Polyamidoamine starburst dendrimer-activated chromatography paper-based assay for sensitive detection of telomerase activity

Publication date: 1 February 2018 Source:Talanta, Volume 178 Author(s): Hua Zhang, Zhen Lei, Rongrong Tian, Zhenxin Wang Telomerase is extensively expressed in various cancer cells and recognized as a target for cancer drug dis…

Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Hua Zhang, Zhen Lei, Rongrong Tian, Zhenxin Wang

Telomerase is extensively expressed in various cancer cells and recognized as a target for cancer drug discovery. In the present study, a simple and amplification-free fluorescence assay based on polyamidoamine starburst dendrimer (PAMAM dendrimer)-activated paper device is proposed for sensitive detection of telomerase activity through hybridization of Cy5 modified single strand DNA probes with telomerase extension products. The paper substrate is fabricated by hand drawing according to a template, which is low cost, instrument free and easy operation. PAMAM is rich in amino groups on its surface and employed to immobilize the telomerase substrate (TS) primer. Highly sensitive detection of telomerase activity in HeLa cell lysate of 10 cells is achieved since the PAMAM dendrimer-activated paper surface can provide high density of binding sites for immobilization of TS primer. The experimental results also demonstrate that the assay can be employed to evaluate telomerase activity levels of various cell lines and screen telomerase inhibitors.

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Use of a small molecule as an initiator for interchain staudinger reaction: A new ATP sensing platform using product fluorescence

Publication date: 1 February 2018 Source:Talanta, Volume 178 Author(s): Huan Yu, Jing Zheng, Sheng Yang, Abdullah M. Asiri, Khalid A. Alamry, Mingtai Sun, Kui Zhang, Suhua Wang, Ronghua Yang We demonstrated that a sma…

Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Huan Yu, Jing Zheng, Sheng Yang, Abdullah M. Asiri, Khalid A. Alamry, Mingtai Sun, Kui Zhang, Suhua Wang, Ronghua Yang

We demonstrated that a small molecule induced interchain Staudinger reaction can be employed for highly selective detection of adenosine triphosphate (ATP), an important energy-storage biomolecule. A designed ATP split aptamer (A1) was first functionalized with a weakly fluorescent coumarin derivative due to an azide group (azido-coumarin). The second DNA strand (A2) was covalently linked with triphenylphosphine, which could selectively and efficiently reduce azido to amino group through the Staudinger reaction. The A2 was then hybridized with a half of another designed longer DNA strand (T1). The second half of T1 was a split aptamer and selectively recognized ATP with A1 to form a sandwich structure. The specific interaction between ATP and the aptamers drew the two functionalized DNA strands (A1 and A2) together to initiate the interchain Staudinger reduction at fmol-nmol concentration level, hence produced fluorescent 7-aminocoumarin which could be used as an indicator for the presence of trace ATP. The reaction process had a concentration dependent manner with ATP in a large concentration range. Such a strategy of interchain Staudinger reaction can be extended to construct biosensors for other small functional molecules on the basis of judiciously designed aptamers.

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Ratiometric fluorescence and visual imaging detection of dopamine based on carbon dots/copper nanoclusters dual-emitting nanohybrids

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Weijie He, Rijun Gui, Hui Jin, Benqian Wang, Xiangning Bu, Yongxin Fu
In this article, blue-emitting carbon dots (CDs) were prepared via hydrothermal treatment of sodium citrate and NH4HCO3, and then combined with 3-aminophenylboronic acid (APBA) to prepare APBA modified-CDs. APBA acted as the receptor of dopamine (DA). Using bovine serum albumin (BSA) as a stabilizer and N2H4·H2O as a reducing reagent, BSA-stabilized and red-emitting copper nanoclusters (CuNCs) were prepared. By carbodiimide-activated coupling, novel nanohybrids consisting of CDs and CuNCs were constructed and exhibited dual-emitting fluorescence (FL). In the presence of DA, marked FL (at 440nm) quenching of nanohybrids was detected. Specific coupling interactions between boric acid of APBA and cis-glycol of DA induced the combination of DA and APBA on the surface of CDs. As a superior electron receptor, DA triggered the electron transfer from CDs to DA, resulting in the FL quenching of CDs in nanohybrids. The FL (at 640nm) of CuNCs in nanohybrids was almost unchanged after the addition of DA, and so further used for a reference FL to develop a novel ratiometric FL probe for DA detection. In addition to high sensitivity and selectivity, superior analytical performances of this probe were confirmed in applications, including dual-signal FL sensing of DA and naked-eye visual FL imaging of DA in aqueous solution and on filter paper.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Weijie He, Rijun Gui, Hui Jin, Benqian Wang, Xiangning Bu, Yongxin Fu

In this article, blue-emitting carbon dots (CDs) were prepared via hydrothermal treatment of sodium citrate and NH4HCO3, and then combined with 3-aminophenylboronic acid (APBA) to prepare APBA modified-CDs. APBA acted as the receptor of dopamine (DA). Using bovine serum albumin (BSA) as a stabilizer and N2H4·H2O as a reducing reagent, BSA-stabilized and red-emitting copper nanoclusters (CuNCs) were prepared. By carbodiimide-activated coupling, novel nanohybrids consisting of CDs and CuNCs were constructed and exhibited dual-emitting fluorescence (FL). In the presence of DA, marked FL (at 440nm) quenching of nanohybrids was detected. Specific coupling interactions between boric acid of APBA and cis-glycol of DA induced the combination of DA and APBA on the surface of CDs. As a superior electron receptor, DA triggered the electron transfer from CDs to DA, resulting in the FL quenching of CDs in nanohybrids. The FL (at 640nm) of CuNCs in nanohybrids was almost unchanged after the addition of DA, and so further used for a reference FL to develop a novel ratiometric FL probe for DA detection. In addition to high sensitivity and selectivity, superior analytical performances of this probe were confirmed in applications, including dual-signal FL sensing of DA and naked-eye visual FL imaging of DA in aqueous solution and on filter paper.

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Thin-film microextraction coupled to surface enhanced Raman scattering for the rapid detection of benzoic acid in carbonated beverages

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Lemei Cai, Jing Dong, Yiru Wang, Xi Chen
Benzoic acid (BA) is widely used as an antimicrobial preservative in carbonated beverages. In this study, silica gel thin-film microextraction (TFME) coupled to surface enhanced Raman scattering (SERS) was applied for the rapid detection of BA in carbonated beverages. The TFME process was performed by placing small pieces of silica gel substrate in a simple homemade device, and then the content of BA was detected using SERS after colloidal gold was uniformly dropped onto the substrate. The obtained SERS signals of BA were strong and of high reproducibility. A good linearity between the concentration of BA and the SERS signal intensity at 994cm−1 in the range of 25–500μgmL−1 was obtained under optimal experimental conditions. The detection limit value was found to be 3.6μgmL−1 and the recovery of the spiked BA was in the range 85.0–103.0%. The developed method was successfully applied to detect BA in carbonated beverage samples as the results were consistent with those using high performance liquid chromatography, suggesting that it is a rapid, convenient and sensitive way to achieve BA detection in carbonated beverages.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Lemei Cai, Jing Dong, Yiru Wang, Xi Chen

Benzoic acid (BA) is widely used as an antimicrobial preservative in carbonated beverages. In this study, silica gel thin-film microextraction (TFME) coupled to surface enhanced Raman scattering (SERS) was applied for the rapid detection of BA in carbonated beverages. The TFME process was performed by placing small pieces of silica gel substrate in a simple homemade device, and then the content of BA was detected using SERS after colloidal gold was uniformly dropped onto the substrate. The obtained SERS signals of BA were strong and of high reproducibility. A good linearity between the concentration of BA and the SERS signal intensity at 994cm−1 in the range of 25–500μgmL−1 was obtained under optimal experimental conditions. The detection limit value was found to be 3.6μgmL−1 and the recovery of the spiked BA was in the range 85.0–103.0%. The developed method was successfully applied to detect BA in carbonated beverage samples as the results were consistent with those using high performance liquid chromatography, suggesting that it is a rapid, convenient and sensitive way to achieve BA detection in carbonated beverages.

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A flow injection procedure using Layered Double Hydroxide for on line pre-concentration of fluoride

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Diego P. Rocha, Gabriel C. Terra, Thaís S. Nery, Jairo Tronto, Frederico G. Pinto, Sidnei G. Silva, Nívia M.M. Coelho
This work showed a flow system designed with solenoid valves for preconcentration of fluoride using SPADNS method in water samples. The analyte was preconcentrated in a mini-column coated with Layered Double Hydroxides (LDH) used as adsorbent. Then, the fluoride ions were eluted with 0.5molL−1 sodium hydroxide and determined by spectrophotometry. The variables that affect the system such adsorbent mass, type of eluent, solutions flow rate, reagent concentration and pH effect were critically evaluated. Under optimized conditions, the detection limit, coefficient of variation, linear range and preconcentration factor were estimated at 15µgL−1 (99.7% confidence level), 0.8% (500µgL−1, n = 10), 50–500µgL−1 and 10, respectively. The accuracy of the method was evaluated by analysis of ALPHA APS 1076 (Simulated Rain Water) certified material, the values were not significantly different at a 95% level of confidence. The method was applied for fluoride determination in water samples and the levels found were below the maximum values established by Brazilian environmental and health legislations.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Diego P. Rocha, Gabriel C. Terra, Thaís S. Nery, Jairo Tronto, Frederico G. Pinto, Sidnei G. Silva, Nívia M.M. Coelho

This work showed a flow system designed with solenoid valves for preconcentration of fluoride using SPADNS method in water samples. The analyte was preconcentrated in a mini-column coated with Layered Double Hydroxides (LDH) used as adsorbent. Then, the fluoride ions were eluted with 0.5molL−1 sodium hydroxide and determined by spectrophotometry. The variables that affect the system such adsorbent mass, type of eluent, solutions flow rate, reagent concentration and pH effect were critically evaluated. Under optimized conditions, the detection limit, coefficient of variation, linear range and preconcentration factor were estimated at 15µgL−1 (99.7% confidence level), 0.8% (500µgL−1, n = 10), 50–500µgL−1 and 10, respectively. The accuracy of the method was evaluated by analysis of ALPHA APS 1076 (Simulated Rain Water) certified material, the values were not significantly different at a 95% level of confidence. The method was applied for fluoride determination in water samples and the levels found were below the maximum values established by Brazilian environmental and health legislations.

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Alteration in the liver metabolome of rats with metabolic syndrome after treatment with Hydroxytyrosol. A Mass Spectrometry And Nuclear Magnetic Resonance – based metabolomics study

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Ioanna Dagla, Dimitra Benaki, Eirini Baira, Nikolaos Lemonakis, Hemant Poudyal, Lindsay Brown, Anthony Tsarbopoulos, Alexios-Leandros Skaltsounis, Emmanouel Mikros, Evagelos Gikas
Metabolic syndrome (MetS) represents a group of abnormalities that enhances the risk for cardiovascular disease, diabetes and stroke. The Mediterranean diet seems to be an important dietary pattern, which reduces the incidence of MetS. Hydroxytyrosol (HT) – a simple phenol found in olive oil – has received increased attention for its antioxidant activity. Recently, the European Foods Safety Authority (EFSA) claimed that dietary consumption of HT exhibits a protective role against cardiovascular disease. In this study, an experimental protocol has been setup, including isolated HT administration in a diet induced model of MetS in young Wistar rats, in order to find out whether HT has a protective effect against MetS. Rats were randomly divided into two groups nurtured by high-carbohydrate high-fat (H) (MetS inducing diet) and high-carbohydrate high-fat + HT (HHT). HT (20mg/kg/d oral gavage, water vehicle) was administered for 8 weeks on the basal diet. Previous pharmacological evaluation of HT showed that hepatic steatosis was reduced and the inflammatory cells into the liver were infiltrated. These indicate that HT shows bioactivity against metabolic syndrome. Therefore, the metabolomics evaluation of liver extracts would indicate the putative biochemical mechanisms of HT activity. Thus, the extracts of liver tissues were analyzed using Ultra Performance Liquid Chromatography – High Resolution Mass Spectrometry (UPLC-HRMS, Orbitrap Discovery) and Nuclear Magnetic Resonance (NMR) spectroscopy (Bruker Avance III 600MHz). Multivariate analysis was performed in order to gain insight on the metabolic effects of HT administration on the liver metabolome. Normalization employing multiple internal standards and Quality Control–based Robust LOESS (LOcally Estimated Scatterplot Smoothing) Signal Correction algorithm (QC-RLSC) was added in the processing pipeline to enhance the reliability of metabolomic analysis by reducing unwanted information. Experimentally, HHT rats were clearly distinguished from H in PLS-DA, showing differences in the liver metabolome between the groups and specific biomarkers were determined supporting the pharmacological findings. More specifically, HT has shown to be effective towards the mobilization of lipids as various lipid classes being differentially regulated between the H and HHT groups. Interestingly branched fatty acid esters of hydroxy oleic acids (OAHSA) lipids have been shown to be up regulated to the HHT group, denoting the alleviation of the MetS to the animals administered with HT.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Ioanna Dagla, Dimitra Benaki, Eirini Baira, Nikolaos Lemonakis, Hemant Poudyal, Lindsay Brown, Anthony Tsarbopoulos, Alexios-Leandros Skaltsounis, Emmanouel Mikros, Evagelos Gikas

Metabolic syndrome (MetS) represents a group of abnormalities that enhances the risk for cardiovascular disease, diabetes and stroke. The Mediterranean diet seems to be an important dietary pattern, which reduces the incidence of MetS. Hydroxytyrosol (HT) - a simple phenol found in olive oil - has received increased attention for its antioxidant activity. Recently, the European Foods Safety Authority (EFSA) claimed that dietary consumption of HT exhibits a protective role against cardiovascular disease. In this study, an experimental protocol has been setup, including isolated HT administration in a diet induced model of MetS in young Wistar rats, in order to find out whether HT has a protective effect against MetS. Rats were randomly divided into two groups nurtured by high-carbohydrate high-fat (H) (MetS inducing diet) and high-carbohydrate high-fat + HT (HHT). HT (20mg/kg/d oral gavage, water vehicle) was administered for 8 weeks on the basal diet. Previous pharmacological evaluation of HT showed that hepatic steatosis was reduced and the inflammatory cells into the liver were infiltrated. These indicate that HT shows bioactivity against metabolic syndrome. Therefore, the metabolomics evaluation of liver extracts would indicate the putative biochemical mechanisms of HT activity. Thus, the extracts of liver tissues were analyzed using Ultra Performance Liquid Chromatography – High Resolution Mass Spectrometry (UPLC-HRMS, Orbitrap Discovery) and Nuclear Magnetic Resonance (NMR) spectroscopy (Bruker Avance III 600MHz). Multivariate analysis was performed in order to gain insight on the metabolic effects of HT administration on the liver metabolome. Normalization employing multiple internal standards and Quality Control–based Robust LOESS (LOcally Estimated Scatterplot Smoothing) Signal Correction algorithm (QC-RLSC) was added in the processing pipeline to enhance the reliability of metabolomic analysis by reducing unwanted information. Experimentally, HHT rats were clearly distinguished from H in PLS-DA, showing differences in the liver metabolome between the groups and specific biomarkers were determined supporting the pharmacological findings. More specifically, HT has shown to be effective towards the mobilization of lipids as various lipid classes being differentially regulated between the H and HHT groups. Interestingly branched fatty acid esters of hydroxy oleic acids (OAHSA) lipids have been shown to be up regulated to the HHT group, denoting the alleviation of the MetS to the animals administered with HT.

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Forensic utility of a nitrogen and oxygen isotope ratio time series of ammonium nitrate and its isolated ions

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Brittany L. Grimm, Libby A. Stern, Alexander J. Lowe
Ammonium nitrate (AN) based fertilizers are inexpensive and easily obtained, characteristics that often lead to their use in homemade explosive devices. The stable nitrogen and oxygen isotope ratios (15N/14N and 18O/16O, expressed as δ15N and δ18O) of AN have the potential to aid in forensic investigations by providing supplemental properties for sample-to-sample comparison in materials which are otherwise chemically identical. The forensic utility of stable isotope analyses depends on demonstrated variation between different sources and minimal variation within a source. To test the variability within a single manufacturer (here considered a source), a total of 26 samples representing two production time periods and two product lines were analyzed for bulk δ15N and δ18O. Additionally, because AN is known to have a modest isotopic range, a potassium nitrate precipitation method was developed to separate the component ions (NO3 and NH4+) for individual δ15N analysis and increased discriminatory power. The average δ15N and δ18O of bulk AN (− 0.10‰ and + 22.8‰, respectively) is similar to the isotopic signature of atmospheric N2 and O2, the starting reactants in AN production. The bulk δ15N, δ18O, and NO3 δ15N show average values from both product lines that differ by 1.5‰, 2.0‰, and 2.6‰, respectively, between the production periods of June and November 2015. Conversely, the NH4+ δ15N remained relatively consistent over time. Furthermore, whereas samples in the two product lines produced on the same day in June are isotopically similar, there are isotopic differences between samples in the two product lines manufactured within 6h of each other in November. The observed variability could be useful in comparing AN from two or more bombs, or a bomb and a stash of AN in a suspect’s possession, but the observed lot-to-lot differences within one manufacturer could complicate attribution efforts. In contrast, the NH4+ δ15N values, which appear to be the most consistent over time within this factory, need to be further explored as a potentially reliable signal.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Brittany L. Grimm, Libby A. Stern, Alexander J. Lowe

Ammonium nitrate (AN) based fertilizers are inexpensive and easily obtained, characteristics that often lead to their use in homemade explosive devices. The stable nitrogen and oxygen isotope ratios (15N/14N and 18O/16O, expressed as δ15N and δ18O) of AN have the potential to aid in forensic investigations by providing supplemental properties for sample-to-sample comparison in materials which are otherwise chemically identical. The forensic utility of stable isotope analyses depends on demonstrated variation between different sources and minimal variation within a source. To test the variability within a single manufacturer (here considered a source), a total of 26 samples representing two production time periods and two product lines were analyzed for bulk δ15N and δ18O. Additionally, because AN is known to have a modest isotopic range, a potassium nitrate precipitation method was developed to separate the component ions (NO3 - and NH4 +) for individual δ15N analysis and increased discriminatory power. The average δ15N and δ18O of bulk AN (− 0.10‰ and + 22.8‰, respectively) is similar to the isotopic signature of atmospheric N2 and O2, the starting reactants in AN production. The bulk δ15N, δ18O, and NO3 - δ15N show average values from both product lines that differ by 1.5‰, 2.0‰, and 2.6‰, respectively, between the production periods of June and November 2015. Conversely, the NH4 + δ15N remained relatively consistent over time. Furthermore, whereas samples in the two product lines produced on the same day in June are isotopically similar, there are isotopic differences between samples in the two product lines manufactured within 6h of each other in November. The observed variability could be useful in comparing AN from two or more bombs, or a bomb and a stash of AN in a suspect's possession, but the observed lot-to-lot differences within one manufacturer could complicate attribution efforts. In contrast, the NH4 + δ15N values, which appear to be the most consistent over time within this factory, need to be further explored as a potentially reliable signal.

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Simultaneous determination of tert-butylhydroquinone, propyl gallate, and butylated hydroxyanisole by flow-injection analysis with multiple-pulse amperometric detection

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Dmytro Bavol, Anastasios Economou, Jiri Zima, Jiri Barek, Hana Dejmkova
We report the first amperometric method for the simultaneous determination of tert-butylhydroquinone (tBHQ), propyl gallate (PG), and butylated hydroxyanisole (BHA) using flow injection analysis coupled to multiple-pulse amperometry. A sequence of potential pulses was selected in order to detect tBHQ, PG, and BHA separately in a single injection step at a glassy carbon electrode without the need of a preliminary separation. A mixture of methanol and 0.040M Britton-Robinson buffer was used both as a carrier solution and for dilution of analyzed solutions before injection. The method is precise (RSD < 5%, n = 10), fast (a frequency of 140 injections h−1), provides sufficiently low quantification limits (2.51, 1.45, and 0.85μmolL–1 for tBHQ, PG, and BHA, respectively) and can be easily applied without high demands on instrumentation. As a practical application, the determination of these antioxidants contained in commercial chewing gum samples was carried out by applying a simple extraction procedure.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Dmytro Bavol, Anastasios Economou, Jiri Zima, Jiri Barek, Hana Dejmkova

We report the first amperometric method for the simultaneous determination of tert-butylhydroquinone (tBHQ), propyl gallate (PG), and butylated hydroxyanisole (BHA) using flow injection analysis coupled to multiple-pulse amperometry. A sequence of potential pulses was selected in order to detect tBHQ, PG, and BHA separately in a single injection step at a glassy carbon electrode without the need of a preliminary separation. A mixture of methanol and 0.040M Britton-Robinson buffer was used both as a carrier solution and for dilution of analyzed solutions before injection. The method is precise (RSD < 5%, n = 10), fast (a frequency of 140 injections h−1), provides sufficiently low quantification limits (2.51, 1.45, and 0.85μmolL–1 for tBHQ, PG, and BHA, respectively) and can be easily applied without high demands on instrumentation. As a practical application, the determination of these antioxidants contained in commercial chewing gum samples was carried out by applying a simple extraction procedure.

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One-step detection for two serological biomarker species to improve the diagnostic accuracy of hepatocellular carcinoma

Publication date: 1 February 2018 Source:Talanta, Volume 178 Author(s): Tao Gao, Jun Zhi, Chaoli Mu, Shiyu Gu, Jing Xiao, Jie Yang, Zhaoxia Wang, Yang Xiang At present, the accuracy of clinical hepatocellular carcinoma …

Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Tao Gao, Jun Zhi, Chaoli Mu, Shiyu Gu, Jing Xiao, Jie Yang, Zhaoxia Wang, Yang Xiang

At present, the accuracy of clinical hepatocellular carcinoma (HCC) diagnosis needs to be further improved. In this work, two kinds of serological biomarker species, microRNA and protein biomarker, have been detected simultaneously to identify HCC. Herein, a dual-aptamer hairpin DNA oligonucleotide is designed as the electrochemical sensing probe (ESP) to achieve this goal. The hairpin-structured DNA probe consists microRNA-16 (miR-16) complementary sequence and alpha fetoprotein (AFP) aptamer sequence, so it can both capture miR-16 and AFP. Once it hybridizes with miR-16, the hairpin structure is unlocked so that the terminal modified signal molecule (methylene blue, MB) would give a decreased electrochemical signal. Meanwhile, once it recognizes AFP, concanavalin A (ConA) modified silver nanoparticles (AgNPs) can bind to AFP at the sensing surface. An obvious electrochemical signal of AgNPs can thus be generated for AFP detection. In this way, one-step and simultaneous detection of miRNA-16 and AFP can easily be realized by collecting the two sensitive and non-interfering electrochemical signals. Compared with traditional single biomarker detection methods, this assay strategy can improve the accuracy of HCC by monitoring two kinds of serological biomarkers species. Besides, this novel electrochemical biosensor based on ESP is simple, low-cost and efficient, which make it promising to improve the accuracy and specificity for the diagnosis HCC in the future.

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Controlled modification of electrochemical microsystems with polyethylenimine/reduced graphene oxide using electrophoretic deposition: Sensing of dopamine levels in meat samples

Publication date: 1 February 2018 Source:Talanta, Volume 178 Author(s): Karima Kahlouche, Roxana Jijie, Ioana Hosu, Alexandre Barras, Tijani Gharbi, Reda Yahiaoui, Guillaume Herlem, Marhoun Ferhat, Sabine Szunerits, R…

Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Karima Kahlouche, Roxana Jijie, Ioana Hosu, Alexandre Barras, Tijani Gharbi, Reda Yahiaoui, Guillaume Herlem, Marhoun Ferhat, Sabine Szunerits, Rabah Boukherroub

Microsystems play an important role in many biological and environmental applications. The integration of electrical interfaces into such miniaturized systems provides new opportunities for electrochemical sensing where high sensitivity and selectivity towards the analyte are requested. This can be only achieved upon controlled functionalization of the working electrode, a challenge for compact microsystems. In this work, we demonstrate the benefit of electrophoretic deposition (EPD) of reduced graphene oxide/polyethylenimine (rGO/PEI) for the selective modification of a gold (Au) microelectrode in a microsystem comprising a Pt counter and a Ag/AgCl reference electrode. The functionalized microsystem was successfully applied for the sensing of dopamine with a detection limit of 50nM. Additionally, the microsystem exhibited good performance for the detection of dopamine levels in meat samples.

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Evaluation of electrochemical, UV/VIS and Raman spectroelectrochemical detection of Naratriptan with screen-printed electrodes

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Carla Navarro Hernández, Daniel Martín-Yerga, María Begoña González-García, David Hernández-Santos, Pablo Fanjul-Bolado
Naratriptan, active pharmaceutical ingredient with antimigraine activity was electrochemically detected in untreated screen-printed carbon electrodes (SPCEs). Cyclic voltammetry and differential pulse voltammetry were used to carry out quantitative analysis of this molecule (in a Britton-Robinson buffer solution at pH 3.0) through its irreversible oxidation (diffusion controlled) at a potential of +0.75V (vs. Ag pseudoreference electrode). Naratriptan oxidation product is an indole based dimer with a yellowish colour (maximum absorption at 320nm) so UV–VIS spectroelectrochemistry technique was used for the very first time as an in situ characterization and quantification technique for this molecule. A reflection configuration approach allowed its measurement over the untreated carbon based electrode. Finally, time resolved Raman Spectroelectrochemistry is used as a powerful technique to carry out qualitative and quantitative analysis of Naratriptan. Electrochemically treated silver screen-printed electrodes are shown as easy to use and cost-effective SERS substrates for the analysis of Naratriptan.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Carla Navarro Hernández, Daniel Martín-Yerga, María Begoña González-García, David Hernández-Santos, Pablo Fanjul-Bolado

Naratriptan, active pharmaceutical ingredient with antimigraine activity was electrochemically detected in untreated screen-printed carbon electrodes (SPCEs). Cyclic voltammetry and differential pulse voltammetry were used to carry out quantitative analysis of this molecule (in a Britton-Robinson buffer solution at pH 3.0) through its irreversible oxidation (diffusion controlled) at a potential of +0.75V (vs. Ag pseudoreference electrode). Naratriptan oxidation product is an indole based dimer with a yellowish colour (maximum absorption at 320nm) so UV–VIS spectroelectrochemistry technique was used for the very first time as an in situ characterization and quantification technique for this molecule. A reflection configuration approach allowed its measurement over the untreated carbon based electrode. Finally, time resolved Raman Spectroelectrochemistry is used as a powerful technique to carry out qualitative and quantitative analysis of Naratriptan. Electrochemically treated silver screen-printed electrodes are shown as easy to use and cost-effective SERS substrates for the analysis of Naratriptan.

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Assessment of cyanide contamination in soils with a handheld mid-infrared spectrometer

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): José M. Soriano-Disla, Leslie J. Janik, Michael J. McLaughlin
We examined the feasibility of using handheld mid-infrared (MIR) Fourier-Transform infrared (FT-IR) instrumentation for detecting and analysing cyanide (CN) contamination in field contaminated soils. Cyanide spiking experiments were first carried out, in the laboratory, to test the sensitivity of infrared Fourier transform (DRIFT) spectrometry to ferro- and ferricyanide compounds across a range of reference soils and minerals. Both benchtop and handheld diffuse reflectance infrared spectrometers were tested. Excellent results were obtained for the reference soils and minerals, with the MIR outperforming the near-infrared (NIR) range. Spectral peaks characteristic of the –C≡N group were observed near 2062 and 2118cm-1 in the MIR region for the ferro- and ferricyanide compounds spiked into soils/minerals, respectively. In the NIR region such peaks were observed near 4134 and 4220cm-1. Cyanide-contaminated samples were then collected in the field and analyzed with the two spectrometers to further test the applicability of the DRIFT technique for soils containing aged CN residues. The prediction of total CN in dry and ground contaminated soils using the handheld MIR instrument resulted in a coefficient of determination (R2) of 0.88–0.98 and root mean square error of the cross-validation (RMSE) of 21–49mgkg-1 for a CN range of 0–611mgkg-1. A major peak was observed in the MIR at about 2092cm-1 which was attributed to “Prussian Blue” (Fe4[Fe(CN)6]3·xH2O). These results demonstrate the potential of handheld DRIFT instrumentation as a promising alternative to the standard laboratory method to predict CN concentrations in contaminated field soils.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): José M. Soriano-Disla, Leslie J. Janik, Michael J. McLaughlin

We examined the feasibility of using handheld mid-infrared (MIR) Fourier-Transform infrared (FT-IR) instrumentation for detecting and analysing cyanide (CN) contamination in field contaminated soils. Cyanide spiking experiments were first carried out, in the laboratory, to test the sensitivity of infrared Fourier transform (DRIFT) spectrometry to ferro- and ferricyanide compounds across a range of reference soils and minerals. Both benchtop and handheld diffuse reflectance infrared spectrometers were tested. Excellent results were obtained for the reference soils and minerals, with the MIR outperforming the near-infrared (NIR) range. Spectral peaks characteristic of the –C≡N group were observed near 2062 and 2118cm-1 in the MIR region for the ferro- and ferricyanide compounds spiked into soils/minerals, respectively. In the NIR region such peaks were observed near 4134 and 4220cm-1. Cyanide-contaminated samples were then collected in the field and analyzed with the two spectrometers to further test the applicability of the DRIFT technique for soils containing aged CN residues. The prediction of total CN in dry and ground contaminated soils using the handheld MIR instrument resulted in a coefficient of determination (R2) of 0.88–0.98 and root mean square error of the cross-validation (RMSE) of 21–49mgkg-1 for a CN range of 0–611mgkg-1. A major peak was observed in the MIR at about 2092cm-1 which was attributed to “Prussian Blue” (Fe4[Fe(CN)6]3·xH2O). These results demonstrate the potential of handheld DRIFT instrumentation as a promising alternative to the standard laboratory method to predict CN concentrations in contaminated field soils.

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SI-traceable calibration-free analysis for the active concentration of G2-EPSPS protein using surface plasmon resonance

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Ping Su, Zhangjing He, Liqing Wu, Liang Li, Kangle Zheng, Yi Yang
Active proteins play important roles in the function regulation of human bodies and attract much interest for use in pharmaceuticals and clinical diagnostics. However, the lack of primary methods to analyze active proteins means there is currently no metrology standard for active protein measurement. In recent years, calibration-free concentration analysis (CFCA), which is based on surface plasmon resonance (SPR) technology, has been proposed to determine the active concentration of proteins that have specific binding activity with a binding partner without any higher order standards. The CFCA experiment observes the changes of binding rates at totally different two flow rates and uses the known diffusion coefficient of an analyte to calculate the active concentration of proteins, theoretically required, the binding process have to be under diffusion-limited conditions. Measuring the active concentration of G2-EPSPS protein by CFCA was proposed in this study. This method involves optimization of the regeneration buffer and preparation of chip surfaces for appropriate reaction conditions by immobilizing ligands (G2-EPSPS antibodies) on sensor chips (CM5) via amine coupling. The active concentration of G2-EPSPS was then determined by injection of G2-EPSPS protein samples and running buffer over immobilized and reference chip surfaces at two different flow rates (5 and 100μLmin−1). The active concentration of G2-EPSPS was obtained after analyzing these sensorgrams with the 1:1 model. Using the determined active concentration of G2-EPSPS, the association, dissociation, and equilibrium constants of G2-EPSPS and its antibody were determined to be 2.18 ± 0.03 × 106M−1s−1, 5.79 ± 0.06 ×10−3s−1, and 2.65 ± 0.06 × 10−9M, respectively. The performance of the proposed method was evaluated. The within-day precisions were from 3.26% to 4.59%, and the between-day precision was 8.36%. The recovery rate of the method was from 97.46% to 104.34% in the concentration range of 1.5–8nM. The appropriate concentration range of G2-EPSPS in the proposed method was determined to be 1.5–8nM. The active G2-EPSPS protein concentration determined by our method was only 17.82% of that obtained by isotope dilution mass spectrometry, showing the active protein was only a small part of the total G2-EPSPS protein. The measurement principle of the proposed method can be clearly described by equations and the measurement result can be expressed in SI units. Therefore, the proposed method shows promise to become a primary method for active protein concentration measurement, which can benefit the development of certified reference materials for active proteins.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Ping Su, Zhangjing He, Liqing Wu, Liang Li, Kangle Zheng, Yi Yang

Active proteins play important roles in the function regulation of human bodies and attract much interest for use in pharmaceuticals and clinical diagnostics. However, the lack of primary methods to analyze active proteins means there is currently no metrology standard for active protein measurement. In recent years, calibration-free concentration analysis (CFCA), which is based on surface plasmon resonance (SPR) technology, has been proposed to determine the active concentration of proteins that have specific binding activity with a binding partner without any higher order standards. The CFCA experiment observes the changes of binding rates at totally different two flow rates and uses the known diffusion coefficient of an analyte to calculate the active concentration of proteins, theoretically required, the binding process have to be under diffusion-limited conditions. Measuring the active concentration of G2-EPSPS protein by CFCA was proposed in this study. This method involves optimization of the regeneration buffer and preparation of chip surfaces for appropriate reaction conditions by immobilizing ligands (G2-EPSPS antibodies) on sensor chips (CM5) via amine coupling. The active concentration of G2-EPSPS was then determined by injection of G2-EPSPS protein samples and running buffer over immobilized and reference chip surfaces at two different flow rates (5 and 100μLmin−1). The active concentration of G2-EPSPS was obtained after analyzing these sensorgrams with the 1:1 model. Using the determined active concentration of G2-EPSPS, the association, dissociation, and equilibrium constants of G2-EPSPS and its antibody were determined to be 2.18 ± 0.03 × 106 M−1 s−1, 5.79 ± 0.06 ×10−3 s−1, and 2.65 ± 0.06 × 10−9 M, respectively. The performance of the proposed method was evaluated. The within-day precisions were from 3.26% to 4.59%, and the between-day precision was 8.36%. The recovery rate of the method was from 97.46% to 104.34% in the concentration range of 1.5–8nM. The appropriate concentration range of G2-EPSPS in the proposed method was determined to be 1.5–8nM. The active G2-EPSPS protein concentration determined by our method was only 17.82% of that obtained by isotope dilution mass spectrometry, showing the active protein was only a small part of the total G2-EPSPS protein. The measurement principle of the proposed method can be clearly described by equations and the measurement result can be expressed in SI units. Therefore, the proposed method shows promise to become a primary method for active protein concentration measurement, which can benefit the development of certified reference materials for active proteins.

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Design and construction of an injection port for coupling stir-bar sorptive extraction with ion mobility spectrometry

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Mohammad T. Jafari, Mohammad R. Rezayat, Mehdi Mossaddegh
An appropriate injection port was designed and constructed for direct analysis of stir-bar sorptive extractions using an ion mobility spectrometry (IMS). The novel design of the port offers great simplicity in use, high sensitivity, and high thermal and mechanical stability. The sol-gel technique was applied to prepare polydimethylsiloxane absorbent on a stir-bar. The parameters affecting extraction efficiency including stirring rate, extraction temperature, extraction time, salt addition and desorption temperature were optimized. The detection limit of the method was calculated to be 1.5μgL−1, for diazinon, an organophosphorus pesticide selected as a test compound. The linear dynamic range was obtained to be 5.0–200.0μgL−1 with a determination coefficient of 0.9991 for the test compound. The intra- and inter-day relative standard deviations were calculated to be 4% and 5%, respectively. Agricultural wastewater, well water, and apple were selected as real samples. The detection limit was calculated to be 1.5μgL−1 and 7.5μgkg−1 for the real water samples and the apple sample, respectively. The recovery values (%) were 105 ± 6, 107 ± 3 and 96 ± 6 for the spiked agricultural wastewater, well water and apple samples, respectively. The results revealed that the injection port can be used for direct analysis of samples extracted by any sorbent support, without any further sample preparation.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Mohammad T. Jafari, Mohammad R. Rezayat, Mehdi Mossaddegh

An appropriate injection port was designed and constructed for direct analysis of stir-bar sorptive extractions using an ion mobility spectrometry (IMS). The novel design of the port offers great simplicity in use, high sensitivity, and high thermal and mechanical stability. The sol-gel technique was applied to prepare polydimethylsiloxane absorbent on a stir-bar. The parameters affecting extraction efficiency including stirring rate, extraction temperature, extraction time, salt addition and desorption temperature were optimized. The detection limit of the method was calculated to be 1.5μgL−1, for diazinon, an organophosphorus pesticide selected as a test compound. The linear dynamic range was obtained to be 5.0–200.0μgL−1 with a determination coefficient of 0.9991 for the test compound. The intra- and inter-day relative standard deviations were calculated to be 4% and 5%, respectively. Agricultural wastewater, well water, and apple were selected as real samples. The detection limit was calculated to be 1.5μgL−1 and 7.5μgkg−1 for the real water samples and the apple sample, respectively. The recovery values (%) were 105 ± 6, 107 ± 3 and 96 ± 6 for the spiked agricultural wastewater, well water and apple samples, respectively. The results revealed that the injection port can be used for direct analysis of samples extracted by any sorbent support, without any further sample preparation.

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Growth of Escherichia coli on the GaAs (001) surface

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Elnaz Nazemi, Walid M. Hassen, Eric H. Frost, Jan J. Dubowski
Detection of pathogenic bacteria and monitoring their susceptibility to antibiotics are of great importance in the fields of medicine, pharmaceutical research, as well as water and food industries. In order to develop a photonic biosensor for detection of bacteria by taking advantage of photoluminescence (PL) of GaAs-based devices, we have investigated the capture and growth of Escherichia coli K12 on bare and biofunctionalized surfaces of GaAs (001) – a material of interest for capping different semiconductor microstructures. The results were compared with the capture and growth of Escherichia coli K12 on Au surfaces that have commonly been applied for studying a variety of biological and biochemical reactions. We found that neither GaAs nor Au-coated glass wafers placed in Petri dishes inoculated with bacteria inhibited bacterial growth in nutrient agar, regardless of the wafers being bare or biofunctionalized. However, the capture and growth of bacteria on biofunctionalized surfaces of GaAs and Au wafers kept in a flow cell and exposed to different concentrations of bacteria and growth medium revealed that the initial surface coverage and the subsequent bacterial growth were dependent on the biofunctionalization architecture, with antibody-coated surfaces clearly being most efficient in capturing bacteria and offering better conditions for growth of bacteria. We have observed that, as long as the GaAs wafers were exposed to bacterial suspensions at concentrations of at least 105 CFU/mL, bacteria could grow on the surface of wafers, regardless of the type of biofunctionalization architecture used to capture the bacteria. These results provide important insight towards the successful development of GaAs-based devices designed for photonic monitoring of bacterial reactions to different biochemical environments.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Elnaz Nazemi, Walid M. Hassen, Eric H. Frost, Jan J. Dubowski

Detection of pathogenic bacteria and monitoring their susceptibility to antibiotics are of great importance in the fields of medicine, pharmaceutical research, as well as water and food industries. In order to develop a photonic biosensor for detection of bacteria by taking advantage of photoluminescence (PL) of GaAs-based devices, we have investigated the capture and growth of Escherichia coli K12 on bare and biofunctionalized surfaces of GaAs (001) – a material of interest for capping different semiconductor microstructures. The results were compared with the capture and growth of Escherichia coli K12 on Au surfaces that have commonly been applied for studying a variety of biological and biochemical reactions. We found that neither GaAs nor Au-coated glass wafers placed in Petri dishes inoculated with bacteria inhibited bacterial growth in nutrient agar, regardless of the wafers being bare or biofunctionalized. However, the capture and growth of bacteria on biofunctionalized surfaces of GaAs and Au wafers kept in a flow cell and exposed to different concentrations of bacteria and growth medium revealed that the initial surface coverage and the subsequent bacterial growth were dependent on the biofunctionalization architecture, with antibody-coated surfaces clearly being most efficient in capturing bacteria and offering better conditions for growth of bacteria. We have observed that, as long as the GaAs wafers were exposed to bacterial suspensions at concentrations of at least 105 CFU/mL, bacteria could grow on the surface of wafers, regardless of the type of biofunctionalization architecture used to capture the bacteria. These results provide important insight towards the successful development of GaAs-based devices designed for photonic monitoring of bacterial reactions to different biochemical environments.

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Au-Pt bimetallic nanoparticles decorated on sulfonated nitrogen sulfur co-doped graphene for simultaneous determination of dopamine and uric acid

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Kangning Zhang, Xiaoling Chen, Zhuang Li, Yan Wang, Sen Sun, Li’na Wang, Tong Guo, Dongxia Zhang, Zhonghua Xue, Xibin Zhou, Xiaoquan Lu
In this work, a novel nanohybrid (AuPtNPs/S-NS-GR) of well-defined Au-Pt bimetallic nanoparticles (Au-PtNPs) decorated on sulfonated nitrogen sulfur co-doped graphene (S-NS-GR) was developed. Firstly, nitrogen sulfur co-doped graphene (NS-GR) was synthesized by one-step thermal annealing method. Secondly, phenyl SO3H- group was introduced onto the surface of NS-GR via diazotization reaction, which could provide more binding sites for the formation of metal nanoparticles. Finally, Au-Pt bimetallic nanoparticles were anchored on the surface of S-NS-GR by using electrochemical deposition. The prepared material was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and electrochemical impedance spectra (EIS). In addition, the electrocatalytic activity towards dopamine (DA) and uric acid (UA) was systematically studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Under optimum conditions, the linear ranges for the detection of DA and UA were 1.0×10−8 – 4.0×10−4 M and 1.0×10−6 – 1.0×10−3 M with the limits of detection (LOD, S/N = 3) of 0.006μM and 0.038μM, respectively. Furthermore, the modified electrode was applied to real sample analysis.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Kangning Zhang, Xiaoling Chen, Zhuang Li, Yan Wang, Sen Sun, Li’na Wang, Tong Guo, Dongxia Zhang, Zhonghua Xue, Xibin Zhou, Xiaoquan Lu

In this work, a novel nanohybrid (AuPtNPs/S-NS-GR) of well-defined Au-Pt bimetallic nanoparticles (Au-PtNPs) decorated on sulfonated nitrogen sulfur co-doped graphene (S-NS-GR) was developed. Firstly, nitrogen sulfur co-doped graphene (NS-GR) was synthesized by one-step thermal annealing method. Secondly, phenyl SO3H- group was introduced onto the surface of NS-GR via diazotization reaction, which could provide more binding sites for the formation of metal nanoparticles. Finally, Au-Pt bimetallic nanoparticles were anchored on the surface of S-NS-GR by using electrochemical deposition. The prepared material was characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy and electrochemical impedance spectra (EIS). In addition, the electrocatalytic activity towards dopamine (DA) and uric acid (UA) was systematically studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Under optimum conditions, the linear ranges for the detection of DA and UA were 1.0×10−8 – 4.0×10−4 M and 1.0×10−6 – 1.0×10−3 M with the limits of detection (LOD, S/N = 3) of 0.006μM and 0.038μM, respectively. Furthermore, the modified electrode was applied to real sample analysis.

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Suspect screening of halogenated carboxylic acids in drinking water using ion exchange chromatography – High resolution (Orbitrap) mass spectrometry (IC-HRMS)

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Matteo D. Gallidabino, Laurence Hamdan, Bronagh Murphy, Leon P. Barron
Retrospective in silico screening of analytical data for the identification of new or emerging disinfection by-products in drinking waters could be useful to assess quality and potential hazards, as well as help implement mitigation procedures more rapidly. Herein, the first study coupling ion exchange chromatography (IC) with high resolution mass spectrometry (HRMS) for the determination of halogenated carboxylic acid disinfectant by-products is reported. Separation was achieved using a Metrohm A Supp 5 column and a Na2CO3/NaHCO3 gradient eluent from 1/0.31 to 10/3.1mM. A variety of solid phase extraction (SPE) sorbents were tested for added selectivity to organic ions and Isolute ENV+ cartridges were selected because of their best overall extraction performance. Method LODs were in the μgL−1 concentration range, with R2 ≥ 0.99 for all the analytes, and isobaric ions could be easily discriminated using HRMS. The method was applied to municipal drinking water. Targeted quantitative analysis revealed the presence of 10 haloacetic acids at levels not exceeding the limits set by WHO and USEPA. Furthermore, suspect screening for additional halogenated carboxylic acids via retrospective HRMS data analysis also indicated the presence of other iodinated HAAs and chlorinated propionic acids, of which one (i.e. monochloropropionic acid) is discussed here for the first time. Most importantly, several potential suspects could be eliminated from further consideration through HRMS data analysis alone. To our knowledge, this represents the first time that a retrospective IC-HRMS screen of halogenated carboxylic acids in drinking water has been reported.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Matteo D. Gallidabino, Laurence Hamdan, Bronagh Murphy, Leon P. Barron

Retrospective in silico screening of analytical data for the identification of new or emerging disinfection by-products in drinking waters could be useful to assess quality and potential hazards, as well as help implement mitigation procedures more rapidly. Herein, the first study coupling ion exchange chromatography (IC) with high resolution mass spectrometry (HRMS) for the determination of halogenated carboxylic acid disinfectant by-products is reported. Separation was achieved using a Metrohm A Supp 5 column and a Na2CO3/NaHCO3 gradient eluent from 1/0.31 to 10/3.1mM. A variety of solid phase extraction (SPE) sorbents were tested for added selectivity to organic ions and Isolute ENV+ cartridges were selected because of their best overall extraction performance. Method LODs were in the μgL−1 concentration range, with R2 ≥ 0.99 for all the analytes, and isobaric ions could be easily discriminated using HRMS. The method was applied to municipal drinking water. Targeted quantitative analysis revealed the presence of 10 haloacetic acids at levels not exceeding the limits set by WHO and USEPA. Furthermore, suspect screening for additional halogenated carboxylic acids via retrospective HRMS data analysis also indicated the presence of other iodinated HAAs and chlorinated propionic acids, of which one (i.e. monochloropropionic acid) is discussed here for the first time. Most importantly, several potential suspects could be eliminated from further consideration through HRMS data analysis alone. To our knowledge, this represents the first time that a retrospective IC-HRMS screen of halogenated carboxylic acids in drinking water has been reported.

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Assessment of potential false positives via orbitrap-based untargeted lipidomics from rat tissues

Publication date: 1 February 2018 Source:Talanta, Volume 178 Author(s): Lina Xu, Xueying Wang, Yupei Jiao, Xiaohui Liu Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/…

Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Lina Xu, Xueying Wang, Yupei Jiao, Xiaohui Liu

Untargeted lipidomics is increasingly popular due to the broad coverage of lipid species. Data dependent MS/MS acquisition is commonly used in order to acquire sufficient information for confident lipid assignment. However, although lipids are identified based on MS/MS confirmation, a number of false positives are still observed. Here, we discuss several causes of introducing lipid false identifications in untargeted analysis. Phosphotidylcholines and cholesteryl esters generate in-source fragmentation to produce dimethylated phosphotidylethanolamine and free cholesterol. Dimerization of fatty acid results in false identification of fatty acid ester of hydroxyl fatty acid. Realizing these false positives is able to improve confidence of results acquired from untargeted analysis. Besides, thresholds are established for lipids identified using LipidSearch v4.1.16 software to reduce unreliable results.

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A robust and effective intact protein fractionation strategy by GO/PEI/Au/PEG nanocomposites for human plasma proteome analysis

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Nan Deng, Yuanbo Chen, Bo Jiang, Qi Wu, Yuan Zhou, Xiaodan Zhang, Zhen Liang, Lihua Zhang, Yukui Zhang
Identification of human plasma proteins with deep coverage is considered as a great challenge due to its extreme complexity. In this work, an intact proteins fractionation strategy based on multi-interaction between proteins and GO/PEI/Au/PEG nanocomposites (GPAP strategy) was developed for human plasma proteome deep analysis. Compared with untreated method, the number of identified proteins was increased from 858 to 2023, among which the number of low-abundance proteins (< 100ng/mL) was increased from 2 to 11. The concentration range of the identified proteins was broaden to 9 orders of magnitude. Furthermore, the spectral count of the top three proteins in human plasma (Plasma Albumin, Human IgG, Serotransferrin) were decreased in the range of 37.4–82.6%. An excellent reproducibility of GPAP strategy was verified via stable isotope dimethyl label strategy. The functionalized material was demonstrated to be an efficient method to achieve deep coverage identification of human plasma proteome.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Nan Deng, Yuanbo Chen, Bo Jiang, Qi Wu, Yuan Zhou, Xiaodan Zhang, Zhen Liang, Lihua Zhang, Yukui Zhang

Identification of human plasma proteins with deep coverage is considered as a great challenge due to its extreme complexity. In this work, an intact proteins fractionation strategy based on multi-interaction between proteins and GO/PEI/Au/PEG nanocomposites (GPAP strategy) was developed for human plasma proteome deep analysis. Compared with untreated method, the number of identified proteins was increased from 858 to 2023, among which the number of low-abundance proteins (< 100ng/mL) was increased from 2 to 11. The concentration range of the identified proteins was broaden to 9 orders of magnitude. Furthermore, the spectral count of the top three proteins in human plasma (Plasma Albumin, Human IgG, Serotransferrin) were decreased in the range of 37.4–82.6%. An excellent reproducibility of GPAP strategy was verified via stable isotope dimethyl label strategy. The functionalized material was demonstrated to be an efficient method to achieve deep coverage identification of human plasma proteome.

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Fluorescent ligand fishing combination with in-situ imaging and characterizing to screen Hsp 90 inhibitors from Curcuma longa L. based on InP/ZnS quantum dots embedded mesoporous nanoparticles

Publication date: 1 February 2018
Source:Talanta, Volume 178
Author(s): Yue Hu, Anchen Fu, Zhaoyi Miao, Xiaojing Zhang, Tianlin Wang, An Kang, Jinjun Shan, Dong Zhu, Wei Li
Although ligand fishing has been shown to be an efficient technique for the identification of bioactive components from complex mixtures such as natural products, it cannot be applied to biomedical image processing. Herein, a specific fluorescent ligand fishing combined with in situ imaging approach is presented for the identification of heat shock protein 90 (Hsp 90) inhibitors from complex matrixes, Curcuma longa L., using N-terminus immobilized Hsp 90α functionalized InP/ZnS quantum dots embedded mesoporous nanoparticles (i.e. Hsp 90α (NT)-FQDNs) as extraction sorbents and fluorescent tracer. The fished ligands were identified by liquid chromatography time-of-flight/mass spectrometry (LC-TOF/MS) and gas chromatography-mass spectrometry (GC-MS). Moreover, in situ imaging by confocal laser scanning microscopy (CLSM) was applied for evaluating the effect of fished-ligands on bioactivity-induced apoptosis morphologically in HeLa cells. MTT assay verified the bioactivity of the ligands and molecular docking results further provided convincing information to verify the feasible binding mode between ligands and protein. Twelve ligands as potential Hsp 90 inhibitors were ultimately fished and identified from Curcuma longa L. crude extracts. The proposed approach based on Hsp 90α functionalized nanocomposites is superior in the combination of highly specific screening efficiency and concurrent visual in situ imaging, which could have great promise for the development of other plant-derived Hsp 90 inhibitors, and providing a rapid and reliable platform for discovering biologically active molecules in natural products.

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Publication date: 1 February 2018
Source:Talanta, Volume 178

Author(s): Yue Hu, Anchen Fu, Zhaoyi Miao, Xiaojing Zhang, Tianlin Wang, An Kang, Jinjun Shan, Dong Zhu, Wei Li

Although ligand fishing has been shown to be an efficient technique for the identification of bioactive components from complex mixtures such as natural products, it cannot be applied to biomedical image processing. Herein, a specific fluorescent ligand fishing combined with in situ imaging approach is presented for the identification of heat shock protein 90 (Hsp 90) inhibitors from complex matrixes, Curcuma longa L., using N-terminus immobilized Hsp 90α functionalized InP/ZnS quantum dots embedded mesoporous nanoparticles (i.e. Hsp 90α (NT)-FQDNs) as extraction sorbents and fluorescent tracer. The fished ligands were identified by liquid chromatography time-of-flight/mass spectrometry (LC-TOF/MS) and gas chromatography-mass spectrometry (GC-MS). Moreover, in situ imaging by confocal laser scanning microscopy (CLSM) was applied for evaluating the effect of fished-ligands on bioactivity-induced apoptosis morphologically in HeLa cells. MTT assay verified the bioactivity of the ligands and molecular docking results further provided convincing information to verify the feasible binding mode between ligands and protein. Twelve ligands as potential Hsp 90 inhibitors were ultimately fished and identified from Curcuma longa L. crude extracts. The proposed approach based on Hsp 90α functionalized nanocomposites is superior in the combination of highly specific screening efficiency and concurrent visual in situ imaging, which could have great promise for the development of other plant-derived Hsp 90 inhibitors, and providing a rapid and reliable platform for discovering biologically active molecules in natural products.

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