Molybdenum disulfide (MoS 2 ) nanosheets have received considerable interest due to their superior physicochemical performances to graphene nanosheets. As the lateral size and layer thickness decrease, the formed MoS 2 quantum dots (QDs) show more promise as photocatalysts, endowing them with potential antimicrobial properties under environmental conditions. However, studies on the antibacterial photodynamic therapy of MoS 2 QDs have rarely been reported. Here, we show that MoS 2 QDs more effectively promote the creation and separation of electron−hole pair than MoS 2 nanosheets, resulting in the formation of multiple reactive oxygen species (ROS) under simulated solar light irradiation. As a result, photoexcited MoS 2 QDs show remarkably enhanced antibacterial activity, and the ROS-mediated oxidative stress plays a dominant role in the antibacterial mechanism. The in vivo experiments showed that MoS 2 QDs are efficacious in wound healing under simulated solar light irradiation and exert protective effects on normal tissues, suggesting good biocompatibility properties. Our findings provide a full description of the photochemical behavior of MoS 2 QDs and the resulting antibacterial activity, which might advance the development of MoS 2 -based nanomaterials as photodynamic antibacterial agents under environmental conditions.

Background Nanomaterials that exhibit intrinsic enzyme-like characteristics have shown great promise as potential antibacterial agents. However, many of them exhibit inefficient antibacterial activity and biosafety problems that limit their usefulness. The development of new nanomaterials with good biocompatibility and rapid bactericidal effects is therefore highly desirable. Here, we show a new type of terbium oxide nanoparticles (Tb 4 O 7 NPs) with intrinsic oxidase-like activity for in vitro and in vivo antibacterial application. Results We find that Tb 4 O 7 NPs can quickly oxidize a series of organic substrates in the absence of hydrogen peroxide. The oxidase-like capacity of Tb 4 O 7 NPs allows these NPs to consume antioxidant biomolecules and generate reactive oxygen species to disable bacteria in vitro. Moreover, the in vivo experiments showed that Tb 4 O 7 NPs are efficacious in wound-healing and are protective of normal tissues. Conclusions Our results reveal that Tb 4 O 7 NPs have intrinsic oxidase-like activity and show effective antibacterial ability both in vitro and in vivo. These findings demonstrate that Tb 4 O 7 NPs are effective antibacterial agents and may have a potential application in wound healing. Electronic supplementary material The online version of this article (10.1186/s12951-019-0487-x) contains supplementary material, which is available to authorized users.

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BackgroundAflatoxin B1 (AFB1), deoxynivalenol (DON), HT-2, ochratoxin A (OTA), zearalenone (ZEA) are the most common mycotoxins that are found in corn-based animal feed which have multiple toxic effects on animals and humans. Previous studies reported that these mycotoxins impaired mammalian oocyte quality. However, the effective concentrations of mycotoxins to animal oocytes were different.MethodsIn this study we aimed to compare the sensitivity of mouse and porcine oocytes to AFB1, DON, HT-2, OTA, and ZEA for mycotoxin research. We adopted the polar body extrusion rate of mouse and porcine oocyte as the standard for the effects of mycotoxins on oocyte maturation.Results and DiscussionOur results showed that 10 μM AFB1 and 1 μM DON significantly affected porcine oocyte maturation compared with 50 μM AFB1 and 2 μM DON on mouse oocytes. However, 10 nM HT-2 significantly affected mouse oocyte maturation compared with 50 nM HT-2 on porcine oocytes. Moreover, 5 μM OTA and 10 μM ZEA significantly affected porcine oocyte maturation compared with 300 μM OTA and 50 μM ZEA on mouse oocytes. In summary, our results showed that porcine oocytes were more sensitive to AFB1, DON, OTA, and ZEA than mouse oocytes except HT-2 toxin.

The objective of this study was to unveil insights into the effects of on the development of volatile compounds and metabolites during the dough fermentation in making Chinese steamed bread. Changes in gluten structure under the influence of baker's yeast were studied using scanning electron micrographs (SEM). A unique aroma profile was found comprising some previously reported aromatic compounds and some unreported aromatic aldehydes ((E)-2-Decenal and 2-Undecenal) and ketones (2-Heptanone and 2-Nonanone) in the baker's yeast fermentation. Among metabolites, the most preferred sugar for this yeast (glucose) showed a significant decrease in contents during the initial few hours of the fermentation and at last an increase was observed. However, most of the amino acids increased either slightly or decreased by the fermentation time. SEM of fermented dough showed that the yeast had a very little effect on starch stability. This study provided some fermentation features of the bakers' yeast which could be used for the tailored production of steamed bread.