Drug addiction is a chronic brain disease that is a serious social problem and causes enormous financial burden. Because mitochondrial abnormalities have been associated with opiate addiction, we examined the effect of morphine on mtDNA levels in rat and mouse models of addiction and in cultured cells. We found that mtDNA copy number was significantly reduced in the hippocampus and peripheral blood of morphine-addicted rats and mice compared with control animals. Concordantly, decreased mtDNA copy number and elevated mtDNA damage were observed in the peripheral blood from opiate-addicted patients, indicating detrimental effects of drug abuse and stress. In cultured rat pheochromocytoma (PC12) cells and mouse neurons, morphine treatment caused many mitochondrial defects, including a reduction in mtDNA copy number that was mediated by autophagy. Knockdown of the Atg7 gene was able to counteract the loss of mtDNA copy number induced by morphine. The mitochondria-targeted antioxidant melatonin restored mtDNA content and neuronal outgrowth and prevented the increase in autophagy upon morphine treatment. In mice, coadministration of melatonin with morphine ameliorated morphine-induced behavioral sensitization, analgesic tolerance and mtDNA content reduction. During drug withdrawal in opiate-addicted patients and improvement of protracted abstinence syndrome, we observed an increase of serum melatonin level. Taken together, our study indicates that opioid addiction is associated with mtDNA copy number reduction and neurostructural remodeling. These effects appear to be mediated by autophagy and can be salvaged by melatonin.

Cu-based catalysts are exceptionally advantageous for the electrochemical CO2 reduction reaction (CO2RR) to fuels and chemical products utilizing clean and renewable energy.

In this work, we report on the microwave-assisted hydrothermal synthesis of Sn 2+ -doped ZnWO 4 nanocrystals with controlled particle sizes and lattice structures for tunable optical and photocatalytic properties. The samples were carefully characterized by X-ray diffraction, transmission electron microscopy, inductive coupled plasma optical emission spectroscopy, UV−vis diffuse reflectance spectroscopy, and Barrett−Emmett−Teller technique. The effects of Sn 2+ doping in ZnWO 4 lattice on the crystal structure, electronic structure, and photodegradation of methylene orange dye solution were investigated both experimentally and theoretically. It is found that part of the Sn 2+ ions were homogeneously incorporated in the ZnWO 4 host lattice, leading to a monotonous lattice expansion, and part of Sn 2+ ions were expelled at surface sites for decreased crystallinity and particle size reduction. By Sn 2+ doping, ZnWO 4 nanocrystals showed a significant XPS binding energy shift of Zn 2p, W 4f, and O 1s, which is attributed to the combination of electronegativity between Sn 2+ and Zn 2+ , lattice variation, and particle size reduction. Meanwhile, the BET surface areas were also greatly enlarged from 40.1 to ∼110 m 2 ·g −1 . Contrary to the theoretical predictions of the quantum size effect, Sn 2+ -doped ZnWO 4 nanocrystals showed an abnormal band gap narrowing, which can be well-defined as a consequence of bulk and surface doping effects as well as lattice variations. With well-controlled particle size, crystallinity, and electronic structure via Sn 2+ doping, the photocatalytic performance of Sn 2+ -doped ZnWO 4 nanocrystals was optimized at Sn 2+ doping level of 0.451. ■ INTRODUCTIONSemiconductor nanomaterials have distinct properties that promise new inventions and new materials for widespread technological applications and economic impacts. 1 It is a wellestablished fact that the physical properties of nanocrystals are strongly influenced by particle size, chemical composition, and surface chemistry. 2 Till now, vigorous efforts have been dedicated to tailoring the fundamental properties of semiconductors as a function of particle size, chemical composition as well as surface chemistry, including structural and electronic properties of ZnS nanoclusters, 3 photocatalytic performance of TiO 2 -based photocatalyts, 4 magnetic properties of EuS nanoparticles, 5 and so on. From the viewpoint of solid-state physics, the reduction of particle sizes and variation of chemical compositions often predict variations in lattice parameters and surface structures, which can have consequences on the electronic structures and properties. 6 Therefore, the ability to manipulate the size, shape, composition, crystal structure, and surface properties of nanocrystals is essential for uncovering the nature of structure-related physical properties.Metal tungstate is a very important family of inorganic materials that has high potential applications in various fields, such as photoluminescence, microwave applications, optical fibers, and sc...