Facile synthesis of catalase@ZIF-8 composite by biomimetic mineralization for efficient biocatalysis.

Enzymes immobilized in metal-organic frameworks (MOFs) have attracted great attention as a promising hybrid material. In the study, a novel biomimetic mineralization encapsulation process for a highly stable and easily reusable catalase (CAT)@ZIF-8 composite has been designed. This immobilization process provides a high enzyme loading of 70 wt %. The CAT@ZIF-8 composites exhibited a much lower Km value and better enzyme activity than those of free CAT, exhibiting good stability against enzymatic hydrolysis and protein denaturation under harsh conditions. The inhibitory effects of pesticides such as pH, temperature, solvent (i.e., methanol, dimethyl sulfoxide and tetrahydrofuran) and storage at room temperature (6 months) on the activity of free and immobilized catalase enzyme were investigated. The CAT@MOF composites also exhibited excellent reusability, an obvious advantage for treating a wastewater from food processing. The CAT@MOF developed is promising for the efficient removal of H2O2 under harsh conditions.

Application of Angiotensin Receptor-Neprilysin Inhibitor in Chronic Kidney Disease Patients: Chinese Expert Consensus.

Chronic kidney disease (CKD) is a global public health problem, and cardiovascular disease is the most common cause of death in patients with CKD. The incidence and prevalence of cardiovascular events during the early stages of CKD increases significantly with a decline in renal function. More than 50% of dialysis patients die from cardiovascular disease, including coronary heart disease, heart failure, arrhythmia, and sudden cardiac death. Therefore, developing effective methods to control risk factors and improve prognosis is the primary focus during the diagnosis and treatment of CKD. For example, the SPRINT study demonstrated that CKD drugs are effective in reducing cardiovascular and cerebrovascular events by controlling blood pressure. Uncontrolled blood pressure not only increases the risk of these events but also accelerates the progression of CKD. A co-crystal complex of sacubitril, which is a neprilysin inhibitor, and valsartan, which is an angiotensin receptor blockade, has the potential to be widely used against CKD. Sacubitril inhibits neprilysin, which further reduces the degradation of natriuretic peptides and enhances the beneficial effects of the natriuretic peptide system. In contrast, valsartan alone can block the angiotensin II-1 (AT1) receptor and therefore inhibit the renin-angiotensin-aldosterone system. These two components can act synergistically to relax blood vessels, prevent and reverse cardiovascular remodeling, and promote natriuresis. Recent studies have repeatedly confirmed that the first and so far the only angiotensin receptor-neprilysin inhibitor (ARNI) sacubitril/valsartan can reduce blood pressure more effectively than renin-angiotensin system inhibitors and improve the prognosis of heart failure in patients with CKD. Here, we propose clinical recommendations based on an expert consensus to guide ARNI-based therapeutics and reduce the occurrence of cardiovascular events in patients with CKD.

Trace analysis on chromium (VI) in water by pre-concentration using a superhydrophobic surface and rapid sensing using a chemical-responsive adhesive tape.

Heavy metal ions in water resources present great threats to human health. Chromium (Cr), as the frequently used heavy metal in industrial processes and everyday life, requires a low-cost, fast and effective means to determine its concentration, especially in drinking water. Conventional colorimetric paper-based analytical devices (PADs), due to the limited sensitivity, are unable to quantify the most harmful heavy metal ions to the drinking water standard. In this work, we present a method of using a superhydrophobic (SH) paper to concentrate Cr6+ from solutions of very low concentration to obtain the precipitated Cr6+ salt particulates. A known volume of Cr6+-containing solution was concentrated to "a spot" on the SH paper through drying, so that trace amount of Cr6+ can be quantified via the application of a specifically-designed chemical-responsive adhesive tape (CAT) sensor, loaded with Cr6+- specific indicator, on to the concentrated Cr6+ spot. The detection limit of the SH-CAT method for Cr6+ is 0.05 mg/L, which is the permitted maximum concentration in drinking water and is significantly lower than that of conventional PADs. The interference and the accuracy studies also show the reliability of this method for measuring trace amounts of analytes.

Photocatalytic degradation of an organophosphorus pesticide using a ZnO/rGO composite.

A zinc oxide (ZnO)/reduced graphene oxide (rGO) nanocomposite was synthesized via a hydrothermal synthesis method and used for the photocatalytic degradation of dimethoate. In the synthesis process of the ZnO/rGO nanocomposite, hexamethylenetetramine (HMT) was used as both a mineralizer and reducing agent. When the ZnO nanoparticles formed on the surfaces of graphene oxide sheets, the sheets were simultaneously reduced by HMT to form rGO. The photodegradation rate and photodegradation efficiency of dimethoate by the ZnO/rGO nanocomposite were 4 and 1.5 times, respectively, higher than those of bare ZnO. The ZnO/rGO nanocomposite possessed a high surface area of 41.0 m2 g-1 and pore volume of 4.72 × 10-3 cm3 g-1, which were conducive to the adsorption and mass transfer of pesticides and oxygen. The enhanced photocatalytic performance of the ZnO/rGO nanocomposite was attributed to the decrease in electron-hole recombination rate and effective carrier transport caused by the presence of rGO. Photoelectrochemical measurements confirmed that the nanocomposite exhibited a high charge transfer rate at the ZnO/rGO interface. These results indicate that ZnO/rGO nanocomposites have great application potential in pollutant degradation.

Facile synthesis of highly efficient fluorescent carbon dots for tetracycline detection.

Rampant use of tetracycline in animal feed is a threat to food security, the environment, and human health because of the risk of drug residues. Therefore, it is necessary to establish a sensitive, efficient, and reliable method for qualitative and quantitative detection of tetracycline. In this paper, we synthesized fluorescent carbon dots (FCDs) by thermal cracking of crab shell waste, and obtained a fluorescence quantum yield of 30%. Characterization of the FCDs by transmission electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet visible absorption spectroscopy, and photoluminescence spectroscopy showed that they were fluorescent and evenly distributed with an average size of approximately 10 nm. We designed a sensitive probe for detecting tetracycline using the fluorescence intensity change of the FCDs. This method is sensitive, inexpensive, and environmentally friendly. The concentration of tetracycline was examined by comparing the fluorescence intensities of the FCDs before and after tetracycline addition. The limit of detection for tetracycline was 0.005 mg/L (signal-to-noise ratio = 3), which is promising for method development.

In situ synthesis of ZnO-GO/CGH composites for visible light photocatalytic degradation of methylene blue.

A novel ZnO-GO/CGH composite was prepared using an in situ synthesis process for photodegradation of methylene blue under visible light illumination. The chitin-graphene composite hydrogel (CGH) was used to provide uniform binding of the nano ZnO-GO composite to the hydrogel surface and prevent their agglomeration. GO provides multi-dimensional protons and electron transport channels for ZnO with a flower-like structure, which possessed improved photo-catalytic activity. SEM analysis indicates that the hydrogel has good adsorption properties with rougher surfaces and porous microstructure, which enables it to adsorb the dyes effectively. Under synergetic enhancement of adsorption and photo-catalysis, catalytic activity and nano ZnO-GO/CGH recycling improved greatly. Synthesized nano ZnO-GO/CGH showed high dye removal efficiency of 99%, about 2.2 times that of the pure chitin gel under the same condition. This suggests the potential application of the new photocatalytic composites to remove organic dyes from wastewater.