A computational and experimental study of cis-trans isomeric pesticides based on collision-induced dissociation of high-resolution mass spectrometry.

RATIONALE: Pesticide isomers are widely available in agricultural production and may vary widely in biological activity, potency, and toxicity. Chromatographic and mass spectrometric analysis of pesticide isomers is challenging due to structural similarities. METHODS: Based on liquid chromatography time-of-flight mass spectrometry, identification of cis-trans isomeric pesticides was achieved through retention time, characteristic fragment ions, and relative abundance ratio. Furthermore, theoretical and basic research has been conducted on the differences in characteristic fragment ions and their relative abundance ratios of cis-trans isomers. On the one hand, the cleavage pathways of six cis-trans isomers were elucidated through collision-induced dissociation to explain different fragment ions of the isomers. On the other hand, for those with the same fragment ions but different abundance ratios, energy-resolved mass spectrometry combined with computational chemical density functional theory in terms of kinetics, thermodynamics, and bond lengths was employed to explain the reasons for the differences in characteristic fragment ions and their abundance ratios. RESULTS: A high-resolution mass spectrometry method was developed for the separation and analysis of cis-trans isomers of pesticides in traditional Chinese medicine Radix Codonopsis, and six pesticide isomers were distinguished by retention time, product ions, and relative abundance ratios. The limits of quantification of the six pesticides were up to 10 µg/kg, and the linear ranges of them were 10-200 µg/kg, with coefficients of determination (R2) > 0.99, which demonstrated the good linearity of the six pesticides. The recoveries of the pesticides at spiked concentrations of 10, 20, and 100 µg/kg reached 70-120% with relative standard deviations ≤20%. CONCLUSIONS: It was demonstrated that the application of the method was well suited for accurate qualitative and quantitative analysis for isomers with different structures, which could avoid false-negative results caused by ignoring other isomers effectively.

Comparative efficacy of different growth hormone supplementation protocols in improving clinical outcomes in women with poor ovarian response undergoing assisted reproductive therapy: a network meta-analysis.

Growth hormone (GH) has a long-standing history of use as an adjunctive therapy in the treatment of poor ovarian response (POR), but the optimal dosage and timing remains unclear. The aim of this study was to evaluate and compare the efficacy of different GH supplementation protocols through a network meta-analysis (NMA) and determine the optimal treatment protocol. This study was reported based on the Preferred Reporting Items for Systematic Reviews for Network Meta-Analysis (PRISMA-NMA) statement. Databases including PubMed, Web of Science, Cochrane Library and Embase were searched until June 2023. A total of 524 records were retrieved in our search, and 23 clinical studies comprising 4889 cycles were involved. Seven different GH protocols were identified. Results showed that compared to the control group, daily administration of 4-8 IU of GH during the follicular phase of the stimulation cycle had the best comprehensive therapeutic effects on improving the number of retrieved oocytes, mature oocytes, endometrial thickness, and reducing gonadotropin requirements in POR patients undergoing assisted reproductive therapy, with a relatively brief treatment duration and a moderate total GH dose. Subgroup analysis demonstrated that this protocol could significantly improve the clinical pregnancy rate of POR patients in the randomized controlled trials (RCT) subgroup and the African subgroup. Therefore, its clinical application is suggested. Besides, the potential advantages of long-term GH supplementation protocol (using GH for at least 2 weeks before oocyte retrieval) has merit for further research. Rigorous and well-designed multi-arm RCTs are needed in the future to confirm the conclusions drawn from this study.

Flavor characterization of Citri Reticulatae Pericarpium (Citrus reticulata 'Chachiensis') with different aging years via sensory and metabolomic approaches.

Guangchenpi (GCP), which is the peel of Citrus reticulata 'Chachiensis', is widely used as an herbal medicine, tea and food ingredient in southeast Asia. Prolonging its aging process results in a more pleasant flavor and increases its profitability. Through the integration of sensory evaluation with flavoromic analysis approaches, we evaluated the correlation between the flavor attributes and the profiles of the volatiles and flavonoids of GCP with various aging years. Notably, d-limonene, γ-terpinene, dimethyl anthranilate and α-phellandrene were the characteristic aroma compounds of GCP. Besides, α-phellandrene and nonanal were decisive for consumers' perception of GCP aging time due to changes of their odor activity values (OAVs). The flavor attributes of GCP tea liquid enhanced with the extension of aging time, and limonene-1,2-diol was identified as an important flavor enhancer. Combined with machine learning models, key flavor-related metabolites could be developed as efficient biomarkers for aging years to prevent GCP adulteration.

New steroidal saponins from the aerial parts of Paris polyphylla var. yunnanensis and their effects on blood coagulation.

Five new steroidal saponins, paripolins D-H (1-5), and 6 known compounds (6-11) were isolated from the aerial parts of Paris polyphylla var. yunnanensis. The structures of 1-5 were determined using spectroscopic analyses in conjunction with acid hydrolysis. It is for the first time to report the 12-hydroxysteroidal saponins from the genus Paris. The effect of all isolated compounds on blood coagulation was determined in vitro using the plasma recalcification time method. Compounds 1 and 2 showed potent procoagulant activity, and 5-11 exhibited significant anticoagulant activity.

Characterisation and identification of chemical constituents in aqueous extract of Fomes officinalis Ames based on ultrahigh-performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometry.

INTRODUCTION: Fungal species are an attractive resource for physiologically functional food and drug precursor. Fomes officinalis Ames, a medicinal fungus, is traditionally used as a folk medicine in traditional Chinese medicine prescription for the therapy of cough and asthma. The water-soluble substances in Chinese herbal medicines are likely to play an important physiological function. However, information on probing and identifying chemical components of the aqueous extract of Fomes officinalis Ames (AFO) remains unknown. OBJECTIVE: This study was conducted to screen and characterise the chemical components of AFO. MATERIAL AND METHODS: An effective and sensitive ultrahigh-performance liquid chromatography tandem quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap-HRMS) method with the Full MS/PIL/dd-MS2 acquisition approach was applied for the profiling of chemical components in AFO. An HSS T3 column was used for component separation, and a strategy of simultaneous targeted and untargeted multicomponent characterisation was implemented. Multiple identification approaches were used, including accurate molecular mass and elemental composition matching, literature and database searching, and fragmentation rules elucidation. RESULTS: A total of 115 components, including 20 amino acids and derivatives, six nucleobases, nine nucleosides, 75 dipeptides, two tripeptides, and three other components, were tentatively identified. Among them, the targeted exploring method screened six nucleobases and nine nucleosides including modified nucleosides. To our best knowledge, this is the first time a report has been done on the presence of the 115 compounds in AFO. CONCLUSION: Profiling and characterisation compounds of AFO enriched its material basis, which would lay the foundation for improving potential medicinal and nutritional values and effecting comprehensive quality control of Fomes officinalis Ames.

New Target for Minoxidil in the Treatment of Androgenetic Alopecia.

Objective: To investigate the mechanism of minoxidil in treating androgenetic alopecia (AGA). Methods: The mechanism of action of minoxidil on AGA was first systematically investigated from the viewpoint of network pharmacology, including minoxidil-AGA target prediction, protein-protein interaction (PPI) network analysis, molecular docking and enrichment analysis of targets related to minoxidil and AGA, and dermal papilla cell assays to confirm the viability of prediction. Results: The combined analysis revealed that minoxidil treatment of AGA not only acts on androgenic receptors (AR) but also on 2 new targets, steroid 17-alpha-hydroxylase/17,20 lyase (CYP17A1) and aromatase (CYP19A1). The biological processes linked to these targets were concentrated on several pathways, including enzymes and hormones. Further experiments have revealed that minoxidil suppresses the expression of AR and CYP17A1, boosts the activity of CYP19A1, decreases the formation and binding of dihydrotestosterone, and enhances the production of estradiol. Through these changes, minoxidil acts as a treatment for AGA. Conclusion: Minoxidil may act by altering hormonal and enzymatic pathways. Our study finds two new targets (CYP17A1, CYP19A1) of minoxidil and demonstrates that minoxidil inhibits AR. These targets may provide new ideas for drug research.

The efficacy of acupuncture combined with other therapies in post stroke cognitive impairment: A network meta-analysis.

BACKGROUND: The network meta-analysis was used to evaluate the efficacy of acupuncture combined with other therapies in the treatment of post stroke cognitive impairment (PSCI). METHODS: The China National Knowledge Infrastructure, Wanfang DATA, Vip Chinese Periodic Service Platform, PUBMED, Cochrane Library, Web of Science, and Embase were searched for randomized controlled trials (RCTs) published before March 18, 2023. Two researchers independently reviewed articles and extracted data, and then qualified papers were included in the study. STATA 14.0 was used for network meta-analysis. RESULTS: A total of 29 articles including 2241 patients were included in this study. The treatment of the intervention group includes acupuncture combined with traditional Chinese medicine prescriptions (TCMP), acupuncture combined with hyperbaric oxygen (HBO), acupuncture combined with repetitive transcranial magnetic stimulation (rTMS), acupuncture combined with cognitive rehabilitation (CR), acupuncture combined with donepezil. The intervention of the control group includes acupuncture, HBO, rTMS, CR, TCMP, and donepezil. In terms of improving the score of Minimum Mental State Examination (MMSE), acupuncture combined with TCMP was most likely to be the best treatment (P < .05). In terms of improving the score of Montreal Cognitive Assessment (MoCA), acupuncture combined with TCMP was most likely to be the best treatment (P < .05). In terms of improving the total effective rate of clinical treatment, acupuncture combined with rTMS was most likely to be the best treatment (P < .05). CONCLUSION: Acupuncture combined with TCMP may be the best treatment method among all of the above treatments for PSCI.

Magnetic graphitized carbon black based on crystal growth method combined with high-resolution mass spectrometry for screening of 300 pesticide residues in Radix Codonopsis and Angelica sinensis.

In this study, a high-throughput method for analyzing 300 pesticide residues in Radix Codonopsis and Angelica sinensis was established by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-Q-TOF/MS) using iron tetroxide loaded graphitized carbon black magnetic nanomaterial (GCB/Fe3O4) as the purification material. It was optimized that saturated salt water and 1 % acetate acetonitrile were used as the extraction solution, then the supernatant was purified with 2 g anhydrous CaCl2 and 300 mg GCB/Fe3O4. As a result, 300 pesticides in Radix Codonopsis and 260 in Angelica sinensis achieved satisfactory results. The limits of quantification of 91 % and 84 % of the pesticides in Radix Codonopsis and Angelica sinensis reached 10 µg/kg, respectively. The matrix-matched standard curves ranging from 10 to 200 µg/kg were established with correlation coefficients (R) above 0.99. The pesticides meeting SANTE/12682/2021 accounted for 91.3 %, 98.3 %, 100.0 % and 83.8 %, 97.3, 100.0 % of the total pesticides added in Radix Codonopsis and Angelica sinensis respectively, which were spiked at 10, 20,100 µg/kg. The technique was applied to screen 20 batches of Radix Codonopsis and Angelica sinensis. Five pesticides were detected, three of which were prohibited according to the Chinese Pharmacopoeia (2020 Edition). The experimental results showed that GCB/Fe3O4 coupled with anhydrous CaCl2 exhibited good adsorption performance and could be used for sample pretreatment of various pesticide residues in Radix Codonopsis and Angelica sinensis. Compared with the reported methods for determining pesticides in traditional Chinese medicine (TCM), the proposed method has the advantage of less time-consuming in the clean-up procedure. Furthermore, as a case study on root TCM, this approach may serve as a reference for other TCM.

Effects of programmed flexor-extensor alternating electrical acupoint stimulation on upper limb motor functional reconstruction after stroke: study protocol for a double-blind, randomized controlled trial.

BACKGROUND: Stroke's prevalence and morbidity are increasing (Guano, et al. Neuro 89:53-61, 2017), and limb motor dysfunction is left in most patients (Gittler, et al. JAMA 319:820-821, 2018). Particularly, the rehabilitation of upper limbs is more difficult and time-consuming (Borges, et al. The Cochrane database of systematic reviews 10:CD011887, 2018). METHODS: A double-blind randomized controlled trial (RCT) will be conducted to investigate whether a new functional electrical stimulation (FES) combined with acupoint therapy is more effective in the rehabilitation of upper limb motor dysfunction after stroke. Patients who meet the inclusion criteria will be randomly divided into two groups: programmed flexor-extensor alternating electrical acupoint stimulation group (PES group) and conventional flexor-extensor alternating electrical acupoint stimulation group (CES group), which will be treated for 3 weeks. The primary outcome measures are electroencephalogram (EEG) and surface electromyogram (sEMG). The secondary outcome variables include MBI (modified Barthel index), China Stroke Scale (CSS), FMA-U (Fugl-Meyer assessment upper limb), MMT (manual muscle testing), and Brunnstrom. DISCUSSION: The results of this study are expected to verify the efficacy of PES therapy in the rehabilitation of upper limb motor function after stroke. This may promote the widespread use of the therapy in hospitals, communities, and homes for early and continuous treatment. TRIAL REGISTRATION: ClinicalTrials.gov NCT05333497. Registered on April 11, 2022.

A liquid chromatography-time-of-flight/mass spectrometry method for analysis of pesticides and transfer behavior in Radix Codonopsis and Angelica sinensis decoctions.

The safety of traditional Chinese medicine (TCM) has garnered considerable interest worldwide. In this study, a high-throughput method for the determination of 255 pesticide residues in decoctions of Radix Codonopsis and Angelica sinensis was developed using liquid chromatography-time-of-flight/mass spectrometry. The methodological verification demonstrated the accuracy and reliability of this method. The frequently detected pesticides in Radix Codonopsis and Angelica sinensis were determined to build a correlation between pesticide properties and the transfer rate of pesticide residues in their decoctions. Water solubility (WS) with a higher correlation coefficient (R) made a significant contribution to the accuracy of the transfer rate prediction model. The regression equations for Radix Codonopsis and Angelica sinensis were T = 13.64 log WS + 10.56 with a correlation coefficient (R) of 0.8617 and T = 10.66 log WS + 25.48 with a correlation coefficient (R) of 0.8072, respectively. This study provides preliminary data on the potential risk of exposure to pesticide residues in Radix Codonopsis and Angelica sinensis decoctions. Furthermore, as a case study on root TCM, this approach may serve as a model for other TCMs.

Uptake, Translocation, and Terminal Residue of Chlorantraniliprole and Difenoconazole in Rice: Effect of the Mixed-Application with Adjuvant.

Plant oil adjuvants are widely used to improve the utilization rate of pesticides. In this study, the uptake, translocation, and terminal residue of chlorantraniliprole and difenoconazole spraying with plant oil adjuvant in rice (Oryza sativa L.) were evaluated. After being mixed with the tank-mixed plant oil adjuvant, the cuticular wax of rice leaf was destroyed, which decreased the hydrophobicity of the rice leaf and facilitated the wetting, spreading, and penetration of pesticides onto the rice leaf. Additionally, the adjuvant promoted the translocation of difenoconazole from leaves to stems, but had little effect on the translocation of difenoconazole from leaves to roots, while inhibiting chlorantraniliprole translocation. Although adjuvant increased the initial deposition of chlorantraniliprole and difenoconazole on rice, the terminal residue was not significantly affected. The findings can promote the safe use of chlorantraniliprole and difenoconazole in rice production, especially when used with plant oil adjuvants. In the future, studies on more rice cultivars will be necessary to determine the generality of the conclusions.

Electrochemical Detection of ompA Gene of C. sakazakii Based on Glucose-Oxidase-Mimicking Nanotags of Gold-Nanoparticles-Doped Copper Metal-organic Frameworks.

The present work developed an electrochemical genosensor for the detection of virulence outer membrane protein A (ompA, tDNA) gene of Cronobacter sakazakii (C. sakazakii) by exploiting the excellent glucose-oxidase-mimicking activity of copper Metal-organic frameworks (Cu-MOF) doped with gold nanoparticle (AuNPs). The signal nanotags of signal probes (sDNA) that biofunctionalized AuNPs@Cu-MOF (sDNA-AuNPs@Cu-MOF) were designed using an Au-S bond. The biosensor was prepared by immobilization capture probes (cDNA) onto an electrodeposited AuNPs-modified glassy carbon electrode (GCE). AuNPs@Cu-MOF was introduced onto the surface of the GCE via a hybridization reaction between cDNA and tDNA, as well as tDNA and sDNA. Due to the enhanced oxidase-mimicking activity of AuNPs@Cu-MOF to glucose, the biosensor gave a linear range of 1.0 × 10-15 to 1.0 × 10-9 mol L-1 to tDNA with a detection limit (LOD) of 0.42 fmol L-1 under optimized conditions using differential pulse voltammetry measurement (DPV). It can be applied in the direct detection of ompA gene segments in total DNA extracts from C. sakazakii with a broad linear range of 5.4-5.4 × 105 CFU mL-1 and a LOD of 0.35 CFU mL-1. The biosensor showed good selectivity, fabricating reproducibility and storage stability, and can be used for the detection of ompA gene segments in real samples with recovery between 87.5% and 107.3%.

Anti-Inflammatory Activity of Panax notoginseng Flower Saponins Quantified Using LC/MS/MS.

Panax notoginseng (Burk) F. H. Chen is a traditional Chinese medicinal and edible plant. However, Panax notoginseng flower (PNF) is rarely used. Therefore, the purpose of this study was to explore the main saponins and the anti-inflammatory bioactivity of PNF saponins (PNFS). We explored the regulation of cyclooxygenase 2 (COX-2), a key mediator of inflammatory pathways, in human keratinocyte cells treated with PNFS. A cell model of UVB-irradiation-induced inflammation was established to determine the influence of PNFS on inflammatory factors and their relationship with LL-37 expression. An enzyme-linked immunosorbent assay and Western blotting analysis were used to detect the production of inflammatory factors and LL37. Finally, liquid chromatography-tandem mass spectrometry was employed to quantify the main active components (ginsenosides Rb1, Rb2, Rb3, Rc, Rd, Re, Rg1, and notoginsenoside R1) in PNF. The results show that PNFS substantially inhibited COX-2 activity and downregulated the production of inflammatory factors, indicating that they can be used to reduce skin inflammation. PNFS also increased the expression of LL-37. The contents of ginsenosides Rb1, Rb2, Rb3, Rc, and Rd in PNF were much higher than those of Rg1, and notoginsenoside R1. This paper provides data in support of the application of PNF in cosmetics.

Screening Multidrug Resistance Reversal Agents in Traditional Chinese Medicines by Efflux Kinetics of D-Luciferin in MCF-7/DOXFluc Cells.

In this study, we established a simple and rapid in vitro method for screening multidrug resistance (MDR) reversal agents in traditional Chinese medicines (TCMs), which could better correspond to the MDR reversing effect in vivo. Here, D-luciferin, a substrate for the enzyme firefly luciferase and also a substrate for ATP-binding cassette transporters (ABC transporters), was used as the probe to detect its efflux kinetics caused by ABC transporters. First, we established a stable doxorubicin (DOX)-resistant cell line (MCF-7/DOXFluc) that overexpressed luciferase. Then, some kinds of TCMs were chosen for the MDR reversal agents to measure its effect on inhibiting the D-luciferin outflow from MCF-7/DOXFluc, and the ideal reversal agent with the least D-luciferin efflux from MCF-7/DOXFluc was selected to further investigate its effect combined with DOX on MCF-7/DOXFluc tumor-bearing mice. The results indicated that quercetin (Qu) could remarkably increase the retention of D-luciferin in MCF-7/DOXFluc in vitro and in vivo. Also, the combination of Qu and DOX could exceedingly inhibit the tumor growth, which proved the feasibility of this in vitro screening method. The study proposed a feasible method for mass screening of MDR agents from TCMs in vitro.

Effect of tank-mixed adjuvant on the behavior of chlorantraniliprole and difenoconazole in soil.

In this study, both laboratory and field studies were performed to analyze the effect of the presence of tank-mixed methylated plant oil adjuvant on the adsorption and degradation of chlorantraniliprole (CAP) and difenoconazole (DIF) in soil. Adsorption kinetics and isotherms experiments were conducted according to the equilibrium oscillation method. Fourier transform infrared spectroscopy (FT-IR) analysis, soil contact angle, and zeta potential were used to research the interaction mechanism of adsorption. Fluorescence excitation emission matrix (FEEM) measurements were conducted to characterize soil dissolved organic matter. Field experiment was conducted to investigate the degradation of CAP and DIF combined with adjuvant. DIF exhibited a significantly higher Freundlich maximum adsorption capacity than CAP, which is consistent with the higher octanol-water partition coefficient of DIF. The sorption of CAP and DIF under laboratory conditions was significantly increased with the presence of adjuvant. Soils with high humic acids have strong adsorption capacity and contribute to significant adsorption of CAP and DIF. The half-lives of CAP and DIF tested in fluvo-aquic soil under field conditions were slightly reduced by the adjuvant. Adjuvant reduced the Groundwater Ubiquity Score (GUS) indices of CAP from 1.51 to 1.31, whereas that of DIF from 0.39 to 0.25. Combination between the pesticides and soil molecules can be enhanced, thereby promoting the adsorption and degradation of CAP and DIF in soil, and further reducing their potential to leach into groundwater when 0.1% methylated plant oil adjuvant was mixed and applied.

The mediating effects of coping styles on the relationship between trait mindfulness and romantic relationship satisfaction.

The purpose of the current study was to explore the influence of coping styles and trait mindfulness on the satisfaction of romantic relationships (RRS) among college students. Of the 305 participants, 258 (males: 115, 44.6%) had previously been in, or were presently in a romantic relationship. All participants completed the MAAS, CSQ, and questions about RRS. There was a significant meditating role of mature coping styles in the relationship between trait mindfulness and RRS (indirect effect [95% CI] = 0.021 [0.001, 0.052]). However, the mediating effect of immature coping styles was not significant (indirect effect [95% CI] = 0.038 [-0.020, 0.097]). Mature coping style plays an important mediating role in the relationship between mindfulness and relationship satisfaction.

Development of a photothermal-sensing microfluidic paper-based analytical chip (PT-Chip) for sensitive quantification of diethylstilbestrol.

The continuous intake of diethylstilbestrol (DES) residue seriously threatens the health of consumers, so the rapid and sensitive detection of DES is helpful for timely food safety warning. In this study, a photothermal-sensing microfluidic paper-based analytical chip (PT-Chip) was developed for effectively screening of DES residue in foods. Competitive inhibition immunochromatography was introduced and the composite of black phosphorus nanosheets and gold nanoparticles (BP-Au) was used as signal indicators. Then, the test area was irradiated by an 808 nm laser and the photothermal transduction signal was recorded by a thermal imager to achieve sensitive photothermal detection. The amount of DES was obtained by analyzing the temperature change curve of test area. The PT-Chip can achieve accurate quantification of DES with a detection limit of 0.1 µg/L. And the successful determination of DES in different food samples indicating that the PT-Chip can be used as a promising detection device.

Sample size estimation in acupuncture imaging research. / æ ·æœ¬é‡ä¼°ç®—åœ¨é’ˆç¸å½±åƒå­¦ç ”ç©¶ä¸­çš„åº”ç”¨ä¸Žæ€è€ƒ.

The size of the sample significantly impacts the accuracy of research outcomes. While preliminary results have been achieved in acupuncture imaging research, sample size estimation is often subjective and arbitrary, leading to insufficient reliability of study results. This article reviews the current application of sample size estimation in acupuncture imaging research, and provides recommendations to address existing issues. It is suggested that future researches should include the sample sizes that meet statistical power based on the characteristics of functional magnetic resonance imaging (fMRI) protocols, with group sizes of 12 and 20-30 cases having become the "minimum requirement" for confirmatory studies and a common choice. Additionally, the adoption of adaptive design approaches, which dynamically adjust sample sizes based on accumulated data, can be considered. Furthermore, efforts should be made to establish an open platform for sharing acupuncture imaging data to enhance data accessibility, and consequently, improve the quality and overall impact of acupuncture imaging research.

A fluorescent aptasensor based on gold nanoparticles quenching the fluorescence of rhodamine B to detect acetamiprid.

Pesticide residue detection is one of the main safety issues in the utilization of medicinal plants. In this work, a highly selective and sensitive aptasensor for acetamiprid determination was designed. The mechanism of the proposed method is based on the fluorescence resonance energy transfer (FRET) between gold nanoparticles (AuNPs) and rhodamine B (RB). Aptamers protect AuNPs from salt-induced aggregation, which causes fluorescence quenching of RB by the AuNPs via surface energy transfer. In the absence of acetamiprid, AuNPs were coated with aptamers on the surface and dispersed in NaCl solution. At this time, the dispersed AuNPs could perfectly quench the fluorescence intensity of RB. In contrast, in the presence of acetamiprid, aptamers specifically combine with acetamiprid to form a complex. With a high salt concentration, AuNPs would be aggregated without aptamer protection, weakening the RB quenching effect. Therefore, the concentration of acetamiprid could be obtained from the change in fluorescence intensity in the system. A fluorescent sensing method was established with a linear range from 0.1 to 3 µg mL-1, and the LOD was 0.0285 µg mL-1. The recoveries of acetamiprid in traditional Chinese medicine (TCM) samples were 96.23-105.75%. This method has great application value for the detection of acetamiprid in a complex sample matrix.

An electrochemical biosensor for the detection of aflatoxin B1 based on the specific aptamer and HCR biological magnification.

Aflatoxin B1 (AFB1) is a highly toxic mycotoxin, which causes severe acute or cumulative poisoning. Therefore, it is important to develop sensitive and selective detection methods for AFB1 for the safety of food and medicinal herbs. Herein, we have developed a "signal-on" electrochemical aptasensor based on the high specificity of the aptamer and hybridization chain reaction (HCR) biological amplification for AFB1 detection. In this work, thiol-modified complementary DNA (cDNA) immobilized on the surface of a gold electrode (GE) served as an initiator DNA. When AFB1 was present, it competed with the cDNA for binding to the aptamers, which resulted in the detaching of aptamers from the cDNA-aptamer duplexes. Then, the single-stranded cDNA acted as an initiator to trigger the HCR signal amplification. Therefore, long double-stranded DNA (dsDNA) products were produced, which could load large amounts of methylene blue (MB) molecules to generate a distinct electrochemical signal. Under the optimized conditions, the proposed electrochemical aptasensor achieved the ultrasensitive detection of AFB1 with a linear detection range of 0.01-100 pg mL-1, and a limit of detection (LOD) down to 2.84 fg mL-1. Furthermore, the electrochemical aptasensor was successfully applied for detecting AFB1 in corn and two kinds of traditional Chinese medicine samples, indicating the potential value for AFB1 detection in practical samples.