Multielement authentication of apples from the cold highlands in southwest China.

BACKGROUND: Half of all apple production worldwide comes from China. However, the geographic authentication of Chinese apples has not been well studied. We highlight the multi-element-based geographical discrimination of apples from the southwest cold highlands (SCH) of China. 565 samples from the SCH (138) and others (427) were obtained, and the content of fifteen elements were applied to construct models for discrimination. RESULTS: The SCH apples from 2017 to 2019 had higher concentrations of Mn, Zn, Cr, Cd, Se, Pb, and Fe, but lower concentrations of Na, B, Ni, and P. With sufficient training, linear discriminant analysis (LDA) discriminated the SCH, and the testing accuracy averaged 92.5% and 92.2%. Nonlinear discrimination models were more suitable than the linear models. Optimized random forest analysis was the model with the best fit, and with averaged training and testing it obtained a level of accuracy of 98.2% and 98.5%. CONCLUSION: The multielement-based discrimination of SCH apples could aid further studies of geographical origins. © 2021 Society of Chemical Industry.

Geographical origin of Chinese apples based on multiple element analysis.

BACKGROUND: Apples from different regions of China show different qualities and internal characteristics, and appeal to different customers. However, these aspects have not been studied in depth. We characterized the profiles of 14 elements in 317 apple samples collected from five regions of China. Principal component analysis (PCA), linear discriminant analysis (LDA), and back-propagation artificial neural networks analysis (BP-ANN) were used to build models for apple authentication. RESULTS: Fourteen elements were successfully identified in apple samples by performing graphite furnace atomic absorption spectrometry (GFAAS) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) analyses. Comparative analysis showed significantly different element profiles in samples from different regions. The first five principal components obtained by PCA accounted for 71.8% of the total variance. The LDA obtained 70.0% classification rates. The BP-ANN obtained 82.7% classification rates. CONCLUSION: This study indicated the possibility that apples could be authenticated based on differences in their element profiles, and provided a basis for further geographical origin studies. © 2019 Society of Chemical Industry.

Voltammetric immunoassay for α-fetoprotein by using a gold nanoparticle/dendrimer conjugate and a ferrocene derived ionic liquid.

An immunosensor is described for the voltammetric determination of α-fetoprotein. It is making use of an AuNP-dendrimer conjugate and an ionic liquid. A gold electrode was first modified with chitosan. Then, the AuNP-dendrimer conjugate was covalently immobilized on the electrode. Following this, an ionic liquid was placed on the electrode via formation of a covalent bond between the amino groups of PAMAM and the aldehyde groups of an ionic liquid containing ferrocene. Thus, the redox probe ferrocene becomes immobilized on the electrode surface. PAMAM increases the amount of ferrocene immobilized on the electrode due to its globular shape and rich amino groups. The use of AuNPs improves the conductivity of the electrode. The modified electrode was applied to the determination of α-fetoprotein in human serum and has a linear response that covers the 0.05 to 30 ng mL-1 α-fetoprotein concentration range, with a detection limit of 0.02 ng mL-1. This assay is stable, selective and reproducible. It is perceived to provide a powerful tool for the early detection of cancer markers. Graphical abstract Schematic of a voltammetric immunoassay for α-fetoprotein based on a gold nanoparticle/dendrimer conjugate and ionic liquids anchored with both aldehyde and ferrocene. Chit: chitosan; GA: glutaraldehyde ; PAMAM: G4 polyamidoaminic dendrimers; AuNP: Au nanoparticle; Fc: ferrocene; IL: ionic liquid. PB: phosphate buffer solution.

The fabrication of a label-free electrochemical immunosensor using Nafion/carbon nanotubes/charged pyridinecarboxaldehyde composite film.

A label-free electrochemical immunosensor based on Nafion/carbon nanotubes (CNTs)/charged pyridinecarboxaldehyde composite film was developed for the detection of hepatitis B surface antigen. Nafion/CNTs/charged pyridinecarboxaldehyde nanocomposites were prepared by dispersing charged pyridinecarboxaldehyde and CNTs in Nafion solution. The nanocomposites were cast on the electrode surface to form aldehyde-terminated composite film that can covalently bind antibody on the film without using other reagent. The immunosensor response was linearly changed with hepatitis B surface antigen concentration in the range from 0.1 to 25 ng ml(-1) with a detection limit (signal/noise ratio = 3) of 0.04 ng ml(-1). Some important advantages such as simple preparation, good stability, reproducibility, and selectivity of the immunosensor were achieved.

Electrochemical immunosensor based on Pd-Au nanoparticles supported on functionalized PDDA-MWCNT nanocomposites for aflatoxin B1 detection.

This paper reports a label-free electrochemical immunosensor for the determination of aflatoxin B1 (AFB1), which is based on a gold electrode modified by a biocompatible film of carbon nanotubes/poly(diallyldimethylammoniumchloride)/Pd-Au nanoparticles (CNTs/PDDA/Pd-Au). The nanocomposite was characterized by transmission electron microscopy and the electrochemical behavior of modified electrodes was investigated by cyclic voltammetry. The CNTs/PDDA/Pd-Au nanocomposites film showed good electron transfer ability, which ensured high sensitivity to detect AFB1 in a range from 0.05 to 25 ng mL(-1) with a detection limit of 0.03 ng mL(-1) obtained at 3σ (where σ is the standard deviation of the blank solution, n = 10). The proposed immunosensor provides a simple tool for AFB1 detection. This strategy can be extended to any other antigen detection by using the corresponding antibodies.

Direct immobilization of antibodies on a new polymer film for fabricating an electrochemical impedance immunosensor.

A new polymer bearing aldehyde groups was designed and synthesized by grafting 4-pyridinecarboxaldehyde onto poly(epichlorohydrin). Antibodies can be directly immobilized on the surface of the polymer film through the covalent bonding of aldehyde groups of the film with amino groups of antibodies. In this study, human immunoglobulin G (IgG) was used as a model analyte for the fabrication of an electrochemical impedance immunosensor. Using the proposed immunosensor, IgG in the range from 0.1 to 80 ng ml(-1) was detected with a detection limit of 0.07 ng ml(-1) (signal/noise [S/N]=3). In addition, the electrochemical impedance immunosensor displays good stability and reproducibility.

One-step immobilization of antibodies for α-1-fetoprotein immunosensor based on dialdehyde cellulose/ionic liquid composite.

A novel immunosensor for α-1-fetoprotein based on dialdehyde cellulose/ionic liquid composite film as a matrix has been developed. Microcrystalline cellulose was activated by sodium metaperiodate to produce dialdehyde cellulose. Antibodies can be immobilized on the electrode by a one-step method through covalent bonding of the aldehyde groups of dialdehyde cellulose with the amino groups of antibodies, in which no additional chemical cross-linking step is required. Moreover, ionic liquid added can improve the conductivity of the sensing interface and, therefore, can enhance the electrochemical signal. In this work, α-1-fetoprotein was detected within the range from 0.1 to 60ngml(-1) with a detection limit of 0.07ngml(-1) (signal/noise=3). The proposed immunosensor had good specificity and reproducibility. It was used to determine real samples with satisfactory results.

The development of an electrochemical immunosensor using a thiol aromatic aldehyde and PAMAM-functionalized Fe3O4@Au nanoparticles.

In this work, a novel thiol aromatic aldehyde was synthesized. It can be used as a substrate to directly immobilize antibodies on a gold electrode, for which no additional chemical cross-linker is required. It was also applied as a linker to prepare Fe3O4@Au/PAMAM/Ab2-horseradish peroxidase bioconjugates, which introduced multiple enzymes onto a sensing interface owing to the high surface-to-volume ratio of Fe3O4@Au nanoparticles and many functional groups of the poly(amidoamine) dendrimer (PAMAM). The introduced multiple enzymes greatly improved the detection signal. Under optimal conditions, the proposed electrochemical immunosensor exhibited desirable performance for detection of IgG in the range 0.005-50 ng ml(-1) with a detection limit of 3 pg ml(-1) based on a signal-to-noise ratio of 3. It has great potential application in the area of clinical analysis.

DNA Interaction, Photocleavage and Topoisomerase I Inhibition by Ru(II) Complex with a New Ligand Possessing Phenazine Unit.

A new ruthenium complex with a dppz-like ligand pyidppz, [Ru(bpy)2(pyidppz)](2+) (pyidppz = 2-(pyridine-2-yl)imidazo-[4,5-b]dipyrido-[3,2-a:2',3'-c]phenazine) has been synthesized and characterized by ES-MS, elemental analysis, (1)H NMR. Intercalative mode of the complex bound to calf thymus DNA has been supported by different spectroscopic methods and viscosity measurements. The introduction of phenazine unit may be one of the main reasons for the weak emission of Ru(II) complex in aqueous solution. Under irradiation, this complex can efficiently cleave DNA. And the photocleavage reaction of the complex is found to be inhibited in the presence of singlet oxygen scavenger. Topoisomerase inhibition and DNA strand passage assay demonstrated that [Ru(bpy)2(pyidppz)](2+) and its parent complex [Ru(bpy)2(pyip)](2+) (pyip = 2-(pyridine-2-yl)imidazo[4,5-f][1,10]phenanthroline) can act as efficient catalytic inhibitor of DNA topoisomerase I.

In vivo and in vitro metabolism of aspirin eugenol ester in dog by liquid chromatography tandem mass spectrometry.

Aspirin eugenol ester (AEE) is a promising drug candidate for treatment of inflammation, pain and fever and prevention of cardiovascular diseases with fewer side effects than its precursor, aspirin. Investigation into its metabolic process in target animal species will help to illustrate its mechanism of action and to establish its residual mark compound to formulate its dosage. Six beagle dogs were orally given a dose of 20 mg kg(-1) of AEE and one dog was used to prepare blank liver microsomes. Their liver microsomes were prepared for in vitro study and their plasma and urine were collected for in vivo metabolic analysis using liquid chromatography tandem mass spectrometry. In this study we identified 10 metabolites, M1, M2, M3, M4, M5 in phase I and M6, M7, M8, M9, M10 in phase II. Based on the metabolites of AEE, the pathways of AEE metabolism in dog were demonstrated.

Sensitive detection of acetylcholine based on a novel boronate intramolecular charge transfer fluorescence probe.

A highly sensitive and selective fluorescence method for the detection of acetylcholine (ACh) based on enzyme-generated hydrogen peroxide (H2O2) and a new boronate intramolecular charge transfer (ICT) fluorescence probe, 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-N-butyl-1,8-naphthalimide (BN), was developed. This strategy involves the reaction of ACh with acetylcholinesterase (AChE) to produce choline, which is further oxidized by choline oxidase (ChOx) to obtain betaine and H2O2. The enzyme-generated H2O2 reacts with BN and results in hydrolytic deprotection of BN to generate fluorescent product (4-hydroxyl-N-butyl-1,8-naphthalimide, ON). Two consecutive linear response ranges allow determining ACh in a wide concentration range with a low detection limit of 2.7 nM (signal/noise=3). Compared with other fluorescent probes based on the mechanism of nonspecific oxidation, this reported boronate probe has the advantage of no interference from other biologically relevant reactive oxygen species (ROS) on the detection of ACh. This study provides a new method for the detection of ACh with high selectivity and sensitivity.

Discrimination of apples from the surrounding Bohai Bay and the loess plateau: A combined study of ICP-MS and UPLC-Q-TOF-MS based element and metabolite fingerprints.

Apples are important fruits in China, and their authentication is beneficial for quality control. However, the differentiation between apples from two primary producing regions, the surrounding Bohai Bay (BHB) and the Loess Plateau (LP), has not been well studied. This study used element and metabolite fingerprints combined with mathematical recognition techniques to discriminate between BHB and LP apples. A total of 235 samples were collected from these regions during 2018-2019. The apple element and metabolite profiles were obtained via instrument analysis. Differential elements and metabolites between BHB and LP apples were identified, and linear and nonlinear discriminant models were constructed. Nonlinear models demonstrated higher accuracy and effectiveness in model optimization. The final random forest (RF) model, constructed with 11 elements and 51 metabolites, achieved a training accuracy of 91.51% and a validation accuracy of 98.57%. This study discriminated between BHB and LP apples, providing a foundation for apple authentication.

Visualization of cysteine in AD mouse with a high-quantum yield NIR fluorescent probe.

Alzheimer's disease (AD) has gradually received enthusiastic attention with the aging process, and studying its biological relevance is expected. Excitingly, fluorescence probes were considered to be powerful tools for exploring biological correlations. Therefore, a highly selective near-infrared (NIR) fluorescent probe (DCM-Cl-Acr) for imaging cysteine (Cys) in AD was designed and synthesized. Through structural optimization, the probe exhibited high fluorescence quantum yield and low detection limit (20 nM) towards Cys. Meanwhile, based on the high selectivity and high sensitivity response exhibited by the probe to Cys, it was successfully applied to visualize endogenous and exogenous Cys in living cells and zebrafish, and showed good discrimination from homocysteine (Hcy) and glutathione (GSH). Further, the correlation between AD and Cys concentration was clarified by imaging studies in hippocampus tissue of AD mouse, and the abnormal accumulation of Cys in the hippocampus of AD brain was demonstrated.

Quantitative lipidomics reveals the changes of lipids and antioxidant capacity in egg yolk from laying hens with fatty liver hemorrhagic syndrome.

In laying hens, fatty liver hemorrhagic syndrome (FLHS) is a common metabolic disorder, which can affect egg production and nutritional value. However, the impact of FLHS on the lipid content in egg yolks was not clear. In this study, FLHS model was induced by using high-energy low-protein diet, and the egg quality was evaluated. Egg yolk lipids were quantitatively analyzed by using ultra-performance liquid chromatography-mass spectrometry combined with multivariate statistical analysis. Gene expressions of the lipoprotein were determined by qRT-PCR and antioxidant capacity of the egg yolk were determined by kits. The elevated blood lipids and extensive lipid droplets observed indicated successful establishment of the FLHS model in laying hens. Measurements of egg quality showed that egg yolk weight was increased in the FLHS group. Lipidomics revealed that 1,401 lipids, comprising 27 lipid subclasses in the egg yolk. According to score plots of principal component analysis and orthogonal partial least squares discriminant analysis, different lipid profile was observed between the control and FLHS groups. A total of 97 different lipid species were screen out. Sphingolipid and glycerophospholipid metabolism were identified as key pathways. Free polyunsaturated fatty acids (PUFA) exhibited an increase in the FLHS group (P < 0.05). Notably, the form of PUFAs was changed that the FLHS group showed an increase in triacylglycerol-docosahexenoic acid and triacylglycerol-arachidonic acid in the egg yolk, while triacylglycerol-α-linolenic acid was decreased (P < 0.05). Total superoxide dismutase was decreased in the egg yolks affected by FLHS. Gene expressions of vitellogenin 2 (VTG2), VTG3, very low-density apolipoprotein II and apolipoprotein B were increased in the liver of laying hens with FLHS (P < 0.05). In conclusion, FLHS promoted the lipid transport from the liver to the yolk by upregulating lipoprotein expression, which altered lipid profile, and reduced antioxidant capacity in the yolk. This study provided a foundation for understanding the changes in lipids, lipid transport and lipid antioxidation capacity in egg yolk from laying hens with FLHS.

Simple Coumarin-Based Fluorescent Probe for Recognition of Pd(II) and Its Live Cell Imaging.

A simple coumarin hydrazine Schiff base bearing a thioether recognition fragment (compound CBBS) has been rationally designed and easily prepared. CBBS exhibited an excellent selectivity for Pd(II) and a low detection limit of 65 nM (S/N = 3). The fluorescence emission intensities of CBBS at 495 nm were linear to Pd(II) concentrations in a wide range from 0 to 80 µM. Moreover, CBBS has been well used in fluorescence imaging of Pd(II) in living A549 cells. CBBS as a simple coordination-based fluorescent probe will inspire the researchers to develop a polymer for selective detection and adsorption of Pd(II).

An ESIPT-based reversible ratiometric fluorescent sensor for detecting HClO/H2S redox cycle in living cells.

HClO and H2S, as two kinds of crucial small biomolecules, are endowed various roles in biological organisms. The redox balance between HClO and H2S is closely related to the physiological and pathological processes. Thus, it is significant to monitor the redox process between HClO and H2S. Inspired by the advantages of ratiometric fluorescent probes, we firstly developed a reversible ratiometric fluorescent probe (BT-Se) for HClO and H2S via combination of phenyl selenide as the response group and 2-(2'-hydroxyphenyl)benzothiazole dye as the fluorophore. The proposed probe BT-Se could detect HClO with well-separated dual emission (110 nm), fast response, good selectivity and sensitivity owing to the oxidation reaction of the Se atom induced by HClO. Moreover, only H2S could effectively recover the fluorescence of the detection system to the original state via H2S induced-reduction of selenoxide. Cell imaging studies demonstrated that the probe BT-Se was capable of ratiometric monitoring the changes of intracellular HClO/H2S, which suggested that it has great potential for researching the biological functions of HClO and H2S.

A mitochondrion targetable dimethylphosphorothionate-based far-red and colorimetric fluorescent probe with large Stokes shift for monitoring peroxynitrite in living cells.

Peroxynitrite (ONOO-) is a biological oxidant that is related to numerous physiological and pathological processes. An overdose of ONOO- is the cause of various serious diseases. Some evidence demonstrates that mitochondria are the major sites of ONOO- production. Therefore, monitoring mitochondrial ONOO- is important to understand the related pathological processes in living systems. Herein, a colorimetric and far-red fluorescent sensing probe (PCPA) for the determination of ONOO- was constructed based on a dicyanoisophorone skeleton using dimethylphosphorothionate as the recognition group and pyridine salt as the mitochondrion-targeting unit. PCPA showed a far-red fluorescence response to ONOO- accompanied by a distinct color change from colorless to yellow via the ONOO- induced deprotection of dimethylphosphorothionate. In addition, PCPA exhibited a large Stokes shift (200 nm), high selectivity detection and high sensibility (LOD = 39 nM). Furthermore, PCPA was successfully employed for imaging ONOO- and tracing ONOO- in mitochondria. PCPA presents a new recognition group and has potential applications in the biology field.

Authentication of apples from the Loess Plateau in China based on interannual element fingerprints and multidimensional modelling.

Apple is an important fruit, and fruit authentication is significant for quality and safety control. The Loess Plateau (LP) in China is an important apple-producing region. However, the geographic authentication of LP apples has not been well studied. In this study, we discriminated LP apples based on multielement analysis. We analysed the differences in 29 elements of 522 samples collected from LP and others in 2018-2020 and constructed discriminant models for LP apple authentication. Linear discriminant analysis, partial least square-discriminant analysis, back-propagation artificial neural networks, and random forest (RF) showed different rates in training and validation accuracy. RF showed better tolerance to the removal of the less-important elements in model optimization. The final RF was optimized on 11 elements, which obtained 95.30% training accuracy for the 2018-2019 samples and 97.29% validation accuracy for the 2020 samples. The multielement-based authentication of LP apples could aid further studies of geographical origins.

Effect of peach trichome removal on post-harvest brown rot and on the fruit surface microbiome.

Postharvest peaches undergo rapid soft ripening and are susceptible to fungal diseases, which often result in severe losses during storage. The peach epidermis contains trichomes that form a specific structure on the peach surface. However, the relationship between trichomes and postharvest disease and involved mechanisms has not been well studied. In this study, the removal of trichomes reduced the disease incidence of peach brown rot caused by Monilinia fructicola. Cryo-scanning electron microscope observations showed that the fungal hyphae were found attached to the surface of trichomes. The fungal and bacterial communities on the peach surface at 0 d and 6 d were obtained by amplicon sequencing technology. Fungal communities on the peach surface contained a total of 1089 amplicon sequence variants (ASVs), which were demarcated into eight fungal phyla, 25 classes, 66 orders, 137 families, and 228 genera. The bacterial communities contained 10,821 ASVs assigned to 25 phyla, 50 classes, 114 orders, 220 families, and 507 genera. Higher bacterial diversity than fungal diversity was recorded on the peach epidermis. Trichome removal changed the microbial diversity and community on the peach surface. Compared with peach epidermis samples, the peach epidermis excluded trichomes samples contained similar fungal alpha diversity but significantly lower bacterial diversity. Seventeen different fungal genera and twenty-eight different bacterial genera were identified between peach trichome and peach epidermis excluded trichomes samples. The fungal and bacterial diversity on the peach epidermis showed a decreasing trend during storage. Beta diversity analysis revealed that the microbial communities of the peach epidermis and trichomes show different change trends between 0 d and 6 d. Trichome removal decreased relative abundance of Monilinia spp. and increased relative abundance of potential yeast and bacterial biocontrol agents. This study suggested that trichomes might modulate the microbial communities on fruit surfaces, and trichome removal technology after harvest might be developed to control peach postharvest decay.

Boosting cycling stability through Al(PO3)3 loading in a Na4MnV(PO4)3/C cathode for high-performance sodium-ion batteries.

Mn-based NASICON-type Na4MnV(PO4)3 (NMVP) has been widely investigated as one of the most promising alternatives to Na3V2(PO4)3 cathodes for sodium-ion batteries (SIBs) due to its higher energy density, higher abundance, and lower cost and toxicity compared to V. However, electrochemical performance for large-scale applications is limited by NMVP's inferior conductivity and structural degradation during cycling. Herein, a facile strategy to modify the surface/interphase properties of NMVP/C was reported using the thermally stable Al(PO3)3 precursor with a wet process followed by heat treatment to enhance the interface stability of electrodes. The nanomodified layer has the benefits of an ionic conductor (slight NaPO3) and robust composite (Al(PO3)3), which can facilitate the stability of Mn-based cathode materials and ionic conductivity. These merits endow 1 wt% Al(PO3)3-loaded NMVP/C cathodes with a high rate performance (102/61 mAh g-1 at 0.2/50 C) and impressive cyclability (88.5%/89.7% at 5 C/10 C after 3000/4000 cycles) in Na-ion batteries at 2.5-3.8 V. Moreover, when the cutoff voltage is raised to 4 V, improved electrochemical properties (111.6/50.8 mAh g-1 at 0.2/10 C and 71.4% after 1000 cycles at 5 C) are also realized. Such an enhancement indicates that facial surface modification engineering limits organic electrolyte erosion, inhibits transition metal dissolution and suppresses surface lattice degradation, which is confirmed by ex situ X-ray diffractometry and transmission electron microscopy. Therefore, the Al(PO3)3 surface modification strategy combined with mechanism analysis can provide a possible reference for advanced electrochemical properties in energy storage devices.