Developing the high-performance semiconductor photocatalytic materials is an eternal topic under the background of the current energy and environment requirements. In recent years, single-atom photocatalysts (SAPCs) have been brought a lot of attention in energy conversion and environmental purification because of their unique characteristics and properties, including the unique coordination patterns, outstanding atomic utilization, quantum confinement effects, high catalytic activity, etc. Hence, this critical review focuses on the summarized various synthetic methods and the recent important applications of SAPCs, including photocatalytic H2 evolution (PHE) from water splitting, photocatalytic CO2 reduction, photodegradation of organic pollutants, etc. The prospects and challenges for future research topics of SAPCs with excellent activity and stability for various photocatalytic applications are prospected at the end of this review. We sincerely expect that this critical review can promote deep-level insight into the SAPCs subject for the future significant applications in other fields.

Nicotine, a major teratogen of cigarettes smoke induces embryonic abnormalities during the early stages of organogenesis. In this study, the protective effect of β-carotene against nicotine–induced embryos was evaluated by morphologic scoring, nile blue staining, lipid peroxidation, SOD activity assay and real-time PCR. The embryos exposed to nicotine (1 μM) revealed remarkable morphological anomalies compared to normal control group (p<0.05), but when β-carotene (1×10‒4 μM or 5×10‒4 μM) was added concurrently to the embryos exposed to nicotine, morphological parameters were significantly improved (p<0.05). Nicotine induced oxidative stress by increased lipid peroxidation, expression of proinflammatory cytokines (TNF-α and IL-1β), caspases-3 and decreased SOD activity. However, administration of β-carotene (1×10‒4 μM or 5×10‒4 μM) restored the SOD level and decreased oxidative damage in the embryos. These results indicate that β-carotene effectively counteracts the deleterious effects of nicotine on embryos and attenuates oxidative damage possibly through its antioxidant effects.

Nicotine, a major toxic component in tobacco smoke, leads to severe embryonic damages on organogenesis. We investigated if resveratrol can inhibit the nicotine–induced teratogenesis in the cultured mouse embryos (embryonic day 8.5) for 48 hours using a whole embryo culture system. The embryos exposed to nicotine (1 μM) revealed severe morphological anomalies, the increased levels of caspase-3 mRNA and lipid peroxidation, and further the lowered levels of mitochondrial manganese superoxide dismutase (SOD), cytosolic glutathione peroxidase (GPx), phospholipid hydroperoxide GPx, hypoxia-inducible factor 1α, and sirtuin mRNAs and SOD activity significantly compared to normal control group (p<0.05). However, whenre sveratrol(1×10‒5 μMor1 ×10‒4 μM) was added concurrently to the embryos exposed to nicotine, these all parameters were significantly improved (p<0.05).These findings indicate that resveratrol has a protective effect against nicotine-induced teratogenesis in mouse embryos throughout antioxidative and anti-apoptotic activities.