Redox-active NiS@bacterial cellulose nanofiber composite separators with superior rate capability for lithium-ion batteries.

Separator is an essential component of lithium-ion batteries (LIBs), which is placed between the electrodes to impede their electrical contact and provide the transport channels for lithium ions. Traditionally, the separator contributes the overall mass of LIBs, thereby reducing the gravimetric capacity of the devices. Herein, a dual-layer redox-active cellulose separator is designed and fabricated to enhance the electrochemical performances of LIBs by introducing NiS. The presented separator is composed of an insulating bacterial cellulose (BC) nanofiber layer and a conductive, and redox-active NiS@BC/carbon nanotubes layer. By using the NiS@BC separator, the discharge capacity of the LiFePO4//Li half battery is enhanced to 117 mAh g-1 at a current of 2C owing to the redox-activity of NiS. Moreover, the functional separator-electrode interface can facilitate the homogenous Li stripping/plating and depress the polarization upon the repeated stripping/plating process. Consequently, the battery containing the redox-active separator exhibits outstanding cycle stability and rate capability. The present study contributes a novel strategy for the developments of functional separators to improve the electrochemical properties of LIBs.

Sustainable production of bacterial flocculants by nylon-6,6 microplastics hydrolysate utilizing Brucella intermedia ZL-06.

Nylon-6,6 microplastics (NMPs) in aquatic systems have emerged as potential contaminants to the global environment and have garnered immense consideration over the years. Unfortunately, there is currently no efficient method available to eliminate NMPs from sewage. This study aims to address this issue by isolating Brucella intermedia ZL-06, a bacterium capable of producing a bacterial polysaccharide-based flocculant (PBF). The PBF generated from this bacterium shows promising efficacy in effectively flocculating NMPs. Subsequently, the precipitated flocs (NMPs + PBF) were utilized as sustainable feedstock for synthesizing PBF. The study yielded 6.91 g/L PBF under optimum conditions. Genome sequencing analysis was conducted to study the mechanisms of PBF synthesis and nylon-6,6 degradation. The PBF exhibited impressive flocculating capacity of 90.1 mg/g of PBF when applied to 0.01 mm NMPs, aided by the presence of Ca2+. FTIR and XPS analysis showed the presence of hydroxyl, carboxyl, and amine groups in PBF. The flocculation performance of PBF conformed to Langmuir isotherm and pseudo-first-order adsorption kinetics model. These findings present a promising approach for reducing the production costs of PBF by utilizing NMPs as sustainable nutrient sources.

Flexible, ultrathin and integrated nanopaper supercapacitor based on cationic bacterial cellulose.

Cellulose composite nanopaper is extensively employed in flexible energy storage systems owing to their light weight, good flexibility and high specific surface area. Nevertheless, achieving flexible and ultrathin nanopaper supercapacitors with excellent electrochemical performance remains a challenge. Herein, surface cationization of bacterial cellulose (BC) nanofibers was conducted using 2,3-epoxypropyltrimethylammonium chloride (EPTMAC). Anion-doped polypyrrole (PPy) was incorporated onto the surface of the cationic bacterial cellulose (BCE) nanofibers by an interfacial electrostatic self-assembly process. The obtained PPy@BCE electrode exhibited excellent electrochemical performance, including an areal capacitance of 3988 mF cm-2 at 1.0 mA cm-2 and a capacitance retention of 97 % after 10,000 cycles. A laminated paper-forming strategy was adopted to design and fabricate all-in-one integrated flexible supercapacitors (IFSCs) using PPy@BCE nanopaper as electrodes and BC nanopaper as a separator. The IFSCs showed superior areal capacitance (3669 mF cm-2 at 1 mA cm-2), high energy density (193.7 µWh cm-2 at a power density of 827.3 µW cm-2), and outstanding mechanical flexibility (with no significant capacitance attenuation after repeatedly bending for 1000 times). The present strategy paves a way for the large-scale production of paper-based energy storage devices.

[Efficacy and safety of multiple-dose intravenous tranexamic acid for reducing blood loss in complex tibial plateau fractures: A prospective randomized controlled trial].

Objective: To investigate the efficacy and safety of multiple-dose intravenous tranexamic acid (TXA) for reducing blood loss in complex tibial plateau fractures with open reduction internal fixation by a prospective randomized controlled trial. Methods: A study was conducted on patients with Schatzker type Ⅳ-Ⅵ tibial plateau fractures admitted between August 2020 and December 2022. Among them, 88 patients met the selection criteria and were included in the study. They were randomly allocated into 3 groups, the control group (28 cases), single-dose TXA group (31 cases), and multiple-dose TXA group (29 cases), using a random number table method. There was no significant difference ( P>0.05) in terms of age, gender, body mass index, the Schatzker type and side of fracture, laboratory examinations [hemoglobin (Hb), activated partial thromboplastin time (APTT), prothrombin time (PT), fibrinogen (Fib), international normalized ratio (INR), D-dimer, and interleukin 6 (IL-6)], and preoperative blood volume. The control group received intravenous infusion of 100 mL saline at 15 minutes before operation and 3, 6, and 24 hours after the first administration. The single-dose TXA group received intravenous infusion of 1 g TXA (dissolved in 100 mL saline) at 15 minutes before operation, followed by an equal amount of saline at each time point after the first administration. The multiple-dose TXA group received intravenous infusion of 1 g TXA (dissolved in 100 mL saline) at each time point. The relevant indicators were recorded and compared between groups to evaluate the effectiveness and safety of TXA, including hospital stays, operation time, occurrence of infection; the occurrence of lower extremity deep vein thrombosis, intermuscular vein thrombosis, and pulmonary embolism at 1 week after operation; the lowest postoperative Hb value and Hb reduction rate, the difference (change value) between pre- and post-operative APTT, PT, Fib, and INR; D-dimer and IL-6 at 24 and 72 hours after operation; total blood loss, intraoperative blood loss, hidden blood loss, drainage flow during 48 hours after operation, and postoperative blood transfusion. Results: ① TXA efficacy evaluation: the lowest Hb value in the control group was significantly lower than that in the other two groups ( P<0.05), and there was no significant difference between the single- and multiple-dose TXA groups ( P>0.05). The Hb reduction rate, total blood loss, intraoperative blood loss, drainage flow during 48 hours after operation, and hidden blood loss showed a gradual decrease trend in the control group, single-dose TXA group, and multiple-dose TXA group. And differences were significant ( P<0.05) in the Hb reduction rate and drainage flow during 48 hours after operation between groups, and the total blood loss and hidden blood loss between control group and other two groups. ② TXA safety evaluation: no lower extremity deep vein thrombosis or pulmonary embolism occurred in the three groups after operation, but 3, 4, and 2 cases of intermuscular vein thrombosis occurred in the control group, single-dose TXA group, and multiple-dose TXA group, respectively, and the differences in the incidences between groups were not significant ( P>0.05). There was no significant difference in the operation time between groups ( P>0.05). But the length of hospital stay was significantly longer in the control group than in the other groups ( P<0.05); there was no significant difference between the single- and multiple-dose TXA groups ( P>0.05). ③ Effect of TXA on blood coagulation and inflammatory response: the incisions of the 3 groups healed by first intention, and no infections occurred. The differences in the changes of APTT, PT, Fib, and INR between groups were not significant ( P>0.05). The D-dimer and IL-6 in the three groups showed a trend of first increasing and then decreasing over time, and there was a significant difference between different time points in the three groups ( P<0.05). At 24 and 72 hours after operation, there was no significant difference in D-dimer between groups ( P>0.05), while there was a significant difference in IL-6 between groups ( P<0.05). Conclusion: Multiple intravenous applications of TXA can reduce perioperative blood loss and shorten hospital stays in patients undergoing open reduction and internal fixation of complex tibial plateau fractures, provide additional fibrinolysis control and ameliorate postoperative inflammatory response.

Polyethylene terephthalate hydrolysate increased bacterial cellulose production.

A major challenge to large-scale production and utilization of bacterial cellulose (BC) for various applications is its low yield and productivity by bacterial cells and the high cost of feedstock. A supplementation of the classical expensive Hestrin and Schramm (HS) medium with 1 % polyethylene terephthalate ammonia hydrolysate (PETAH) resulted in 215 % high yield. Although the physicochemical properties of BC were not significantly influenced, the BC produced in 1 % PETAH-supplemented HS medium showed a higher surface area, which showed 1.39 times higher adsorption capacity for tetracycline than BC produced in HS medium. The 1 % PETAH-supplemented HS medium respectively enhanced the activity of α-UDP-glucose pyrophosphorylase and α-phosphoglucomutase by 30.63 % and 135.24 % and decreased the activity of pyruvate kinase and phosphofructokinase by 40.34 % and 52.63 %. The results of this study provide insights into the activation mechanism of Taonella mepensis by PETAH supplementation for high yield and productivity of BC.

Synthesis of bimetal MOFs for rapid removal of doxorubicin in water by advanced oxidation method.

Doxorubicin (DOX) has been an emerging environmental pollutant due to its significant genotoxicity to mankind. Advanced oxidation processes are a potential strategy to remove DOX in water solution. To develop a highly efficient catalytic agent to remove DOX, bimetal MOFs were synthesized, with Cu2+ and Co2+ as the central ions and adenine as the organic ligand. This study investigated the degradation of DOX by Co/Cu-MOFs combined with peroxymonosulfate (PMS). It was found that the degradation of DOX by Co/Cu-MOFs can reach 80% in only 10 seconds. This can be explained by the charge transfer from Co(iii) to Co(ii) being accelerated by Cu2+, resulting in the rapid generation of free radicals, which was proved by the EIS Nyquist diagram. Co/Cu-MOFs can be reused by simply washing with water without inactivation. Therefore, Co/Cu-MOFs can be used as an efficient catalytic agent to degrade DOX in environmental water.

Distribution, sources and transport of polycyclic aromatic hydrocarbons (PAHs) in karst spring systems from Western Hubei, Central China.

Karst groundwater is an important water resource but it is vulnerable to contaminants, due to the distinctive geological features of abundant transmissive fractures and conduits in the karst area which connect the surface to the underground systems. Anthropogenic activity-derived polycyclic aromatic hydrocarbons (PAHs) on the surface environment could enter groundwater easily and rapidly and threaten water security in karst areas. Samples in the multimedia environment from 10 specific karst spring systems from Western Hubei of Central China were collected to analyze 16 priority PAHs and to investigate their transport in these karst spring systems. The total concentrations of PAHs in the soil, river water, river sediments, spring water, and spring sediments ranged between 6.04 and 67.7 ng g-1, 4.56 and 11.4 ng L-1, 29.9 and 1041 ng g-1, 4.09 and 222 ng L-1, and 5.88 and 83.0 ng g-1, respectively. Levels of PAHs in this area were relatively low when compared to other karst areas. Proportions of low-molecular-weight (LMW)-PAHs in the water, sediments and soil (average 58.2-78.8%) were much higher than those of high-molecular-weight (HMW)-PAHs. The proportion of LMW-PAHs in the sediments (especially in river sediments) was higher than that in the soil. Characteristic ratio analysis and principal component analysis showed that PAHs were from high-temperature combustion of the mixture of coal and biomass, and vehicle emission, where coal and biomass combustion were the dominant sources. Significant correlations of PAH compositions in different media of karst spring systems were observed, especially in the Yuquangdong (YQD)-Migongquan (MGQ), Jiuzhenziquan (JZZQ), Xianyudong (XYD) and Fengdong (FD) karst spring systems, indicating the rapid PAH transport from the recharge area soil to the discharge area of spring water and sediments.

Preparation of a bacterial flocculant by using caprolactam as a sole substrate and its application in amoxicillin removal.

High cost is one of the limiting factors in the industrial production of bioflocculant. Simultaneous preparation of bioflocculant from the contaminants in wastewater was considered as a potential approach to reduce the production cost. In this study, caprolactam was verified as sole feedstock for the growth of strain Alcaligenes faecalis subsp. phenolicus ZY-16 in batch experiments. Chemical analysis showed that the as-prepared MBF-16 consisted of heteropolysaccharides (88.3%) and peptides (9.4%). XPS result indicated the plentiful acylamino, hydroxyl and amino groups in MBF-16, which have an indispensable role in amoxicillin flocculation. The flocculation of amoxicillin can be well stimulated by Freundlich isotherm equation, and the Kf was up to 178.6524 for amoxicillin. The kinetic fitting results proved that the flocculation of amoxicillin by MBF-16 was chemisorbed. This contribution may develop a novel technology for the preparation of bacterial flocculants that can consume toxic substrates (caprolactam) and have potential applications in amoxicillin removal.

Smartphone-assisted visual ratio-fluorescence detection of hypochlorite based on copper nanoclusters.

A sensitive naked eye and ratio-fluorescence sensor for Curcumin (CCM) and hypochlorite (ClO-) determination based on copper nanoclusters (Cu NCs) was developed. The fluorescence of the Cu NCs can be quenched due to inner filter effect (IFE) between CCM and Cu NCs, and the ratio fluorescence probe was formed. After adding ClO- to Cu NCs-CCM system, the phenolic and methoxy groups of CCM were oxidized to quinones, then the fluorescence of CCM was quenched and the fluorescence of Cu NC was restored. Moreover, the continuous detection of CCM and ClO- is accompanied by the change of solution color. Therefore, CCM and ClO- semiquantitative visual and fluorescence dual channel detection were realized. The detection results show that the detection based on Cu NCs-CCM probe has a wide detection range (0-412 µM) and low detection limit (24 µM), and a good recovery rate is obtained in adulterated milk and tap water detection. Furthermore, smartphone was introduced for image digital colorimetric analysis through the acquisition, recognition and RGB data processing of solution colors, providing an effective scheme for the field rapid detection of hypochlorite.

Different fluorescence emitting copper nanoclusters protected by egg white and double-emission fluorescent probe for fast detection of ethanol.

Green emitting copper nanoclusters (G-Cu NCs), yellow emitting Cu NCs (Y-Cu NCs), orange emitting Cu NCs (O-Cu NCs) and red emitting Cu NCs (R-Cu NCs) were prepared using chicken egg white as the stabilizer by changing the reaction conditions. This is a green, facile and cheap method to explore different color emitting CuNCs by the same precursor and stabilizers. The G-Cu NCs were employed for the detection of ethanol due to their aggregation induced emission enhancement (AIEE) effect. The fluorescence emission of Cu NCs at 526 nm under the excitation of 444 nm can be effectively enhanced in the presence of ethanol due to AIEE effect, thus realizing the quantitative determination of ethanol content in the range 5-60%. In addition, a visual dual-emission fluorescence probe with the combination of G-Cu NCs and silicon nanoparticles (Si NPs/G-Cu NCs) was designed to evaluate ethanol content conveniently and rapidly. Desirable linear relationship is observed between ratio of fluorescence intensity (I525/I441) and ethanol content under the excitation of 383 nm. Visible color transformation of this probe is observed in the ethanol content range 2-20%. Moreover, the ethanol sensing platforms were applied to the detection and evaluation of the alcohol content of liquor, and the recoveries in liquor were in the range 99.7% to 113%, broadening the applications of Cu NCs and providing a sensitive detection method for ethanol.

Facile microwave-assisted synthesis of Ti3C2 MXene quantum dots for ratiometric fluorescence detection of hypochlorite.

A dual-channel "naked-eye" colorimetric and ratio fluorescent probe has been developed based on titanium carbide quantum dots for the detection of curcumin and hypochlorite (ClO-). The fluorescence emission of Ti3C2 MXene quantum dots (Ti3C2 MQDs) is in the range 350-600 nm, and the maximum emission peak is at 430 nm that overlaps with the UV absorption of curcumin at 430 nm to a large extent. This facilitates the fluorescence resonance energy transfer (FRET) between Ti3C2 MQDs and curcumin. When ClO- is added, the phenolic and methoxy groups of curcumin are oxidized to quinones, resulting in the restoration of the fluorescence of Ti3C2 MQD. In addition, the probe designed makes it easier to distinguish colors with the naked eye to detect curcumin and ClO-. The linear detection range of curcumin was 0.05-10 µM, and the detection limit was 20 nM. The linear detection ranges of ClO- are 25-150 µM and 150-275 µM, and the detection limit is 5 µM. This study is the first report on the determination of curcumin and ClO- based on Ti3C2 MQDs by dual-channel "naked-eye" colorimetric and ratio fluorescence method.

Bacterial cellulose production from terylene ammonia hydrolysate by Taonella mepensis WT-6.

Hydrothermal degradation was used to pretreat terylene with an aim of noticeably improving the yield of fermentable monomers: terephthalic acid (TPA), mono (2- hydroxyethyl) terephthalic acid (MHET), bis-hydroxyethyl terephthalate (BHET), and ethylene glycol (EG). After 0.5 h of reaction time at 180 °C, hydrothermal degradation with ammonia led to almost complete conversion of the terylene to TPA, MHET, BHET and EG, which were then transformed by Taonella mepensis WT-6 to bacterial cellulose (BC). Furthermore, the optimum fermentation conditions with the maximum BC yield were 5.0 g/L yeast extract, 30.0 °C, pH 9.0, 8.0% inoculum, and hydrolysate TOC (5.02 g/L). Additionally, mechanical and thermal analysis revealed that the properties of BC produced from TAH medium were similar to those of BC produced with HS medium. Considering the substantial amount of global terylene waste being produced, this study provides an alternative solution for the biosynthesis of BC.

Production of a bioflocculant from ramie biodegumming wastewater using a biomass-degrading strain and its application in the treatment of pulping wastewater.

The major bottleneck for industrial applications of microbial flocculants is the high production cost. Here, a novel bacterium, Diaphorobacter nitroreducens R9, was isolated that can secret ligninase and cellulase and simultaneously produce bioflocculants (MBF-9) through conversion of ramie biomass. The production of MBF-9 was closely related to the ligninase and cellulase activities of D. nitroreducens. Both ligninase and cellulase showed peak activity at pH 8.5 and 6.0 and retained approximately 80% of cellulase activity and 95% of ligninase activity at pH 8.0. The optimal production conditions with the highest bioflocculant yield (3.86 g/L degumming wastewater) were determined at a fermentation time of 48 h, fermentation temperature of 30 °C, inoculum size of 4.0%, CODCr of ramie degumming wastewater of 1500 mg/L and initial pH of 8.0. In addition, MBF-9 removed 96.2% turbidity, 79.5% chemical oxygen demand (COD), 59.2% lignin, and 63.1% sugar from the pulping wastewater at an MBF-9 dosage of 831.57 mg/L.

A ''naked-eye'' colorimetric and ratiometric fluorescence probe for uric acid based on Ti3C2 MXene quantum dots.

In this work, we developed a ''naked-eye'' colorimetric and ratiometric fluorescence probe for a very important biomarker of uric acid (UA). The method was based on the oxidation of UA by uricase to allantoin and hydrogen peroxide, and then o-Phenylenediamine (OPD) was oxidized to the yellow-colored 2,3-diaminophenazine (oxOPD) in the presence of horseradish peroxidase (HRP) and hydrogen peroxide. The fluorescence emission of glutathione functionalized Ti3C2 MQDs (GSH-Ti3C2 MQDs) centered at 430 nm overlaps with the UV absorption of oxOPD at 425 nm to a large extent, which facilitates fluorescence resonance energy transfer (FRET) between GSH-Ti3C2 MQDs and oxOPD. With the increase of the UA concentration, the emission at 430 nm of GSH-Ti3C2 MQDs is progressively quenched and the emission at 568 nm of oxOPD was gradually increased. Moreover, the probe we designed is easier to distinguish with color change by naked eye for the detection of UA. This is the first report about the determination of UA by a ''naked-eye'' colorimetric and ratiometric fluorescence method combining GSH-Ti3C2 MQDs and uricase/HRP enzymes. This work enables assays to perform fluorescence and visual detection of biomarker in biological fluids based on Ti3C2 MQDs.

Bioconversion of citrus peel wastes into bioflocculants and their application in the removal of microcystins.

In this study, the mechanism for converting citrus peel wastes (CPW) into bioflocculants using Alcaligenes faecalis subsp. phenolicus ZY-16 was analysed. The results demonstrated that the ZY-16 strain could produce various lignocellulolytic enzymes, containing cellulase, hemicellulase, pectinase, protease, and ligninase, enhancing the hydrolysis of citrus peel wastes. Molecular distillation removes antimicrobial limonene, which could inhibit bioflocculant production. The optimal fermentation conditions with the highest bioflocculant yield (3.49 g/L) were 38.79 g/L of CPW, 35.54 °C, and pH 4.48. Furthermore, the bioflocculant was used to eliminate microcystins for the first time, and the highest removal efficiency (90.05%) was achieved at a pH of 3.0, after 800 mg/L of bioflocculant was added into the microcystins solution (10 mg/L) for 60 min. Therefore, this paper demonstrated that CPW could be a cost-effective feedstock for the production of bioflocculants, which have potential application in microcystin removal.

A dual-modal fluorometric and colorimetric nanoprobe based on graphitic carbon nitrite quantum dots and Fe (II)-bathophenanthroline complex for detection of nitrite in sausage and water.

A fluorometric and colorimetric dual-mode sensing platform based on graphitic carbon nitrite quantum dots (g-CNQDs) and Fe (II)-bathophenanthroline complex (BPS-Fe2+) was designed to the sensitive detection of nitrite (NO2-) in sausage and water. In this system, the fluorescence of g-CNQDs was quenched by BPS-Fe2+ complex due to the inner filter effect (IFE). When NO2- was present, Fe2+ was oxidized by nitrite to form BPS-Fe3+ complex with BPS, leading to the recovery of the fluorescence from g-CNQDs. Therefore, we constructed a "turn-off-on" fluorescence probe for detection of NO2-. Moreover, with the increase of NO2- concentration, the color of the solution changed from red to colorless, so the UV-vis measurements and on-site visual detection were realized. The method is capable of detecting NO2- in the concentration range of 2.32-34.8 µM with good selectivity and high sensitivity. In addition, the method has the potential to determine NO2- in water samples and sausage samples.

Effects of electrical-hydrothermal aging degradation on dielectric and trap properties of high temperature vulcanized silicone rubber materials.

In this paper, a new aging platform combined the high voltage electric field and the hydrothermal environment was built. To investigate the aging mechanism, physicochemical, dielectric and trap properties of HTV SR before and after electrical-hydrothermal aging for 24 days were discussed. The results indicated that, compared with hydrothermal aging, more cracks and holes appeared on the surface of HTV SR after electrical-hydrothermal aging, and the content of flame retardant decreased significantly. Due to the main chain and side chain scission of PDMS, lots of low weight molecular (LWM) substances and free radicals were produced. And the tensile strength and elongation at break significantly decreased. Various physical and chemical defects appeared in the HTV SR specimen in the process of electrical-hydrothermal degradation, as a result of which, the dielectric constant significantly increased and the peak trap density increased by about 2.5 times compared to the virgin sample. The increase in trap density in turn accelerated the charge accumulation and enhanced the breakdown probability, resulting in the electric field strength decrease from 21.8 kV mm-1 to 16.1 kV mm-1 and severe degradation of HTV SR.

ε-Poly-L-lysine-protected Ti3C2 MXene quantum dots with high quantum yield for fluorometric determination of cytochrome c and trypsin.

Titanium carbide quantum dots functionalized with ε-poly-L-lysine (PLL) were synthesized by sonication cutting and hydrothermal synthesis. The deprotonated Ti3C2 MXene quantum dots (Ti3C2 MQDs) exhibit excitation wavelength-dependent blue photoluminescence with typical excitation/emission peaks at 330/415 nm and a quantum yield of 22% due to strong quantum confinement. The fluorescence of ε-poly-L-lysine protected Ti3C2 MQDs (PLL-protected Ti3C2 MQDs) is reduced via an inner filter effect after the addition of cytochrome c (cyt-c). Response to cyt-c is linear in the 0.2 to 40 µM concentration range and the detection limit is 20.5 nM. In the presence of trypsin, cyt-c is hydrolyzed to small peptides, and the Fe3+ ion in cyt-c probably is reduced to Fe2+ with the aid of the digestive enzyme. This results in the restoration of the blue fluorescence of the modified MQDs. Fluorescence increases linearly in the 0.5 to 80 µg mL-1 trypsin concentration range with the detection limit of 0.1 µg mL-1. The method was successfully applied to the determination of cyt-c and trypsin in spiked serum samples. Graphical abstractSchematic of a method for the fluorometric "turn-off-on" determination of cytochrome c and trypsin based on ε-poly-L-lysine (PLL) protect MXene quantum dots (Ti3C2 MQDs).

Carbon dots co-doped with nitrogen and chlorine for "off-on" fluorometric determination of the activity of acetylcholinesterase and for quantification of organophosphate pesticides.

Nitrogen and chlorine dually-doped carbon dots (N,Cl-CDs) were hydrothermally prepared starting from 4-chloro-1,2-diaminobenzene and dopamine. The N,Cl-CDs exhibit strong orange fluorescence, with excitation/emission maxima at 420/570 nm and a relative high quantum yield (15%). The N,Cl-CDs were employed to detect acetylcholinesterase (AChE) activity and organophosphate pesticides (OPs) which are enzyme inhibitors. Acetylthiocholine is enzymatically split by AChE to produce thiocholine which triggers the decomposition of Ellmans's reagent to form a yellow colored product (2-nitro-5-thiobenzoate anion). The product causes an inner filter effect (IEF) on the fluorescence of the N,Cl-CDs. Fluorescence decreases linearly in the 0.017 to 5.0 Unit·L-1 AChE activity range, and the detection limit is 2 mUnit·L-1. If organophosphates are present, the activity of AChE becomes increasingly blocked, and this leads to a less expressed IFE and an increasing recovery of fluorescence. This was used for the quantification of OPs. Response is linear in the 0.3-1000 µg·L-1 OP concentration range with a 30 ng·L-1 detection limit. Graphical abstractSchematic representation of the synthesis of nitrogen and chlorine dually-doped carbon dots (N,Cl-CDs) and the recognition of organophosphate pesticides by N,Cl-CDs.