Hinge-like paper-based dual-channel enzyme-free ratiometric fluorescent microfluidic platform for simultaneous visual detection of carbaryl and glyphosate.

On-site multi-pesticide residues detection is particularly urgent and challenging. Here, we fabricated an enzyme-free ratiometric fluorescent detection system in combination with a hinge-like dual-channel 3D microfluidic paper analytical device (3D µPAD) for simultaneous visual detection of carbaryl and glyphosate. Blue-emission 1-naphthol (Em. 470 nm) was hydrolyzed from carbaryl, while yellow-emission 2,3-diaminophenazine (Em. 570 nm) was produced with the aid of Cu2+ for glyphosate sensing. Inner-filter effect between 1-naphthol or 2,3-diaminophenazine and green-emission carbon dots (Em. 510 nm) realized two ratiometric fluorescent detection systems. Remarkable color variation of green-blue for carbaryl (50.00-1100 µΜ) and yellow-green for glyphosate (5.00-600 µΜ) were observed on a dual-channel 3D µPAD without crosstalk. Their detection limits were 1.11 and 0.63 µΜ, respectively. The strategy realized simultaneous visual detection of carbaryl and glyphosate in food/herbal with excellent accuracy (spiked recoveries, 91.00-107.2%), high precision (RSD ≤ 8.43%), and superior selectivity.

Design of a sustainable light-up flavonol probe for dual-ratiometric fluorescent sensing and visual differentiating ammonia and hydrazine.

Ammonia (NH3) and hydrazine (N2H4) present potential risks to human health, food and environmental safety. A sustainable flavonol-based probe, quercetin pentaacetate (QPA, weak blue emission 417 nm), was fabricated for dual-ratiometric fluorescent sensing and visual differentiating NH3 and N2H4. Excited state intramolecular proton transfer-on products with green (487 nm) and yellow (543 nm) emissions occurred as meeting with NH3 and N2H4, respectively, for their different nucleophilicities. Such a promising response offered a great opportunity of QPA to discriminatively detect NH3 and N2H4 with large Stokes shifts (>122 nm), high sensitivity (limit of detection: 35.4 µM and 0.70 ppm for NH3 solution and gas; 0.26 µM for N2H4 solution), excellent accuracy (spiked recoveries from 98.6 % to 105 %), and superior selectivity. Importantly, QPA was utilized for monitoring NH3 vapor in fish spoilage procedures and detecting N2H4 in water samples for food and environmental safety evaluation.

Threaded 3D microfluidic paper analytical device-based ratiometric fluorescent sensor for background-free and visual detection of organophosphorus pesticides.

With the increasing concerns of food safety and environmental protection, it is desirable to develop reliable, effective, and portable sensors for detection of organophosphorus pesticides (OPs). Here, a cascade reaction system integrated with threaded 3D microfluidic paper analytical device (3D µPAD) was firstly developed for background-free and visual detection of OPs in agricultural samples. Butyrylcholinesterase (BChE) hydrolyzed acetylcholine into thiocholine (TCh), which reduced MnO2 nanosheets into Mn2+. With addition of OPs, BChE activity was irreversibly inhibited, and the generation of TCh and the reduction of MnO2 nanosheets were prevented. Then the remaining MnO2 nanosheets oxidized o-phenylenediamine into 2,3-diaminophenazine with yellow-emission fluorescence, which quenched the fluorescence intensity of red-emission carbon dots (RCDs) via inner-filter effect. Based on above mechanism, a ratiometric fluorescent system was established for OPs detection. Threaded 3D µPAD consisted of 4 layers, which allowed to load and/or add reagents to trigger the cascade reaction system for OPs detection. The fluorescent images presented distinguishable color variations from red to yellow with dichlorvos concentrations ranging from 2.5 to 120 µg L-1, and the limit of detection was 1.0 µg L-1. In the practical samples testing, threaded 3D µPAD can eliminate background influence on fluorescent signal for OPs detection. Threaded 3D µPAD integrated with ratiometric sensing platform has merits of accuracy response, facile operation, and background-free detection, which supplies a new alternative approach for on-site pesticide detection.

A dual-emission carbon dots-based nonenzymatic fluorescent sensing platform for simultaneous detection of parathion-methyl and glyphosate.

Simultaneous and high-performance detection of pesticides is still a considerable challenge and urgent need. Herein, a dual-emission carbon dots (CDs)-based nonenzymatic fluorescent sensing platform has been developed, which shows excellent sensitivity and selectivity in simultaneously detecting parathion-methyl (MP) and glyphosate. CDs with emissions at 440 nm (bCDs) and 660 nm (rCDs) were prepared by hydrothermal treatment of mulberry leaves and sodium hydroxide. bCDs response to hydrolyzed MP via inner filter effect, while rCDs sense glyphosate with the aid of Cu2+ by static quenching effect. Excellent linear correlations were found for MP (0.3-65.0 µM) and glyphosate (1.0-110.0 µM) with limits of detection at 0.14 and 0.60 µM. Notably, the presented dual-channel strategy was successfully applied in simultaneously detecting MP and glyphosate in food/herbal samples with acceptable recoveries, good precision, and high selectivity. Moreover, an ORlogicgatewas achieved for estimating food, herbal, or environmental safety.

Weaving microscale wool ball-like hollow covalent organic polymers from nanorods for efficient adsorption and sensing.

Microscale covalent organic polymers with a unique 3D hollow wool ball-like morphology have been woven from 1D nanorods by a cascade emulsion strategy with a large surface area (284 m2 g-1), which showed great potential for simultaneous removal (Qmax, 358.15 mg g-1) and fluorescent detection (detection limit, 8.0 µg L-1) of bisphenol A.

Screening of potent α-glucosidase inhibitory and antioxidant polyphenols in Prunella vulgaris L. by bioreaction-HPLC-quadrupole-time-of-flight-MS/MS and in silico analysis.

Prunella vulgaris L. is a well-known traditional Chinese medicine for blood glucose homeostasis and antioxidant potential. Ethyl acetate fraction of P. vulgaris L. demonstrated higher phenolic content (85.53 ± 6.74 mg gallic acid equivalents per gram dry weight), α-glucosidase inhibitory (IC50 , 69.13 ± 2.86 µg/ml), and antioxidant (IC50 , 8.68 ± 1.01 µg/ml) activities. However, the bioactive polyphenols responsible for the beneficial properties remain unclear. Here, bioreaction-HPLC-quadrupole-time-of-flight-MS/MS method was developed for rapid, accurate, and efficient screening and identification of polyphenols with α-glucosidase inhibitory and antioxidant activities from P. vulgaris L. Bioactive polyphenols can specifically bind with α-glucosidase or react with 1,1-diphenyl-2-picryl-hydrazyl radical, which was easily discriminated from nonactive compounds. Subsequently, 20 bioactive polyphenols (16 phenyl propionic acid derivatives and four flavonoids) were screened and identified. Furthermore, molecular docking analysis revealed that screened 20 polyphenols bind with the active sites of α-glucosidase through hydrogen bonding and π-π stacking. Density functional theory calculations demonstrated their electron transport ability and chemical reactivity. The in silico analysis confirmed the screened results. In summary, this study provided a valuable strategy for rapid discovering bioactive compounds from complex natural products and offered scientific evidence for further development and application of P. vulgaris L.

Rapid profiling of potential antitumor polymethoxylated flavonoids in natural products by integrating cell biospecific extraction with neutral loss/diagnostic ion filtering-based high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry.

INTRODUCTION: Citri Reticulatae Pericarpium Viride (CRPV, Qing Pi in Chinese) has been widely used in traditional Chinese medicine. Polymethoxylated flavonoids (PMFs), which are a special group of flavonoids with strong antitumor activity, are broadly distributed in citrus peels. However, systematic investigation of antitumor PMFs in CRPV has received little attention to date. OBJECTIVES: An MCF-7 cell biospecific extraction method integrated with neutral loss/diagnostic ion filtering-based HPLC-QTOF-MS/MS strategy was developed for rapid and specific profiling of antitumor PMFs and systematic identification of PMFs in CRPV. METHODOLOGY: By incubating MCF-7 cells with CRPV extract, potential antitumor PMFs specifically bound to cells and were isolated. Then, by systematic investigation of fragmentation pathways, neutral loss and diagnostic ion filtering strategies were proposed to comprehensively and accurately identify PMFs. RESULTS: Sixteen antitumor PMFs were unambiguously or tentatively identified. Among them, minor compound 15 (5-hydroxy-6,7,8,3',4'-pentamethoxyflavone with a free hydroxyl group at C-5) exhibited excellent antitumor activity, with an IC50 value of 2.81 ± 0.76 µg/mL, which is lower than that of 5-fluorouracil (IC50 , 4.92 ± 0.83 µg/mL). Nobiletin (12) and tangeretin (16), two major PMFs, presented moderate antitumor activities with IC50 values of 13.06 ± 1.85 and 17.07 ± 1.18 µg/mL, respectively, and their contents were sensitively and precisely determined. CONCLUSIONS: To the best of our knowledge, this is the first report on the systematic investigation of antitumor PMFs in CRPV. The study will lay a foundation for the quality control and clinical application of CRPV.

Online Extraction-DPPH-HPLC-DAD-QTOF-MS System for Efficient Screening and Identification of Antioxidants from Citrus aurantium L. var. amara (Rutaceae): Integrating Sample Preparation and Antioxidants Profiling.

The lack of a direct connection between solid edible or medical natural products and bioactive compound profiling is a bottleneck in natural product research and quality control. Here, a novel integrated system, online extraction (OLE)-2,2'-diphenyl-1-picrylhydrazyl (DPPH)-HPLC-DAD-QTOF-MS, was fabricated to extract, screen, and identify antioxidants from the whole fruit of Citrus aurantium L. var. amara (CAVA, Rutaceae) simply, rapidly, and efficiently. The system consumes less sample (1.0 mg of CAVA powder) and requires a shorter analytical time (45 min for sample extraction, antioxidants screening, separation, and identification). Eight antioxidant flavonoids were screened and identified, and six available flavanones were sensitively, precisely, and accurately quantified. Two major flavanone glycosides, naringin (50.37 ± 0.43 mg/g) and neohesperidin (38.20 ± 0.27 mg/g), exhibit potent DPPH scavenging activities with IC50 values of 111.9 ± 10.06 and 178.55 ± 11.28 µg/mL. A minor flavanone aglycone, hesperitin (0.73 ± 0.06 mg/g), presents stronger DPPH scavenging activity (IC50, 39.07 ± 2.51 µg/mL). Furthermore, density functional theory calculations demonstrated their electron transport ability and chemical reactivity, which confirmed the screened results. The results indicate that the developed OLE-DPPH-HPLC-DAD-QTOF-MS system provides new perspectives for analysis of antioxidants from complex natural products, which also contribute to the quality evaluation of CAVA.

Highly specific esterase activated AIE plus ESIPT probe for sensitive ratiometric detection of carbaryl.

Fabrication of facile, sensitive, and accurate pesticide detection strategies plays crucial roles in food safety, environmental protection, and human health. Here, a novel esterase activatable aggregation-induced emission (AIE) plus excited-state intramolecular proton transfer (ESIPT) probe, kaempferol tetraacetate, was designed and synthesized from purified natural kaempferol for ratiometric sensing of carbaryl. Acetate groups are introduced as the esterase reactive sites and AIE plus ESIPT initiator. Kaempferol tetraacetate is an aggregation-caused quenching compound that shows fluorescent (FL) emission at 415 nm. Esterase specifically hydrolyzes kaempferol tetraacetate to kaempferol with AIE plus ESIPT characteristics (distinct FL emission, 530 nm; a large Stokes shift, 165 nm within a short time (8 min). Molecular docking and kinetics performance indicate the high affinity and specific hydrolysis of esterase and kaempferol tetraacetate. Carbaryl inhibits the activity of esterase to efficiently suppress the production of kaempferol. Thus, a facile ratiometric assay strategy is constructed for carbaryl detection. By measuring the FL intensity ratio, the proposed strategy presents high selectivity and reliability with a wide linear range from 0.02 to 2.00 µg L-1 and a very low limit of detection at 0.007 µg L-1. Furthermore, appropriate recovery from 93.75% to 108.67% with a relative standard deviation less than 5.66% for real sample analysis indicates good accuracy and precision. All results indicate that the fabricated strategy offers a new way for facile, sensitive, and accurate detection of carbaryl in real complex samples.

3D origami paper-based ratiometric fluorescent microfluidic device for visual point-of-care detection of alkaline phosphatase and butyrylcholinesterase.

On-site multiplex enzyme detection is crucial for diagnosis, therapeutics and prognostic. To date, it is still a daunting challenge to develop portable, low-cost, and efficient multi-enzyme detection methods. Herein, a novel sample-in-result-out platform integrating ratiometric fluorescent assays with 3D origami microfluidic paper-based device (µPAD) was developed for simultaneous visual point-of-care testing (POCT) of alkaline phosphatase (ALP) and butyrylcholinesterase (BChE). Cascade catalytic reaction with the same two fluorescent signal indicators was rationally designed to ratiometric fluorescent detection of ALP and BChE: substrate of ALP (pyrophosphate) and product of BChE (thiocholine) can strongly complex with Cu2+, Cu2+ oxidizes o-phenylenediamine to fluorescent 2,3-diaminophenazine (oxOPD) (emission, 565 nm), oxOPD quenches the fluorescence of carbon dots (CDs, emission at 445 nm) via inner filter effect, thus oxOPD/CDs values are relevant to ALP and BChE activities. Then 3D origami µPAD composing of four layers and two parallel channels was fabricated and simply prepared by one-step plotting with black oil-based marker and specific metal molds. After simple folding and unfolding neighboring layers to sequentially initiate reactions of pre-loaded reagents, fluorescent images on the detection zone can be captured by smartphone and analyzed by red-green-blue software for quantitative analysis. Under optimal conditions, the proposed platform was successfully performed to detect ALP and BChE with activity difference at 3 orders of magnitude in human serum samples without any pretreatment procedures. Excellent selectivity, good precision, favorable linear range, and high accuracy were exhibited. Importantly, the platform opens a promising horizon for high-throughput POCT of multiplex biomarkers.

Online extraction and enrichment coupling with high-speed counter-current chromatography for effective and target isolation of antitumor anthraquinones from seeds of Cassia obtusifolia.

Traditional bioassay-guided investigation of bioactive compounds from natural products comprises critical steps, such as extraction, repeated column separation, and activity assay. Thus, the development of facile, rapid, and efficient technology is critically important. Here, a HepG2 cell-based extraction method was first developed to rapidly screen potential antitumor compounds from the seeds ofCassia obtusifolia. Then, an online extraction and enrichment-high-speed counter-current chromatography (HSCCC) strategy was fabricated to facilely and efficiently isolate target antitumor compounds, which included direct extraction from solid C. obtusifolia, removal of polar interferences, enrichment of target compounds, and preparative isolation by HSCCC using flow rate stepwise increasing mode. After further purification by Sephadex LH-20 column, five antitumor anthraquinones, aurantio-obtusin, 1-desmethylaurantio-obtusin, chryso-obtusin, obtusin, and questin, were obtained for structural characterization and bioassay verification. The results may not only provide new perspectives for facile and rapid investigation of bioactive compounds from complex natural products, but also offer a scientific basis for the potential applications of C. obtusifolia.

Simultaneous sensing γ-glutamyl transpeptidase and alkaline phosphatase by robust dual-emission carbon dots.

Rapid, convenient, sensitive and simultaneous detection of distinct enzymes is urgently needed for diagnosis, therapeutics and prognostic of related diseases. Here, a new strategy for simultaneous monitoring γ-glutamyl transpeptidase (GGT) and alkaline phosphatase (ALP) activity has been fabricated based on dual-emission carbon dots (CDs). CDs were prepared by solvothermal treatment of Actinidia chinensis, which presents two fluorescent emissions at 471 nm (blue channel) and 671 nm (red channel). GGT and ALP activity can be detected based on inner filter effect (IFE) and static quenching effect (SQE) of blue and red channels of CDs, respectively. Linear ranges were 2.5-90 U L-1 and 5-200 U L-1, and limit of detection (LOD) were 0.71 U L-1 and 1.2 U L-1 for GGT and ALP, respectively. Developed CDs can monitor GGT and ALP activity in human serum samples with satisfied recoveries (99.3%-108.6% for GGT, 98.4%-105.4% for ALP). Furthermore, the combination of CDs to sense GGT and ALP activity with OR logic gate can predict human health status. The design and application of dual-emission CDs can also be extended as promising tools to detect multianalytes using different channel signals.

Diagnostic ion filtering targeted screening and isolation of anti-inflammatory iridoid glycosides from Hedyotis diffusa.

Efficient and targeted screening and isolation of bioactive compounds from complex natural products is still a challenging work. Herein, diagnostic ion filtering based high-performance liquid chromatography-quadrupole time-of-flight-tandem mass spectrometry was firstly developed to screen six main iridoid glycosides from Hedyotis diffusa. Then, online extraction-high-speed counter current chromatography was proposed for targeted enrichment and preparative isolation using ethyl acetate/n-butanol/water (4.5:0.5:5, v/v/v) as solvent system. After that, Sephadex LH-20 column chromatography using methanol as solvent system was selected for further purification of six iridoid glycosides with purities over 98%. They were finally identified as monotropein, desacetylasperuloside acid, asperuloside, 6-O-(Z)-p-coumaroyl scandoside methyl ester, 6-O-(Z)-feruloyl scandoside methyl ester, and 6-O-(E)-p-coumaroyl scandoside methyl ester. And their anti-inflammatory activities were evaluated and confirmed by lipopolysaccharide activated RAW 264.7 macrophages. Obviously, the results provide a scientific basis for the potential applications of H. diffusa, and the developed methodology is efficient and reliable for targeted screening and isolation of bioactive compounds from natural products.

Red pitaya peels-based carbon dots for real-time fluorometric and colorimetric assay of Au3+, cellular imaging, and antioxidant activity.

The synthesis of fascinating multifunctional carbon dots (CDs) attracted immense attention. Here, a facile solvothermal treatment of red pitaya peels in acetic acid produced CDs (designated as ACDs, excitation/emission wavelengths at 357/432 nm). ACDs with high sp2-hybridized carbon and carboxylic group contents can rapidly and selectively reduce Au3+ to Au0, and stabilize produced Au nanoparticles (AuNPs). The synergetic effect of electron transfer from ACDs to Au3+ and inner filter effect (IFE) from ACDs to AuNPs quenches the fluorescence within 30 s. Simultaneously, the resulting AuNPs have a purple color with a maximum absorption at 545 nm for visual detection. Therefore, for the first time, we reported a fluorometric and colorimetric dual-mode sensing system for real-time, highly sensitive and selective detection of Au3+. The fluorescence quenching ratio and absorbance change linearly with the increase of Au3+ concentration in the range of 0.3-8.0 µM and 3.3-60.0 µM with limits of detection (LODs) at 0.072 µM and 2.2 µM, respectively. The assay was applied for Au3+ determination in spiked real water samples with recoveries from 95.5 to 105.0%, and relative standard deviation (RSD) of less than 6.5%. Furthermore, ACDs with good photostability, low cytotoxicity, and excellent biocompatibility were successfully applied for intracellular Au3+ sensing and imaging. In addition, ACDs exhibited an extraordinarily high antioxidant activity, with an IC50 value for DPPH radical scavenging (0.70 µg mL-1) much lower than that of ascorbic acid (4.34 µg mL-1). The proposed strategy demonstrates the outstanding properties of ACDs in chemical and biomedical analysis. Graphical abstract.

Indole-based alkaloids from Ophiocordyceps xuefengensis.

Seven undescribed indole-based alkaloids, xuefengins A-D and xuefenglasins A-C, were isolated from natural Ophiocordyceps xuefengensis, along with six known alkaloids. Their structures were elucidated by comprehensive spectroscopy, with absolute configurations confirmed by comparison with calculated electronic circular dichroism spectra. Eleven of the isolates were tested for cytotoxicity against the U937, NB4, MCF-7, Hep G2, and A549 cancer cell lines. Two compounds exhibited moderate activities, with IC50 values of 2.83-25.68 µM and 1.54-12.16 µM. Further pharmacological studies showed that these two compounds inhibit cell proliferation by inducing apoptosis, and decreasing p38 and caspase-3 levels in A549 cells.

Rapid and comprehensive profiling of α-glucosidase inhibitors in Buddleja Flos by ultrafiltration HPLC-QTOF-MS/MS with diagnostic ions filtering strategy.

Buddleja Flos is used as yellow rice colorant and a well-known traditional Chinese medicine. But its biochemical profiling is still lack due to complex matrix. Here, ultrafiltration high-performance liquid chromatograph-quadrupole time-of-flight tandem mass spectrometry (HPLC-QTOF-MS/MS) with diagnostic ions filtering strategy was proposed for rapid and comprehensive investigation of its α-glucosidase inhibitors. As a result, 33 bioactive compounds (13 phenylethanoid glycosides and 20 flavonoids) were successfully screened and identified. In addition, α-glucosidase inhibitory activities of twenty-two references were verified. Six flavonoid aglycones (4, 28, and 30-33) showed excellent α-glucosidase inhibitory activities (IC50, from 5.11 ± 0.85 to 32.49 ± 9.76 µg/mL), much higher than that of acarbose (IC50, 195.49 ± 10.05 µg/mL). Five flavonoid-monoglycosides (7, 12, 13, 20, and 22) presented moderate inhibitory activities with IC50 from 160.98 ± 23.19 to 249.37 ± 35.83 µg/mL. Results showcased the high efficiency of proposed strategy in profiling of bioactive compounds from natural products.

Correction to: One-pot fabrication of dual-emission and single-emission biomass carbon dots for Cu2+ and tetracycline sensing and multicolor cellular imaging.

The authors would like to call the reader's attention to the fact that unfortunately the wrong file was published as Fig. 2.

One-pot fabrication of dual-emission and single-emission biomass carbon dots for Cu2+ and tetracycline sensing and multicolor cellular imaging.

Dual-emission and single-emission carbon dots (DCDs and SCDs) have been simultaneously synthesized by one-pot solvothermal treatment of leek. Different graphitization and surface functionalization were responsible for their distinction in fluorescence characteristics. DCDs with an average size of 5.6 nm exhibited two emissions at 489 and 676 nm under 420-nm excitation. Complexation between DCDs' surface porphyrins and Cu2+ led to quenching of the 676-nm emission, which resulted in the ratiometric determination of Cu2+ with a limit of detection (LOD) of 0.085 µM. SCDs, containing additional sulfur element (0.50%) with an average size of 7.7 nm, presented a single emission at 440 nm under 365-nm excitation. The static quenching and inner filter effects between SCDs and tetracyclines (TCs) made SCDs a fluorescence nanoprobe for TCs' determination with LODs of 0.26-0.48 µM. Applications of DCDs and SCDs for respective determination of Cu2+ and TCs in milk and pig liver samples were successfully demonstrated. Moreover, good photostability, low toxicity, and outstanding biocompatibility made DCDs and SCDs suitable for multicolor cellular imaging. Results indicate that natural products are excellent raw materials to controllably synthesize CDs with prominent physicochemical and fluorescence properties.Graphical abstract.

Applications of blockchain in ensuring the security and privacy of electronic health record systems: A survey.

Due to the popularity of blockchain, there have been many proposed applications of blockchain in the healthcare sector, such as electronic health record (EHR) systems. Therefore, in this paper we perform a systematic literature review of blockchain approaches designed for EHR systems, focusing only on the security and privacy aspects. As part of the review, we introduce relevant background knowledge relating to both EHR systems and blockchain, prior to investigating the (potential) applications of blockchain in EHR systems. We also identify a number of research challenges and opportunities.

Dual-emissive carbon dots for dual-channel ratiometric fluorometric determination of pH and mercury ion and intracellular imaging.

Dual-emissive carbon dots (CDs) were fabricated for dual-channel ratiometric fluorometric determination of pH and mercury ion (Hg2+) and intracellular imaging. Dual-emissive CDs were synthesized by one-pot solvothermal treatment of cabbage. The CDs exhibited two distinctive fluorescence emissions at 500 and 678 nm under single excitation at 410 nm. The green emission (500 nm) had reversible linear response to pH (7.0-12.0) due to deprotonation and protonation of surface functional groups and their non-covalent interactions. On the other hand, the red emission (678 nm) had efficient and selective fluorescence response to Hg2+ by formation of non-emission complex between CDs and Hg2+. The limit of detection (LOD) and limit of quantification (LOQ) for Hg2+ were 6.25 and 20.63 nM, respectively. The CDs have been successfully applied for label-free ratiometric fluorometric determination of pH and Hg2+ in fish and human serum samples with good recoveries (92.0-108.3%). In addition, the CDs had excellent photostability, low cytotoxicity, and good biocompatibility for intracellular imaging. All in all, the system was multi-functional in determination, high in sensitivity, and excellent in selectivity, which demonstrated wide and promising applicability for biosensing and bioimaging in the future. Graphical abstract Schematic presentation of dual-emission carbon dots (CDs) synthesized by solvothermal treatment of cabbage for dual-channel determination of pH and Hg2+.