For scientific reasons (small-scale studies, control of phenomena, etc.) but also with regard to minimizing costs, risks, and waste, such developments are increasingly carried out on milli- or microfluidic devices. The logic is the same for the chemical analyses associated with their follow-up and interpretation. Due to this, over the last few years, opto-microfluidic analysis devices adapted to the monitoring of different processes (dissolution, liquid-liquid extraction, precipitation, etc.) have been increasingly designed and developed. In this work, we prove that photonic lab-on-a-chip (PhLoC) technology is fully suitable for all actinides concentration monitoring along the plutonium uranium refining extraction (plutonium, uranium, reduction, extraction, or Purex) process. Several PhLoC microfluidic platforms were specifically designed and used in different nuclear research and development (R&D) laboratories, to tackle actinides analysis in multiple oxidation states even in mixtures. The detection limits reached (tens of µmol·L-1) are fully compliant with on-line process monitoring, whereas a range of analyzable concentrations of three orders of magnitude can be covered with less than 150µL of analyte. Finally, this work confirms the possibility and the potential of coupling Raman and ultraviolet-visible (UV-Vis) spectroscopies at the microfluidic scale, opening the perspective of measuring very complex mixtures.

Chemical Bonding Topology of Superconductors

Microtubule assembly requires a set of chaperones known as tubulin-binding cofactors (TBCs). We used cryo-electron microscopy to visualize how human TBCD, TBCE, TBCC, and guanosine triphosphatase (GTPase) Arl2 mediate αβ-tubulin assembly and disassembly. We captured multiple conformational states, revealing how TBCs orchestrate tubulin heterodimer biogenesis. TBCD stabilizes monomeric β-tubulin and scaffolds the other cofactors. Guanosine triphosphate (GTP) binding to Arl2 induces conformational changes that toggle the complex between assembly and disassembly. TBCD and TBCE guide α- and β-tubulin into a partially assembled interface, and TBCC, acting as a molecular clamp, completes the heterodimer. TBCD also functions as a GTPase activating protein for β-tubulin. β-tubulin GTP hydrolysis is coupled to Arl2's GTPase activity, establishing a checkpoint that ensures that only fully matured heterodimers proceed. These findings provide a structural framework for tubulin heterodimer biogenesis and recycling, supporting cytoskeletal proteostasis.

High affinity truncated aptamers for ultra-sensitive colorimetric detection of bisphenol A with label-free aptasensor

Extracts from the parenchymous leaf-gel of the Aloe vera plant (Aloe barbadensis Miller) were shown to contain glutathione peroxidase (GSHPx) activity. The activity was purified to homogeneity by ion exchange and gel filtration (FPLC) chromatography in the presence of 0.5 mM glutathione. The native enzyme has an apparent molecular weight of 62 kD as determined by gel filtration. In the presence of sodium dodecylsulfate (SDS), the molecular weight was estimated to be about 16 kD as determined by polyacrylamide-gel electrophoresis (SDS-PAGE). The native enzyme is proposed to be constituted of four identical subunits; it also contains one atom of selenium per subunit, as found with most glutathione peroxidases from animal sources. The Km values were determined to be 3.2 mM for glutathione and 0.26 mM for the hydroperoxide substrate, cumene hydroperoxide. The enzyme is competitively inhibited by N, S, bis-FMOC glutathione (Ki = 0.32 mM), a potent inhibitor of glyoxalase II. Inhibitors of glyoxalase I (e.g. S-octylglutathione) have no effect on the peroxidase activity.

This work describes a general approach for calculating the redox speciation of systems with multiple oxidation states. The calculational approach provides solutions for the distribution functions (andI±I»I€I·I±;) and degree of oxidation (η) of redox systems as a function of pe or redox potential. From these parameters the poising capacity (ρ) or electron buffer capacity of multicomponent redox systems can be calculated. This allows direct calculation of redox titration curves without segmentation or approximations. The titration curves can be calculated for individual species or for multiple redox species typical of many environmental systems. A contour surface of poising capacity as a function of both pe and pH allows automated generation of pe–pH diagrams. All of these calculations are readily implemented using spreadsheet software making them accessible for classroom instruction.

SummaryBackgroundChina has the highest prevalence of hepatitis B virus (HBV) infection worldwide. Universal HBV screening might enable China to reach the WHO 2030 target of 90% diagnostics, 80% treatment, and 65% HBV-related death reduction, and eventually elimination of viral hepatitis. We evaluated the cost-effectiveness of implementing universal HBV screening in China and identified optimal screening strategies.MethodsWe used a Markov cohort model, inputting parameters based on data from previous studies and public databases, to assess the cost-effectiveness of four HBV serological screening strategies in China in different screening scenarios. We simulated universal screening scenarios in 15 adult age groups between 18 and 70 years, with different years of screening implementation (2021, 2026, and 2031) and compared to the status quo (ie, no universal screening); in total, we investigated 180 different screening scenarios. We calculated the incremental cost-effectiveness ratio (ICER) between the different screening strategies and the status quo (current screening strategy). We performed probabilistic and one-way deterministic sensitivity analyses to assess the robustness of our findings.FindingsWith a willingness-to-pay level of three times the Chinese gross domestic product (GDP) per capita (US$30 828), all universal screening scenarios in 2021 were cost-effective compared with the status quo. The serum HBsAg/HBsAb/HBeAg/HBeAb/HBcAb (five-test) screening strategy in people aged 18–70 years was the most cost-effective strategy in 2021 (ICER $18 295/quality-adjusted life-years [QALY] gained). This strategy remained the most cost-effective, when the willingness-to-pay threshold was reduced to 2 times GDP per capita. The two-test strategy for people aged 18–70 years became more cost-effective at lower willingness-to-pay levels. The five-test strategy could prevent 3·46 million liver-related deaths in China over the lifetime of the cohort. It remained the most cost-effective strategy when implementation was delayed until 2026 (ICER $20 183/QALY) and 2031 (ICER $23 123/QALY). Screening young people (18–30 years) will no longer be cost-effective in delayed scenarios.InterpretationThe five-test universal screening strategy in people aged 18–70 years, implemented within the next 10 years, is the optimal HBV screening strategy for China. Other screening strategies could be cost-effective alternatives, if budget is limited in rural areas. Delaying strategy implementation reduces overall cost-effectiveness. Early screening initiation will aid global efforts in achieving viral hepatitis elimination.FundingNational Natural Science Foundation of China.

The recent discovery of a new class of nanomaterials called nanozymes, which have the action of enzymes and are thus of tremendous significance, has altered our understanding of these previously believed to be biologically inert nanomaterials. As a significant and exciting class of synthetic enzymes, nanozymes have distinct advantages over natural enzymes. They are less expensive, more stable, and easier to work with and store, making them a viable substitute. This practical advantage of nanozymes over natural enzymes reassures us about the potential of this new technology. Peroxidase-like nanozymes have been investigated for the purpose of creating adaptable biosensors via the use of molecularly imprinted polymers (MIPs) or particular bio recognition ligands, including enzymes, antibodies, and aptamers. This review delves into the distinctions between synthetic and natural enzymes, explaining their structures and analytical applications. It primarily focuses on carbon-based nanozymes, particularly those that contain both carbon and hydrogen, as well as metal-based nanozymes like Fe, Cu, and Au, along with their metal oxide (FeO, CuO), which have applications in many fields today. Analytical chemistry finds great use for nanozymes for sensing and other applications, particularly in comparison with other classical methods in terms of selectivity and sensitivity. Nanozymes, with their unique catalytic capabilities, have emerged as a crucial tool in the early diagnosis of COVID-19. Their application in nanozyme-based sensing and detection, particularly through colorimetric and fluorometric methods, has significantly advanced our ability to detect the virus at an early stage.