ABSTRACT
In this article, the synthesis procedure and sensing properties toward acetone of rGO-HM-SnO2/Zn2SnO4 composites with a hollow mesoporous structure are presented comprehensively. The rGO-HM-SnO2/Zn2SnO4 heterojunction structure is prepared through a self-sacrificial template strategy with a concise acid-assisted etching method. The as-prepared hollow mesoporous architectures are investigated by SEM, TEM, and HRTEM. The phase structure and valence state are also characterized by XRD and XPS, respectively. It is obvious that the hollow mesoporous architecture affords a large specific surface area, which can provide more reaction active sites of sensing materials significantly. Compared to the initial SnO2/Zn2SnO4 composites, the gas sensor fabricated by rGO-HM-SnO2/Zn2SnO4 shows the best gas-sensing properties, and the response value toward 100 ppm acetone is as high as 107 at 200 °C. Moreover, the rGO-HM-SnO2/Zn2SnO4 sensing material reveals excellent properties of shorter response-recovery times and higher long-term stability. This excellent performance can be ascribed to the synergistic effect of the hollow mesoporous n-n heterojunction and abundant-defect rGO. The relevant sensing mechanism of rGO-HM-SnO2/Zn2SnO4 sensing materials is investigated in detail.
ABSTRACT
Qishiwei Zhenzhu pills (QSW) was first recorded in the Tibetan medicine classic Si Bu Yi Dian and has been used to treat "Baimai" disease, stroke, paralysis, hemiplegia, cerebral hemorrhage, and other diseases till today. This prescription contains more than 70 medicines including myrobalan, pearl, agate, opal, bezoar, coral, musk, gold, silver, and a mineral mixture Zuotai. As a result, QSW contains a large amount of mercury, copper, lead, and other trace elements. The aim of this study was to determine the 18 trace elements (lithium, beryllium, scandium, vanadium, chromium, manganese, cobalt, nickel, copper, arsenic, strontium, argentum, cadmium, cesium, barium, lead, aurum, and mercury) in 10 batches of QSW produced by 5 pharmaceutical companies (Ganlu Tibetan Medicine Co., Ltd. has 6 different batches) by direct inductively coupled plasma-mass spectrometry (ICP-MS). ICP-MS is a rapid, sensitive, accurate methodology allowing the determination of 18 elements simultaneously. The results showed that each element had an excellent linear relationship in the corresponding mass concentration range. The results showed that the rank order of the elements in QSW was copper > mercury > lead from high to low, with the mass fraction higher than 6000 µg/kg; the mass fractions of argentum, arsenic, manganese, aurum, strontium, barium, chromium, and nickel were in the range of 33-1034 µg/kg; and the mass fractions of vanadium, cobalt, lithium, beryllium, cadmium, scandium, and cesium were lower than 10 µg/kg. The reproducibility from the same manufacturer (Tibet Ganlu Tibetan Medicine Co., Ltd.) was relatively high; however, the element amounts among 5 manufacturers were different, which could affect the efficacy and toxicity of QSW. All in all, ICP-MS can be used as an effective tool for the analysis of trace elements in QSW and standard quality control needs to be enforced across different manufactures.
ABSTRACT
Cerebral ischemia is a series of harmful reactions, such as acute necrosis of tissue, inflammation, apoptosis, autophagy, and blood-brain barrier injury, due to the insufficient blood supply to the brain. Inflammatory response and gut microbiota imbalance are important concomitant factors of cerebral ischemia and may increase the severity of cerebral ischemia through the gut-brain axis. Qishiwei Zhenzhu pills (QSW) contain more than 70 kinds of medicinal materials, which have the effects of anti-cerebral infarction, anti-convulsion, anti-dementia, and so on. It is a treasure of Tibetan medicine commonly used in the treatment of cerebral ischemia in Tibetan areas. In this study, we gave rats QSW (66.68 mg/kg) once by gavage in advance and then immediately established the rat middle cerebral artery occlusion (MCAO) model. After 24 hours of treatment, the neuroprotection, intestinal pathology, and gut microbiota were examined. The results showed that QSW could significantly reduce the neurobehavioral abnormalities and cerebral infarction rate in MCAO rats. Furthermore, qPCR, western blot, and immunohistochemistry results showed that QSW could effectively inhibit IL-6, IL-1ß, and other inflammatory factors so as to effectively reduce the inflammatory response of MCAO rats. Furthermore, QSW could improve intestinal integrity and reduce intestinal injury. 16S rRNA sequencing showed that QSW could significantly improve the gut microbiota disorder of MCAO rats. Specifically, at the phylum level, it can regulate the abundance of Firmicutes and Proteobacteria in the gut microbiota of rats with MCAO. At the genus level, it can adjust the abundance of Escherichia and Shigella. At the species level, it can adjust the abundance of Lactobacillus johnsonii and Lactobacillus reuteri. All in all, this study is the first to show that QSW can reduce the severity of cerebral ischemia-reperfusion injury by regulating gut microbiota and inhibiting the inflammatory response.
ABSTRACT
The aim of this study is to determine 18 elements in Tibetan medicine Qishiwei Zhenzhu pills (QSW) and their absorption, distribution, and excretion in rats with cerebral ischemia. Microwave digestion and inductively coupled plasma mass spectrometry (ICP-MS) were used to determine 18 elements of QSW in simulated gastrointestinal (GI) juice. Rats were given QSW (66.68 mg/kg) followed by middle cerebral artery occlusion (MCAO). Sham rats received saline and were not subjected to MCAO. ICP-MS was applied to determine the content of 18 elements in hepatic venous blood, abdominal aortic blood, brain, liver, kidney, hair, urine, and feces 24 h after MCAO. In vitro results showed that the extraction rate of Mn, Cu, Sr, Pb, Au, and Hg of QSW in gastric juice (1 h) was higher than that in water, and the contents of Cu, Au, Sr, and As were higher in intestinal juice (4 h) than in water. In vivo results showed that the contents of elements in the blood were quite low, and QSW increased Ni, Cr, Sr, Co, and V in artery blood and decreased V in venous blood. Elements in the tissues were also low, and QSW increased brain Li but decreased Cr and Cd; QSW increased kidney Ag and Cs and liver Mn but decreased liver Ni. QSW increased urinary excretion of Li, Sr, Hg, Cs, and V; QSW increased Hg content in hair but decreased Ni. Stool is the main excretion pathway of the elements in QSW, with Ba, Mn, Sr, Cd, V, Cu, Cs, Li, Pb, Ag, Hg, Cr, As, and Co the highest. In summary, this study examined the distribution of 18 elements in QSW-treated MCAO rats. The accumulation of these elements in blood and tissues was extremely low, and the majority was excreted in feces within 24 h, highlighting the importance of the gut-microbiota-brain axis in QSW-mediated brain protection.
ABSTRACT
Herein, it is demonstrated that N-rich carbonized silk fibroin materials (CSFs) can serve as efficient peroxidase, and oxidase mimics. Their enzyme-like activities are highly dependent on carbonization conditions. CSFs obtained at low temperatures do not exhibit significant catalytic reactivity, while their enzyme-like catalysis performance is greatly activated after high-temperature treatment. Such a phenomenon is mainly ascribed to the increase of graphitization degree and graphitic nitrogen and the emergence of disordered graphitic structures during the formation of turbostratic carbon. In addition, inspired by the excellent photothermal conversion efficiency, and temperature-dependent catalytic behavior of CSFs, near-infrared light can be used to remotely control their enzyme-like activities. More importantly, as-prepared robust silk-derived nanosheets can be applied to photothermal-catalytic cancer therapy and sensing. It is believed that such a smart artificial enzyme system will throw up exciting new opportunities for the chemical industry and biotechnology.
Subject(s)
Fibroins , Silk , Carbon , Nitrogen , TemperatureABSTRACT
Light-activated nanozymes can provide a wealth of new opportunities for the chemical industry and biotechnology. However, present remote-controlled catalytic systems are still far from satisfactory. Herein, we present an interesting example of applying ultrathin Pd nanosheets (Pd NSs) as a light-controllable peroxidase mimic. Since most of Pd atoms are exposed on their surface, Pd NSs with a thickness of 1.1 nm possess high peroxidase-like activity. More importantly, under light excitation, such intrinsic activity can be further activated by a nearly 2.4- to 3.2-fold. Such a phenomenon can be ascribed to the unique optical property of ultrathin Pd NSs, which can efficiently capture photons to generate hot electrons via surface plasmon resonance effect and thus promote the in situ decomposition of H2O2 into reactive oxygen species radicals (O*). This enhanced catalysis can also be used for real-time and highly sensitive colorimetric detection of H2O2. We expect our work can provide valuable insights into the rational design of artificial nanozymes with controllable and efficient activity in biomedical diagnostics, drug delivery, and environmental chemistry.
ABSTRACT
Due to the abuse of antibiotics and the tendency of bacteria to form protective biofilms, the design and development of new efficient agents that can eliminate bacteria and biofilms are still highly desired but remain a great challenge; on the other hand, natural enzymes with unique catalytic characteristics can cause an irreversible damage to the bacteria without inducing drug-resistance in the bacteria. However, the intrinsic drawbacks, such as insufficient stability and high purification cost, of enzymes significantly limit their antimicrobial applications. Therefore, significant research efforts have been devoted towards the development of quality-equivalent or even superior enzyme substitutes with low cost and high stability. In this regard, nanomaterials with extraordinary enzyme-mimetic catalytic activities (termed as nanozymes) are considered as suitable candidates. To date, nanozymes have been proved to be promising materials for combating bacteria and biofilms under mild conditions. In this review, we have summarized the recent progress of nanozymes in this highly active field. The antibacterial mechanisms of nanozymes and the roles of their sizes, morphologies, compositions, surface modifications and microenvironment on their overall performance have been discussed. Moreover, the current challenges and prospects in this research area have been discussed. We believe that nanozymes with unique features and functions can provide a wealth of opportunities via their clinical and industrial applications.
