Effective photocatalysts and their surface engineering are essential for the efficient conversion of solar energy into chemical energy in photocatalyzed organic transformations. Herein, we report an effective approach for structuring Pd nanoparticles (NPs) on exfoliated 2H-WS nanosheets (WS/PdNPs), resulting in hybrids with extraordinary photocatalytic activity in Suzuki reactions under visible light. Pd NPs of different sizes and densities, which can modulate the photocatalytic activity of the as-prepared WS/PdNPs, were effectively structured on the basal plane of 2H-WS nanosheets via a sonic wave-assisted nucleation method without any reductants at room temperature. As the size of Pd NPs on WS/PdNPs increased, their photocatalytic activity in Suzuki reactions at room temperature increased substantially. In addition, it was found that protic organic solvents play a crucial role in activating WS/PdNPs catalysts in photocatalyzed Suzuki reactions, although these solvents are generally considered much less effective than polar aprotic ones in the conventional Suzuki reactions promoted by heterogeneous Pd catalysts. A mechanistic investigation suggested that photogenerated holes are transferred to protic organic solvents, whereas photogenerated electrons are transferred to Pd NPs. This transfer makes the Pd NPs electron-rich and accelerates the rate-determining step, i.e., the oxidative addition of aryl halides under visible light. WS/PdNPs showed the highest turnover frequency (1244 h) for photocatalyzed Suzuki reactions among previously reported photocatalysts.

No abstract

Sepsis is an aberrant systemic inflammatory response mediated by excessive production of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Developing an efficient antioxidant therapy for sepsis via scavenging ROS and RNS remains a big challenge owing to the insufficient activity and sustainability of conventional antioxidants. Herein, biocompatible transition-metal dichalcogenide antioxidants with excellent scavenging activity and sustainability for H2O2, O2 •–, OH•, and nitric oxide are developed for effective sepsis treatment. WS2, MoSe2, and WSe2 nanosheets exfoliated and functionalized with a biocompatible polymer effectively scavenge mitochondrial and intracellular ROS and RNS in inflammatory cells. Among the nanosheets, WS2 most efficiently suppresses the excessive secretion of inflammatory cytokines along with scavenging ROS and RNS without affecting the expression levels of the anti-inflammatory cytokine and ROS-producing enzymes. The WS2 nanosheets significantly improve the survival rate up to 90% for severely septic mice by reducing systemic inflammation. The pharmacokinetics suggests that the WS2 nanosheets can be excreted from mice 3 days after intravenous injection. This work demonstrates the potential of therapeutic nanosheet antioxidants for effective treatment of ROS and RNS-related diseases.

Designing artificial nanomaterials capable of selectively detecting targets without the use of expensive and fragile antibodies is of great interest in the applications of nanomedicine. Here, we show that the photoluminescence (PL) of graphene oxide (GO) was chemically modulated for the selective detection of a neurotransmitter without the use of antibodies. GO was functionalized with nitrotriacetic acid (NTA) on which four different metal ions were chelated (M-NTA-GO), which led to its different PL responses to neurotransmitters. In particular, the Cu-NTA-GO hybrid was able to selectively detect norepinephrine at nanomolar concentrations in a simple manner via its "turn-on" PL. Moreover, it was successfully applied to the selective detection of norepinephrine secreted from living PC-12 cells.

Modulating the dimensions and phases of transition metal dichalcogenides is of great interest to enhance their intrinsic properties or to create new physicochemical properties. Herein, we report an effective approach to synthesize 2H-WS quantum dots (QDs) via the dimension and phase engineering of 1T-WS nanosheets. The solvothermal reaction of chemically exfoliated 1T-WS nanosheets in N-methyl-2-pyrrolidone (NMP) under an N atmosphere induced their chopping and phase transition at lower temperature to produce 2H-WS QDs with a high quantum yield (5.5 ± 0.3%). Interestingly, this chopping and phase transition process showed strong dependency on solvent; WS QDs were not produced in other solvents such as 1,4-dioxane and dimethyl sulfoxide. Mechanistic investigations suggested that NMP radicals played a crucial role in the effective production of 2H-WS QDs from 1T-WS nanosheets. WS QDs were successfully applied for the selective, sensitive, and rapid detection of dopamine in human serum (4 min, as low as 23.8 nM). The intense fluorescence of WS QDs was selectively quenched upon the addition of dopamine and Au ions due to fluorescence resonance energy transfer between WS QDs and the quickly formed Au nanoparticles. This new sensing principle enabled us to discriminate dopamine from dopamine-derivative neurotransmitters including epinephrine and norepinephrine, as well as other interference compounds.