Assessing the effects of drought on rainfed maize water footprints based on remote sensing approaches.

BACKGROUND: Drought affects the characteristics of water use during crop production and so quantitatively evaluating the impacts is important. However, it remains unclear how crop water use responds to drought. To address this gap, water footprint (WF) and standardized precipitation evapotranspiration index (SPEI) were calculated by remote sensing approaches to assess the effects of drought on crop water use. Rainfed maize is the most important crop in Jilin Province, and its growth and water use are more susceptible to drought. The present study explored not only the impact of growing season drought on the maize WF values in Jilin Province, but also the response of WF values to drought at different time scales. RESULTS: Spatially, 72.94% of the WFblue pixels showed a non-significant increase, and the WFgreen in 68% pixels decreased significantly, being mainly concentrated in the middle region. Furthermore, the pixels affected by monthly time scale drought were mainly in the middle region, whereas the pixels affected by annual time scale drought were mainly in the western region. CONCLUSION: Drought not only affected on the source and structure of agricultural water consumption, but also had different effects on WF values at different time scale. These effects had obvious spatial differences. The present study systematically explored the effects of drought on the WF values for rainfed maize in different climate regions and a consideration of these effects could provide valuable information on rainfed maize growth and the agricultural water use response to a changing climate. © 2023 Society of Chemical Industry.

A polyoxometalate-based heterojunction nanozyme with peroxidase-mimic catalytic activity for sensitive biomolecule detection.

Nanozymes are a class of nanomaterials that can specifically mimic the structures and catalytic activities as well as overcome limitations of natural enzymes and have hence been considered as a competitive alternative to natural enzymes. At present, plenty of nanozymes, especially those with peroxidase (POD)-like catalytic activity, have been extensively explored for biosensing. In this work, we proposed polyoxometalate-based heterojunction GdP5W30O110@WS2 nanoclusters (NCs) to exert intrinsic POD-like catalytic activity even under harsh catalytic conditions. Detailedly, GdP5W30O110@WS2 NCs possessing conducive POD-like catalytic activity can oxidize chromogenic substrates into colored substances in the presence of H2O2. On the strength of the POD-like catalytic activity of GdP5W30O110@WS2 NCs, a reliable analytical platform is then constructed after the optimization of catalytic conditions for the detection of H2O2, glutathione (GSH) and glucose via a simple TMB colorimetric strategy. This work advances the utilization of versatile polyoxometalate-based nanomaterials for biosensing, dramatically broadening the potential applications of other nanozyme-based biosensors.

A novel full solar light spectrum responsive antimicrobial agent of WS2 quantum dots for photocatalytic wound healing therapy.

Photocatalytic antimicrobial therapy (PCAT) is considered to be a potential therapeutic treatment for bacterial-infection diseases. However, the antibacterial efficiency is unsatisfactory due to the limited application scope of photocatalysis. In this work, full-spectrum responsive tungsten disulfide quantum dots (WS2 QDs) are prepared for killing bacteria and enabling wound healing through photocatalytic reactive oxygen species (ROS) generation and glutathione (GSH) depletion. On the one hand, these ultrasmall WS2 QDs exhibit an excellent full spectrum (UV-Vis-NIR)-responsive photocatalytic effect by hindering the recombination of electron-hole pairs, thereby achieving the full use of the energy spectrum. Furthermore, the full-spectrum photocatalytic property of the as-prepared WS2 QDs can be effectively strengthened by redox reaction to deplete GSH for accelerated wound healing. In a word, the as-prepared nanoplatform exhibits the ability to act as an admirable antibacterial reagent with full-spectrum catalytic performance for photocatalytic wound healing therapy. Therefore, this work will not only provide an effective full-spectrum photocatalytic reagent for anti-bacteria therapy and wound healing, but also provide a rational idea for the development of other novel antibacterial agents for applications in the biomedical field.

Tumor microenvironment-activated single-atom platinum nanozyme with H2O2 self-supplement and O2-evolving for tumor-specific cascade catalysis chemodynamic and chemoradiotherapy.

Nanozyme-based tumor collaborative catalytic therapy has attracted a great deal of attention in recent years. However, their cooperative outcome remains a great challenge due to the unique characteristics of tumor microenvironment (TME), such as insufficient endogenous hydrogen peroxide (H2O2) level, hypoxia, and overexpressed intracellular glutathione (GSH). Methods: Herein, a TME-activated atomic-level engineered PtN4C single-atom nanozyme (PtN4C-SAzyme) is fabricated to induce the "butterfly effect" of reactive oxygen species (ROS) through facilitating intracellular H2O2 cycle accumulation and GSH deprivation as well as X-ray deposition for ROS-involving CDT and O2-dependent chemoradiotherapy. Results: In the paradigm, the SAzyme could boost substantial ∙OH generation by their admirable peroxidase-like activity as well as X-ray deposition capacity. Simultaneously, O2 self-sufficiency, GSH elimination and elevated Pt2+ release can be achieved through the self-cyclic valence alteration of Pt (IV) and Pt (II) for alleviating tumor hypoxia, overwhelming the anti-oxidation defense effect and overcoming drug-resistance. More importantly, the PtN4C-SAzyme could also convert O2·- into H2O2 by their superior superoxide dismutase-like activity and achieve the sustainable replenishment of endogenous H2O2, and H2O2 can further react with the PtN4C-SAzyme for realizing the cyclic accumulation of ∙OH and O2 at tumor site, thereby generating a "key" to unlock the multi enzymes-like properties of SAzymes for tumor-specific self-reinforcing CDT and chemoradiotherapy. Conclusions: This work not only provides a promising TME-activated SAzyme-based paradigm with H2O2 self-supplement and O2-evolving capacity for intensive CDT and chemoradiotherapy but also opens new horizons for the construction and tumor catalytic therapy of other SAzymes.

A Biofilm Microenvironment-Activated Single-Atom Iron Nanozyme with NIR-Controllable Nanocatalytic Activities for Synergetic Bacteria-Infected Wound Therapy.

Biofilm microenvironment (BME)-activated antimicrobial agents display great potential for improved biofilm-related infection therapy because of their superior specificities and sensitivities, effective eliminations, and minimal side effects. Herein, BME-activated Fe-doped polydiaminopyridine nanofusiform-mediated single-atom nanozyme (FePN SAzyme) is presented for photothermal/chemodynamic synergetic bacteria-infected wound therapy. The photothermal therapy (PTT) function of SAzyme can be specifically initiated by the high level of H2 O2 and further accelerated through mild acid within the inflammatory environment through "two-step rocket launching-like" process. Additionally, the enhanced chemodynamic therapy (CDT) for the FePN SAzyme can also be endowed by producing hydroxyl radicals through reacting with H2 O2 and consuming glutathione (GSH) of the BME, thereby contributing to more efficient synergistic therapeutic effect. Meanwhile, FePN SAzyme could catalyze biofilm-overexpressed H2 O2 decomposing into O2 and overcome the hypoxia of biofilm, which significantly enhances the susceptibility of biofilm and increases the synergistic efficacy. Most importantly, the synergistic therapy of bacterial-induced infection diseases can be switched on by the internal and external stimuli simultaneously, resulting in minimal nonspecific damage to healthy tissue. These remarkable characteristics of FePN SAzyme not only develop an innovative strategy for the BME-activated combination therapy but also open a new avenue to explore other nanozyme-involved nanoplatforms for bacterial biofilm infections.

Fe-Based Single-Atom Nanozyme with Superior Peroxidase-Mimicking Activity for Enhanced Ultrasensitive Biosensing.

Nanomaterials with intrinsic enzyme-mimicking characteristics, refered to as nanozymes, have become a hot research topic owing to their unique advantages of comparative low cost, high stability and large-scale preparation. Among them, Single-atom nanozymes (SAzymes), as novel nanozymes with abundant atomically dispersed active sites, have caused specific attention in the development of nanozymes for their remarkable catalytic activities, maximum atomic utilization and excellent selectivity, the homogeneous catalytic sites and clear catalytic mechanisms. Herein, a novel single-atom nanozyme based on Fe(III)-doped polydiaminopyridine nanofusiforms (Fe-PDAP SAzyme) was successfully proposed via facile oxidation polymerization strategy. With well-defined coordination structure and abundant Fe-Nx active sites similar to natural metalloproteases, the Fe-PDAP SAzyme exhibits superior peroxidase-like activity by efficiently decomposing H2O2 for hydroxyl radical (.OH) species formation. Based on their superior peroxidase-like activity, colorimetric biosensing of H2O2 and glucose in vitro was performed by using a typical 3,3,5,5-tetramethylbenzidine through a multienzyme biocatalytic cascade platform, exhibiting the superior specificity and sensitivity. This work not only provides a novel promising SAzyme-based biosensor but also paves an avenue for evaluating enzyme activity and broadens the application of other nanozyme-based biosensors in the fields of biomedical diagnosis.

LncRNA LUADT1 sponges miR-195 to prevent cardiac endothelial cell apoptosis in sepsis.

BACKGROUND: The oncogenic role of the newly identified lncRNA LUADT1 has been revealed in lung adenocarcinoma. It was reported that LUADT1 plays a critical role in multiple human diseases. This study was carried out to investigate the role of LUADT1 in sepsis. METHODS: Sixty patients with sepsis and sixty healthy volunteers were recruited for this study. Plasma samples were collected from all participants. Human primary coronary artery endothelial cells were also used in this study. The expression of Pim-1, miR-195 and LUADT1 were detected by RT-qPCR. The interaction between miR-195 and LUADT1 was determined by overexpression experiments and luciferase activity assay. Cell apoptosis was detected by flow cytometry. The expression of apoptosis-related protein was detected by Western blotting. RESULTS: Bioinformatics analysis revealed the potential interaction between LUADT1 and miR-195, which was confirmed by dual luciferase reporter assay. LUADT1 was downregulated in patients with sepsis. Moreover, LPS treatment downregulated the expression of LUADT1 in primary cardiac endothelial cells. Overexpression of LUADT1 and miR-195 did not affect the expression of each other in primary cardiac endothelial cells. Interestingly, overexpression of LUADT1 was found to upregulate the expression of Pim-1, a target of miR-195. In addition, it was found that overexpression of LUADT1 and Pim-1 reduced the enhancement effects of miR-195 on LPS-induced cardiac endothelial cell apoptosis. CONCLUSION: In summary, LUADT1 may protect cardiac endothelial cells against apoptosis in sepsis by regulating the miR-195/Pim-1 axis.

Rice carotenoid ß-ring hydroxylase CYP97A4 is involved in lutein biosynthesis.

Lutein is the most abundant plant carotenoid and plays essential roles in photosystem assembly and stabilization, as well as protection against photostress. To date, only a few lutein biosynthesis genes have been identified in crop plants. In this study, the rice Cyt P450 gene CYP97A4 encoding a carotenoid ß-ring hydroxylase was shown to be involved in lutein biosynthesis. The results revealed that CYP97A4 was preferentially expressed in leaf compared with spikelet, sheath, stalk and root, and encoded a protein localized at the subcellular level to the chloroplasts. Compared with the wild type, the three allelic mutants of CYP97A4 displayed lutein reductions of 12-24% with substantially increased α-carotene, while Chl a/b levels were unaltered. The increased α-carotene in the mutants led to greater sensitivity under high light stress. Similarly, reactive oxygen species (ROS) imaging of leaves treated with intense light showed that the mutants generally accumulated greater levels of ROS compared with wild-type plants, which probably caused detrimental effects to the plant photosystem. In conclusion, this study demonstrated the important role of CYP97A4 in α-carotene hydroxylation in rice, and knock-out of the gene reduced lutein and increased α-carotene, contributing to sensitivity to intense light.