Different functional groups of carbon dots influence the formation of protein crowns and pepsin characteristic in vitro digestion.

Application of nanomaterials (NMs) in agriculture poses an ingestion risk to humans and may affect the digestive process. Different fates of NMs with differential charges in the gastrointestinal tract should be considered. In this study, the interaction between three carbon dots (CDs) carried with different functional groups (-NH2, -OH, and -COOH) and pepsin was analyzed through an in vitro digestion model. The results showed that CDs significantly reduced pepsin activity. Among them, CDs-NH2 had the greatest effect, following by CDs-OH, and CDs-COOH. Besides, molecular docking demonstrated the specific binding site of CDs to pepsin, while the most stable binding energy (-8.10 kcal/mol) was formed between CDs-NH2 and pepsin. Further, CDs formed a nanomaterial-protein crown structure with pepsin. The present study enriches the functional group properties of CDs in the digestion and provides new ideas for the potential human health of NMs.

High Toughness, Multi-dynamic Self-Healing Polyurethane for Outstanding Energy Harvesting and Sensing.

Triboelectric nanogenerators (TENGs) are an emerging class of energy harvesting devices with considerable potential across diverse applications, including wearable electronic devices and self-powered sensors. However, sustained contact, friction, and incidental scratches during operation can lead to a deterioration in the electrical output performance of the TENG, thereby reducing its overall service life. To address this issue, we developed a self-healing elastomer by incorporating disulfide bonds and metal coordination bonds into the polyurethane (PU) chain. The resulting elastomer demonstrated exceptional toughness, with a high value of 85 kJ m-3 and an impressive self-healing efficiency of 85.5%. Specifically, the TENG based on that self-healing PU elastomer generated a short circuit current of 12 µA, an open circuit voltage of 120 V, and a transfer charge of 38.5 nC within a 2 cm × 2 cm area, operating in contact-separation mode. With an external resistance of 20 MΩ, the TENG achieved a power density of 2.1 W m-2. Notably, even after self-healing, the electrical output performance of the TENG was maintained at 95% of the undamaged device. Finally, the self-healing TENG was employed to construct a self-powered noncontact sensing system that can be applied to monitor human motion accurately. This research may expand the application prospects of PU materials in future human-computer interaction and self-powered sensing fields.

Recent Advances in Tailored Fabrication and Properties of Biobased Self-Healing Polyurethane.

With the emergence of challenges in the environmental degradation and resource scarcity fields, the research of biobased self-healing polyurethane (BSPU) has become a prevailing trend in the technology of the polyurethane industry and a promising direction for developing biomass resources. Here, the production of BSPU from lignocellulose, vegetable oil, chitosan, collagen, and coumarin is classified, and the principles of designing polyurethane based on compelling examples using the latest methods and current research are summarized. Moreover, the impact of biomass materials on self-healing and mechanical properties, as well as the tailored performance method, are presented in detail. Finally, the applications of BSPU in biomedicine, sensors, coatings, etc. are also summarized, and the possible challenges and development prospects are explored to helpfully make progress in the development of BSPU. These findings demonstrate valuable references and practical significance for future BSPU research.

Selenium nanomaterials alleviate Brassica chinensis L cadmium stress: Reducing accumulation, regulating microorganisms and activating glutathione metabolism.

Agricultural heavy metal contamination can cause significant crop damage, highlighting the urgent need to mitigate its negative effects. Under Cd2+ stress, selenium nanomaterials (Se NMs, 2 mg kg-1) can significantly improve Brassica chinensis L. root growth and vigor, enhance photosynthesis (31.4%), and increase biomass. Se NMs treatment also reduces Brassica chinensis L root and shoot Cd concentration by 67.2 and 72.9%, respectively. This reduction is mainly due to the gene expression of Cd2+ absorption (BcITR1 and BcHMA2) which was down-regulated 51.9 and 67.0% by Se NMs, respectively. Meanwhile, Se NMs can increase the abundance of Cd-resistant microorganisms (Gemmatimonas, RB41, Haliangium, Gaiella, and Steroidobacter) in rhizosphere soil while also reducing Cd migration from soil to plants. Additionally, Se NMs also contribute to reducing ROS accumulation by improving the oxidation-reduction process between GSH and GSSG through enhancing γ-ECS (15.6%), GPx (50.2%) and GR (97.3%) activity. Remarkably, crop Se content can reach 50.8 µg/100 g, which fully meets the standards of Se-rich vegetables. These findings demonstrate the potential of Se NMs in relieving heavy metal stress, while simultaneously increasing crop Se content, making it a promising technology for sustainable agricultural production.

Dynamics of organic acid exudation and rhizobacteria in maize rhizosphere respond to N-CDs.

To sustainably feed the growing global population, it is essential to increase crop yields on limited land while reducing the use of fertilizers and agrochemicals. The rhizosphere regulation shows significant potential to address this challenge. Here, foliar applied doping of nitrogen in carbon dots (N-CDs) entered maize leaves, and were transported to the stems and roots. The internalized N-CDs significantly increased the biomass (26.4-93.8%) and photosynthesis (17.0-20.3 %) of maize seedling during the three-week application of N-CDs, providing the substrate for tricarboxylic acid cycle (TCA) in shoots and roots. Correspondingly, more organic acids involved in TCA cycle, such as citric acid (14.0-fold), succinic acid (4.4-fold) and malic acid (3.4-fold), were synthesized and then secreted into rhizosphere after exposed to N-CDs for one day. As the exposure time increased, greater secretion of above organic acids by the roots was induced. However, no significant change was observed in the relative abundance of rhizobacteria after foliar application with N-CDs for one day. After one week, the relative abundances of Azotobacter, Bacillus, Lysobacter, Mucilaginibacter, and Sphingomonas increased by 0.8-3.8 folds. The relative abundance of more beneficial rhizobacteria (Sphingomonas, Lysobacter, Rhizobium, Azotobacter, Pseudomonas, Mucilaginibacter and Bacillus) enriched by 0.3-6.0 folds after two weeks, and Sphingomonas, Flavisolibacter and Bacillus improved by 0.6-3.2 folds after three weeks. These dynamic changes suggested that N-CDs initiate the synthesis and secretion of organic acids and then recruited beneficial rhizobacteria. The hierarchical partitioning analysis further indicated that N-CDs-induced secretion of organic acids from the roots was the main drivers of rhizobacteria community dynamics. The differential microbes altered by N-CDs were mainly involved in nitrogen (N) and phosphorus (P) cycles, which are beneficial for N and P uptake, and maize growth. These results provide insights into understanding the rhizosphere regulation of nanomaterials to improve plant productivity and nutrient-use efficiency.

Biomass-derived carbon dots with light conversion and nutrient provisioning capabilities facilitate plant photosynthesis.

Carbon dots (CDs)-enabled agriculture has been developing rapidly, but small-scale synthesis and high costs hinder the agricultural application of CDs. Herein, biomass-derived carbon dots (B-CDs) were prepared on a gram-level with low cost, and these B-CDs significantly improved crop photosynthesis. The B-CDs, exhibiting small size and blue fluorescence, were absorbed by crops and enhanced photosynthesis via light-harvesting. Foliar application of B-CDs (10 mg·kg-1) could promote chlorophyll synthesis (30-100 %), Ferredoxin (Fd, 40-80 %), Rubisco enzyme (20-110 %) and upregulated gene expression (20-70 %), resulting in higher net photosynthetic rates (130-300 %), dry biomass (160-300 %) and fresh biomass (80-150 %). Further, the B-CDs could increase crop photosynthesis under nutrient deficient conditions, which was attributed to the release of nutrients from B-CDs. Therefore, the B-CDs enhanced the photosynthesis via enhancing light conversion and nutrient supply. This study provides a promising material capable of enhancing photosynthesis for sustainable agriculture production.

Selenium nanomaterials improve the quality of lettuce (Lactuca sativa L.) by modulating root growth, nutrient availability, and photosynthesis.

Macro- or micro-nutrients are essential for crop yield and nutritional quality. In this work, selenium engineering nanomaterials (Se ENMs, 0.5 mg‧kg-1) significantly increased the yield and nutritional quality of lettuce, which was better than that of selenite (Na2SeO3). Under the treatment of Se ENMs, macro-nutrients including nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) were increased by 15.8%, 98.5%, 42.8%, 146.9%, and 62.5%, respectively, and micro-nutrients including manganese (Mn), iron (Fe), copper (Cu), and zinc (Zn) were also increased by 87.4%, 78.0%, 61.1%, and 56.1%, respectively. As a result, the improved nutritional status of lettuce leaves increased photosynthesis (59.2%) and yield (37.6%). Root diameters and root tips of lettuce were increased by 23.9% and 18.6%, respectively, upon exposure to Se ENMs, which may be responsible for facilitating the absorption of macro and micro nutrients from the soil. These effects were significantly better than SeO32- treated group. Metabolome results indicated that Se ENMs could improve the shikimic acid, phenylalanine, and tyrosine pathway, resulting in an enhancement of the beneficial compounds, including quercetin, rutin, and coumarin, by 2.9, 2.7, and 2.4-fold, respectively. Besides, pyruvic acid and TCA cycle were also improved by Se ENMs. These results provide new insight into the positive effect of Se ENMs on crop yield and nutritional quality, which demonstrate that the Se ENMs-enabled agriculture practices have a promising prospect as a sustainable crop strategy.

Selenium content and nutritional quality of Brassica chinensis L enhanced by selenium engineered nanomaterials: The role of surface charge.

Selenium engineered nanomaterials (Se ENMs)-enabled agriculture has developed rapidly, however, the roles of surface charge in the bioavailability and enrichment efficiency of Se ENMs are still unknown. Herein, various Se ENMs of homogenous size (40-60 nm) and different surface charges (3.2 ± 0.7, -29.0 ± 0.4, and 45.5 ± 1.3 mV) were prepared to explore the Se content and nutritional quality in Brassica chinensis L. The results demonstrated that soil application of various Se ENMs (0.05 mg kg-1) displayed different bio-availabilities via modulating the secretion of root exudates (e.g., tartaric, malic, and citric acids), microbial community composition (e.g., Flavobacterium, Pseudomonas, Paracoccus, Bacillus and Rhizobium) and root cell wall. Negatively charged Se ENMs (Se (-)) showed the highest Se content in the shoot of B. chinensis (3.7-folds). Se (-) also significantly increased yield (156.9%) and improved nutritional quality (e.g., ascorbic acid, amino acids, flavonoids, fatty acids, and tricarboxylic acid) of B. chinensis. Moreover, after harvest, the Se (-) did not lead to significant change in Se residue in soil, but the amount of Se residue in soil was increased by 5.5% after applying the traditional Se fertilizer (selenite). Therefore, this study provides useful information for producing Se-fortified agricultural products, while minimizing environmental risk.

Multiomics understanding of improved quality in cherry radish (Raphanus sativus L. var. radculus pers) after foliar application of selenium nanomaterials.

A selenium (Se)-nanoenabled agriculture strategy was established in this work to improve crop yield and quality. The results demonstrated that Se engineering nanomaterials (Se ENMs, 10 mg·L-1) were absorbed and translocated in cherry radish (Raphanus sativus L. var. radculus pers) from shoots to taproots after foliar application. RNA-Seq and metabolomic results indicated that the glucolysis, pyruvate and tricarboxylic acid (TCA) cycle metabolism pathways were accelerated by exposure to Se ENMs, resulting in increased production of flavonoids (3.2-fold), amino acids (1.4-fold), and TCA (2.5-fold) compared with the control. Moreover, Se content was enhanced by 5.4 and 2.6 times in pericarp and pulp upon Se ENMs exposure, respectively, which was more efficient (2.2 and 1.1 times) than SeO32- treatment. Additionally, the yield of cherry radish was increased by 67.6% under Se ENMs, whereas SeO32- exposure only led to an increase of 7.4%. Therefore, the application of Se ENMs could reduce the amount of fertilizer used to minimize the environmental impact in agriculture while improve crop production and quality. These findings highlighted the significant potential of Se ENMs-enabled agriculture practices as an eco-friendly and sustainable crop strategy.

The molecular mechanisms of silica nanomaterials enhancing the rice (Oryza sativa L.) resistance to planthoppers (Nilaparvata lugens Stal).

Herein, fluorescent silica (F-SiO2) ENMs (50 nm) were synthesized, which could be taken up and translocated from rice root to shoot, promoting the plant growth and resistance to planthopper compared with Si ion fertilizers under hydroponic conditions. Particularly, upon exposure F-SiO2 ENMs (5 mg‧L-1) suspension for 9 days, the fresh and dry weight (FW and DW) of shoot, the root length, surface area, and tip number were increased by 33.58%, 65.22%, 15.26%, 20.26% and 29.01%, respectively. Notably, in the presence of planthopper, the shoot FW and DW still increased by 61.88% and 114.75%, respectively. The increased lignin content (by 30.13%) and formation of silica cells in stem after F-SiO2 ENMs exposure (5 mg‧L-1) could be mechanical barriers against planthoppers. The transcriptome data revealed that F-SiO2 ENMs could upregulate the expression of genes involved in plant-pathogen interactions, plant hormone signal transduction, glucose metabolism and carbon fixation pathway, promoting the growth and resistance of rice seedlings. Our findings provide first evidence for the underlying molecular mechanisms of SiO2 ENMs enhancing the rice resistance to planthopper.

Fluorescent g-C3N4 nanosheets enhanced photosynthetic efficiency in maize.

Nano-enabled agriculture becomes a new and rapidly evolving area of research, particularly, nanomaterials (NMs) with light-harvesting capacities for enhancing photosynthesis. However, mechanisms for the interactions between these NMs and plants are not fully understood. Herein, fluorescent and water-soluble graphitic carbon nitride (g-C3N4) nanosheets were prepared and used as artificial antenna to amplify light harvesting ability and enhance photosynthesis in maize. Upon root exposure to 10 mg·L-1 g-C3N4 nanosheets, the g-C3N4 can be taken up and distributed in leaves. Also, the nutrients (Mg, P, Fe, and Mn), chlorophyll content, electron transfer rate, net photosynthetic rate, and carbohydrates content in maize were increased significantly by 1.1%, 51.8%, 44.6%, 121.8%, 12.1%, 44.5%, 30.0% and 32.3%, respectively. In addition, the gene expressions of psbA (photosystem II reaction center protein A) and psaA (photosystem I P700 chlorophyll A apoprotein A1) were up-regulated by 56.3% and 26.8%, respectively. Moreover, the activities of phosphoenolpyruvate carboxylase (PEPC) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) were significantly increased by 242.3% and 156.3%, respectively. This study provides a new perspective on the use of g-C3N4 nanosheets to promote plant growth and develop nano-enabled agricultural technology.

CuO nanoparticles doping recovered the photocatalytic antialgal activity of graphitic carbon nitride.

In this work, graphitic carbon nitride (g-C3N4) and CuO nanoparticles doped g-C3N4 (Cu-g-C3N4) was synthesized, and the mechanisms of humic acid (HA) impact on the photocatalytic antialgal activities of g-C3N4 and Cu-g-C3N4 to harmful algae were investigated. The 72 h median effective concentrations of g-C3N4 and Cu-g-C3N4 to two algae (Microcystis aeruginosa, Chlorella vulgaris) were (56.4, 89.6 mg/L) and (12.5, 20.6 mg/L), respectively. Cu-g-C3N4 exhibited higher photocatalytic antialgal activity than g-C3N4 because that: I) Cu-g-C3N4 was easier to aggregate with algal cells due to its lower surface potential and higher hydrophobicity than g-C3N4; II) Cu-g-C3N4 generated more O2-, OH*, and h+ due to its higher full-wavelength light utilization efficiency and higher electron-hole pairs separation efficiency than g-C3N4. HA (10 mg/L) inhibited the photocatalytic antialgal activity of g-C3N4, however, HA had no effect on that of Cu-g-C3N4. The mechanisms were that: I) doped CuO nanoparticles occupied the adsorption sites of HA on g-C3N4, which alleviated the inhibition of HA on the g-C3N4-algae heteroaggregation; II) HA adsorbed on CuO nanoparticles enhanced the oxygen reduction rate of Cu-g-C3N4. This work provides new insight into the inhibition mechanisms of NOM on g-C3N4 photocatalytic antialgal activity and addresses the optimization of g-C3N4 for environmental application.

High Stability and Strong Fluorescence of Carbon Nanodots as Nanosensor for Hg2+ in Environmental Waters.

Pollution of toxic heavy-metal ions such as mercury ions (Hg2+) is well known to severely threaten ecological environment and human health. Correspondingly, development of a fast and sensitive method for detecting heavy-metal ions is urgently needed and has been received widespread attention in recent years. In this study, carbon nanodots (CDs) with strong blue fluorescence were synthesized by a microwave-assisted hydrothermal method. The as-prepared blue fluorescent CDs not only have excellent stability (e.g. photostability, salt stability and pH stability), but also have extremely high selectivity and sensitivity for probing Hg2+ via fluorescence quenching. Specifically, fluorescence of CDs is gradually quenched along with the increase in Hg2+ concentration, and a low concentration of Hg2+ can be identified (with low detection limit, 15 nM). Therefore, the novel fluorescent CDs could be developed for detecting Hg2+ in aqueous conditions, and have great potential for fast probing Hg2+ in environmental samples.