Subjects -> CHEMISTRY (Total: 986 journals)
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ANALYTICAL CHEMISTRY (59 journals)

Showing 1 - 46 of 46 Journals sorted alphabetically
Accounts of Chemical Research     Hybrid Journal   (Followers: 63)
Acta Analytica     Hybrid Journal   (Followers: 6)
Advances in Analytical Chemistry     Open Access   (Followers: 29)
American Journal of Analytical Chemistry     Open Access   (Followers: 31)
Analitika i kontrol` (Analytics and control)     Open Access  
Analytica Chimica Acta     Hybrid Journal   (Followers: 43)
Analytica Chimica Acta : X     Open Access  
Analytical and Bioanalytical Chemistry     Hybrid Journal   (Followers: 27)
Analytical and Bioanalytical Chemistry Research     Open Access   (Followers: 2)
Analytical Chemistry     Hybrid Journal   (Followers: 238)
Analytical Chemistry Insights     Open Access   (Followers: 21)
Analytical Chemistry Letters     Hybrid Journal   (Followers: 2)
Analytical Letters     Hybrid Journal   (Followers: 9)
Annual Review of Analytical Chemistry     Full-text available via subscription   (Followers: 12)
Chemical Data Collections     Hybrid Journal  
Chinese Journal of Analytical Chemistry     Full-text available via subscription   (Followers: 5)
Composites Communications     Full-text available via subscription   (Followers: 2)
Comprehensive Analytical Chemistry     Full-text available via subscription   (Followers: 7)
Critical Reviews in Analytical Chemistry     Hybrid Journal   (Followers: 27)
Current Analytical Chemistry     Hybrid Journal   (Followers: 10)
Drug Testing and Analysis     Hybrid Journal   (Followers: 10)
Electroanalysis     Hybrid Journal   (Followers: 6)
Field Analytical Chemistry and Technology     Hybrid Journal   (Followers: 6)
International Journal of Analytical Chemistry     Open Access   (Followers: 21)
International Journal of Environmental Analytical Chemistry     Hybrid Journal   (Followers: 7)
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 8)
Journal of Analysis and Testing     Hybrid Journal  
Journal of Analytical Atomic Spectrometry     Hybrid Journal   (Followers: 8)
Journal of Analytical Chemistry     Hybrid Journal   (Followers: 21)
Journal of Electroanalytical Chemistry     Hybrid Journal   (Followers: 7)
Journal of Essential Oil Research     Hybrid Journal   (Followers: 3)
Journal of Progressive Research in Chemistry     Open Access  
Journal of Radioanalytical and Nuclear Chemistry     Hybrid Journal   (Followers: 7)
Journal of Thermal Analysis and Calorimetry     Hybrid Journal   (Followers: 24)
Microchemical Journal     Hybrid Journal   (Followers: 4)
Nature Catalysis     Hybrid Journal   (Followers: 6)
Nigerian Journal of Chemical Research     Full-text available via subscription   (Followers: 1)
Opflow     Full-text available via subscription   (Followers: 1)
Pharmaceutical Analytical Chemistry: Open Access     Open Access   (Followers: 1)
Phytochemical Analysis     Hybrid Journal   (Followers: 3)
Polish Journal of Chemical Technology     Open Access   (Followers: 1)
Surface and Interface Analysis     Hybrid Journal   (Followers: 15)
TrAC Trends in Analytical Chemistry     Full-text available via subscription   (Followers: 46)
Trends in Environmental Analytical Chemistry     Hybrid Journal   (Followers: 3)
Vibrational Spectroscopy     Hybrid Journal   (Followers: 11)
World Journal of Analytical Chemistry     Open Access   (Followers: 3)
Similar Journals
Journal Cover
Analytical and Bioanalytical Chemistry
Journal Prestige (SJR): 0.978
Citation Impact (citeScore): 3
Number of Followers: 27  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1618-2650 - ISSN (Online) 1618-2642
Published by Springer-Verlag Homepage  [2537 journals]
  • Correction to: Development and validation of an LC–MS/MS method for the
           quantitation of 30 legacy and emerging per- and polyfluoroalkyl substances
           (PFASs) in human plasma, including HFPO‑DA, DONA, and cC6O4

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      PubDate: 2022-01-14
       
  • Unravelling the role of membrane pore size in polar organic chemical
           integrative samplers (POCIS) to broaden the polarity range of sampled
           analytes

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      Abstract: Polar organic chemical integrative samplers (POCIS) are widely used in their standard configuration for sampling contaminants in water bodies. A wider polyethersulfone (PES) membrane pore size was employed in POCIS exposed in a static calibration experiment to investigate the uptake of 21 emerging contaminants ranging from hydrophilic (perfluoroalkyl compounds, xanthines, an artificial sweetener) to more hydrophobic compounds (pharmaceuticals, oestrogens, UV filters). Compared to standard POCIS with 0.1-µm pore size PES membranes, the POCIS with 5-µm pore size PES membranes did not increase sampling rates for compounds of relatively low and mid-hydrophobicity. However, the uptake of more hydrophobic and anionic compounds, which either poorly diffuse through or are retained within the standard 0.1-µm PES membrane, showed a marked increase. This led to the first ever recorded sampling rates for triclosan (0.249 L day−1) and two UV filters (0.075–0.123 L day−1). Based on these results, more attention should be placed on the choice of the appropriate membrane for each POCIS application. The most suitable configuration depends on the studied compound physico-chemical characteristics—such as the polarity and the compound membrane-to-sorbent partitioning coefficient—but also on the site conditions (deployment time, fouling, flow variations, et.). Graphical abstract
      PubDate: 2022-01-14
       
  • Co–N–C single-atom nanozymes with oxidase-like activity for highly
           sensitive detection of biothiols

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      Abstract: Biothiol detection is of great importance for clinical disease diagnosis. Previous nanozyme-based colorimetric sensors for biothiol detection showed unsatisfactory catalytic activity, which led to a high detection limit. Therefore, developing new nanozymes with the high catalytic activity for biothiol detection is extremely necessary. Recently, single-atom nanozymes (SAzymes) have attracted much attention in biosensing due to their 100% atom utilization and excellent catalytic activity. Most previous works focus on the peroxidase-like activity of Fe-based SAzymes by using unstable and destructive H2O2 as the oxidant. It is essential to develop new SAzymes with high oxidase-like activity for biosensing to break through the limitation. Herein, Co–N–C SAzymes with high oxidase-like activity are explored. Furthermore, Co–N–C SAzymes are used as a biosensor for colorimetric detection of biothiols (GSH/Cys) based on the inhibition of thiols toward the oxidase-like activity of Co–N–C SAzymes, which showed high sensitivity with a low detection limit of 0.07 µM for GSH and 0.06 µM for Cys. Besides, the method showed good reproducibility and high selectivity against other amino acids. This work offers new insights using Co–N–C SAzymes in the biosensing field.
      PubDate: 2022-01-14
       
  • Microdialysis techniques and microdialysis-based patient-near diagnostics

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      Abstract: This article will debate the usefulness of POCT measurements and the contribution microdialysis can make to generating valuable information. A particular theme will be the rarely considered difference between ex vivo sampling, which typically generates only a static measure of concentration, and in vivo measurements that are subject to dynamic changes due to mass transfer. Those dynamic changes provide information about the patients’ physiological state.
      PubDate: 2022-01-14
       
  • Development of an electrochemical aptasensor based on Au nanoparticles
           decorated on metal–organic framework nanosheets and p-biphenol
           electroactive label for the measurement of aflatoxin B1 in a rice flour
           sample

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      Abstract: This study purposes designing a new aptasensor to detect aflatoxin B1 (AFB1). The AFB1 aptasensor was developed by growing gold nanoparticles on the surface of nickel-based metal–organic framework nanosheets (AuNPs/Ni-MOF) and an electroactive indicator (p-biphenol, PBP). The AFB1 aptamer was immobilized on the AuNPs/Ni-MOF and then hybridized with the complementary DNA (cDNA). PBP was intercalated within the double helix of the cDNA–aptamer. The difference between electrochemical responses of intercalated PBP before and after incubation of AFB1 with the immobilized aptamer was considered as an analytical response. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to monitor the construction processes of the aptasensor. By recording the differential pulse voltammograms of PBP in phosphate buffer (pH 7.0, 0.1 M), the linear range and the detection limit of AFB1 were found to be 5.0 × 10−3–150.0 ng mL−1 and 1.0 × 10−3 ng mL−1 (S/N = 3), respectively. Finally, the designed aptasensor has been successfully used to measure AFB1 in a rice flour sample with satisfying results. Graphical abstract Schematic illustrated the different steps of constructing the electrochemical aptasensor based on Au nanoparticles decorated on Ni-metal–organic framework nanosheets and p-biphenol electroactive label for measuring aflatoxin B1 (AFB1).
      PubDate: 2022-01-14
       
  • Development of a sample preparation procedure for Sr isotope analysis of
           Portland cements

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      Abstract: The 87Sr/86Sr isotope ratio can, in principle, be used for provenancing of cement. However, while commercial cements consist of multiple components, no detailed investigation into their individual 87Sr/86Sr isotope ratios or their influence on the integral 87Sr/86Sr isotope ratio of the resulting cement was conducted previously. Therefore, the present study aimed at determining and comparing the conventional 87Sr/86Sr isotope ratios of a diverse set of Portland cements and their corresponding Portland clinkers, the major component of these cements. Two approaches to remove the additives from the cements, i.e. to measure the conventional 87Sr/86Sr isotopic fingerprint of the clinker only, were tested, namely, treatment with a potassium hydroxide/sucrose solution and sieving on a 11-µm sieve. Dissolution in concentrated hydrochloric acid/nitric acid and in diluted nitric acid was employed to determine the 87Sr/86Sr isotope ratios of the cements and the individual clinkers. The aim was to find the most appropriate sample preparation procedure for cement provenancing, and the selection was realised by comparing the 87Sr/86Sr isotope ratios of differently treated cements with those of the corresponding clinkers. None of the methods to separate the clinkers from the cements proved to be satisfactory. However, it was found that the 87Sr/86Sr isotope ratios of clinker and cement generally corresponded, meaning that the latter can be used as a proxy for the clinker 87Sr/86Sr isotope ratio. Finally, the concentrated hydrochloric acid/nitric acid dissolution method was found to be the most suitable sample preparation method for the cements; it is thus recommended for 87Sr/86Sr isotope analyses for cement provenancing. Graphical abstract
      PubDate: 2022-01-14
       
  • Comparison of chemometric strategies for potential exposure marker
           discovery and false-positive reduction in untargeted metabolomics:
           application to the serum analysis by LC-HRMS after intake of Vaccinium
           fruit supplements

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      Abstract: Untargeted liquid chromatographic-high-resolution mass spectrometric (LC-HRMS) metabolomics for potential exposure marker (PEM) discovery in nutrikinetic studies generates complex outputs. The correct selection of statistically significant PEMs is a crucial analytical step for understanding nutrition-health interactions. Hence, in this paper, different chemometric selection workflows for PEM discovery, using multivariate or univariate parametric or non-parametric data analyses, were comparatively tested and evaluated. The PEM selection protocols were applied to a small-sample-size untargeted LC-HRMS study of a longitudinal set of serum samples from 20 volunteers after a single intake of (poly)phenolic-rich Vaccinium myrtillus and Vaccinium corymbosum supplements. The non-parametric Games-Howell test identified a restricted group of significant features, thus minimizing the risk of false-positive retention. Among the forty-seven PEMs exhibiting a statistically significant postprandial kinetics, twelve were successfully annotated as purine pathway metabolites, benzoic and benzodiol metabolites, indole alkaloids, and organic and fatty acids, and five (i.e. octahydro-methyl-β-carboline-dicarboxylic acid, tetrahydro-methyl-β-carboline-dicarboxylic acid, citric acid, caprylic acid, and azelaic acid) were associated to Vaccinium berry consumption for the first time. The analysis of the area under the curve of the longitudinal dataset highlighted thirteen statistically significant PEMs discriminating the two interventions, including four intra-intervention relevant metabolites (i.e. abscisic acid glucuronide, catechol sulphate, methyl-catechol sulphate, and α-hydroxy-hippuric acid). Principal component analysis and sample classification through linear discriminant analysis performed on PEM maximum intensity confirmed the discriminating role of these PEMs. Graphical abstract
      PubDate: 2022-01-14
       
  • Nanoceria-based lateral flow immunoassay for hydrogen peroxide-free
           colorimetric biosensing for C-reactive protein

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      Abstract: During the recent several decades, lateral flow immunoassay (LFIA) constructed with gold nanoparticle (AuNP) has been widely utilized to conveniently detect target analyte. However, AuNP-based LFIA has limitations, such as limited detection sensitivity and quantification capability. Herein, to overcome these constraints, we have developed cerium oxide nanoparticle (nanoceria)-based LFIA for C-reactive protein (CRP) detection in human serum samples. It was fabricated with nanoceria, a notable nanozyme that shows an oxidase activity to quickly oxidize organic substrate, such as 3,3′,5,5′-tetramethylbenzidine (TMB), to produce colored product without any oxidizing agent (e.g., hydrogen peroxide), which is advantageous for realizing point-of-care testing (POCT) applications. By employing human blood serum spiked with CRP, the nanoceria-based LFIA showed two blue-colored lines on the test and control region within 3 min via TMB oxidation, by the captured nanoceria through antigen–antibody interaction. The produced blue-colored lines were distinguished by naked eyes and quantitated with real images acquired by a conventional smartphone with the ImageJ software. With this strategy, target CRP was specifically determined down to 117 ng mL−1 with high detection precisions yielding coefficient of variation of 9.8–11.3% and recovery of 90.7–103.2% using human blood serum samples. This investigation demonstrates the potential of oxidase-like nanoceria for developing LFIA, which is particularly useful in instrumentation-free POCT environments. Graphical abstract
      PubDate: 2022-01-14
       
  • A photonic crystal fiber–based fluorescence sensor for simultaneous and
           sensitive detection of lactic acid enantiomers

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      Abstract: A photonic crystal fiber (PCF)–based fluorescence sensor is developed for rapid and sensitive detection of lactic acid (LA) enantiomers in serum samples. The sensor is fabricated by chemical binding dual enzymes on the inner surface of the PCF with numerous pore structures and a large specific surface area, which is suitable to be utilized as an enzymatic reaction carrier. To achieve simultaneous detection of l-LA and d-LA, the PCF with an aldehyde-activated surface is cut into two separate pieces, one of which is coated with l-LDH/GPT enzymes and the other with d-LDH/GPT enzymes. By being connected and carefully aligned to each other by a suitable sleeve tube connector, the responses of both l-LA and d-LA sensors are determined by laser-induced flourescence (LIF) detection. With the aid of enzyme-linked catalytic reactions, the proposed PCF sensor can greatly improve the sensitivity and analysis speed for the detection of LA enantiomers. The PCF sensor exhibits a low limit of detection of 9.5 μM and 0.8 μM, and a wide linear range of 25–2000 μM and 2–400 μM for l-LA and d-LA, respectively. The sensor has been successfully applied to accurate determination of LA enantiomers in human serum with satisfactory reproducibility and stability. It is indicated that the present PCF sensors would be used as an attractive analytical platform for quantitative detection of trace-amount LA enantiomers in real biological samples, and thus would play a role in disease diagnosis and clinical monitoring in point-of-care testing. Graphical abstract
      PubDate: 2022-01-13
       
  • Liquid chromatography-mass spectrometry method for the determination of
           polyethylene terephthalate and polybutylene terephthalate cyclic oligomers
           in blood samples

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      Abstract: Food contact materials (FCM) polyethylene terephthalate (PET) and polybutylene terephthalate (PBT) used extensively in food packaging may contain cyclic oligomers which may migrate into food and thus cause toxic effects on human health. A simple, fast, and sensitive ultra-high-performance liquid chromatography method quadrupole time-of-flight mass spectrometer was developed for the analysis of 7 cyclic oligomers in post-mortem blood samples. The targeted analytes were separated on a Waters BEH C18 (150 × 2.1 mm, 1.7 µm) analytical column by gradient elution. Calibration curves were constructed based on standard solutions and blood samples and Student’s t-test was applied to evaluate the matrix effect. The LODs ranged from 1.7 to 16.7 μg mL−1, while the method accuracy was assessed by recovery experiments and resulting within the range 84.2–114.6%. Such an analytical method for the determination of PET and PBT cyclic oligomers in biological samples is reported for the first time. The developed methodology allows the determination of these oligomers in blood providing a useful analytical tool to assess the exposure and thus the potential hazard and health risks associated with these non-intentionally added substances (NIAS) from PET and PBT FCM through food consumption. The method was validated and successfully applied to the analysis of 34 post-mortem whole blood samples. Polyethylene terephthalate trimer was detected in four of them, for the first time in literature. Graphical abstract
      PubDate: 2022-01-13
       
  • In-line formation and identification of toxic reductive metabolites of
           aristolochic acid using electrochemistry mass spectrometry coupling

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      Abstract: Small-molecule metabolism has been extensively studied in the past decades, notably driven by the development of new pharmaceutical ingredients. The understanding of metabolism is critical to the anticipation of reactive metabolite formation in vivo that is often associated with toxicity. Electrochemistry has been proposed to simulate the oxidoreductive metabolism reaction catalyzed by cytochrome P450, a family of microsomal enzymes strongly involved in xenobiotic metabolism. The implementation of an electrochemical cell online with mass spectrometry allows for the fast formation and identification of the reaction end products. This study discusses the ability of the synthetic electrochemical approach to simulate a complex lactamization reaction that involves the formation of reactive metabolites. Aristolochic acid I was used as a model molecule to evaluate the ability of electrochemical simulation to generate nitroso, hydroxylamine, N-hydroxylactam, lactam, and nitrenium ion metabolites.
      PubDate: 2022-01-13
       
  • Development of LC-MS-ESI-TOF method for quantification of phytates in food
           using 13C-labelled maize as internal standard

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      Abstract: In this work, the LC-MS-ESI-TOF method for simultaneous determination of phytates (inositol mono-, bis-, tris-, tetrakis-, pentakis-, and hexakisphosphates, abbreviated to IP1, IP2, IP3, IP4, IP5, and IP6, respectively) in food samples was developed and validated. The suitability of U-13C-labelled maize as a source for labelled internal standards for quantification of phytates was elucidated. The effectiveness of liberating IP1, IP2, IP3, IP4, and IP5 from phytic acid extracted form U-13C-labelled maize was evaluated for a variety of hydrolysis conditions, including enzymatic and acid hydrolysis. Enzymatic degradation of phytic acid using phytase (PHYZYME XP 5000 L) was very effective; phytic acid was degraded to lower phytates, but their distribution was unequal. Chemical hydrolysis was conducted under acidic conditions using hydrochloric acid and elevated temperatures up to 140 °C. The highest yields of IP4, IP5, and IP6 and of IP1, IP2, and IP3 were achieved by chemical hydrolysis at 105 °C for 7 h and 24 h, respectively. Thus, a combination of these two chemical treatments was selected for internal standard production. The developed LC-MS-ESI-TOF method was tested and successfully validated using plant-based food samples with different distribution of phytates. With this method, different forms of phytates in foods were separated and quantified simultaneously within 20 min. The high accuracy and precision of the developed method were guaranteed using respective labelled internal standards derived from U-13C-labelled maize. Graphical abstract
      PubDate: 2022-01-13
       
  • A biomimetic enzyme-linked immunosorbent assay (BELISA) for the analysis
           of gonadorelin by using molecularly imprinted polymer-coated microplates

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      Abstract: An original biomimetic enzyme-linked immunoassay (BELISA) to target the small peptide hormone gonadorelin is presented. This peptide has been recently listed among the substances banned in sports by the World Antidoping Agency (WADA) since its misuse by male athletes triggers testosterone increase. Hence, in response to this emerging issue in anti-doping controls, we proposed BELISA which involves the growth of a polynorepinephrine (PNE)–based molecularly imprinted polymer (MIP) directly on microwells. PNE, a polydopamine (PDA) analog, has recently displayed impressive performances when it was exploited for MIP preparation, giving even better results than PDA. Gonadorelin quantification was accomplished via a colorimetric indirect competitive bioassay involving the competition between biotinylated gonadorelin linked to the signal reporter and the unlabeled analyte. These compete for the same MIP binding sites resulting in an inverse correlation between gonadorelin concentration and the output color signal (λ = 450 nm). A detection limit of 277 pmol L−1 was achieved with very good reproducibility in standard solutions (avCV% = 4.07%) and in urine samples (avCV% = 5.24%). The selectivity of the assay resulted adequate for biological specimens and non-specific control peptides. In addition, the analytical figures of merit were successfully validated by mass spectrometry, the reference anti-doping benchtop platform for the analyte. BELISA was aimed to open real perspectives for PNE-based MIPs as alternatives to antibodies, especially when the target analyte is a poorly or non-immunogenic small molecule, such as gonadorelin. Graphical abstract Biomimetic enzyme-linked immunosorbent assay (BELISA)
      PubDate: 2022-01-13
       
  • 1H-NMR-based metabolomics reveals the biomarker panel and molecular
           mechanism of hepatocellular carcinoma progression

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      Abstract: Hepatocellular carcinoma (HCC) is one of the most extensive and most deadly cancers in the world. Biomarkers for early diagnosis of HCC are still lacking, and noninvasive and effective biomarkers are urgently needed. Metabolomics is committed to studying the changes of metabolites under stimulation, and provides a new approach for discovery of potential biomarkers. In the current work, 1H nuclear magnetic resonance (NMR) metabolomics approach was utilized to explore the potential biomarkers in HCC progression, and the biomarker panel was evaluated by receiver operating characteristic (ROC) curve analyses. Our results revealed that a biomarker panel consisting of hippurate, creatinine, putrescine, choline, and taurine might be involved in HCC progression. Functional pathway analysis showed that taurine and hypotaurine metabolism is markedly involved in the occurrence and development of HCC. Furthermore, our results indicated that the TPA activity and the level and expression of PKM2 were gradually increased in HCC progression. This research provides a scientific basis for screening potential biomarkers of HCC. Graphical abstract
      PubDate: 2022-01-13
       
  • Analysis of 19 urinary biomarkers of oxidative stress, nitrative stress,
           metabolic disorders, and inflammation using liquid chromatography–tandem
           mass spectrometry

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      Abstract: Environmental chemical exposures have been associated with cancer, diabetes, hormonal and immunological disorders, and cardiovascular diseases. Some direct effects of chemical exposure that are precursors to adverse health outcomes, including oxidative stress, nitrative stress, hormonal imbalance, neutrophilia, and eosinophilia, can be assessed through the analysis of biomarkers in urine. In this study, we describe a novel methodology for the determination of 19 biomarkers of health effects: malondialdehyde (MDA), 8-isoprostaglandin-F2α (8-PGF2α), 11-β-prostaglandin-F2α (11-PGF2α), 15-prostaglandin-F2α (15-PGF2α), 8-iso-15-prostaglandin-F2α (8,15-PGF2α), 8-hydroxy-2′-deoxyguanosine (8-OHdG), 8-hydroxyguanosine (8-HdG), 8-hydroxyguanine (8-HG), dityrosine (diY), allantoin (Alla), and two metabolic products of 4-hydroxynonenal (HNE), namely 4-hydroxy-2-nonenal glutathione (HNE-GSH) and 4-hydroxy-2-nonenal mercapturic acid (HNE-MA) (in total, 12 oxidative stress biomarkers, OSBs); 8-nitroguanosine (8-NdG), 8-nitroguanine (8-NG), and 3-nitrotyrosine (NY) (3 nitrative stress biomarkers, NSBs); chlorotyrosine (CY) and bromotyrosine (BY) (2 inflammatory biomarkers); and the advanced glycation end-products (AGEs) Nε-carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) (2 metabolic disorder biomarkers). Since these biomarkers are trigged by a variety of environmental insults and produced by different biomolecular pathways, their selective and sensitive determination in urine would help broadly elucidate the pathogenesis of diseases mediated by environmental factors. Graphical abstract
      PubDate: 2022-01-11
       
  • Wearable soft electrochemical microfluidic device integrated with
           iontophoresis for sweat biosensing

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      Abstract: A soft and flexible wearable sweat epidermal microfluidic device capable of simultaneously stimulating, collecting, and electrochemically analyzing sweat is demonstrated. The device represents the first system integrating an iontophoretic pilocarpine delivery system around the inlet channels of epidermal polydimethylsiloxane (PDMS) microfluidic device for sweat collection and analysis. The freshly generated sweat is naturally pumped into the fluidic inlet without the need of exercising. Soft skin-mounted systems, incorporating non-invasive, on-demand sweat sampling/analysis interfaces for tracking target biomarkers, are in urgent need. Existing skin conformal microfluidic-based sensors for continuous monitoring of target sweat biomarkers rely on assays during intense physical exercising. This work demonstrates the first example of combining sweat stimulation, through transdermal pilocarpine delivery, with sample collection through a microfluidic channel for real-time electrochemical monitoring of sweat glucose, in a fully integrated soft and flexible multiplexed device which eliminates the need of exercising. The on-body operational performance and layout of the device were optimized considering the fluid dynamics and evaluated for detecting sweat glucose in several volunteers. Furthermore, the microfluidic monitoring device was integrated with a real-time wireless data transmission system using a flexible electronic board PCB conformal with the body. The new microfluidic platform paves the way to real-time non-invasive monitoring of biomarkers in stimulated sweat samples for diverse healthcare and wellness applications. Graphical abstract
      PubDate: 2022-01-11
       
  • Simple construction of a two-component fluorescent sensor for turn-on
           detection of Hg2+ in human serum

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      Abstract: The simply constructed fluorescent sensor with inexpensive reagents and low toxicity has attracted increasing attention contributing to its practical application. However, the common construction methods usually required a few building blocks and complex procedures, which is inconvenient for their further application. Herein, a simply constructed fluorescent Hg2+ sensor has been developed based on the intrinsic fluorescence quenching power of G-quadruplex. Two components, AGRO 100 and AMT, were used to construct the sensor. AMT was selected as the fluorescent probe because of its distinct merits. The free AMT emits strongly. However, the fluorescence of AMT could be quenched by G-quadruplex DNA. Additionally, AMT is less toxic and inexpensive. AGRO 100 acts as both the quencher and the capture sequence because it consists of G-rich sequences and T-T mismatched base pairs. The fluorescence of AMT could be quenched by the formed G-quadruplex structure of AGRO 100 in the presence of K+. In the presence of Hg2+, G-quadruplex structure of AGRO 100 was switched to hairpin DNA structure because T-T mismatched base pairs in AGRO 100 could specifically recognize and capture Hg2+ with high affinity. Thus, AMT was released and the fluorescence of AMT was recovered. The developed sensing system was successfully applied to detect Hg2+ in human serum with good recovery and reproducibility. Graphical abstract
      PubDate: 2022-01-11
       
  • Heterogeneous nitration reaction of BSA protein with urban air:
           improvements in experimental methodology

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      Abstract: Gas-phase ozone (O3) and nitrogen dioxide (NO2) can react with environmentally exposed proteins to induce chemical modifications such as the formation of nitrotyrosine (NTyr). Certain proteins with these modifications have also been shown to promote adverse health effects and can trigger an immune response. It is hypothesized that proteinaceous material suspended in the atmosphere as particulate matter, e.g., embedded in pollen, can undergo heterogenous reactions to produce chemically modified proteins that impact human health, especially in urban areas. To investigate the protein modification process under ambient outdoor reaction conditions, bovine serum albumin (BSA) protein samples were loaded onto filters and exposed to urban air in Denver, Colorado (USA). Losses and measurement artifacts were measured independently to calculate nitration effects on the protein via high-performance liquid chromatography and to support the experimental methodology. O3 loss from inlet lines using three commonly used particulate filters was quantified, showing a range of ambient O3 concentration losses from 3.2% for Kynar® (polyvinylidene fluoride) filters to > 60% for commonly used HEPA filters. Protein mass extraction efficiency was calculated as a function of filter material and protein mass using both native and nitrated BSA. Finally, we show examples of BSA samples nitrated by exposure to urban air as a proof-of-concept for future studies, highlighting the potential for atmospherically relevant NTyr formation. The methodology vetted here provides support for a wide variety of experimental efforts related to exposure of analytes to O3 and more broadly to an expanding field of protein modification in ambient air.
      PubDate: 2022-01-11
       
  • Structural characterization of phospholipids and sphingolipids by
           in-source fragmentation MALDI/TOF mass spectrometry

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      Abstract: Phospholipids (PLs) and sphingolipids (SLs) perform critical structural and biological functions in cells. The structure of these lipids, including the stereospecificity and double-bond position of fatty acyl (FA) chains, is critical in decoding lipid biology. In this study, we presented a simple in-source fragmentation (ISF) MALDI/TOF mass spectrometry method that affords complete structural characterization of PL and SL molecules. We analyzed several representative unsaturated lipid species including phosphatidylcholine (PC), plasmalogen PC (pPC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), cardiolipin (CL), sphingomyelin (SM), and ceramide (Cer). Fragment ions reflecting the FA chains at sn–1 and sn–2 position, and those characteristics of the head groups of different PL classes, are readily identified. Specific fragment ions from cleavages of the C–C bond immediately adjacent to the cis C=C double-bond position(s) of FA chains and the trans C=C double bond of the sphingosine constituents allow precise localization of double bonds. The identities of the exemplary product ions from vinylic, allylic, and double-bond cleavages were also verified by LIFT-TOF/TOF. Identification of individual PL species in the lipid mixture was also carried out with ISF-MALDI/TOF. Together, this approach provides a simple yet effective method for structural characterization of PLs and SLs without the additional modification on the instrument hardware, and serves as a simple tool for the identification of lipids. Graphical abstract
      PubDate: 2022-01-11
       
  • A ratiometric fluorescent nanoprobe for signal amplification monitoring of
           intracellular telomerase activity

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      Abstract: Telomerase is considered a valuable diagnostic and prognostic cancer biomarker. Accurate and reliable detection of telomerase activity is of great value in clinical diagnosis, screening of inhibitors, and therapeutics. Here, we developed a novel amplified fluorescence resonance energy transfer (FRET) nanoprobe for highly sensitive and reliable monitoring of intracellular telomerase activity. The nanoprobe (QDSA@DNA) was composed of a streptavidin-modified quantum dot (QDSA) which was functionalized with a telomerase primer sequence (TP) and Cy5-tagged signal switching sequence (SS) through biotin-streptavidin interaction. When the nanoprobe was assembled, the Cy5 was in close proximity to the QDSA, resulting in high FRET efficiency from the QDSA to Cy5. In the presence of telomerase, the TP could be extended to produce telomeric repeat units, which was complementary to the loop of SS. Thus, the SS could hybridize with elongated sequences to form a rigid double-stranded structure, which forced the Cy5 away from the surface of the QDSA, causing low FRET efficiency. Furthermore, due to the production of multiple repeat units by telomerase, multiple hairpin structures could be opened, yielding significant fluorescence ratio (FQDsa/FCy5) enhancement for sensing of telomerase activity. In this way, the combination of a FRET and target-assisted strategy in a nanoprobe improved the detection accuracy and amplified the detection signal, respectively. The QDSA@DNA nanoprobe also showed high selectivity, excellent nuclease stability, and good biocompatibility. More importantly, this nanoprobe was found to be an excellent platform for efficient monitoring of intracellular telomerase activity, providing a potential platform in tumor diagnosis and screening of telomerase-related inhibitors. Graphical abstract
      PubDate: 2022-01-10
       
 
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