The 50 most-cited articles in Analytical Chemistry, 2017

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTMass Spectrometry Imaging: A Review of Emerging Advancements and Future InsightsAmanda Rae Buchberger†, Kellen DeLaney†, Jillian Johnson‡, and Lingjun Li*†‡View Author Information† Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States‡ School of Pharmacy, University of Wisconsin-Madison, 777 Highland Avenue, Madison, Wisconsin 53705, United States*E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 240–265Publication Date (Web):November 20, 2017Publication History Published online13 December 2017Published inissue 2 January 2018https://pubs.acs.org/doi/10.1021/acs.analchem.7b04733https://doi.org/10.1021/acs.analchem.7b04733review-articleACS PublicationsCopyright © 2017 American Chemical SocietyRequest reuse permissionsArticle Views17318Altmetric-Citations609LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTAdvances in Solid Phase Microextraction and Perspective on Future DirectionsNathaly Reyes-GarcésNathaly Reyes-GarcésDepartment of Chemistry, University of Waterloo, Ontario, Canada N2L 3G1More by Nathaly Reyes-GarcésView Biography, Emanuela GionfriddoEmanuela GionfriddoDepartment of Chemistry, University of Waterloo, Ontario, Canada N2L 3G1More by Emanuela GionfriddoView Biography, German Augusto Gómez-RíosGerman Augusto Gómez-RíosDepartment of Chemistry, University of Waterloo, Ontario, Canada N2L 3G1More by German Augusto Gómez-RíosView Biography, Md. Nazmul AlamMd. Nazmul AlamDepartment of Chemistry, University of Waterloo, Ontario, Canada N2L 3G1More by Md. Nazmul AlamView Biographyhttp://orcid.org/0000-0002-6442-3569, Ezel BoyacıEzel BoyacıDepartment of Chemistry, Middle East Technical University, Ankara 06800, TurkeyMore by Ezel BoyacıView Biography, Barbara BojkoBarbara BojkoDepartment of Pharmacodynamics and Molecular Pharmacology, Faculty of Pharmacy, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Toruń, 85-067…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTWater Analysis: Emerging Contaminants and Current IssuesSusan D. Richardson*† and Thomas A. Ternes‡View Author Information† Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29205, United States‡ Federal Institute of Hydrology, Koblenz, D-56068, Germany*E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 398–428Publication Date (Web):November 7, 2017Publication History Published online30 November 2017Published inissue 2 January 2018https://doi.org/10.1021/acs.analchem.7b04577Copyright © 2017 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views10421Altmetric-Citations381LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation…

An all-in-one paper-based analytical device (PAD) was successfully developed for visual fluorescence detection of carcinoembryonic antigen (CEA) on CdTe/CdSe quantum dot (QD)-enzyme-impregnated paper by coupling with a bioresponsive controlled-release system from DNA-gated mesoporous silica nanocontainers (MSNs). The assay was carried out in a centrifuge tube by using glucose-loaded MSNs with a CEA aptamer and a QD-enzyme-paper attached on the lid. Initially, single-strand complementary DNA to a CEA aptamer was covalently conjugated to the aminated MSN, and then glucose (enzyme substrate) molecules were gated into the pore with the help of the aptamer. Glucose oxidase (GOD) and CdTe/CdSe QDs were coimmobilized on paper for the visual fluorescence signal output. Upon target CEA introduction in the detection cell, the analyte specifically reacted with the immobilized aptamer on the MSN to open the pore, thereby resulting in the glucose release. The released glucose was oxidized by the immobilized GOD on paper to produce gluconic acid and hydrogen peroxide, and the latter quenched the…

Collision cross section (CCS) measurements resulting from ion mobility–mass spectrometry (IM-MS) experiments provide a promising orthogonal dimension of structural information in MS-based analytical separations. As with any molecular identifier, interlaboratory standardization must precede broad range integration into analytical workflows. In this study, we present a reference drift tube ion mobility mass spectrometer (DTIM-MS) where improvements on the measurement accuracy of experimental parameters influencing IM separations provide standardized drift tube, nitrogen CCS values ( DT CCS N2 ) for over 120 unique ion species with the lowest measurement uncertainty to date. The reproducibility of these DT CCS N2 values are evaluated across three additional laboratories on a commercially available DTIM-MS instrument. The traditional stepped field CCS method performs with a relative standard deviation (RSD) of 0.29% for all ion species across the three additional laboratories. The calibrated single field CCS method, which is compatible with a wide range of chromatographic inlet systems,…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTSmall-Molecule Fluorescent Probes for Imaging and Detection of Reactive Oxygen, Nitrogen, and Sulfur Species in Biological SystemsXiaoyun Jiao†, Yong Li†, Jinye Niu†‡, Xilei Xie†, Xu Wang*†, and Bo Tang*†View Author Information† College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Key Laboratory of Molecular and Nano Probes, Ministry of Education, Institute of Molecular and Nano Science, Shandong Normal University, Jinan 250014, P. R. China‡ School of Chemical Engineering, Shandong University of Technology, Zibo 255049, P. R. China*Fax: +86-531-86180017. E-mail: [email protected]*E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 533–555Publication Date (Web):October 23, 2017Publication History Published online7 November 2017Published inissue 2 January 2018https://pubs.acs.org/doi/10.1021/acs.analchem.7b04234https://doi.org/10.1021/acs.analchem.7b04234review-articleACS PublicationsCopyright © 2017 American…

Aflatoxin B 1 (AFB 1 ) monitoring has attracted extensive attention because food safety is a worldwide public health problem. Herein, we design a novel simultaneously visual and photoelectrochemical (PEC) immunosensing system for rapid sensitive detection of AFB 1 in foodstuff. The immunoreaction was carried out on anti-AFB 1 antibody-modified magnetic beads by using glucose oxidase (GOx)-labeled AFB 1 -bovine serum albumin (AFB 1 –BSA) conjugates as the tags with a competitive-type immunoassay format, while the visual and PEC evaluation was performed via carbon quantum dots (CQDs)-functionalized MnO 2 nanosheets. Accompanying the formation of immunocomplexes, the carried GOx initially oxidized the substrate (glucose) for the generation of H 2 O 2, which reduced/etched MnO 2 nanosheets into Mn 2+ ions, thereby resulting in the dissociation of CQDs from the electrode. Within the applied potentials, the photocurrent of MnO 2 -CQDs-modified electrode decreased with the increasing H 2 O 2 level in the detection cell. Meanwhile, a visual detection could be performed according to the…

False positive and false negative peaks detected from extracted ion chromatograms (EIC) are an urgent problem with existing software packages that preprocess untargeted liquid or gas chromatography-mass spectrometry metabolomics data because they can translate downstream into spurious or missing compound identifications. We have developed new algorithms that carry out the sequential construction of EICs and detection of EIC peaks. We compare the new algorithms to two popular software packages XCMS and MZmine 2 and present evidence that these new algorithms detect significantly fewer false positives. Regarding the detection of compounds known to be present in the data, the new algorithms perform at least as well as XCMS and MZmine 2. Furthermore, we present evidence that mass tolerance in m/z should be favored rather than mass tolerance in ppm in the process of constructing EICs. The mass tolerance parameter plays a critical role in the EIC construction process and can have immense impact on the detection of EIC peaks.

Three-dimensional (3D) printing has emerged as a potential revolutionary technology for the fabrication of microfluidic devices. A direct experimental comparison of the three 3D printing technologies dominating microfluidics was conducted using a Y-junction microfluidic device, the design of which was optimized for each printer: fused deposition molding (FDM), Polyjet, and digital light processing stereolithography (DLP-SLA). Printer performance was evaluated in terms of feature size, accuracy, and suitability for mass manufacturing; laminar flow was studied to assess their suitability for microfluidics. FDM was suitable for microfabrication with minimum features of 321 ± 5 μm, and rough surfaces of 10.97 μm. Microfluidic devices >500 μm, rapid mixing (71% ± 12% after 5 mm, 100 μL/min) was observed, indicating a strength in fabricating micromixers. Polyjet fabricated channels with a minimum size of 205 ± 13 μm, and a surface roughness of 0.99 μm. Compared with FDM, mixing decreased (27% ± 10%), but Polyjet printing is more suited for microfluidic applications where flow splitting is…

Titanium dioxide (TiO 2; as a potential photosensitizer) has good photocurrent performance and chemical stability but often exhibits low utilization efficiency under ultraviolet (UV) region excitation. Herein, we devised a near-infrared light-to-UV light-mediated photoelectrochemical (PEC) aptasensing platform for the sensitive detection of carcinoembryonic antigen (CEA) based on core–shell NaYF 4:Yb,Tm@TiO 2 upconversion microrods by coupling with target-triggered rolling circle amplification (RCA). The upconversion microrods synthesized through the hydrothermal reaction could act as a photosensing platform to convert the near-infrared (near-IR) excitation into UV emission for generation of photoinduced electrons. The target analyte was determined on a functional magnetic bead by using the corresponding aptamers with a sandwich-type assay format. Upon target CEA introduction, a complex was first formed between capture aptamer-1-conjugated magnetic bead (Apt1-MB) and aptamer-2-primer DNA (Apt2-pDNA). Thereafter, the carried primer DNA by the aptamer-2 paired with linear padlock DNA…

The development of simple fluorescent and colorimetric assays that enable point-of-care DNA and RNA detection has been a topic of significant research because of the utility of such assays in resource limited settings. The most common motifs utilize hybridization to a complementary detection strand coupled with a sensitive reporter molecule. Here, a paper-based colorimetric assay for DNA detection based on pyrrolidinyl peptide nucleic acid (acpcPNA)-induced nanoparticle aggregation is reported as an alternative to traditional colorimetric approaches. PNA probes are an attractive alternative to DNA and RNA probes because they are chemically and biologically stable, easily synthesized, and hybridize efficiently with the complementary DNA strands. The acpcPNA probe contains a single positive charge from the lysine at C-terminus and causes aggregation of citrate anion-stabilized silver nanoparticles (AgNPs) in the absence of complementary DNA. In the presence of target DNA, formation of the anionic DNA-acpcPNA duplex results in dispersion of the AgNPs as a result of electrostatic…

Carbon dots (CDs) combined with a nanomaterial-based quencher has created an innovative way for designing promising sensors. Herein, a novel fluorescent-sensing platform was designed for sensitive detection of organophosphorus pesticides (OPs). The preparation of CDs was based on one-step hydrothermal reaction of 3-aminobenzeneboronic acid. The fluorescence of CDs can be quenched by manganese dioxide (MnO 2 ) nanosheets via the Förster resonance energy transfer (FRET). In the presence of butyrylcholinesterase (BChE) and acetylthiocholine, the enzymatic hydrolysate (thiocholine) can efficiently trigger the decomposition of MnO 2 nanosheets, resulting in the recovery of CDs fluorescence. OPs as inhibitors for BChE activity can prevent the generation of thiocholine and decomposition of MnO 2 nanosheets, accompanying the fluorescence “turn-off” of the system. So the BChE-ATCh-MnO 2 –CDs system can be utilized to detect OPs quantitatively based on the fluorescence turn “on–off”. Under the optimum conditions, the present FRET-based approach can detect paraoxon ranging from 0.05 to 5 ng mL…

Measuring the levels of Fe 3+ in human body has attracted considerable attention for health monitoring as it plays an essential role in many physiological processes. In this work, we reported a selective fluorescent nanoprobe for Fe 3+ detection in biological samples based on ultrabright N/P codoped carbon dots. By employing adenosine 5′-triphosphate (ATP) as the carbon, nitrogen, and phosphorus source, the N/P codoped carbon dots could be simply prepared through hydrothermal treatment. The obtained carbon dots exhibited high quantum yields up to 43.2%, as well as excellent photostability, low toxicity, and water solubility. Because of the Fe–O–P bonds formed between Fe 3+ and the N/P codoped carbon dots, this nanoprobe showed high selectivity toward Fe 3+ against various potential interfering substances in the presence of EDTA. The fluorescence quenching of as-fabricated carbon dots was observed with the increasing Fe 3+ concentration, and the calibration curve displayed a wide linear region over the range of 1–150 μM with a detection limit of 0.33 μM. The satisfactory accuracy was…

SUMMARY When using liquid chromatography/mass spectrometry (LC/MS) to perform untargeted metabolomics, it is now routine to detect tens of thousands of features from biological samples. Poor understanding of the data, however, has complicated interpretation and masked the number of unique metabolites actually being measured in an experiment. Here we place an upper bound on the number of unique metabolites detected in Escherichia coli samples analyzed with one untargeted metabolomic method. We first group multiple features arising from the same analyte, which we call “degenerate features”, using a context-driven annotation approach. Surprisingly, this analysis revealed thousands of previously unreported degeneracies that reduced the number of unique analytes to ~2,961. We then applied an orthogonal approach to remove non-biological features from the data by using the 13 C-based credentialing technology. This further reduced the number of unique analytes to less than 1,000.

Because 2,4,6-trinitrophenol (TNP) and its analogues such as 2,4,6-trinitrotoluene (TNT) possess similar chemical structures and properties, the reliable and accurate detection of TNP from its analogues still remains a challenging task. In the present work, a selective and sensitive method based on the water-soluble silicon nanoparticles (SiNPs) for the determination of TNP was established. The SiNPs with good thermostability and excellent antiphotobleaching capability were prepared via a simple one-pot method. Compared with the synthesized time of other nanomaterials with respect to the detection of TNP, this method avoided a multistep and time-consuming synthesis procedure. Significantly, the fluorescence of the SiNPs could be remarkably quenched by TNP via an inner filter effect. A wide linear range was obtained from 0.02 to 120 μg/mL with a limit of detection of 6.7 ng/mL. The method displayed excellent selectivity toward TNP over other nitroaromatic explosives. The proposed fluorescent method was successfully applied to the analysis of TNP. Moreover, a straightforward and…

Recently, the development of new fluorescent probes for the ratiometric detection of target objects inside living cells has received great attention. Normally, the preparation, modification as well as conjugation procedures of these probes are complicated. On this basis, great efforts have been paid to establish convenient method for the preparation of dual emissive nanosensor. In this work, a functional dual emissive carbon dots (dCDs) was prepared by a one-pot hydrothermal carbonization method. The dCDs exhibits two distinctive fluorescence emission peaks at 440 and 624 nm with the excitation at 380 nm. Different from the commonly reported dCDs, this probe exhibited an interesting wavelength dependent dual responsive functionality toward lysine (440 nm) and pH (624 nm), enabling the ratiometric detection of these two targets. The quantitative analysis displayed that a linear range of 0.5-260 μM with a detection limit of 94 nM toward lysine and the differentiation of pH variation from 1.5 to 5.0 could be readily realized in a ratiometric strategy, which was not reported before with…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTPhotoelectrochemical ImmunoassaysWei-Wei Zhao*†‡, Jing-Juan Xu†, and Hong-Yuan Chen†View Author Information† State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, Jiangsu 210023, P.R. China‡ Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States*E-mail: [email protected] or [email protected]. Phone/Fax: +86-25-89684862.Cite this: Anal. Chem. 2018, 90, 1, 615–627Publication Date (Web):November 14, 2017Publication History Published online21 November 2017Published inissue 2 January 2018https://pubs.acs.org/doi/10.1021/acs.analchem.7b04672https://doi.org/10.1021/acs.analchem.7b04672review-articleACS PublicationsCopyright © 2017 American Chemical SocietyRequest reuse permissionsArticle Views5949Altmetric-Citations254LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both…

Orbitraps are high-resolution ion-trap mass spectrometers that are widely used in metabolomics. While the mass accuracy and resolving power of orbitraps have been extensively documented, their spectral accuracy, i.e., accuracy in measuring the abundances of isotopic peaks, remains less studied. In analyzing spectra of unlabeled metabolites, we discovered a systematic under representation of heavier natural isotopic species, especially for high molecular weight metabolites (∼20% under-measurement of [M + 1]/[M + 0] ratio at m/z 600). We hypothesize that these discrepancies arise for metabolites far from the lower limit of the mass scan range, due to the weaker containment in the C-trap that results in suboptimal trajectories inside the Orbitrap analyzer. Consistent with this, spectral fidelity was restored by dividing the mass scan range (initially 75 m/z to 1000 m/z) into two scan events, one for lower molecular weight and the other for higher molecular weight metabolites. Having thus obtained accurate mass spectra at high resolution, we found that natural isotope correction for…

A novel CRISPR/Cas9 triggered isothermal exponential amplification reaction (CAS-EXPAR) strategy based on CRISPR/Cas9 cleavage and nicking endonuclease (NEase) mediated nucleic acids amplification was developed for rapid and site-specific nucleic acid detection. CAS-EXPAR was primed by the target DNA fragment produced by cleavage of CRISPR/Cas9, and the amplification reaction performed cyclically to generate a large number of DNA replicates which were detected using a real-time fluorescence monitoring method. This strategy that combines the advantages of CRISPR/Cas9 and exponential amplification showed high specificity as well as rapid amplification kinetics. Unlike conventional nucleic acids amplification reactions, CAS-EXPAR does not require exogenous primers, which often cause target-independent amplification. Instead, primers are first generated by Cas9/sgRNA directed site-specific cleavage of target and accumulated during the reaction. It was demonstrated this strategy gave a detection limit of 0.82 amol and showed excellent specificity in discriminating single-base mismatch.…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTAnalytical Challenges and Recent Advances in Mass Spectrometry Based LipidomicsYepy H. Rustam† and Gavin E. Reid*†‡§View Author Information† Department of Biochemistry and Molecular Biology, University of Melbourne, Parkville, Victoria 3010, Australia‡ School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia§ Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia*E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 374–397Publication Date (Web):November 22, 2017Publication History Published online8 December 2017Published inissue 2 January 2018https://pubs.acs.org/doi/10.1021/acs.analchem.7b04836https://doi.org/10.1021/acs.analchem.7b04836review-articleACS PublicationsCopyright © 2017 American Chemical SocietyRequest reuse permissionsArticle Views6605Altmetric-Citations223LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals.…

Rapid sampling and multicomponent detection are crucial for monitoring of pesticide residues analysis. Here, a gecko-inspired nanotentacle surface-enhanced Raman spectroscopy (G-SERS) platform is proposed for the first time for the simultaneous detection of three kinds of pesticides via a simple and intuitive “press and peeled-off” approach. The G-SERS platform obtained from seeding deposition of silver nanoparticles (Ag NPs) on 3D PDMS nanotentacle array is flexible and free-standing. Compared with other substrates, this G-SERS substrate can simultaneously provide outstanding SERS activity (enhancement factor = 1.2 × 10 7 ), superior reproducibility (RSD = 5.8%) and countless flexible nanoscale “tentacles” (∼6.7 × 10 8 /cm 2 ). Moreover, the high density of “tentacles” can freely approach the microarea and enable efficient target collection, which were confirmed by SEM and HPLC. By direct sampling from cucumber, apple, and grape surfaces, thiram (TMTD), methyl parathion (MPT), malachite green (MG), and their multiple components have been rapidly and reliably determined. For…

Metal-organic framework (MOF) nanosheets are a class of two-dimensional (2D) porous and crystalline materials that hold promise for catalysis and biodetection. Although 2D MOF nanosheets have been utilized for in vitro assays, ways of engineering them into diagnostic tools for live animals are much less explored. In this work, a series of MOF nanosheets are successfully engineered into a highly sensitive and selective diagnostic platform for in vivo monitoring of heparin (Hep) activity. The iron-porphyrin derivative is selected as a ligand to synthesize a series of archetypical MOF nanosheets with intrinsic heme-like catalytic sites, mimicking peroxidase. Hep-specific AG73 peptides as recognition motifs are physically adsorbed onto MOF nanosheets, blocking active sites from nonspecific substrate-catalyst interaction. Because of the highly specific interaction between Hep and AG73, the activity of AG73-MOF nanosheets is restored upon the binding of Hep, but not Hep analogues and other endogenous biomolecules. Furthermore, by taking advantages of biocompatibility and diagnostic…

Ultrahigh resolution mass spectrometry, such as Fourier transform ion cyclotron resonance mass spectrometry (FT ICR MS), can resolve thousands of molecular ions in complex organic matrices. A Compound Identification Algorithm (CIA) was previously developed for automated elemental formula assignment for natural organic matter (NOM). In this work, we describe software Formularity with a user-friendly interface for CIA function and newly developed search function Isotopic Pattern Algorithm (IPA). While CIA assigns elemental formulas for compounds containing C, H, O, N, S, and P, IPA is capable of assigning formulas for compounds containing other elements. We used halogenated organic compounds (HOC), a chemical class that is ubiquitous in nature as well as anthropogenic systems, as an example to demonstrate the capability of Formularity with IPA. A HOC standard mix was used to evaluate the identification confidence of IPA. Tap water and HOC spike in Suwannee River NOM were used to assess HOC identification in complex environmental samples. Strategies for reconciliation of CIA and IPA…

The present work investigates the capability of single-stranded DNA (ssDNA) in enhancing the intrinsic peroxidase-like activity of the g-C 3 N 4 nanosheets (NSs). We found that ssDNA adsorbed on g-C 3 N 4 NSs could improve the catalytic activity of the nanosheets. The maximum reaction rate of the H 2 O 2 -mediated TMB oxidation catalyzed by the ssDNA-NSs hybrid was at least 4 times faster than that obtained with unmodified NSs. The activity enhancement could be attributed to the strong interaction between TMB and ssDNA mediated by electrostatic attraction and aromatic stacking and by both the length and base composition of the ssDNA. The high catalytic activity of the ssDNA-NSs hybrid permitted sensitive colorimetric detection of exosomes if the aptamer against CD63, a surface marker of exosome, was employed in hybrid construction. The sensor recognized the differential expression of CD63 between the exosomes produced by a breast cancer cell line (MCF-7) and a control cell line (MCF-10A). Moreover, a similar trend was detected in the circulating exosomes isolated from the sera…

Liquid chromatography-mass spectrometry (LC-MS) methods are most often used for untargeted metabolomics and lipidomics. However, methods have not been standardized as accepted "best practice" documents, and reports lack harmonization with respect to quantitative data that enable interstudy comparisons. Researchers use a wide variety of high-resolution mass spectrometers under different operating conditions, and it is unclear if results would yield different biological conclusions depending on the instrument performance. To this end, we used 126 identical human plasma samples and 29 quality control samples from a nutritional intervention study. We investigated lipidomic data acquisitions across nine different MS instruments (1 single TOF, 1 Q/orbital ion trap, and 7 QTOF instruments). Sample preparations, chromatography conditions, and data processing methods were kept identical. Single-point internal standard calibrations were used to estimate absolute concentrations for 307 unique lipids identified by accurate mass, MS/MS spectral match, and retention times. Quantitative results…

Owing to the role of exosome as a cargo for intercellular communication, especially in cancer metastasis, the evidence has been consistently accumulated that exosomes can be used as a noninvasive indicator of cancer. Consequently, several studies applying exosome have been proposed for cancer diagnostic methods such as ELISA assay. However, it has been still challenging to get reliable results due to the requirement of a labeling process and high concentration of exosome. Here, we demonstrate a label-free and highly sensitive classification method of exosome by combining surface-enhanced Raman scattering (SERS) and statistical pattern analysis. Unlike the conventional method to read different peak positions and amplitudes of a spectrum, whole SERS spectra of exosomes were analyzed by principal component analysis (PCA). By employing this pattern analysis, lung cancer cell derived exosomes were clearly distinguished from normal cell derived exosomes by 95.3% sensitivity and 97.3% specificity. Moreover, by analyzing the PCA result, we could suggest that this difference was induced by…

Cysteine (Cys), as an important biothiol, plays a major role in many physiological processes like protein synthesis, detoxification and metabolism, and also is closely associated with a variety of diseases; thus the design of novel highly selective and sensitive near-infrared (NIR) fluorescent probes for Cys detection in vivo is of great significance. Herein, we report a selective and sensitive NIR turn-on fluorescent probe (CP-NIR) with large Stokes shift for detecting Cys in vivo. Upon addition of Cys to the solution of the probe, it is absorption wavelength shifts from 550 to 600 nm, accompanying with an obvious enhancement of NIR fluorescence emission centering around 760 nm. This Michael-addition reaction-based probe shows a large Stokes shift (160 nm), low detection limit (48 nM), fast response time, and low toxicity. Moreover, this novel NIR probe with good cell permeability was successfully applied to monitoring endogenous Cys in living cells and in a mouse model.

Ratiometric fluorescence detection attracts much attention because of its decreased environmental influence and easy-to-differentiate color and intensity change. Herein, a guest-encapsulation metal–organic framework (MOF), Ru@MIL–NH 2, is prepared with 2-aminoterephthalic acid, AlCl 3, and Ru(bpy) 3 2+ by a simple one-pot method for ratiometric fluorescence sensing of water in organic solvents. The rational selection of the excitation wavelength provides dual emission at 465 and 615 nm from Ru@MIL–NH 2 under a single excitation of 300 nm. High sensitivity, low detection limit (0.02% v/v), wide response range (0–100%), and fast response (less than 1 min) are obtained for ratiometric fluorescence sensing of water under single excitation with Ru@MIL–NH 2 as the probe. Moreover, the result of water content is independent of the concentration of Ru@MIL–NH 2 as the merit of ratiometric fluorescence detection. The response mechanism reveals that the protonation of the nitrogen atom of the MIL–NH 2, the π-conjugation system, and the stable fluorescence of Ru(bpy) 3 2+ achieve the…

Successful pathogen detection is crucial for public health as the threat of infectious disease is dramatically increasing globally due to bacteria developing resistance to many antimicrobial drugs. The increase in bacterial infections has led to urgent demands for simpler, faster, and more reliable detection methods to be developed allowing the most appropriate therapy to be provided. Surface enhanced Raman scattering (SERS) is an analytical technique which has gained a great deal of interest for biosensing due to its sensitivity, selectivity, and multiplexing capabilities. A new bionanosensor has been developed for the isolation and detection of multiple bacterial pathogens via magnetic separation and SERS. This novel assay format involves using lectin functionalized magnetic nanoparticles for capture and isolation of bacteria from the sample matrix followed by specifically detecting bacterial pathogens using SERS active nanoparticles functionalized with antibodies which are strain specific. Therefore, the sample is captured using a “magnetic plug” and interrogated with a laser…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTDNAzyme-Mediated Assays for Amplified Detection of Nucleic Acids and ProteinsHanyong Peng, Ashley M. Newbigging, Zhixin Wang, Jeffrey Tao, Wenchan Deng, X. Chris Le*, and Hongquan Zhang*View Author Information Division of Analytical and Environmental Toxicology, Department of Laboratory Medicine and Pathology, Faculty of Medicine and Dentistry, University of Alberta, 10-102 Clinical Sciences Building, Edmonton, Alberta T6G 2G3, Canada*E-mail: [email protected]*E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 190–207Publication Date (Web):November 28, 2017Publication History Published online13 December 2017Published inissue 2 January 2018https://doi.org/10.1021/acs.analchem.7b04926Copyright © 2017 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views14242Altmetric-Citations159LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage…

The ratiometric fluorescence assay, which can eliminate the external effects, has attracted great attention. In this work, a carbon dot (CD)-based nanohybrid dual-emission system was simply prepared by a unique approach of solvothermal treating corn bract and used as a ratiometric fluorescent sensor for Hg 2+ detection. Under a single excitation, the obtained nanohybrid sensor had two emission bands around 470 and 678 nm, which may originate from the intrinsic structure of CDs and chlorophyll-derived porphyrins, respectively. In the presence of Hg 2+, the fluorescence at 678 nm could be remarkably quenched, while the fluorescence intensity at 470 nm was only slightly altered. The fluorescence intensity ratio at 470 and 678 nm exhibited a good linear relationship in the Hg 2+ concentration range from 0 to 40 μM with a detection limit of about 9.0 nM. It also had a satisfying assay performance in serum and river water samples. The prepared CD-based nanohybrid sensor here may hold the further potential applications in biomedicine study, environmental protection, and food safety.

Ion mobility (IM) separations have a broad range of analytical applications, but insufficient resolution often limits their utility. Here, we report on ion mobility separations in a structures for lossless ion manipulations (SLIM) serpentine ultralong path with extended routing (SUPER) traveling wave (TW) ion mobility (IM) module in conjunction with mass spectrometry (MS). Ions were confined in the SLIM by rf fields in conjunction with a DC guard bias, enabling essentially lossless TW transmission over greatly extended paths. The extended routing utilized multiple passes (e.g., ∼1094 m over 81 passes through the 13.5 m serpentine path) and was facilitated by the introduction of a lossless ion switch that allowed ions to be directed to either the MS detector or for another pass through the serpentine separation region, allowing theoretically unlimited IM path lengths. The multipass SUPER IM-MS provided resolution approximately proportional to the square root of the number of passes (or total path length). More than 30-fold higher IM resolution (∼340 vs ∼10) for Agilent tuning mix m/z…

In tandem mass spectrometry (MS/MS)-based proteomics, search engines rely on comparison between an experimental MS/MS spectrum and the theoretical spectra of the candidate peptides. Hence, accurate prediction of the theoretical spectra of peptides appears to be particularly important. Here, we present pDeep, a deep neural network-based model for the spectrum prediction of peptides. Using the bidirectional long short-term memory (BiLSTM), pDeep can predict higher-energy collisional dissociation, electron-transfer dissociation, and electron-transfer and higher-energy collision dissociation MS/MS spectra of peptides with >0.9 median Pearson correlation coefficients. Further, we showed that intermediate layer of the neural network could reveal physicochemical properties of amino acids, for example the similarities of fragmentation behaviors between amino acids. We also showed the potential of pDeep to distinguish extremely similar peptides (peptides that contain isobaric amino acids, for example, GG = N, AG = Q, or even I = L), which were very difficult to distinguish using traditional…

A two-photon reversible fluorescent probe L1 was designed and synthesized. The fluorescence intensity of the probe solution was strong, while the fluorescence of the solution was obviously quenched and the color of the solution was changed after the addition of hypochlorous acid, indicating this is "naked-eye sensor" for the detection of HClO. The probe showed great selectivity for hypochlorous acid over other reactive oxygen species (ROS) and anions. Fluorescence titration experiments showed that the probe has a low detection limit of 0.674 μM. Because of a morpholine group introduced to the naphathalimide framework, probe L1 was successfully applied to detect intracellular HClO in lysosome.

In this work, the use of fused deposition modeling (FDM) in a (bio)analytical/lab-on-a-chip research laboratory is described. First, the specifications of this 3D printing method that are important for the fabrication of (micro)devices were characterized for a benchtop FDM 3D printer. These include resolution, surface roughness, leakage, transparency, material deformation, and the possibilities for integration of other materials. Next, the autofluorescence, solvent compatibility, and biocompatibility of 12 representative FDM materials were tested and evaluated. Finally, we demonstrate the feasibility of FDM in a number of important applications. In particular, we consider the fabrication of fluidic channels, masters for polymer replication, and tools for the production of paper microfluidic devices. This work thus provides a guideline for (i) the use of FDM technology by addressing its possibilities and current limitations, (ii) material selection for FDM, based on solvent compatibility and biocompatibility, and (iii) application of FDM technology to (bio)analytical research by…

Uniform silver-containing metal nanostructures with strong and stable surface-enhanced Raman scattering (SERS) signals hold great promise for developing ultrasensitive probes for biodetection. Nevertheless, the direct synthesis of such ready-to-use nanoprobes remains extremely challenging. Herein we report a DNA-mediated gold-silver nanomushroom with interior nanogaps directly synthesized and used for multiplex and simultaneous SERS detection of various DNA and RNA targets. The DNA involved in the nanostructures can act as not only gap DNA (mediated DNA) but also probe DNA (hybridized DNA), and DNA's involvement enables the nanostructures to have the inherent ability to recognize DNA and RNA targets. Importantly, we were the first to establish a new method for the generation of multicolor SERS probes using two different strategies. First Raman-labeled alkanethiol probe DNA was assembled on gold nanoparticles, and second, thiol-containing Raman reporters were coassembled with the probe DNA. The ready-to-use probes also give great potential to develop ultrasensitive detection methods…

Salmonella causes over a million foodborne illnesses per year in the United States resulting in more hospitalizations and deaths than any other foodborne bacterial pathogen. To help prevent outbreaks, a rapid, portable, sensitive, and reliable method for onsite detection of bacteria that can be used in different sample matrices would be beneficial. Herein, we present a colorimetric paper-based analytical device (PAD) combined with immunomagnetic separation (IMS) for detecting Salmonella typhimurium . IMS anti- Salmonella coated magnetic beads were applied to capture and separate bacteria from the sample matrix and preconcentrate it into small volumes before testing on paper. To directly detect S. typhimurium after IMS, a sandwich immunoassay was implemented into the procedure with β-galactosidase (β-gal) as the detection enzyme. Using the antibody/enzyme complex, we performed a colorimetric assay with chlorophenol red-β- d -galactopyranoside (CPRG) for bacteria quantification. The method was confirmed to be highly specific to S. typhimurium without interference from other pathogenic…

The use of collision cross-section (CCS) values derived from ion mobility-mass spectrometry (IM-MS) has been proven to facilitate lipid identifications. Its utility is restricted by the limited availability of CCS values. Recently, the machine-learning algorithm-based prediction (e.g., MetCCS) is reported to generate CCS values in a large-scale. However, the prediction precision is not sufficient to differentiate lipids due to their high structural similarities and subtle differences on CCS values. To address this challenge, we developed a new approach, namely, LipidCCS, to precisely predict lipid CCS values. In LipidCCS, a set of molecular descriptors were optimized using bioinformatic approaches to comprehensively describe the subtle structure differences for lipids. The use of optimized molecular descriptors together with a large set of standard CCS values for lipids (458 in total) to build the prediction model significantly improved the precision. The prediction precision of LipidCCS was externally validated with median relative errors (MRE) of ∼1% using independent data sets…

Rational design and construction of electrocatalytic nanomaterials is vital for improving the sensitivity and selectivity of nonenzymatic electrochemical sensors. Here, we report a novel graphene supported intermetallic PtPb nanoplates (PtPb/G) nanocomposite as an enhanced electrochemical sensing platform for high-sensitivity detection of H 2 O 2 in neutral solution and also released from the cells. The intermetallic PtPb nanoplates are first synthesized via a simple wet-chemistry process and subsequently assembled on graphene via a solution-phase self-assembly approach. The obtained nanocomposite exhibits excellent electrocatalytic activity for the electrochemical reduction of H 2 O 2 in a half-cell test and can detect H 2 O 2 with a wide linear detection range of 2 nM to 2.5 mM and a very low detection limit of 2 nM. Under the same conditions, the sensitivity of PtPb/G for the detection of H 2 O 2 is more than 12.7 times higher than that of commercial Pt/C. The high-density of electrocatalytic active sites on the unique PtPb nanoplates and the synergistic effect between PtPb…

The development of transparency-based electrochemical and paper-based colorimetric analytic detection platforms is presented as complementary methods for food and waterborne bacteria detection from a single assay. Escherichia coli and Enterococcus species, both indicators of fecal contamination, were detected using substrates specific to enzymes produced by each species. β-galactosidase (β-gal) and β-glucuronidase (β-glucur) are both produced by E. coli, while β-glucosidase (β-gluco) is produced by Enterococcus spp. Substrates used produced either p -nitrophenol (PNP), o -nitrophenol (ONP), or p -aminophenol (PAP) as products. Electrochemical detection using stencil-printed carbon electrodes (SPCEs) was found to provide optimal performance on inexpensive and disposable transparency film platforms. Using SPCEs, detection limits for electrochemically active substrates, PNP, ONP, and PAP were determined to be 1.1, 2.8, and 0.5 μM, respectively. A colorimetric paper-based well plate system was developed from a simple cardboard box and smart phone for the detection of PNP and ONP.…

Recently, the fluorescent detection of carbon monoxide (CO) in living cells has attracted great attention. However, due to the lack of effective ways to construct fluorescent CO probes, fluorescent detection of CO in living cells is still in its infancy. In this paper, we report for the first time the use of allyl ether as a reaction site for construction of fluorescent CO probes. By this way, two readily available allyl fluorescein ethers were prepared, which were found to be highly selective and sensitive probes for CO in the presence of PdCl 2 . These probes have the merits of good stability, good water-solubility, and rapid and distinct colorimetric and remarkable fluorescent turn-on signal changes. Moreover, a very low dose of these two probes can be used to detect and track CO in living cells, indicating that these two probes could be very promising biological tools for CO detection in living systems. Overall, this work provided not only two new promising fluorescent CO probes but also a new way to devise fluorescent CO probes.

Adenosine triphosphate (ATP) is mainly produced in the mitochondrion and used as a universal energy source for various cellular events. Various fluorescent probes for ATP have been established successfully, but most of them are not appropriate for monitoring the fluctuation of the mitochondrial ATP level. Herein, a fluorescent probe named Mito-Rh is first synthesized and used to recognize ATP in mitochondrion. In the probe, rhodamine, diethylenetriamine, and triphenylphosphonium are selected as fluorophore, reaction site, and mitochondrion-targeting group, respectively. Probe Mito-Rh shows high sensitivity to ATP with 81-fold fluorescence enhancement, and the detection range (0.1-10 mM) can match the concentration level of ATP in the mitochondrion. Moreover, Mito-Rh provides excellent selectivity toward ATP over other biological anions (ADP, AMP, GTP, CTP, UTP) owing to a concurrent effect of dual recognition sites (hydrogen bond and π-π stacking). In particular, the probe can localize in mitochondrion specifically and demonstrates utility in the real-time detection of mitochondrial…

A novel signal-amplified strategy based on dopamine-loaded liposome (DLL) was developed for competitive-type nonenzymatic photoelectrochemical (PEC) immunoassay of small- molecular aflatoxin B 1 (AFB 1 ) in foodstuff, using Mn 2+ -doped Zn 3 (OH) 2 V 2 O 7 ·2H 2 O nanobelts. The signal was amplified by high-loaded capacity of liposome and the highly efficient dopamine molecule to enhance photocurrent of Mn 2+ -doped Zn 3 (OH) 2 V 2 O 7 ·2H 2 O nanobelts. The loaded dopamine in the liposome was used as an electron donor to scavenge the hole and inhibit the charge recombination. To design such an immunoassay system, a AFB 1 –bovine serum albumin (AFB 1 –BSA) conjugate was covalently bound with the multifunctional liposome via the cross-linkage glutaraldehyde, whereas monoclonal anti-AFB 1 antibody was labeled onto a magnetic bead by typical carbodiimide coupling. Upon addition of target AFB 1, a competitive immunoreaction was carried out between the analyte and the AFB 1 –BSA–DLL for the conjugated antibody on the magnetic bead. Followed by magnetic separation, the carried DLL on the…

Herein, we developed a general strategy for rapid, highly selective, and ultratrace naked-eye colorimetric detection of Hg 2+ in aqueous solutions. Two dimensional rGO/PEI/Pd nanohybrids, where rGO, PEI, and Pd were referred to as reduced graphene oxide, polyethylenimine, and Pd nanoparticles, respectively, were synthesized and used as mimetic peroxidase for selective and ultrasensitive detection of Hg 2+ in water and human serum samples. In the presence of mercury ions, the peroxidase mimetic activity of rGO/PEI/Pd nanohybrids was found to be stimulated and enhanced significantly, which promoted the effective oxidation and color change of 3,3′,5,5′-tetramethylbenzidine (TMB) in solution to dark blue that was detected by the naked-eye and the absorption spectroscopic method. The proposed sensing strategy coupled with spectroscopic detection method showed an ultralow detection limit of 0.39 nM for Hg 2+ in ddH 2 O and ∼1 nM in wastewater as well as serum samples, respectively. On the basis of the colorimetric assay, a minimum concentration of ∼10 nM for Hg 2+ in wastewater and human…

Upconversion nanoparticles (UCNPs) are attractive candidates for energy transfer-based analytical applications. In contrast to classical donor-acceptor pairs, these particles contain many emitting lanthanide ions together with numerous acceptor dye molecules at different distances to each other, strongly depending on the particle diameter. UCNPs with precisely controlled sizes between 10 and 43 nm were prepared and functionalized with rose bengal and sulforhodamine B by a ligand-exchange procedure. Time-resolved studies of the upconversion luminescence of the UCNP donor revealed a considerable shortening of the donor lifetime as a clear hint for Förster resonance energy transfer (FRET). FRET was most pronounced for 21 nm-sized UCNPs, yielding a FRET efficiency of 60%. At larger surface-to-volume ratios, the FRET efficiency decreased by an increasing competition of nonradiative surface deactivation. Such dye-UCNP architectures can also provide an elegant way to shift the UCNP emission color, since the fluorescence intensity of the organic dyes excited by FRET was comparable to that…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTMultidimensional Gas Chromatography: Advances in Instrumentation, Chemometrics, and ApplicationsSarah E. Prebihalo†, Kelsey L. Berrier†, Chris E. Freye†, H. Daniel Bahaghighat†‡, Nicholas R. Moore†, David K. Pinkerton†, and Robert E. Synovec*†View Author Information† Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195, United States‡ Department of Chemistry and Life Science, United States Military Academy, West Point, New York 10996, United States*Phone: +1-206-685-2328. Fax: +1-206-685-8665. E-mail: [email protected]Cite this: Anal. Chem. 2018, 90, 1, 505–532Publication Date (Web):October 31, 2017Publication History Published online10 November 2017Published inissue 2 January 2018https://pubs.acs.org/doi/10.1021/acs.analchem.7b04226https://doi.org/10.1021/acs.analchem.7b04226review-articleACS PublicationsCopyright © 2017 American Chemical SocietyRequest reuse permissionsArticle Views4389Altmetric-Citations149LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article…

XCMS and MZmine 2 are two widely used software packages for preprocessing untargeted LC/MS metabolomics data. Both construct extracted ion chromatograms (EICs) and detect peaks from the EICs, the first two steps in the data preprocessing workflow. While both packages have performed admirably in peak picking, they also detect a problematic number of false positive EIC peaks and can also fail to detect real EIC peaks. The former and latter translate downstream into spurious and missing compounds and present significant limitations with most existing software packages that preprocess untargeted mass spectrometry metabolomics data. We seek to understand the specific reasons why XCMS and MZmine 2 find the false positive EIC peaks that they do and in what ways they fail to detect real compounds. We investigate differences of EIC construction methods in XCMS and MZmine 2 and find several problems in the XCMS centWave peak detection algorithm which we show are partly responsible for the false positive and false negative compound identifications. In addition, we find a problem with MZmine…