NIN-LIKE PROTEIN3.2 inhibits repressor Aux/IAA14 expression and enhances root biomass in maize seedlings under low nitrogen.

Plants generally enhance their root growth in the form of greater biomass and/or root length to boost nutrient uptake in response to short-term low nitrogen (LN). However, the underlying mechanisms of short-term LN-mediated root growth remain largely elusive. Our genome-wide association study, haplotype analysis, and phenotyping of transgenic plants showed that the crucial nitrate signaling component NIN-LIKE PROTEIN3.2 (ZmNLP3.2), a positive regulator of root biomass, is associated with natural variations in root biomass of maize (Zea mays L.) seedlings under LN. The monocot-specific gene AUXIN/INDOLE-3-ACETIC ACID14 (ZmAux/IAA14) exhibited opposite expression patterns to ZmNLP3.2 in ZmNLP3.2 knockout and overexpression lines, suggesting that ZmNLP3.2 hampers ZmAux/IAA14 transcription. Importantly, ZmAux/IAA14 knockout seedlings showed a greater root dry weight (RDW), whereas ZmAux/IAA14 overexpression reduced RDW under LN compared with wild-type plants, indicating that ZmAux/IAA14 negatively regulates the RDW of LN-grown seedlings. Moreover, in vitro and vivo assays indicated that AUXIN RESPONSE FACTOR19 (ZmARF19) binds to and transcriptionally activates ZmAux/IAA14, which was weakened by the ZmNLP3.2-ZmARF19 interaction. The zmnlp3.2 ZmAux/IAA14-OE seedlings exhibited further reduced RDW compared to ZmAux/IAA14 overexpression lines when subjected to LN treatment, corroborating the ZmNLP3.2-ZmAux/IAA14 interaction. Thus, our study reveals a ZmNLP3.2-ZmARF19-ZmAux/IAA14 module regulating root biomass in response to nitrogen limitation in maize.

A retrotransposon insertion in the Mao1 promoter results in erect pubescence and higher yield in soybean.

Adaptive changes in crops contribute to the diversity of agronomic traits, which directly or indirectly affect yield. The change of pubescence form from appressed to erect is a notable feature during soybean domestication. However, the biological significance and regulatory mechanism underlying this transformation remain largely unknown. Here, we identified a major-effect locus, PUBESCENCE FORM 1 (PF1), the upstream region of Mao1, that regulates pubescence form in soybean. The insertion of a Ty3/Gypsy retrotransposon in PF1 can recruit the transcription factor GAGA-binding protein to a GA-rich region, which up-regulates Mao1 expression, underpinning soybean pubescence evolution. Interestingly, the proportion of improved cultivars with erect pubescence increases gradually with increasing latitude, and erect-pubescence cultivars have a higher yield possibly through a higher photosynthetic rate and photosynthetic stability. These findings open an avenue for molecular breeding through either natural introgression or genome editing toward yield improvement and productivity.

"Blue-free" orange ZnO-related light-emitting diode based on a natural interface layer of Ga2O3 and ZnGa2O4.

To fabricate a ZnO-related light-emitting diode (LED) with zero emission at blue wavelengths ("blue-free"), an ingenious strategy is employed. Specifically, for the first time to the best of our knowledge, a natural oxide interface layer, possessing remarkable visible emission potential, is introduced into the Au/i-ZnO/n-GaN metal-insulator-semiconductor (MIS) structure. The unique Au/i-ZnO/interface layer/n-GaN structure successfully eliminated the harmful blue emissions (400-500 nm) from the ZnO film, and the remarkable orange electroluminescence is mainly attributed to the impact ionization process of the natural interface layer at high electric field. It is worth mentioning that the device achieved ultra-low color temperature (2101 K) and excellent color rendering index (92.8) under electrical injection, indicating that the device could fulfill the requirements of electronic display systems and general illumination, and might even play unexpected roles in special lighting domains. The results obtained provide a novel and effective strategy for the design and preparation of ZnO-related LEDs.

"Urban Respiration" Revealed by Atmospheric O2 Measurements in an Industrial Metropolis.

Urban regions, which "inhale" O2 from the air and "exhale" CO2 and atmospheric pollutants, including harmful gases and fine particles, are the largest sinks of atmospheric O2, yet long-term O2 measurements in urban regions are currently lacking. In this study, we report continuous measurements of atmospheric O2 in downtown Lanzhou, an industrial metropolis in northwestern China. We found declines in atmospheric O2 associated with deteriorated air quality and robust anticorrelations between O2 and gaseous oxides. By combining O2 and pollutants measurements with a Lagrangian atmospheric transport model, we quantitatively break down "urban respiration" (ΔO2URB) into human respiration (ΔO2RES) and fossil fuel combustion (ΔO2FF). We found increased ΔO2FF contribution (from 66.92% to 72.50%) and decreased ΔO2RES contribution (from 33.08 to 27.50%) as O2 declines and pollutants accumulate. Further attribution of ΔO2FF reveals intracity transport of atmospheric pollutants from industrial sectors and suggests transportation sectors as the major O2 sink in downtown Lanzhou. The varying relationships between O2 and pollutants under different conditions unfold the dynamics of urban respiration and provide insights into the O2 and energy consumption, pollutant emission, and intracity atmospheric transport processes.

Light-driven biodegradation of azo dyes by Shewanella decolorationis-CdS biohybrid in wastewater lacking electron donors.

The lack of electron donors prevents the effective degradation of azo dyes by bacteria, which severely limits the practical application of conventional biological treatment. Herein, we innovatively designed a bio-photoelectric reduction degradation system composed of CdS and Shewanella decolorationis, which could effectively degrade amaranth in anaerobic conditions driven by light when electron donors were unavailable. Compared with bare S. decolorationis and S. decolorationis (heat-killed)-CdS biohybrid, S. decolorationis-CdS biohybrid had 39.36-fold and 3.82-fold higher first-order kinetic constants, respectively. The morphology, particle size, elemental composition, crystalline type, photovoltaic properties, and band structure of the nanoparticles synthesized by S. decolorationis were carefully examined and analyzed. Light-driven biodegradation experiments showed that amaranth was degraded by the synergy of CdS and S. decolorationis. Reductive degradation of amaranth by electrons was demonstrated by electron and hole trapping. The effect of potential coexisting contaminants, which might serve as hole scavengers, on the degradation of amaranth was evaluated. Membrane protein inhibition experiments also suggested that NADH dehydrogenase, menaquinone, and cytochrome P450 played an important role in electron transfer between CdS and Shewanella decolorationis. The cyclic conversion of NAD+/NADH was probably the most critical rate-limiting step. Electrochemical measurements suggested that faster electron transfer might facilitate the degradation of amaranth. Our findings might contribute to the degradation of azo dyes in wastewater lacking electron donors and deepen our recognition of the microbe-material interface. KEY POINTS: • A BPRDS was constructed with Shewanella decolorationis and CdS. • Amaranth was effectively degraded by BPRDS in anaerobic conditions driven by light. • NDH, MQ, and CYP450 were involved in electron transfer.

Silicon-Cantilever-Enhanced Single-Fiber Photoacoustic Acetylene Gas Sensor.

A single-fiber photoacoustic (PA) sensor with a silicon cantilever beam for trace acetylene (C2H2) gas analysis was proposed. The miniature gas sensor mainly consisted of a microcantilever and a non-resonant PA cell for the real-time detection of acetylene gas. The gas diffused into the photoacoustic cell through the silicon cantilever beam gap. The volume of the PA cell in the sensor was about 14 µL. By using a 1 × 2 fiber optical coupler, a 1532.8 nm distributed feedback (DFB) laser and a white light interference demodulation module were connected to the single-fiber photoacoustic sensor. A silicon cantilever was utilized to improve the performance when detecting the PA signal. To eliminate the interference of the laser-reflected light, a part of the Fabry-Perot (F-P) interference spectrum was used for phase demodulation to achieve the highly sensitive detection of acetylene gas. The minimum detection limit (MDL) achieved was 0.2 ppm with 100 s averaging time. In addition, the calculated normalized noise equivalent absorption (NNEA) coefficient was 4.4 × 10-9 W·cm-1·Hz-1/2. The single-fiber photoacoustic sensor designed has great application prospects in the early warning of transformer faults.

Photocatalytic performance of an α-Fe2O3 electrode and its effects on the growth and metabolism of Citrobacter freundii.

Electronic exchanges occur between semiconductor minerals and microorganisms. However, researchers have focused on the photocatalytic degradation of pollutants by semiconductor minerals, and there is a limited amount of studies on semiconductor photogenerated electrons that influence the growth and energetic mechanisms of bacteria. Bioelectrochemical systems (BES) are important new bioengineering technologies for investigating the mechanisms by which bacteria absorb electrons. In this work, we built a BES that used α-Fe2O3 nanorods as a photoanode and Citrobacter freundii as bio-cathode bacteria to explore the effect of photoelectrons on C. freundii growth and metabolism. The photoanode was prepared by a hydrothermal synthesis method. As confirmed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), the photoanode was made of α-Fe2O3. Corresponding scanning electron microscope (SEM) images showed that α-Fe2O3 nanorod arrays formed with a diameter of 50 nm, and the band gap was 2.03 eV, as indicated by UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The C. freundii growth metabolism changed significantly because of photoelectrons; under light conditions, the growth rate of C. freundii significantly accelerated, and as inferred from the three-dimensional fluorescence spectrum, the protein, humic acid, and NADH concentrations were significantly higher at 72 h. According to the changes in the organic acid content, photoelectrons participated in the reductive tricarboxylic acid cycle (rTCA) to enhance growth and metabolism. The results of the study have broad implications for advancing fields that study the effects of semiconductor minerals on electroactive microorganisms and the semiconductor-photoelectronic transport mechanisms of electroautotrophic microorganisms. KEY POINTS: • For the first time, A BES was built that used α-Fe2O3 nanorods as a photoanode and C. freundii as a bio-cathode bacteria. • Photoelectrons produced by α-Fe2O3 photoelectrode promote the growth of C. freundii. • Effects of photoelectrons on C. freundii metabolism were conjectured by the changes of organic acids and NADH.

The Anticancer Effect of a Novel Quinoline Derivative 91b1 through Downregulation of Lumican.

Quinoline derivatives have been reported to possess a wide range of pharmaceutical activities. Our group previously synthesized a series of quinoline compounds, in which compound 91b1 showed a significant anticancer effect. The purpose of this study was to evaluate the anticancer activity of compound 91b1 in vitro and in vivo, and screen out its regulated target. A series of cancer cell lines and nontumor cell lines were treated with compound 91b1 by MTS cytotoxicity assay and cell-cycle assay. In vivo anticancer activity was evaluated by a xenografted model on nude mice. Target prediction of 91b1 was assessed by microarray assay and confirmed by pancancer analysis. Relative expression of the target gene Lumican was measured by qRT-PCR. 91b1 significantly reduced tumor size in the nude mice xenograft model. Lumican was downregulated after 91b1 treatment. Lumican was proven to increase tumorigenesis in vivo, as well as cancer cell migration, invasion, and proliferation in vitro. The results of this study suggest that the anticancer activity of compound 91b1 probably works through downregulating the gene Lumican.

Clinical value of propranolol combined with oxaliplatin and tigio in concurrent chemoradiotherapy for locally advanced gastric cancer.

Objectives: To investigate the clinical value of propranolol combined with oxaliplatin and tigio in concurrent chemoradiotherapy for locally advanced gastric cancer. Methods: A total of 74 patients with locally advanced gastric cancer admitted to the First Affiliated Hospital of Hainan Medical University from August 2018 to June 2020 were selected as the subject and divided into two groups by random number table method: Group-A and Group-B, with 37 cases in each group. Patients in Group-A were treated with oxaliplatin injection and oral administration of tigio combined with concurrent radiotherapy, while patients in Group-B were given propranolol on the basis of treatment in Group-A. The clinical efficacy and incidence of adverse reactions in the two groups were observed. Results: The response rate (RR) of Group-B was higher than that of Group-A, but with no statistically significant difference (P>0.05). No statistical difference was observed in the incidence of gastrointestinal reaction, bone marrow suppression, oral mucositis, and the incidence of grade III-IV adverse reactions in the two groups (P>0.05). There were no serious adverse reactions related to propranolol in Group-B, and the levels of tumor markers CEA, CA50, CA125, and CA242 in Group-B were lower than those in Group-A. Conclusion: Propranolol combined with oxaliplatin and tigio boasts satisfactory sensitization safety in radiotherapy for gastric cancer, but its sensitization effect needs to be further investigated in a multi-center study involving large sample size.

Mesenchymal stem cell-secreted extracellular vesicles carrying TGF-ß1 up-regulate miR-132 and promote mouse M2 macrophage polarization.

The effects of mesenchymal stem cells (MSCs) on different types of diseases are controversial, and the inner mechanisms remain unknown, which retards the utilization of MSCs in disease therapy. In this study, we aimed to elucidate the mechanisms of MSCs-extracellular vesicles (EVs) carrying transforming growth factor-beta 1 (TGF-ß1) in M2 polarization in mouse macrophages via the microRNA-132 (miR-132)/E3 ubiquitin ligase myc binding protein 2 (Mycbp2)/tuberous sclerosis complex 2 (TSC2) axis. Mouse MSCs were isolated for adipogenic and osteogenic induction, followed by co-culture with mouse macrophages RAW264.7. Besides, mouse macrophages RAW264.7 were co-cultured with MSCs-EVs in vitro, where the proportion of macrophages and inflammation were detected by flow cytometry and ELISA. The experimental data revealed that MSCs-EVs promoted M2 polarization of macrophages, and elevated interleukin (IL)-10 expression and inhibited levels of IL-1ß, tumour necrosis factor (TNF)-α and IL-6. MSC-EV-treated macrophages RAW264.7 increased TGF-ß1 expression, thus elevating miR-132 expression. MiR-132 directly bound to Mycbp2, as confirmed by luciferase activity assay. Meanwhile, E3 ubiquitin ligase Mycbp2 could ubiquitinate TSC2 protein. Furthermore, silencing TGF-ß1 inhibited M2 polarization of MSC-EV-treated macrophages. Taken conjointly, this study provides evidence reporting that MSC-secreted EVs carry TGF-ß1 to promote M2 polarization of macrophages via modulation of the miR-132/Mycbp2/TSC2 axis.

Bu-Shen-Jian-Pi-Yi-Qi Therapy Prevents Alcohol-Induced Osteoporosis in Rats.

Bu-Shen-Jian-Pi-Yi-Qi therapy, which refers to reinforcing kidney, regulating qi, and invigorating spleen, is a traditional Chinese medicine, and we investigated its efficacy in treatment of alcohol-induced osteoporosis and its underlying mechanism. Forty adult male Sprague-Dawley rats were randomly assigned into alcohol-supplemented group, JIAN-GU-LING (JGL) group, calcium D3 + alfacalcidol group, and sham-treated group. Bone mineral density (BMD), bone mineral content (BMC), and bone biomechanical properties were assessed. Biochemical analyses of serum and urine specimens were detected. Reverse transcription-polymerase chain reaction was used to detect the mRNA level of vitamin D receptor (VDR). There were markedly lower bone metabolic markers and biomechanical properties in alcohol-supplemented group compared with sham-treated group (all P < 0.05). BMD, BMC, 25(OH)D3, and 1,25(OH)2D3 were elevated in JGL group relative to calcium D3 + alfacalcidol group (all P < 0.05). U-Ca/Cr and U-P/Cr in JGL group were higher than those in the calcium D3 + alfacalcidol group (all P < 0.05). VDR mRNA level in the JGL group was elevated markedly in comparison with alcohol + calcium D3 + alfacalcidol group (P < 0.05). Based on our results, Bu-Shen-Jian-Pi-Yi-Qi therapy inhibits bone loss, promotes bone formation, and effectively improves bone metabolism in rats with experimental alcoholic osteoporosis. The disease reversal is evidenced by increased BMD and BMC, improved biomechanical properties, elevated VDR mRNA level, enhanced response sensitivity of 1, 25(OH)2D3, and reduced S-Ca/P.

An Effective Correction Method for Seriously Oblique Remote Sensing Images Based on Multi-View Simulation and a Piecewise Model.

Conventional correction approaches are unsuitable for effectively correcting remote sensing images acquired in the seriously oblique condition which has severe distortions and resolution disparity. Considering that the extraction of control points (CPs) and the parameter estimation of the correction model play important roles in correction accuracy, this paper introduces an effective correction method for large angle (LA) images. Firstly, a new CP extraction algorithm is proposed based on multi-view simulation (MVS) to ensure the effective matching of CP pairs between the reference image and the LA image. Then, a new piecewise correction algorithm is advanced with the optimized CPs, where a concept of distribution measurement (DM) is introduced to quantify the CPs distribution. The whole image is partitioned into contiguous subparts which are corrected by different correction formulae to guarantee the accuracy of each subpart. The extensive experimental results demonstrate that the proposed method significantly outperforms conventional approaches.

Adaptive Collaborative Gaussian Mixture Probability Hypothesis Density Filter for Multi-Target Tracking.

In this paper, an adaptive collaborative Gaussian Mixture Probability Hypothesis Density (ACo-GMPHD) filter is proposed for multi-target tracking with automatic track extraction. Based on the evolutionary difference between the persistent targets and the birth targets, the measurements are adaptively partitioned into two parts, persistent and birth measurement sets, for updating the persistent and birth target Probability Hypothesis Density, respectively. Furthermore, the collaboration mechanism of multiple probability hypothesis density (PHDs) is established, where tracks can be automatically extracted. Simulation results reveal that the proposed filter yields considerable computational savings in processing requirements and significant improvement in tracking accuracy.

Data-driven method for estimating emission factors of multiple pollutants from excavators based on portable emission measurement system and online driving characteristic identification.

This study aims to explore the factors that influence the emission characteristics of multiple pollutants from non-road mobile machinery (NRMM) under real-world conditions and to establish a data-driven method for calculating accurate emission factors. This research focused on NRMM excavators meeting the third-stage emission standards and identified the actual work characteristics of 108 excavators in different scenarios based on a self-developed testing system for 368,000 h. Additionally, a portable emission testing system (PEMS) was used to study the instantaneous emission characteristics under different driving styles and modes for 10 EC210 excavators with the largest engineering construction inventory. The results showed that the average time proportions of idling, working, and moving modes for excavators were 21 %, 66 %, and 13 %, respectively. The results also revealed that the instantaneous emission rates of multiple pollutants varied significantly under different driving styles and modes. Driving style affected the hydraulic pump power change rate through hydraulic pilot pressure, and engine load surge caused turbocharger response delay and in-cylinder combustion deterioration, which affected pollutant emissions. Driving mode affected the emission characteristics of idling, high-speed idling, moving, and working modes of excavators through the external characteristics corresponding to the engine speed gear set. The data-driven method for calculating emission factors differed from the traditional method for most indicators to varying degrees. In terms of fuel-based emission factors (EFfs), except for the EFfNOx indicator, which was 7.859 % higher than the traditional method, the other three indicators were significantly lower than the traditional method. In terms of power-based emission factors (EFps), except for EFpPM and EFpPN, the other two indicators were much higher than the traditional method. EFpCO and EFpNOx were 7.93 % and 20.332 % higher than the traditional method, respectively. It is recommended to use the data-driven method based on the actual driving data distribution to provide scientific support for accurately establishing the emission inventory.

Crown Ether Copolymerized Polyimide Film: Enhanced Mechanical, Thermal Properties and Low Dielectric Constant under High Frequency.

Polymer materials with a low dielectric constant and low dielectric loss have the potential to be applied to high-frequency signal transmissions, such as mobile phone antennas and millimeter wave radars. Two types of diamines, 4,4'-diamino-p-tetraphenyl (DPT) and crown ether diamine (CED), were prepared for ternary copolymerization with BPDA in this study. Cross-links with molecular chains were formed, increasing molecular chain distance by utilizing rings of CED. The MPI films exhibit a good thermal performance with the increase in CED addition, with Tg > 380 °C and CTE from -4 × 10-6 K-1 to 5 × 10-6 K-1. The Young's modulus can reach 8.6 GPa, and the tensile strength is above 200 MPa when 5% and 7% CED are introduced. These MPI films exhibit good mechanical performances. The dielectric constant of PI-10% film can go as low as 3.17. Meanwhile, the relationship between dielectric properties and molecular structure has been demonstrated by Molecular Simulation (MS). PI molecules are separated by low dielectric groups, resulting in a decrease in the dielectric constant.

Adhesion and Transparency Enhancement between Flexible Polyimide-PDMS Copolymerized Film and Copper Foil for LED Transparent Screen.

With the increasing demand for innovative electronic products, LED transparent screens are gradually entering the public eye. Polyimide (PI) materials combine high temperature resistance and high transparency, which can be used to prepare flexible copper-clad laminate substrates. The physical and chemical properties of PI materials differ from copper, such as their thermal expansion coefficients (CTEs), surface energy, etc. These differences affect the formation and stability of the interface between copper and PI films, resulting in a short life for LED transparent screens. To enhance PI-copper interfacial adhesion, aminopropyl-terminated polydimethylsiloxane (PDMS) can be used to increase the adhesive ability. Two diamine monomers with a trifluoromethyl structure and a sulfone group structure were selected in this research. Bisphenol type A diether dianhydride is a dianhydride monomer. All three of the above monomers have non-coplanar structures and flexible structural units. The adhesion and optical properties can be improved between the interface of the synthesized PI films and copper foil. PI films containing PDMS 0, 1, 3, and 5 wt% were analyzed using UV spectroscopy. The transmittance of the PI-1/3%, PI-1/5%, PI-2/3%, and PI-2/5% films were all more than 80% at 450 nm. Meanwhile, the Td 5% and Td 10% heat loss and Tg temperatures decreased gradually with the increase in PDMS. The peel adhesion of PI-copper foil was measured using a 180° peel assay. The effect of PDMS addition on peel adhesion was analyzed. PIs-3% films had the greatest peeling intensities of 0.98 N/mm and 0.85 N/mm.

Association of residential greenness with obstructive sleep apnea among Chinese old adults and the mediation role of PM2.5 and leisure-time physical activity.

Few studies have investigated the association of residential greenness with obstructive sleep apnea (OSA). This study was to comprehensively examine the association of residential greenness exposure with OSA and explore the mediating effect of leisure-time physical activity (LTPA) and PM2.5 on the association among Chinese old adults. A prospective cohort study that enrolled 2027 adults aged ≥65 was conducted between 1st July 2015 and 30th September 2019 in Southern China. OSA was ascertained by Berlin Questionnaire. Greenness exposure was measured by contemporaneous and cumulative average normalized difference vegetation index (NDVI) in the 1000 m radius around each participant's residential address. Hazard ratios (HRs) with 95 % confidence intervals (CIs) were calculated by Cox proportional hazards model to assess the impact of greenness exposure on the incidence of OSA after adjusting for confounders. LTPA and PM2.5 were examined as potential mediators in the aforementioned models. A total of 293, nearly 14.5 %, participants developed OSA within 59,251 person-months of follow-up. When comparing the highest with lowest tertiles, both contemporaneous NDVI (>0.351 vs. ≤0.325: HR = 0.20, 95 % CI = 0.13-0.31) and cumulative NDVI (> 0.346 vs. ≤ 0.317: HR = 0.32, 95 % CI = 0.21-0.47) were associated with a reduced risk of OSA after adjusting for confounders. LTPA and PM2.5 significantly mediated the association between greenness and OSA. In conclusion, this study indicated that exposure to higher residential greenness could decrease OSA risk, and this benefit may be achieved by promoting physical activity and decreasing PM2.5 concentration. The findings suggest to formulate targeted interventional strategies by expanding residential greenness to prevent OSA and reduce disease burden.

Visual evaluation of acetylcholinesterase inhibition by an easy-to-operate assay based on N-doped carbon nanozyme with high stability and oxidase-like activity.

Acetylcholinesterase (AChE) is the key enzyme associated with neurotransmission, and thus many drugs have been explored for their inhibitory effect on AChE, such as donepezil for Alzheimer's disease and organophosphorus pesticides (OPs). Compared with clinical trials, in vitro screening bioassays for AChE inhibitors are preferable in terms of operability and cost. Herein, we developed an easy-to-operate nanozyme-based colorimetric assay for the evaluation of AChE inhibitory strength with excellent anti-interference ability and low dependence on professional equipment. The metal-free carbon nanozyme NC900 played an important role in the signal output due to its features of efficient oxidase-like activity, excellent water dispersibility, high stability and low color interference. Employing various AChE-targeted or non-targeted pesticides as examples, the as-proposed assay exhibited excellent distinguishing ability for different chemicals. The higher absorption intensity at 652 nm represents a stronger inhibitory effect, as well as blue color. In addition, this method was used to study the influence of pH on the degradation of prodrugs, and the efficiency of mixed pesticides. This work provides a simple and reliable assay to screen AChE inhibitors, which is promising for the preliminary evaluation of a large number of potential candidates.

Specific detection of fungicide thiophanate-methyl: A smartphone colorimetric sensor based on target-regulated oxidase-like activity of copper-doped carbon nanozyme.

Nanozyme-based colorimetric assays have shown great potential in the rapid and sensitive determination of pesticide residue in environment. However, the non-specific enzyme inhibition makes the assays generally lack of selectivity. In this study, we proposed a colorimetric sensing platform for the specific detection of the agricultural fungicide thiophanate-methyl (TM) based on its distinctive inhibitory effect on the nanozyme activity. Since TM contains the symmetric ethylenediamine- and bisthiourea-like groups, it displays strong affinity to the metal site, leading to a loss of the catalytic activity. Accordingly, a Cu-doped carbon nanozyme with excellent oxidase-like properties was designed, and the oxidation process of chromogenic substrate is promoted by Cu-induced generation of reactive oxygen species. Interestingly, the nanozyme activity can be directly and strongly restrained by TM, rather than other probably coexistent pesticides. Consequently, the as-proposed analytical method exhibits specific response toward TM and good linear relationship in the range of 0.2-15 µg mL-1 with a low limit of detection of 0.04 µg mL-1 (S/N = 3). Besides, a smartphone-assisted rapid detection was achieved through identifying the RGB value of the chromogenic system. This work provides a new nanozyme inhibition strategy for the specific detection of TM in environmental sample.