Monolayer molybdenum disulfide (MoS 2 ) has attracted tremendous attention due to its promising applications in high-performance field-effect transistors, phototransistors, spintronic devices and nonlinear optics. The enhanced photoluminescence effect in monolayer MoS 2 was discovered and, as a strong tool, was employed for strain and defect analysis in MoS 2 . Recently, large-size monolayer MoS 2 has been produced by chemical vapour deposition, but has not yet been fully explored. Here we systematically characterize chemical vapour deposition-grown MoS 2 by photoluminescence spectroscopy and mapping and demonstrate non-uniform strain in single-crystalline monolayer MoS 2 and strain-induced bandgap engineering. We also evaluate the effective strain transferred from polymer substrates to MoS 2 by three-dimensional finite element analysis. Furthermore, our work demonstrates that photoluminescence mapping can be used as a non-contact approach for quick identification of grain boundaries in MoS 2 .

Carbon dots (C-dots) with sulfur-doped (S-doped) was synthesized using a simple and straightforward hydrothermal method. The as-prepared S-doped C-dots exhibit significant high fluorescence quantum yield (67%) and unique emission property. The form spherical shaped S-doped C-dots have average diameter 4.6 nm and the fluorescence of S-doped C-dots can be effectively and selectively quenched by 10

This review summarized the recent progress in the synthesis, characterization, properties, photoluminescence mechanism and biological applications of carbon dots.

Defects are common but important in graphene, which could significantly tailor the electronic structures and physical and chemical properties. In this study, the density functional theory (DFT) method was applied to study the electronic structure and catalytic properties of graphene clusters containing various point and line defects. The electron transfer processes in oxygen reduction reaction (ORR) on perfect and defective graphene clusters in fuel cells was simulated, and the free energy and reaction energy barrier of the elementary reactions were calculated to determine the reaction pathways. It was found that the graphene cluster with the point defect having pentagon rings at the zigzag edge, or line defects (grain boundaries) consisting of pentagon-pentagon-octagon or pentagon-heptagon chains also at the edges, shows the electrocatalytic capability for ORR. Four-electron and two-electron transfer processes could occur simultaneously on graphene clusters with certain types of defects. The energy barriers of the reactions are comparable to that of platinum(111). The catalytic active sites were determined on the defective graphene.

Ischemic stroke is a leading cause of long-term disability and death worldwide. Current drug delivery vehicles for the treatment of ischemic stroke are less than satisfactory, in large part due to their short circulation lives, lack of specific targeting to the ischemic site, and poor controllability of drug release. In light of the upregulation of reactive oxygen species (ROS) in the ischemic neuron, we herein developed a bioengineered ROS-responsive nanocarrier for stroke-specific delivery of a neuroprotective agent, NR2B9C, against ischemic brain damage. The nanocarrier is composed of a dextran polymer core modified with ROS-responsive boronic ester and a red blood cell (RBC) membrane shell with stroke homing peptide (SHp) inserted. These targeted "core-shell" nanoparticles (designated as SHp-RBC-NP) could thus have controlled release of NR2B9C triggered by high intracellular ROS in ischemic neurons after homing to ischemic brain tissues. The potential of the SHp-RBC-NP for ischemic stroke therapy was systematically evaluated in vitro and in rat models of middle cerebral artery occlusion (MCAO). In vitro results showed that the SHp-RBC-NP had great protective effects on glutamate-induced cytotoxicity in PC-12 cells. In vivo pharmacokinetic (PK) and pharmacodynamic (PD) testing further demonstrated that the bioengineered nanoparticles can drastically prolong the systemic circulation of NR2B9C, enhance the active targeting of the ischemic area in the MCAO rats, and reduce ischemic brain damage.

Quantum dots, derived from two-dimensional (2D) materials, have shown promising applications in bioimaging, photocatalysis, biosensors and white light emission devices (W-LEDs).

Ischemic stroke caused by a thrombus clog and ischemia is one of the most lethal and disabling cerebrovascular diseases. A sequentially targeted delivery system is highly desired to deliver thrombolytics and neuroprotectant to the site of the thrombus and ischemic penumbra, respectively, to pursue a maximized combinational effect. Inspired by the vital roles that platelets play in thrombus formation, herein, we develop a bioengineered "nanoplatelet" (tP-NP-rtPA/ZL006e) for sequentially site-specific delivery of recombinant tissue plasminogen activator (rtPA) and neuroprotectant (ZL006e) for ischemic stroke treatment. The tP-NP-rtPA/ZL006e consists of a ZL006e-loaded dextran derivative polymeric nanoparticle core and platelet membrane shell conjugated with thrombin-cleavable Tat-peptide-coupled rtPA. Mediated by the cloak of the platelet membrane, tP-NP-rtPA/ZL006e targets the thrombus site and rtPA is triggered to release by the upregulated thrombin. Subsequently, the in situ exposed Tat peptide enhanced penetration of the "nanoplatelet" across the blood−brain barrier into ischemic brain for ZL006e site-specific delivery. From the in vitro and in vivo evaluation, tP-NP-rtPA/ZL006e is demonstrated to significantly enhance the anti-ischemic stroke efficacy in the rat model with middle cerebral artery occlusion, showing a 63 and 72% decrease in ischemic area and reactive oxygen species level compared to that with free drug combination, respectively.

Smart windows are a promising way to modulate solar light transmittance, which is crucial for energy saving buildings. We provide an overview of the recent progress in hydrogel-based smart windows.