CpG loaded MoS2 nanosheets as multifunctional agents for photothermal enhanced cancer immunotherapy.

Single or few-layered MoS2 nanosheets, as a novel class of 2D nanomaterials, have received tremendous attention due to their fantastic physical and chemical properties. Here, we fabricated MoS2-PEG-CpG with a small and uniform size as a multifunctional platform for photothermal enhanced immunotherapy. MoS2 nanosheets were fabricated by chemical exfoliation and further probe sonication. To realize MoS2-based adjuvant delivery, MoS2 nanosheets were functionalized with cytosine-phosphate-guanine (CpG) and polyethylene glycol (PEG) to form MoS2-PEG-CpG nanoconjugates. As an efficient nanocarrier with excellent near infrared-light (NIR) absorbing performance, MoS2-PEG-CpG significantly promotes CpG intracellular accumulation and the effect can be further enhanced by photothermal treatment. In addition, the enhanced uptake can stimulate the production of proinflammatory cytokines and remarkably elevate the immune response level. Finally, we found that MoS2-PEG-CpG could reduce the proliferative activity of cancer cells when co-cultured with a macrophage-like cell upon NIR irradiation, implying a novel strategy for multifunctional therapeutics against cancers.

Versatile graphene-based photothermal nanocomposites for effectively capturing and killing bacteria, and for destroying bacterial biofilms.

Bacterial infection is a worldwide health problem. Finding new potential antibacterial materials and developing advanced treatment strategies are becoming increasingly important and urgent. Herein, a versatile graphene-based photothermal nanocomposite was prepared for rapidly capturing and effectively eliminating both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli), and for destroying bacterial biofilms with near-infrared (NIR) irradiation. In this work, chitosan-functionalized magnetic graphene oxide (GO-IO-CS) was synthesized as a multifunctional therapy agent through a hydrothermal method. Chitosan could efficiently contact and capture bacteria by its positively charged surface functional groups, and graphene oxide could act as an effective photothermal killer to convert NIR light into local heat to enhance antibacterial activity. The super-paramagnetic properties of GO-IO-CS made it easy to separate and aggregate the bacteria, so improving the photothermal sterilization efficiency. GO-IO-CS was demonstrated to eliminate bacteria effectively after 10 min of NIR irradiation and to destroy bacterial biofilms. Furthermore, this antibiotic agent could be regenerated with an external magnet and reused in a subsequent antibacterial application.

Pt74Ag26 nanoparticle-decorated ultrathin MoS2 nanosheets as novel peroxidase mimics for highly selective colorimetric detection of H2O2 and glucose.

To extend the functionalities of two-dimensional graphene-like layered compounds as versatile materials, the modification of transition metal dichalcogenide nanosheets such as MoS2 with metal nanoparticles is of great and widespread interest. However, few studies are available on the preparation of bimetallic nanoparticles supported on MoS2. Herein, a facile and efficient method to synthesize MoS2-PtAg nanohybrids by decorating ultrathin MoS2 nanosheets with octahedral Pt74Ag26 alloy nanoparticles has been reported. The as-prepared MoS2-Pt74Ag26 nanohybrids were investigated as novel peroxidase mimics to catalyze the oxidation of classical peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, producing a blue colored reaction and exhibiting typical Michaelis-Menten kinetics. MoS2-Pt74Ag26 has a higher affinity for H2O2 than horseradish peroxidase (HRP) and a higher vmax value with TMB as the substrate than MoS2. The improved catalytic activity of hybrids for colorimetric reactions could be attributed to the synergistic effects of octahedral Pt74Ag26 nanoparticles and ultrathin MoS2 nanosheets as supports. Meanwhile, the generation of active oxygen species (˙OH) by H2O2 decomposition with MoS2-Pt74Ag26 was responsible for the oxidation of TMB. On the basis of these findings, a colorimetric method based on MoS2-Pt74Ag26 nanohybrids that is highly sensitive and selective was developed for glucose detection. Lower values of the limit of detection (LOD) were obtained, which is more sensitive than MoS2 nanosheets.