Surface Au-H Species as Self-Generated Prosthetic Groups of a Formate Dehydrogenase-like Au Nanozyme to Engineer Multienzymatic Activities.

Although the past decade has witnessed a rapid development of oxidoreductase-mimicking nanozymes, the mimicry of cofactors that play key roles in mediating electron and proton transfer remains limited. This study explores how surface Au-H species conjugated to Au nanoparticles (NPs) that imitate formate dehydrogenase (FDH) can serve as cofactors, analogous to NADH in natural enzymes, offering diverse possibilities for FDH-mimicking Au nanozymes to mimic various enzymes. Once O2 is present, Au-H species assist Au NPs to complete the on-demand H2O2 generation for cascade reactions. Alternatively, when oxidizing organic molecules are introduced as substrates, Au-H species confer nitro reductase- and aldehyde reductase-like activities on Au NPs under anaerobic conditions. Furthermore, similar to the dehydrogenase-NADH complex, Au NPs possessing Au-H species are gifted with esterase-like activity for ester hydrolysis. By revealing that Au-H species are prosthetic groups for FDH-mimicking Au nanozymes, this work may inspire explorations into future self-generated cofactor mimics for nanozymes, thereby circumventing the need for exogenous cofactors.

Bioinspired Surface Ligand Engineering Regulates Electron Transfers in Gold Clusterzymes to Enhance the Catalytic Activity for Improving Sensing Performance.

Metal nanoclusters feature a hierarchical structure, facilitating their ability to mimic enzyme-catalyzed reactions. However, the lack of true catalytic centers, compounded by tightly bound surface ligands hindering electron transfers to substrates, underscores the need for universal rational design methodologies to emulate the structure and mechanisms of natural enzymes. Motivated by the electron transfer in active centers with specific chemical structures, by integrating the peroxidase cofactor Fe-TCPP onto the surface of glutathione-stabilized gold nanoclusters (AuSG), we engineered AuSG-Fe-TCPP clusterzymes with a remarkable 39.6-fold enhancement in peroxidase-like activity compared to AuSG. Fe-TCPP not only mimics the active center structure, enhancing affinity to H2O2, but also facilitates the electron transfer process, enabling efficient H2O2 activation. By exemplifying the establishment of a detecting platform for trace H2O2 produced by ultrasonic cleaners, we substantiate that the bioinspired surface-ligand-engineered electron transfer can improve sensing performance with a wider linear range and lower detection limit.

The burden of ischemic heart disease attributable to ambient and household particulate matter pollution, 1990-2019: a global analysis.

Elevated risk of ischemic heart disease (IHD) is associated with exposure to fine particulate matter. However, there is limited data on trends and comparisons in the global burden of IHD due to household air pollution from solid fuels (HAP) and ambient particulate matter pollution (APMP), particularly in regions of varying socio-economic levels. Based on the Global Burden of Disease Study 2019 (GBD 2019), we obtained age-standardized mortality rates (ASMR) and age-standardized disability-adjusted life years (ASDR) of IHD due to APMP and HAP from 1990 to 2019. Trends in the burden of IHD attributable to APMP and HAP during the period 1990 to 2019 were calculated by Joinpoint models. We estimated the relationship between ASMR with the socio-demographic indexes (SDI) and the health care accessibility and quality (HAQ) index by the Loess regression model. In 2019, the global burden of IHD ASMR attributed to APMP stabilized, but the most significant increases were observed in low-middle SDI regions. The global IHD ASMR attributed to APMP was 16.60 [95% Uncertainty Interval (UI), 13.61 to 19.44] per 100,000 population, with the highest APMP burden in middle SDI regions. From 1990 to 2019, the global ASMR for HAP-attributable IHD declined. The global ASMR of IHD attributable to HAP in 2019 was 6.30 (95% UI, 4.28 to 8.80) per 100,000 population, with the highest burden observed in the low SDI regions. From 1990 to 2019, the global burden of ASMR and ASDR of IHD attributable to APMP showed stabilization, whereas the HAP burden exhibited a decrease. There are a large burden of APMP particularly in middle SDI countries and a higher burden of HAP in low SDI countries. The burden of IHD due to APMP and HAP in men, the elderly, and populations in low, medium, and low SDI regions should be noticed.

Silver Ion-Facilitated Singular Poulos-Kraut Mechanism of O-O Heterolysis to Enhance the Light Activation of H2O2 over Peroxidase-Mimicking Photonanozymes.

The Poulos-Kraut heterolytic O-O cleavage mechanism is essential for natural peroxidases to activate H2O2. Current existing peroxidase-mimicking nanozymes, including photonanozymes (PNZs), however, are generally believed to prefer the Fenton-type mechanism of O-O homolysis, which produces •OH radicals. Here, Ag+ ions are introduced into TiO2 PNZs to boost the hot hole-driven O-O heterolysis for the expedited H2O2 activation in the peroxidase-like photonanozymatic reaction while inhibiting the Fenton-type O-O homolysis. The Ag+-facilitated Poulos-Kraut heterolytic O-O cleavage mechanism for H2O2 activation is explicated in terms of the speedy capture and exhaustion of photogenerated electrons by Ag+ and the dissociation of the peroxo-oxygen bridge in Ti-O-OH promoted by accumulated hot holes. Moreover, the enhanced photonanozymatic activity of TiO2 PNZs enables the construction of a rapid colorimetric sensing platform for Ag+ determination. This work provides valuable insights into the mechanism of H2O2 activation and exemplifies a novel photoregulation strategy for controlling reaction pathways in nanozymes.

Methyl orange as a novel colorimetric iodide indicator with in situ generation of H2O2 by etching uncoated Ag-Ti3C2 nanohybrids.

Iodine intake remains a major public health concern, as both iodine excess and deficiency are related to adverse effects on health. Therefore, developing simple and economical methods to detect I- is still in great demand. Herein, we constructed a visual I- sensing platform based on the uncoated Ag-Ti3C2 nanohybrids using methyl orange (MO) as a colorimetric indicator. Plasmonic nanostructures are frequently employed in colorimetric analysis, but uncoated Ag nanoparticles (NPs) are unstable because their surface energies are usually high. Considering that Ag NPs can be etched by I- via forming Ag-I bond, we introduce Ag-Ti3C2 nanohybrids because uncoated Ag NPs with immaculate surfaces are more conducive to binding with I- and being etched. Dissolved O2 molecules adsorbed on Ti3+ of Ti3C2 MXenes enable the in situ generation of H2O2 by iodine-etching of uncoated Ag-Ti3C2 nanohybrids. ∙OH radicals promote the degradation of MO through a self-driven Fenton-like process, exhibiting the color variation from orange to transparent. Under optimal conditions, the absorbance of MO at 465 nm decreases linearly with the concentration of I- in the range of 0.5-300 µM, with a limit of detection as low as 0.31 µM. This work opens the feasibility of iodine-etching of Ag in developing novel probes for facile colorimetric determination of I-.

Flow patterns in the venous sinus of pulsatile tinnitus patients with transverse sinus stenosis and underlying vortical flow as a causative factor.

BACKGROUND: Transverse sinus stenosis (TSS) is commonly found in Pulsatile Tinnitus (PT) patients. Vortex flow is prominent in venous sinus with stenosis, and so it is important to determine the distribution and strength of the vortical flow to understand its influence on the occurrence of PT. METHODS: In this study, by using computational fluid dynamics for hemodynamic analysis in patient-specific geometries based on Magnetic Resonance Imaging (MRI), we have investigated the blood flow within the venous sinus of 16 subjects with PT. We have employed both laminar and turbulent flow models for simulations, to obtain (i) streamlines of velocity distribution in the venous sinus, and (ii) pressure distributions of flow patterns in the venous sinus. Then, hemodynamic analysis in the venous sinus recirculation zone was carried out, to determine the flow patterns at the junction of transverse sinuses and sigmoid sinuses. Finally, we have proposed a new model for turbulence evaluation based on the regression analysis of anatomic and hemodynamics parameters. RESULTS: Correlation analysis between the anatomical parameters and the hemodynamic parameters has shown that stenosis at the transverse sinus was the main factor in the local hemodynamics variation in the venous sinus of patients; in this context, it is shown that vorticity can be used as a prime indicator of the severity of the stenosis function. Our results have shown a significant correlation between the vorticity and the stenotic maximum velocity (SMV) (r = 0.282, p = 0.004). Then, a parameterized prediction model is proposed to determine the vorticity in terms of flow and anatomic variables, termed as the turbulence eddy prediction model (TEP model). Our result have shown that the TEP model is sensitive to the dominant flow distribution, with a high correlation to the flow-based vorticity (r = 0.809, p = 0.009). CONCLUSIONS: The quantification of the vorticity (as both vorticity and MVV) in the downstream of TSS could be a marker for indication of turbulent energy at the transverse-sigmoid sinus, which could potentially serve as a hemodynamic marker for the functional assessment of the PT-related TSS.