Photoelectrochemical quenching-recovery biosensor based on NSCQDs/Fe2O3@Bi2S3 for the detection of trypsin.

BACKGROUND: The content of trypsin will change when pancreatic diseases occur, therefore developing a high-performance method for trypsin detection is of great significance for guiding patients on medication plans and improving their prognosis. Photoelectrochemical (PEC) analysis techniques have emerged as a solution to apply for bioassays. RESULTS: Herein, the Fe2O3@Bi2S3 and Nitrogen and sulfur co-doped carbon quantum dots (NSCQDs) were successfully synthesized by a hydrothermal method. Subsequently, NSCQDs/Fe2O3@Bi2S3 with a photocurrent amplification effect covered on fluorine-doped tin oxide (FTO) electrode as the substrate material and apoferritin (APO) as a bio-recognition element to quench the photocurrent of the substrate material which can be excited with light. Due to the decomposition specifically between APO and trypsin, the photocurrent response increased. The linear range for trypsin detection showed satisfied results from 2 to 1000 ng mL-1 under optimal conditions, with a detection limit of 0.42 ng mL-1 and a recovery rate of 97.41 %-103.02 %, enabling efficient quantitative analysis of trypsin. SIGNIFICANCE: In this experiment, a PEC biosensor with simple operation, low detection limit, excellent selectivity and strong stability was successfully prepared, enabling quantitative analysis of trypsin in human serum samples through the quenching-recovery mechanism. It holds great significance for diagnosis and serves as a practical method for the detection of trypsin in the future.

Carbon quantum dots(CQDs)-sensitized CdS/CuInS2 heterojunction as a photoelectrochemical biosensing platform for highly sensitive detection of prostate-specific antigen.

Sensitive and quantitative detection of prostate-specific antigen (PSA) has been determined to be indispensable for clinical diagnostics of prostate cancer, whereas such detection is quite challenging due to the extremely low concentration of biomarkers in human serum samples. In this study, a photoelectrochemical (PEC) sensor was effectively developed for the high-sensitivity analysis of prostate-specific antigen (PSA) using a signal amplification method utilizing sensitized carbon quantum dots (CQDs). In this experiment, cadmium sulfide quantum dots were employed as the substrate materials, and indium copper sulfide quantum dots were loaded on their surfaces. Moreover, the efficient matching of energy levels in these two materials contributed to the generation of photocurrents. The aforementioned heterojunction semiconductor QDs were thus combined with CQDs to produce CQDs on their surfaces. As a result of the presence of CQDs, the ability of heterojunction materials to absorb light was remarkably enhanced, increasing the photocurrent by over ten times. Consequently, in this study, CQDs were combined with PEC sensors, and the developed PEC biosensors exhibited excellent optical performance, sensitivity, repeatability, and stability. The results obtained from the analysis of actual samples were satisfactory and have promising application prospects.

Metabolomics and lipidomics in non-small cell lung cancer.

Due to its insidious nature, lung cancer remains a leading cause of cancer-related deaths worldwide. Therefore, there is an urgent need to identify sensitive/specific biomarkers for early diagnosis and monitoring. The current study was designed to provide a current metabolic profile of non-small cell lung cancer (NSCLC) by systematically reviewing and summarizing various metabolomic/ lipidomic studies based on NSCLC blood samples, attempting to find biomarkers in human blood that can predict or diagnose NSCLC, and investigating the involvement of key metabolites in the pathogenesis of NSCLC. We searched all articles on lung cancer published in Elsevier, PubMed, Web of Science and the Cochrane Library between January 2012 and December 2022. After critical selection, a total of 31 studies (including 2768 NSCLC patients and 9873 healthy individuals) met the inclusion criteria, and 22 were classified as "high quality". Forty-six metabolites related to NSCLC were repeatedly identified, involving glucose metabolism, amino acid metabolism, lipid metabolism and nucleotide metabolism. Pyruvic acid, carnitine, phenylalanine, isoleucine, kynurenine and 3-hydroxybutyrate showed upward trends in all studies, citric acid, glycine, threonine, cystine, alanine, histidine, inosine, betaine and arachidic acid showed downward trends in all studies. This review summarizes the existing metabolomic/lipidomic studies related to the identification of blood biomarkers in NSCLC, examines the role of key metabolites in the pathogenesis of NSCLC, and provides an important reference for the clinical diagnosis and treatment of NSCLC. Due to the limited size and design heterogeneity of the existing studies, there is an urgent need for standardization of future studies, while validating existing findings with more studies.

Preparation of amino functionalized magnetic oyster shell powder adsorbent for selective removal of anionic dyes and Pb (II) from wastewater.

A kind of new magnetic oyster shell (OS) composite (OS-Fe3O4@SiO2@NH2@PEI) was synthesized and used as an adsorbent to remove carmine (CM), sunset yellow (SY) and Pb (II) from water. Firstly, Fe3O4 magnetic nanoparticles were introduced on the surface of waste oyster shell powder, then amino silanization was used to improve the stability of the material, and finally polyethylenimide (PEI) was grafted by Schiff base reaction. The composite was characterized by FT-IR, SEM, EDS, XPS, VSM, BET, TEM and zeta potential. The effects of adsorbent dosage and initial solution pH on the three samples were investigated by adsorption experiments. The adsorption kinetics and isotherms were investigated in depth under the best experimental conditions. The composite adsorbent not only selectively removed anionic azo dyes, but also had good recycling. In addition, OS-Fe3O4@SiO2@NH2@PEI still had good performance in mixed samples. These results indicated that OS-Fe3O4@SiO2@NH2@PEI was successfully used for the removal of a wide range of anionic dyes and heavy metal ions from the environment, and provided a new strategy for recycling waste.

Nitrogen and Sulfur Co-doped Carbon Quantum Dots for Detecting Fe3+, Ascorbic Acid and Alkaline Phosphatase Activities.

A method utilizing nitrogen-doped and sulfur-doped carbon quantum dots (N, S-CQDs) as fluorescent probes for the rapid detection of Fe3+, L-ascorbic acid (AA), and alkaline phosphatase (ALP) was presented. The fluorescence intensity of N, S-CQDs nanoprobes can be rapidly and efficiently quenched by Fe3+ and based on the fluorescence "turn off-on" characteristic of N, S-CQDs nanoprobes, the fluorescence signals of the N, S-CQDs/Fe3+can be recovered after the addition of AA. By coupling a fluorescent nanoprobe to an enzyme and L-ascorbic acid-2-phosphate (AA2P), a green, simple, rapid and effective fluorescent analytical method for the determination of ALP was developed. The prepared N, S-CQDs showed high sensitivity and selectivity to Fe3+, AA and ALP with the detection limit of 0.42 µM, 12.7 nM and 0.017 U·L-1 and their optimal concentration ranges were10-600 µM, 10-200 µM, 0.18-54 U·L-1, respectively. The fluorescence quantum yield of N, S-CQDs (0.2 mg·mL-1) at 393 nm excitation wavelength was 4.41%. Additionally, the fluorescent nanoprobes have been employed to successfully measure ALP in serum samples. It is expected that the established method may offer a new approach for biomolecular detection in clinical diagnosis and pharmaceutical analysis.

Precise Lipidomics Decipher Circulating Ceramide and Sphingomyelin Cycle Associated with the Progression of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a long-term autoimmune condition that causes joint and surrounding tissue inflammation. Lipid mediators are involved in inflammation and deterioration of the joints. Despite attempts to discover effective drug targets to intervene with lipid metabolism in the disease, progress has been limited. In this study, precise lipidomic technology was employed to quantify a broad range of serum ceramides and sphingomyelin (SM) in a large cohort, revealing an association between the accumulation of circulating ceramides and disturbed ceramide/SM cycles during the progression of RA. In our investigation, we discovered that eight ceramides exhibited a positive correlation with the activity of RA, thereby enhancing the accuracy of RA diagnosis, particularly in patients with serum antibody-negative RA. Furthermore, the enzyme SM phosphodiesterase 3 (SMPD3) was found to disrupt the circulating SM cycle and accelerate the progression of RA. The activity of SMPD3 can be inhibited by methotrexate, resulting in decreased metabolic conversion of SM to ceramide. These findings suggest that targeting the SM cycle may provide a new therapeutic option for RA.

Fluorescence Sensor for Zearalenone Detection Based on Oxidized Single-walled Carbon Nanohorns/N-doped Carbon Quantum Dots-aptamer.

Zearalenone (ZEN), a resorcinolactone toxin, which has been a potential threat to agricultural production and human health. In this study, a sample and rapid fluorescence sensor was established for the detection of ZEN, which is based on the fluorescence properties of N-doped carbon dots-aptamer (NCDs-apt) and the quenching ability of oxidized single-walled carbon nanohorns (oxSWCNHs). NCDs synthesized by one-step hydrothermal method were connected with ZEN-aptamer (ZEN-apt), and oxSWCNHs were added to quench the fluorescence of NCDs-apt. Therefore, an oxSWCNHs/NCDs-apt aptasensor based on fluorescence "on-off" for the determination of ZEN in food was formed. Under optimum conditions, the limit of detection (LOD) of this method was 18 ng/mL and the linear range was 20 ~ 100 ng/mL. The possible interfering substances were investigated, and the results showed excellent selectivity. The recoveries were in the range of 99.5%~114.3%, and the relative standard deviations (RSDs) were not more than 6.5%, which demonstrated that this aptasensor was successfully applied for the detection of ZEN in food samples with satisfactory result.

Enzyme immobilized on magnetic fluorescent bifunctional nanoparticles for α-glucosidase inhibitors virtual screening from Agrimonia pilosa Ledeb extracts accompanied with molecular modeling.

Agrimonia pilosa Ledeb (APL) is a significant source of inhibitors for α-glucosidase, which is an essential target enzyme for the treatment of type 2 diabetes, cancer and acquired immune deficiency syndrome. Ligand fishing is a suitable approach for the highly selective screening of bioactive substances in complex mixtures. Yet it is unable to conduct biomedical imaging screening, which is crucial for real-time identification. In this case, a bioanalytical platform combining magnetic fluorescent ligand fishing and in-situ imaging technique was established for the screening and identification of α-glucosidase inhibitors (AGIs) from APL crude extract, utilizing α-glucosidase coated CuInS2/ZnS-Fe3O4@SiO2 (AG-CIZSFS) nanocomposites as extracting material and fluorescent tracer. The AG-CIZSFS nanocomposites prepared through solvothermal and crosslinking methods displayed fast magnetic separation, excellent fluorescence performance and high enzyme activity. The tolerance of immobilized enzyme to temperature and pH was stronger than that of free enzyme. Prior to proof-of-concept with APL crude extract, a number essential parameters (glutaraldehyde concentration, immobilized time, enzyme amount, reaction solution pH, incubation temperature, incubation time, percentage of methanol in eluen, elution times and eluent volume) were optimized using an artificial test mixture. The fished ligands were identified by UPLC-MS/MS and their biological activities were preliminarily evaluated by real-time cellular morphological imaging of human colon carcinoma (HCT-116) cells based on confocal laser scanning microscope (CLSM). Their α-glucosidase inhibitory activities were further verified and studied by classical pNPG method and molecular docking. The isolated compounds exhibited significant α-glucosidase inhibitory activities with a IC50 value of 11.57 µg·mL-1. Six potential AGIs including tribuloside, ivorengenin A, tormentic acid, 1ß, 2ß, 3ß, 19α-Tetra hydroxyurs-12-en-28-oic acid, corosolic acid and pomolic acid were ultimately screened out and identified from APL crude extracts. The proposed approach, which combined highly specific screening with in-situ visual imaging, provided a powerful platform for discovering bioactive components from multi-component and multi-target traditional Chinese medicine (TCM).

pH-responsive magnetic graphene oxide composite as an adsorbent with high affinity for rapid capture of nucleosides.

A novel pH-responsive magnetic graphene oxide composite (MGO@PEI-BA) is proposed for the first time as an adsorbent for the rapid capture and detection of nucleosides (cytidine, uridine, guanosine, and adenosine). The morphology, structure, and magnetic properties of the composite were evaluated using various characterization techniques. The results indicated that the composite was successfully fabricated. A series of parameters that affect extraction and elution were optimized through one-factor-at-a-time and Box-Behnken design of response surface methodology (BBD-RSM). The unique layered structures and easily accessible active sites of the composite facilitated molecular transport, resulting in instantaneous equilibrium of nucleosides adsorption within 5 min. Based on this study, a magnetic dispersive micro-solid-phase extraction (MD-µ-SPE) method assisted by the MGO@PEI-BA was developed in combination with UHPLC-UV analysis for the determination of nucleosides in rat urine. Under the optimum conditions, a wide linear range (10-2000 ng mL-1), good linearity (r > 0.99), low detection limits (1-3 ng mL-1), low relative standard deviations (RSDs ≤ 3.9%), and satisfactory recoveries (82.7-96.3%) were achieved. These results demonstrate that the MGO@PEI-BA is an excellent adsorbent for extracting nucleosides from biological samples.

Vortex-assisted dispersive liquid-liquid microextraction based on the hydrophobic deep eutectic solvent-based ferrofluid for extraction and detection of myclobutanil.

A vortex-assisted dispersive liquid-liquid microextraction (VA-DLLME) procedure using hydrophobic deep eutectic solvent-based ferrofluid (HDES-FF) as an extractant was established. The developed sample preparation method coupled with high-performance liquid chromatography-diode array detector (HPLC-DAD) was applied to the pretreatment and determination of myclobutanil (MYC) in fruit juice. Hydrophobic deep eutectic solvent, synthesized by n-decanoic acid and DL-menthol, was as a carrier and combined with magnetic nanoparticles (Fe3O4@OA) to form HDES-FF as an extractant with high extraction capacity. The synthesized materials were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Parameters affecting extraction efficiency were optimized using single-factor experiments and Box-Behnken design via response surface methodology (BBD-RSM). Parallel tests were performed three times under the optimal conditions predicted by the model, yielding an actual mean recovery of 94.77% with RSD of 2.7% (n = 3) and an enrichment factor of 41.8 ± 0.98 (mean value ± SD, n = 3). Under the optimal conditions, the linear range was 1.0-100.0 µg·mL-1; the limit of detection (LOD) and limit of quantification (LOQ) were 0.25 and 0.80 µg·mL-1, respectively. The average spiked recoveries in the samples ranged from 98.2 to 100.5% with intra-day relative standard deviations (RSDs) of 1.2-3.5% (n = 3) and inter-day RSDs of 1.1-3.8% (n = 3). Finally, the method was successfully applied to the determination of MYC antimicrobial agent in different fruit juice samples. The proposed HDES-FF-VA-DLLME/HPLC-DAD method was verified to widely apply to the extraction of triazole fungicides.

An integrated fecal metabolomic based on 1 H-NMR and UPLC-QTOF-MS revealed the preventive mechanism of Gushudan on glucocorticoid-induced osteoporotic rats.

Gushudan (GSD) has the effect of strengthening bones and nourishing kidneys. However, its specific intervention mechanism still remains unclear. In this study, to investigate the pathogenesis of glucocorticoid-induced osteoporosis (GIOP) and the preventive mechanism of GSD on GIOP, fecal metabolomics based on 1 H-NMR and ultra-high-performance liquid chromatography-quadrupole time-of-flight-mass spectrometry method was established. The changes in endogenous metabolites and the relevant metabolic pathways in the control group, model group, and GSD treatment group were investigated via multivariate statistical analysis. As a result, a total of 39 differential metabolites were identified. Of these, 22 metabolites, such as L-methionine, guanine, and sphingosine, were newly discovered as differential metabolites of GIOP. Amino acid metabolism, energy metabolism, intestinal flora metabolism, and lipid metabolism were significantly changed in the fecal profiles of GIOP rats, and GSD could play an anti-osteoporosis role by regulating these metabolic pathways. Finally, compared with our previous study of the GSD to prevent kidney yang deficiency syndrome, this study suggested that there were some identical differential metabolites and metabolic pathways. It showed that there was some correlation among the metabolic profiles of the intestine, kidney, and bone in GIOP rats. Therefore, this study offered new insights into the in-depth understanding of the pathogenesis of GIOP and the intervention mechanism of GSD.

Effects of biochar on runoff generation, soil and nutrient loss at the surface and underground on the soil-mantled karst slopes.

The effects of biochar (BC) on soil erosion and nutrient output have attracted widespread attention; however, the role of BC in soil and water conservation remains debated. In particular, the effect of BC on underground erosion and nutrient output in soil-mantled karst areas has not been clearly determined. The objective of this study was to investigate the effects of BC on soil and water conservation and nutrient output in surface-underground dual erosion structures in soil-mantled karst areas. Eighteen runoff plots (2 m × 1 m) were established at the Guizhou University research station. Two BC treatments (T1 = 30 t/ha; T2 = 60 t/ha) and a control treatment (CK = 0 t/ha) were used. The BC material was produced from corn straw. The experiment ran from January to December 2021 and a total of 1132.64 mm of rainfall was measured. Runoff and soil and nutrient loss at the surface and underground were collected during natural rainfall. The results showed that 1) compared to CK, the BC application significantly increased surface runoff (SR, P < 0.05) and reduced subsurface runoff (SF, P < 0.05), and underground fissure runoff (UFR) decreased in general but did not reach a significant level (P > 0.05). The total amount of SR collected in each treatment during the test period accounted for 51 %-63 % of the total amount of all collected outlet runoff (SR, SF and UFR); 2) total organic carbon (TOC), total nitrogen (TN) and total phosphorus (TP) were mainly exported through the UFR, and total potassium (TK) was mainly exported through the SR; and 3) compared to CK, the BC reduced TOC, TN and TP output through runoff but had no significant effect on TK output regardless of surface runoff or underground runoff. Thus, BC application reduces nonpoint source (NPS) pollution, and more importantly, it can inhibit TN and TP flow into groundwater through bedrock fissures. Our results provide further evidence for evaluating the soil and water conservation benefits of BC. Therefore, BC in soil-mantled karst agricultural areas can prevent groundwater pollution in karst regions. In general, BC enhances surface erosion and inhibits underground runoff and nutrients loss on soil-mantled karst slopes. This shows that the process through which BC application affects erosion in karst areas is complex, and further research is needed to investigate the long-term effects of BC application in this area.

Integrated serum pharmacochemistry, network pharmacology and pharmacokinetics to explore bioactive components of Gushudan in the treatment of osteoporosis.

Gushudan (GSD), a compound prescription on the basis of traditional Chinese medicine (TCM) theory and clinical practice, has been used in the treatment of osteoporosis (OP) for many years. Although studies have shown that GSD can treat OP, there is a lack of systematic screening method to explore the bioactive components, which are still unclear. Therefore, this study was aimed to establish an integrated method to screen and determine bioactive ingredients of GSD in the treatment of OP by serum pharmacochemistry, network pharmacology and pharmacokinetics. Firstly, 112 components of the GSD extract and 90 serum migrating constituents were identified by the ultra-high performance liquid chromatography-hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), most of which were derived from flavonoids, tanshinones, coumarins and organic acids. Secondly, based on the network pharmacological analysis of the serum migrating constituents, 37 core targets and 20 main pathways related to both GSD and OP were obtained. More importantly, 7 bioactive ingredients were further screened as the PK markers by the network topology parameters including icariin, icariside II, isopimpinellin, bergapten, imperatorin, osthole and tanshinone IIA. Finally, a sensitive and accurate quantitative method based on ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was established and validated for simultaneous determination of the 7 bioactive ingredients in the rat plasma after oral administration of GSD extract, which was then applied to pharmacokinetic study. Besides, the overall pharmacokinetic characteristics were further calculated: Cmax was 180.52 ± 31.18 ng/mL, Tmax was 0.46 ± 0.20 h, t1/2 was 4.09 ± 0.39 h, AUC0-∞ was 567.24 ± 65.29 ng·h/mL, which displayed quick absorption and medium elimination in rats after oral administration of GSD extract. This study provided a new and holistic insight for exploring bioactive constituents and main targets to decode the therapeutic material basis of GSD against OP.

Rapid and sensitive determination of Piroxicam by N-doped carbon dots prepared by plant soot.

Piroxicam (PX) as a nonsteroidal anti-inflammatory drug (NSAID) can be effectively used for anti-inflammatory and analgesia. However, overdoses may induce side effects such as gastrointestinal ulcers and headaches. Therefore, the assay of piroxicam has considerable significance. In this work, nitrogen-doped carbon dots (N-CDs) was synthesized for PX detection. The fluorescence sensor was fabricated by hydrothermal method with plant soot and ethylenediamine. The strategy exhibited a detection range of 6-200 µg/mL and 250-700 µg/mL with the limited detection of 2 µg/mL. The mechanism of the PX assay base on the fluorescence sensor was the process of electron transfer between the PX and N-CDs. The assay subsequently demonstrated could be successfully used in actual sample. The results indicated that the N-CDs could be a superior candidate nanomaterial for piroxicam monitoring in the healthcare product industry.

Integrated gas chromatography-mass spectrometry and ultra-high-performance liquid chromatography-mass spectrometry renal metabolomics and lipidomics deciphered the metabolic regulation mechanism of Gushudan on kidney-yang-deficiency-syndrome rats.

Kidney-yang-deficiency-syndrome is a neuroendocrine disease caused by the dysfunction of the adrenal-pituitary-target gland axis. Gushudan is a traditional Chinese medicine prescription with the functions of tonifying the kidney and strengthening bone, and its bone-strengthening effect has been confirmed by previous anti-osteoporosis research. However, its kidney-tonifying mechanism has not been clear so far. In this study, renal metabolomics and lipidomics based on gas chromatography-mass spectrometry and ultra-high-performance liquid chromatography-high resolution mass spectrometry were integrated to find the metabolic disorders in kidney-yang-deficiency-syndrome rats. Protein precipitation and liquid-liquid extraction were used to extract metabolome and lipidome from the kidney. Gushudan regulated abnormal levels of amino acids, lipids, purines, and carbohydrates, such as L-arginine, hypoxanine, stearic acid, and phosphatidylethanolamine (P-18:1/20:4), which had effects on many metabolic pathways, such as glycerophospholipid metabolism, sphingolipid metabolism, glycine, serine and threonine metabolism and purine metabolism, and so forth. By integrating metabolomics and lipidomics, this study comprehensively revealed the abnormal metabolic activities of amino acids, lipids, and nucleotides in kidney-yang-deficiency-syndrome, and the metabolic regulation mechanism of Gushudan in preventing kidney-yang-deficiency-syndrome, as well as the improvement of Gushudan in maintaining renal cell structure, mitochondrial function, and energy supply, which also provided some new evidence and connotation for "kidney-bone" axis.

San-wei-tan-xiang capsule attenuates atherosclerosis by increasing lysosomal activity in adipose tissue macrophages.

ETHNOPHARMACOLOGICAL RELEVANCE: Dyslipidemia is the leading risk factor of atherosclerosis (AS). Adipose tissue macrophages (ATMs) can regulate postprandial cholesterol levels via uptake and hydrolyzation of lipids and regulation of macrophage cholesterol efflux (MCE). San-wei-tan-xiang (SWTX) capsule, a Traditional Chinese medicine, exerts clinical benefits in patients with atherosclerotic cardiovascular diseases. AIM OF THE STUDY: This work is aimed to evaluate the chemical ingredients and mechanisms of SWTX in anti-AS. MATERIALS AND METHODS: The chemical ingredients of SWTX identified by liquid chromatography coupled with tandem mass spectrometry were used for network pharmacological analysis. The atheroprotective function of SWTX was evaluated in ApoE-/- mice fed a cholesterol-enriched diet. RESULTS: The chemical ingredients identified in SWTX were predicated to be important for lipid metabolism and AS. Animals studies suggested that SWTX effectively attenuated the atherosclerotic plaque growth, elevated postprandial HDL cholesterol levels, elevated the proportion of Tim4 and CD36-expressed ATMs, and upregulated the uptake of lipid and lysosomal activity in ATMs. SWTX-induced elevation of postprandial HDL cholesterol levels was dependent on increased lysosomal activity, since chloroquine, an inhibitor of lysosomal function, blocked the effect of SWTX. Lastly, some predicated bioactive compounds in SWTX can elevate lysosomal activity in vitro. CONCLUSION: SWTX could attenuate atherosclerotic plaque formation by elevating lysosomal activity and enhancing MCE in ATMs.

An environment-friendly approach using deep eutectic solvent combined with liquid-liquid microextraction based on solidification of floating organic droplets for simultaneous determination of preservatives in beverages.

With the increase in environmental protection awareness, the development of strategies to reduce the use of organic solvent used during the extraction process has attracted wide attention. A simple and green ultrasound-assisted deep eutectic solvent extraction combined with liquid-liquid microextraction based on solidification of floating organic droplets method was developed and validated for the simultaneous determination of five preservatives (methyl paraben, ethyl paraben, propyl paraben, isopropyl paraben, isobutyl paraben) in beverages. Extraction conditions including the volume of DES, value of pH, and concentration of salt were statistically optimized through response surface methodology using a Box-Behnken design. Complex Green Analytical Procedure Index (ComplexGAPI) was successfully used to estimate the greenness of the developed method and compare with the previous methods. As a result, the established method was linear, precise, and accurate over the range of 0.5-20 µg mL-1. Limits of detection and limits of quantification were in the range of 0.15-0.20 µg mL-1 and 0.40-0.45 µg mL-1, respectively. The recoveries of all five preservatives ranged from 85.96% to 110.25%, with relative standard deviation less than 6.88% (intra-day) and 4.93% (inter-day). The greenness of the present method is significantly better compared with the previous reported methods. Additionally, the proposed method was successfully applied to analysis of preservatives in beverages and is a potentially promising technique for drink matrices.

Colorimetric determination of cholesterol based on the peroxidase-like activity of Cu-Salt-Fe nanozyme with multiple active sites.

A strategy to enhance the peroxidase-like activity of the hemin composite is presented. The Cu-Salt-Fe with enhanced activity was synthesized by one-step heat treatment and applied to the colorimetric determination of free cholesterol in human serum. Phosphate can act in complexing Cu2+ to form a carrier Cu-Floc with a large specific surface area. The coordination effect of Cu-Floc with hemin was used to disperse and load hemin to form Cu-Floc-Hemin from which Cu-Salt-Fe was prepared. The Cu-Salt-Fe exhibits a synergistic catalytic effect of Cu-Salt, Fe2+, Fe3+, or Fe-Nx active sites in amplification of H2O2 oxidation. As expected, Cu-Salt-Fe triggered H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), resulting in H2O2-dependent absorbance changes at 652 nm. A cholesterol oxidase (ChOx)/Cu-Salt-Fe-TMB colorimetric sensing system exhibited excellent cholesterol determination performance in the range 5-1200 µM with a detection limit of 2.73 µM. Cholesterol recoveries from the three-level spiked serum ranged from 92.2 to 98.9% (RSD ≤ 5.4). This colorimetric sensing system not only provided a strategy for the determination of endogenous substances with H2O2 as an intermediate, but also provided a new design idea (carrier selection, activity enhancement method) for the development of other artificial enzymes with the same catalytic core.

A Bifunctional Fluorescence Probe Based on AIE-ICT Strategy for Visual Detection of Cu2+/Co2+ in Complex Matrix.

A novel fluorescence chemical sensor-based probe 1-{[(E)-(2-aminophenyl)azanylidene]methyl}naphthalen-2-ol (AMN) was designed and synthesized, which performed a "naked eye" detection ability toward Cu2+ and Co2+ based on aggregation-induced emission (AIE) fluorescence strategy. It has sensitive detection ability for Cu2+ and Co2+. In addition, the color changed from yellow-green to orange under the sunlight, realizing the rapid identification of Cu2+/Co2+, which has the potential of on-site visual detection under the "naked eye". Moreover, different "on" and "off" fluorescence expressions were exhibited under excessive glutathione (GSH) in AMN-Cu2+ and AMN-Co2+ systems, which could be employed to distinguish Cu2+ from Co2+. The detection limits for Cu2+ and Co2+ were measured to be 8.29 × 10-8 M and 9.13 × 10-8 M, respectively. The binding mode of AMN was calculated to be 2:1 by Jobs' plot method analysis. Ultimately, the new fluorescence sensor was applied to detect Cu2+ and Co2+ in real samples (tap water, river water, and yellow croaker), and the results were satisfying. Therefore, this high-efficiency bifunctional chemical sensor platform based on "on-off" fluorescence detection will provide significant guidance for the advance development of single-molecule sensors for multi-ion detection.

Be-original break new ground: Fluorescence sensing of humic acid in natural water and soil by pitaya seed carbon dots.

Pitaya seed carbon dots (P-CDs) with good biocompatibility were synthesized by hydrothermal method using natural biological matrix as carbon source, which applied to the detection of humic acid (HA) for the first time. So far, there is no report on the use of biomatrix-derived carbon dots for the detection of HA. This method can bring less pollution to the detection process of HA, which is very important to ensure lower cost, environmental safety and minimized energy consumption. In addition, it was worth noting that, based on the concept of green chemistry, the preparation process of P-CDs is simple, and the fluorescence method is used for analysis. Based on the fluorescence resonance energy transfer (FRET) mechanism, the detection of HA in water and soil can be realized in a short time. The results matched those of high-performance liquid chromatography (HPLC), suggesting that it shows great potential in water and soil quality monitoring.