Surface-state-mediated interfacial charge dynamics between carbon dots and ZnO toward highly promoting photocatalytic activity.

Design of hybrid systems for photocatalytic application tends to be restricted by lacking interfacial coupling and fast charge recombination in the body competing with interface dynamics. In this work, the reduced carbon dots (rCDs) with numerous surface hydroxyl groups were deliberately anchored onto flower-like ZnO spheres with a highly exposed surface area to form heterointerfaces with sufficient interfacial electronic coupling. The incorporated rCDs evidently promote the light harvesting and charge separation of the binary hybrid system, resulting in highly enhanced photocatalytic Cr(VI) degradation performance. Ultrafast time-resolved spectra reveal that the surface C-OH bonds of rCDs play a crucial role at the heterointerfaces to regulate the charge dynamics. The long-lived surface C-OH states not only act as electron donors but also become electron mediators to rapidly capture the photoelectrons from the intrinsic state in the time-domain of 1 ps and induce a much longer lifetime for achieving highly efficient photoelectron injection from rCDs to ZnO. These results manifest that rCDs can be a promising photosensitizer to apply in photocatalytic pollutant treatment and energy conversion fields.

Sodium alginate-based composite microspheres for controlled release of pesticides and reduction of adverse effects of copper in agricultural soils.

Excessive copper (Cu) concentrations pose significant health risks to both plants and humans. In this study, sodium alginate (SA)-gelatin (GEL)-polyvinyl pyrrolidone (PVP)- embedded dinotefuran (DIN) microspheres were prepared using spray-drying technology. The loading content and encapsulation efficiency of optimal microspheres determined by physical modifications were 19.77% and 99.32%, respectively. In addition, the microspheres showed variable stimuli-responsive controlled release capacities in different temperatures and types of soil, as well as showed better control efficiency of larvae of Protaetia brevitarsis at pesticide application in the early stage, with the potential ability to control pest outbreaks at high temperatures. In addition, blank microspheres improved the growth and physiological activity of cucumber seedlings, reduced copper content in leaves, increased soil nutrient content, and prevented soil acidification. Further, the use of blank microspheres increased the relative abundance of soil beneficial functional bacteria communities, which mediate heavy metal (HM) immobilization/tolerance and promote plant growth. Redundancy analysis (RDA) and Spearman correlation analysis showed that these beneficial functional bacteria were mainly positively correlated with soil EC, A-N, and N-N. In summary, this study showed that the technique of combining physically modified carrier materials with pesticides has the potential to reduce Cu contamination in the surrounding agricultural soil during pesticide application, thereby reducing Cu uptake by crops.

Effect of sodium alginate-gelatin-polyvinyl pyrrolidone microspheres on cucumber plants, soil, and microbial communities under lead stress.

Lead is highly persistent and toxic in soil, hindering plant growth. Microspheres are a novel, functional, and slow-release preparation commonly used for controlled release of agricultural chemicals. However, their application in the remediation of Pb-contaminated soil has not been studied; furthermore, the remediation mechanism involved has not been systematically assessed. Herein, we evaluated the Pb stress mitigation ability of sodium alginate-gelatin-polyvinyl pyrrolidone composite microspheres. Microspheres effectively attenuated the Pb toxic effect on cucumber seedlings. Furthermore, they boosted cucumber growth, increased peroxidase activity, and chlorophyll content, while reducing malondialdehyde content in leaves. Microspheres promoted Pb enrichment in cucumber, especially in roots (about 4.5 times). They also improved soil physicochemical properties, promoted enzyme activity, and increased soil available Pb concentration in the short term. In addition, microspheres selectively enriched functional (heavy metal-tolerating and plant growth promoting) bacteria to adapt to and resist Pb stress by improving soil properties and nutrients. These results indicated that even a small amount (0.025-0.3 %) of microspheres can significantly reduce the adverse effects of Pb on plants, soil, and bacterial communities. Composite microspheres have shown great value in Pb remediation, and their application potential in phytoremediation is also worth evaluating to expand the application.

Fabrication of ROS-responsive nanoparticles by modifying the interior pore-wall of mesoporous silica for smart delivery of azoxystrobin.

The suboptimal efficiency in pesticide utilization may elevate residues, posing safety risks to human food and non-target organisms. To address this challenge, delivery systems, such as pathogen infection stimuli-responsive carriers, can be employed to augment the efficiency of fungicide utilization. The bursting of reactive oxygen species (ROS) is a common defense response of host plants to pathogenic infections. In this study, ROS-responsive mesoporous silica nanoparticles (MSN) modified with phenyl sulfide (PHS) as azoxystrobin (AZOX) carrier (MSN-PHS-AZOX) were fabricated. Results demonstrated that MSN-PHS-AZOX exhibited fungicide release kinetics dependent on ROS. In vitro inhibition experiments confirmed the fungicidal effect of MSN-PHS-AZOX on Botrytis cinerea, relying on external ROS. In vivo leaf experiments showcased the superior persistence of MSN-PHS-AZOX in compared to AZOX SC. Furthermore, MSN-PHS-AZOX exhibits favorable biosafety and lower toxicity to aquatic zebrafish compared to AZOX SC, with no adverse impact on cucumber leaf growth. These findings suggest the potential application of this ROS-responsive nano fungicide in managing plant disease in agricultural fields.

Controlled release of dinotefuran with temperature/pH-responsive chitosan-gelatin microspheres to reduce leaching risk during application.

Neonicotinoid-based pesticides are extensively used owing to their broad insecticidal spectrum and activity. We developed neonicotinoid dinotefuran (DIN)-loaded chitosan-gelatin microspheres using a spray-drying technology, resulting in a pH- and temperature-responsive controlled-release system. Upon introducing chitosan into the triple-helix structure of gelatin, the physically modified gelatin microspheres became smooth, round, and solid, improving their thermal storage stability. The spray-drying parameters were optimized using three-dimensional surface plots. When scaled up under optimal conditions, the corresponding loading content and encapsulation efficiency were 21.5% and 98.17%, respectively. Compared with commercial dinotefuran granules, our biodegradable composite carriers achieved the immobilization of dinotefuran to reduce pesticide leaching by 5.57-19.89% in soil, improved the soil half-life of DIN, and improved its cumulative absorption by plants. Therefore, the microspheres showed better efficacy against Trialeurodes vaporariorum. Our results confirm that this simple approach can improve the utilization efficiency of neonicotinoids, decrease leaching loss, and promote ecological safety.

Advancing Applications of Black Phosphorus and BP-Analog Materials in Photo/Electrocatalysis through Structure Engineering and Surface Modulation.

Black phosphorus (BP), an emerging 2D material semiconductor material, exhibits unique properties and promising application prospects for photo/electrocatalysis. However, the applications of BP in photo/electrocatalysis are hampered by the instability as well as low catalysis efficiency. Recently, tremendous efforts have been dedicated toward modulating its intrinsic structure, electronic property, and charge separation for enhanced photo/electrocatalytic performance through structure engineering. Simultaneously, the search for new substitute materials that are BP-analogous is ongoing. Herein, the latest theoretical and experimental progress made in the structural/surface engineering strategies and advanced applications of BP and BP-analog materials in relation to photo/electrocatalysis are extensively explored, and a presentation of the future opportunities and challenges of the materials is included at the end.

Selective and high-sensitive label-free detection of ascorbic acid by carbon nitride quantum dots with intense fluorescence from lone pair states.

Label-free detection of ascorbic acid (AA) with high sensitivity and specificity based on the effects of AA on fluorescence quenching of carbon nitride quantum dots (CNQDs) is described. The CNQDs with a high fluorescence quantum yield of 21% and good dispersibility in water are prepared by reacting g-C3N4 sheets with ethylenediamine (EN). Fluorescence at 510 nm from the CNQDs is quenched gradually by addition of AA. As the AA concentration increases, the activity of the lone pair (LP) state of the CNQDs diminishes resulting in reduced fluorescence from the CNQDs and the mechanism of the static quenching effect is discussed. Since the CNQDs have a large specific surface area and abundant amino groups and AA exists in the anionic form at the physiological pH, the electrostatic interaction between CNQDs and AA inhibits excitation and emission of the LP states in the CNQDs. Owing to steric effects and hydrogen bonding, the CNQDs constitute a sensitive and selective detection platform for AA in a wide range from 0.5 to 200 µM with a detection limit of 150 nM (signal-to-noise ratio of 3). More importantly, the strategy can successfully be applied to the detection of AA concentrations in serum samples. This simple method which provides quantitative AA determination has large potential in clinical and health-related applications and the mechanism provides insights into intracellular AA monitoring.