Aggregation significantly influences the transport, transformation and bioavailability of engineered nanomaterials in aquatic environments. As one of the most well-studied two-dimensional transition metal dichalcogenide nanomaterials, the colloidal stability of molybdenum...

The aggregation−redispersion behavior of nanomaterials determines their transport, transformation, and toxicity, which could be largely influenced by the ubiquitous natural organic matter (NOM). Nonetheless, the interaction mechanisms of two-dimensional (2D) MoS 2 and NOM and the subsequent influences on the redispersion behavior are not well understood. Herein, we investigated the redispersion of single-layer MoS 2 (SL-MoS 2 ) nanosheets as influenced by Suwannee River NOM (SRNOM). It was found that SRNOM played a decisive role on the redispersion of MoS 2 2D nanosheets that varied distinctly from the 3D nanoparticles. Compared to the poor redispersion of MoS 2 aggregates in the absence or post-addition of SRNOM to the aggregates, co-occurrence of SRNOM in the dispersion could largely enhance the redispersion and mobility of MoS 2 by intercalating into the nanosheets. Upon adsorption to SL-MoS 2 , SRNOM enhanced the hydration force and weakened the van der Waals forces between nanosheets, leading to the redispersion of the aggregates. The SRNOM fractions with higher molecular mass imparted better dispersity due to the preferable sorption of the large molecules onto SL-MoS 2 surfaces. This comprehensive study advances current understanding on the transport and fate of nanomaterials in the water system and provides fresh insights into the interaction mechanisms between NOM and 2D nanomaterials.

Deoxynivalenol (DON) is a mycotoxin commonly found in cereals. It has strong toxicity with high stability, thus it is easy to remain in food and cause serious poisoning symptoms to consumers. To establish an efficient and simple DON detection system, a biological nano magnetic particle called bacterial magnetosomes (BMs) extracted from magnetotactic bacteria with ultrasonic crushing and magnetic adsorption was used in this study. A single-stranded DNA aptamer specifically binding to DON was coupled to the surface of MBs by two different crosslinking agents, glutaraldehyde and polyethyleneimine (PEI), respectively, to synthesize two kinds of BMs-aptamer complexes for enriching DON. Then, the adsorption rate of the complex to DON was determined by HPLC. In the results, the absolute DON adsorption capacity of 1 mg BMs-aptamer complex was 27.24 ng when glutaraldehyde was used as crosslinker and 27.64 ng when PEI was used as crosslinker. The optimization results of desorption conditions showed that under the optimal elution conditions (DNase I+methanol for 2 times), the elution rate of DON adsorbed by BMs-glutaraldehyde-aptamer reached 72.7%, while the elution rate of DON adsorbed by BMs-PEI-aptamer complex reached 64.1%. Overall, the current study enriched the applications of magnetosomes in mycotoxin detection, and also provides new idea for the efficient enrichment and recovery of DON.

Cerium oxide (CeO 2 ) nanoparticles are one of the most important engineered nanomaterials with demonstrated applications in industry. Although numerous studies have reported the plant uptake of CeO 2 , its fate and transformation pathways and mechanisms in plant-related conditions are still not well understood. This study investigated the stability of CeO 2 in the presence of organic ligands (maleic and citric acid) and light irradiation. For the first time, we found that organic ligands and visible light had a synergistic effect on the reductive dissolution of CeO 2 with up to 30% Ce releases after 3 days, which is the highest release reported so far under environmental conditions. Moreover, the photoinduced dissolution of CeO 2 in the presence of citrate was much higher than that in maleate, which are adsorbed on the surface of CeO 2 through inner-sphere and outer-sphere complexation, respectively. A novel liganddependent photodissolution mechanism was proposed and highlighted: upon electron− hole separation under light irradiation, the inner-sphere complexed citrate is more capable of consuming the hole, prolonging the life of electrons for the reduction of Ce(IV) to Ce(III). Finally, reoxidation of Ce(III) by oxygen was observed and discussed. This comprehensive work advances our knowledge of the fate and transformation of CeO 2 in plant surroundings.