Graphene-like two-dimensional materials (2DMats) show application potential in optoelectronics and biomedicine due to their unique properties. However, environmental and biological influences of these 2DMats remain to be unveiled. Here we reported the antibacterial activity of two-dimensional (2D) chemically exfoliated MoS₂ (ce-MoS₂) sheets. We found that the antibacterial activity of ce-MoS₂ sheets was much more potent than that of the raw MoS₂ powders used for the synthesis of ce-MoS₂ sheets possibly due to the 2D planar structure (high specific surface area) and higher conductivity of the ce-MoS₂. We investigated the antibacterial mechanisms of the ce-MoS₂ sheets and proposed their antibacterial pathways. We found that the ce-MoS₂ sheets could produce reactive oxygen species (ROS), different from a previous report on graphene-based materials. Particularly, the oxidation capacity of the ce-MoS₂ sheets toward glutathione oxidation showed a time and concentration dependent trend, which is fully consistent with the antibacterial behaviour of the ce-MoS₂ sheets. The results suggest that antimicrobial behaviors were attributable to both membrane and oxidation stress. The antibacterial pathways include MoS₂–bacteria contact induced membrane stress, superoxide anion (O₂˙⁻) induced ROS production by the ce-MoS₂, and the ensuing superoxide anion-independent oxidation. Our study thus indicates that the tailoring of the dimension of nanomaterials and their electronic properties would manipulate antibacterial activity.

Peer reviewed article authored by (Hanagata N). Read article or submit your manuscript for publishing.

Unmethylated cytosine-guanine dinucleotide-containing oligodeoxynucleotides (CpG ODNs), which are synthetic agonists of Toll-like receptor 9 (TLR9), activate humoral and cellular immunity and are being developed as vaccine adjuvants to prevent or treat cancers, infectious diseases, and allergies. Free CpG ODNs have been used in many clinical trials implemented to verify their effects. However, recent research has reported that self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes demonstrate higher adjuvant effects than free CpG ODNs, owing to their improved uptake efficiency into cells expressing TLR9. Moreover, protein/peptide–CpG ODN conjugates and nanomaterial–CpG ODN complexes are able to deliver CpG ODNs and antigens (or allergens) to the same types of cells, which enables a higher degree of prophylaxis or therapeutic effect. In this review, the author describes recent trends in the research and development of CpG ODN nanomedicines containing self-assembled CpG ODNs, protein/peptide–CpG ODN conjugates, and nanomaterial–CpG ODN complexes, focusing mainly on the results of preclinical and clinical studies.