The 50 most-cited articles in Analytical Chemistry, 2018

METLIN originated as a database to characterize known metabolites and has since expanded into a technology platform for the identification of known and unknown metabolites and other chemical entities. Through this effort it has become a comprehensive resource containing over 1 million molecules including lipids, amino acids, carbohydrates, toxins, small peptides, and natural products, among other classes. METLIN's high-resolution tandem mass spectrometry (MS/MS) database, which plays a key role in the identification process, has data generated from both reference standards and their labeled stable isotope analogues, facilitated by METLIN-guided analysis of isotope-labeled microorganisms. The MS/MS data, coupled with the fragment similarity search function, expand the tool's capabilities into the identification of unknowns. Fragment similarity search is performed independent of the precursor mass, relying solely on the fragment ions to identify similar structures within the database. Stable isotope data also facilitate characterization by coupling the similarity search output with…

The development of an effective method for detecting heavy-metal ions remains a serious task because of their high toxicity to public health and environments. Herein, a new electrochemical method based on a graphene aerogel (GA) and metal–organic framework (MOF) composites was developed for simultaneous detection of multiple heavy-metal ions in aqueous solutions. The GA-MOF composites were synthesized via the in situ growth of the MOF UiO-66-NH 2 crystal on the GA matrix. GA not only serves as the backbone for UiO-66-NH 2 but also enhances the conductivity of the composites by accelerating the electron transfer in the matrix. UiO-66-NH 2 worked as a binding site for heavy-metal ions because of the interaction between hydrophilic groups and metal cations. The detection performance of the GA-UiO-66-NH 2 composite-modified electrodes was determined. The developed electrochemical method can be successfully applied for individual and simultaneous detection of heavy-metal ions, namely, Cd 2+, Pb 2+, Cu 2+,and Hg 2+, in aqueous solutions with high sensitivity and selectivity. The method…

We evaluate the performance of a new chemical ionization source called Vocus, consisting of a discharge reagent-ion source and focusing ion-molecule reactor (FIMR) for use in protontransfer-reaction time-of-flight mass spectrometry (PTR-TOF) measurements of volatile organic compounds (VOCs) in air. The reagent ion source uses a low-pressure discharge. The FIMR consists of a glass tube with a resistive coating, mounted inside a radio-frequency (RF) quadrupole. The axial electric field is used to enhance ion collision energies and limit cluster ion formation. The RF field focuses ions to the central axis of the reactor and improves the detection efficiency of product ions. Ion trajectory calculations demonstrate the mass-dependent focusing of ions and enhancement of the ion collision energy by the RF field, in particular for the lighter ions. Product ion signals are increased by a factor of 10 when the RF field is applied (5,000-18,000 cps ppbv -1 ), improving measurement precision and detection limits while operating at very similar reaction conditions as traditional PTR instruments.…

This paper describes the design and characterization of an open-source "universal wireless electrochemical detector" (UWED). This detector interfaces with a smartphone (or a tablet) using "Bluetooth Low Energy" protocol; the smartphone provides (i) a user interface for receiving the experimental parameters from the user and visualizing the result in real time, and (ii) a proxy for storing, processing, and transmitting the data and experimental protocols. This approach simplifies the design, and decreases both the size and the cost of the hardware; it also makes the UWED adaptable to different types of analyses by simple modification of the software. The UWED can perform the most common electroanalytical techniques of potentiometry, chronoamperometry, cyclic voltammetry, and square wave voltammetry, with results closely comparable to benchtop commercial potentiostats. Although the operating ranges of electrical current and voltage of the UWED (±1.5 V, ±180 μA) are more limited than most benchtop commercial potentiostats, its functional range is sufficient for most electrochemical…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Developments in Two-Dimensional Liquid Chromatography: Fundamental Improvements for Practical ApplicationsBob W. J. Pirok*Bob W. J. PirokUniversity of Amsterdam, van 't Hoff Institute for Molecular Sciences, Analytical-Chemistry Group, Science Park 904, 1098 XH Amsterdam, The NetherlandsTI-COAST, Science Park 904, 1098 XH Amsterdam, The Netherlands*E-mail: [email protected]More by Bob W. J. PirokView Biographyhttp://orcid.org/0000-0002-4558-3778, Dwight R. StollDwight R. StollDepartment of Chemistry, Gustavus Adolphus College, Saint Peter, Minnesota 56082, United StatesMore by Dwight R. StollView Biographyhttp://orcid.org/0000-0002-4070-9132, and Peter J. SchoenmakersPeter J. SchoenmakersUniversity of Amsterdam, van 't Hoff Institute for Molecular Sciences, Analytical-Chemistry Group, Science Park 904, 1098 XH Amsterdam, The NetherlandsMore by Peter J. SchoenmakersView BiographyCite this: Anal. Chem. 2019, 91, 1, 240–263Publication Date (Web):November 1, 2018Publication History Published online1 November 2018Published inissue 2…

In this work, an innovative enzyme-free colorimetric immunoassay was proposed for the sensitive detection of alpha-fetoprotein (AFP) by introducing thymolphthalein-modified metal-polydopamine framework (MPDA@TP) for the signal generation and amplification. Using zeolitic imidazolate framework (ZIF-67) as the template, the hollow-structured metal-polydopamine framework (MPDA) with high surface recovery and abundant groups was synthesized and functionalized with thymolphthalein (TP) molecules via typical π-stacking reaction. In the presence of target AFP, an MPDA@TP-linked immunosorbent assay (MLISA) was implemented on the capture antibody-modified microplate by using detection antibody-labeled MPDA@TP as the secondary antibody. Upon alkaline solution introduction, the coated hydrophobic TP on the MPDA was deprotonated into hydrophilic TP 2– ion and dissolved in the solution, thereby resulting in the color change of the solution from nearly colorless to deep blue, and the increasing absorbance of the solution at 595 nm. Importantly, the MPDA@TP-based immunoassay could exhibit high…

Pressure-based bioassays incorporating biomolecular recognition with a catalyzed gas-generation reaction have been developed for gas biosensors, but most involve poor sensitivity and are unsuitable for routine use. Herein we design an innovative gas pressure-based biosensing platform for the detection of Kanamycin (Kana) on polyaniline nanowires-functionalized reduced graphene oxide (PANI/rGO) framework by using platinum nanozyme-catalyzed gas generation. The signal was amplified by coupling with catalytic hairpin assembly (CHA) and strand-displacement amplification (SDA). Upon target Kana introduction, the analyte initially triggered a SDA reaction between hairpin DNA1 and hairpin DNA2, and then induced CHA conjugation between magnetic bead-labeled hairpin DNA3 (MB-H3) and platinum nanoparticle-labeled hairpin DNA4 (Pt-H4) to form a three-dimensional network. Numerous platinum nanoparticles (peroxidase-like nanozymes) were carried over with magnetic beads to reduce hydrogen peroxide into oxygen. The as-produced gas compressed PANI/rGO frameworks (modified to polyurethane sponge,…

A new double photosystems-based ‘Z-scheme’ photoelectrochemical (PEC) sensing platform is designed for ultrasensitive detection of prostate-specific antigen (PSA) by coupling with a three-dimensional (3D) DNA walker. Two photosystems consist of CdS quantum dots (photosystem I; PS I) and BiVO 4 photoactive materials (photosystem II; PS II), whereas gold nanoparticles (AuNPs) photodeposited on high-active {010} facets of BiVO 4 are used as the electron mediators to promote electron transfer from conduction band of PS II to valence band of PS I. 3D DNA walker-based amplification strategy is carried out between hairpin DNA1 conjugated onto the AuNP, hairpin DNA2 labeled with CdS quantum dot (QD-H2), and DNA walker complementary with the PSA aptamer modified to a magnetic bead (Apt-MB). Upon addition of target, DNA walker strand is displaced from DNA walker/Apt-MB to open hairpin DNA1 on AuNP@BiVO 4 . In the presence of QD-H2, DNA walker induces the hybridization of DNA1 with DNA2 on the gold nanoparticles step by step, thereby resulting in the assembly of CdS QDs on the AuNP@BiVO 4 to…

We describe complex organic mixture analysis by 21 tesla (T) Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Ultrahigh mass-resolving power ( m /Δ m 50% > 2 700 000 at m / z 400) and mass accuracy (80 ppb rms) enable resolution and confident identification of tens of thousands of unique elemental compositions. We demonstrate 2.2-fold higher mass-resolving power, 2.6-fold better mass measurement accuracy, and 1.3-fold more assigned molecular formulas compared to our custom-built, state-of-the-art 9.4 T FT-ICR mass spectrometer for petroleum and dissolved organic matter (DOM) analyses. Analysis of a heavy petroleum distillate exemplifies the need for ultrahigh-performance mass spectrometry (49 040 assigned molecular formulas for 21 T versus 29 012 for 9.4 T) and extends the identification of previously unresolved O o, S s O o, and NO o classes. Mass selective ion accumulation (20 Thompson isolation) of an asphalt volcano sample yields 462 resolved mass spectral peaks at m / z 677 and reveals previously unresolved C c H h N n O o S s mass differences at high…

A near-infrared light-activated ratiometric photoelectrochemical aptasensor was fabricated for detection of carcinoembryonic antigen (CEA) coupling with upconversion nanoparticles (UCNPs)-semiconductor nanocrystals-based spatial-resolved technique on a homemade 3D printing device in which a self-regulating integrated electrode was designed for dual signal readout. The as-prepared NaYF 4:Yb,Er UCNPs@CdTe nanocrystals were initially assembled on two adjacent photoelectrodes, then CEA aptamer 1 (A 1 ) and capture DNA (CA) were modified onto two working photoelectrodes (WP 1 and WP 2 ) through covalent binding, respectively, and then gold nanoparticle-labeled CEA aptamer 2 (Au NP-A 2 ) was immobilized on the surface of functional WP 2 for the formation of double-stranded DNA. Upon target CEA introduction, the various concentrations of CEA were captured on the WP 1, whereas the binding of the CEA with Au NP-A 2 could be released from the WP 2 thanks to the highly affinity of CEA toward A 2 . The dual signal readout with the “signal-off” of WP 1 and “signal-on” of WP 2 were employed for…

Abstract A novel photoelectrochemical (PEC) enzyme immunoassay was designed for the ultrasensitive detection of alpha-fetoprotein (AFP) based on near-infrared (NIR) light-excited core–core–shell UCNP@Au@CdS upconversion nanospheres. Plasmonic gold (Au) between the sandwiched layers was not only utilized as an energy harvester for the collection of the incident light but also acted as an energy conveyor to transfer the energy from upconversion NaYF4:Yb3+,Er3+ (UCNP) to semiconductor CdS, thus exciting the efficient separation of electron–hole pairs by the generated H2O2 of enzyme immunoreaction under the irradiation of a 980 nm laser. By virtue of high catalytic activity of natural enzymes, gold nanoparticles heavily functionalized with glucose oxidase (GOx) and polyclonal anti-AFP antibody were utilized to generate H2O2. A sandwiched immunoreaction was first carried out in a monoclonal anti-AFP antibody-coated microplate by using an antibody-labeled gold nanoparticle as secondary antibody. Accompanying the gold nanoparticle, the carried GOx oxidized glucose in H2O2, thereby…

This review describes, with 187 references, progress in the field of potentiometric sensing in the period between January 2016 and August 2018.January 2016 was when the last fundamental review covering the topic of potentiometric sensors appeared in the special issue of Analytical Chemistry and was set as start date.The contributions were sourced from the scientific citation indexing service Web of Science by searching for relevant keywords and author names of recognized experts in the field.We also manually screened the tables of contents of selected journals known for publishing quality work related to electroanalytical chemistry.Owing to the significant number of contributions that are published in the field of potentiometric sensing we may have overlooked some of them or otherwise chosen not to report on it.This contribution should therefore be appreciated as an opinion piece that gives our view on the current state of the field.It is not a comprehensive discussion of all contributions that deal with potentiometric sensors.We would like to apologize if someone feels that his or…

High Resolution Image Download MS PowerPoint Slide A novel paper electrode-based flexible pressure sensor modified with multiwalled carbon nanotubes was designed for point-of-care (POC) immunoassay of carcinoembryonic antigen (CEA) with digital multimeter readout. The portable POC testing device consisted of flexible pressure sensor equipped with a paper electrode and connected through syringe tubing to a single-break microplate. The immunoreaction was initially carried out on the microplate with a sandwich-type assay format using platinum nanozyme-labeled secondary antibody for the gas generation. Upon addition of hydrogen peroxide (H 2 O 2 ), platinum nanozyme (catalase-like mimic) reduced it into hydrogen oxide and oxygen (O 2 ). The overflowing oxygen gas increased the pressure of the multiwalled carbon nanotube-functionalized paper electrode in a homemade pressure-tight system, and the increased pressure could be readily monitored using the paper electrode-based flexible pressure-tight sensor with a digital multimeter readout. The detectable signal mainly derived from the…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTCapillary Electrophoresis: Trends and Recent AdvancesRobert L. C. VoetenRobert L. C. VoetenDivision of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The NetherlandsTI-COAST, Science Park 904, 1098 XH Amsterdam, The NetherlandsMore by Robert L. C. VoetenView Biography, Iro K. VentouriIro K. VentouriTI-COAST, Science Park 904, 1098 XH Amsterdam, The NetherlandsAnalytical Chemistry Group, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The NetherlandsMore by Iro K. VentouriView Biography, Rob Haselberg*Rob HaselbergDivision of BioAnalytical Chemistry, Department of Chemistry and Pharmaceutical Sciences, Vrije Universiteit Amsterdam, de Boelelaan 1085, 1081 HV Amsterdam, The Netherlands*E-mail: [email protected]More by Rob HaselbergView Biographyhttp://orcid.org/0000-0003-1892-1724, and Govert W. SomsenGovert W. SomsenDivision of BioAnalytical Chemistry, Department of Chemistry and…

High Resolution Image Download MS PowerPoint Slide This work has looked to explore an innovative and powerful visible fluorescence immunoassay method through wet NH 3 -triggered structural change of NH 2 -MIL-125(Ti) impregnated on paper for the detection of carcinoembryonic antigen (CEA). Gold nanoparticles heavily functionalized with glutamate dehydrogenase (GDH) and secondary antibody were used for generation of wet NH 3 with a sandwiched immunoassay format. Paper-based analytical device (PAD) coated with NH 2 -MIL-125(Ti) exhibited good visible fluorescence intensity through wet NH 3 -triggeried structural change with high accuracy and reproducibility. Moreover, NH 2 -MIL-125(Ti)-based PAD displayed two visual modes of fluorescence color and physical color with the naked eye and allowed the detection of CEA at a concentration as low as 0.041 ng mL –1 . Importantly, the PAD-based assay provides promise for use in the mass production of miniaturized devices and opens new opportunities for protein diagnostics and biosecurity.

Exosomes, as novel noninvasive biomarkers for disease prediction and diagnosis, have shown fascinating prospects in monitoring cancer-linked public health issues. Herein, a unique Cy3 labeled CD63 aptamer (Cy3-CD63 aptamer)/Ti 3 C 2 MXenes nanocomplex was constructed as a self-standard ratiometric fluorescence resonance energy transfer (FRET) nanoprobe for quantitative detection of exosomes. The Cy3-CD63 aptamer can be selectively adsorbed onto the Ti 3 C 2 MXene nanosheets by hydrogen bond and metal chelate interaction between the aptamer and MXenes, and the fluorescence signal from Cy3-CD63 aptamer was quenched quickly owing to the FRET between the Cy3 and MXenes. The fluorescence of Cy3 greatly recovered after the addition of the exosomes which can specifically combine with the aptamer and release from the surface of Ti 3 C 2 MXenes due to the high affinity between the aptamer and CD63 protein on exosome surface. Meanwhile, the self-fluorescence signal of MXenes in the whole process showed little change, which can be used as a standard reference. Based on the self-standard…

The rapid innovations in metabolite profiling, bioassays and chemometrics have led to a paradigm shift in natural product (NP) research. Indeed, having partial or full structure information about possibly “all” specialized metabolites and an estimation of their levels in plants or microorganisms provides a way to perform pharmacognostic or chemical ecology investigations from a new and holistic perspective. The increasing amount of accurate metabolome data that can be acquired on massive sample sets, notably through data-dependent LC-HRMS/MS and NMR profiling, allows the mapping of natural extracts at an unprecedented level of precision.Most progress made recently in accelerating metabolite identification has been pushed by the need for metabolomics to have tools that provide a confident annotation of the biomarkers highlighted as the results of data mining through multivariate analysis, often on important datasets of complexsamples. Historically, NP chemists have been involved in the unambiguous full de novo identification of unknown compoundsfrom complex natural biological…

Light-absorbing components of atmospheric organic aerosols, which are collectively termed "brown carbon" (BrC), are ubiquitous in the atmosphere. They affect absorption of solar radiation by aerosols in the atmosphere and human health as some of them have been identified as potential toxins. Understanding the sources, formation, atmospheric evolution, and environmental effects of BrC requires molecular identification and characterization of light-absorption properties of BrC chromophores. Identification of BrC components is challenging due to the complexity of atmospheric aerosols. In this study, we employ two complementary ionization techniques, atmospheric pressure photo ionization (APPI) and electrospray ionization (ESI), to obtain broad coverage of both polar and nonpolar BrC components using high-resolution mass spectrometry (HRMS). These techniques are combined with chromatographic separation of BrC compounds with high performance liquid chromatography (HPLC), characterization of their light absorption with a photodiode array (PDA) detector, and chemical composition with HRMS.…

Abstract Exosomes are membrane-enclosed phospholipid extracellular vesicles, which can act as mediators of intercellular communication. Although the original features endow tumor-derived exosomes great potential as biomarkers, efficient isolation and detection methods remain challenging. Here, we presented a two-stage microfluidic platform (ExoPCD-chip), which integrates on-chip isolation and in situ electrochemical analysis of exosomes from serum. To promote exosomes capture efficiency, an improved staggered Y-shaped micropillars mixing pattern was designed to create anisotropic flow without any surface modification. By combining magnetic enrichment based on specific phosphatidylserine-Tim4 protein recognition with a new signal transduction strategy in a chip for the first time, the proposed platform enables highly sensitive detection for CD63 positive exosomes as low as 4.39 × 103 particles/mL with a linear range spanning 5 orders of magnitude, which is substantially better than the existing methods. The reduced volume of sample (30 μL) and simple affinity method also make it…

Liquid chromatography (LC) prefractionation is often implemented to increase proteomic coverage; however, while effective, this approach is laborious, requires considerable sample amount, and can be cumbersome. We describe how interfacing a recently described high-field asymmetric waveform ion mobility spectrometry (FAIMS) device between a nanoelectrospray ionization (nanoESI) emitter and an Orbitrap hybrid mass spectrometer (MS) enables the collection of single-shot proteomic data with comparable depth to that of conventional two-dimensional LC approaches. This next generation FAIMS device incorporates improved ion sampling at the ESI-FAIMS interface, increased electric field strength, and a helium-free ion transport gas. With fast internal compensation voltage (CV) stepping (25 ms/transition), multiple unique gas-phase fractions may be analyzed simultaneously over the course of an MS analysis. We have comprehensively demonstrated how this device performs for bottom-up proteomics experiments as well as characterized the effects of peptide charge state, mass loading, analysis time,…

Additive manufacturing provides a unique tool for prototyping structures toward electrochemical sensing, due to its ability to produce highly versatile, tailored-shaped devices in a low-cost and fast way with minimized waste. Here we present 3D-printed graphene electrodes for electrochemical sensing. Ring- and disc-shaped electrodes were 3D-printed with a Fused Deposition Modeling printer and characterized using cyclic voltammetry and scanning electron microscopy. Different redox probes K 3 Fe(CN) 6:K 4 Fe(CN) 6, FeCl 3, ascorbic acid, Ru(NH 3 ) 6 Cl 3, and ferrocene monocarboxylic acid) were used to assess the electrochemical performance of these devices. Finally, the electrochemical detection of picric acid and ascorbic acid was carried out as proof-of-concept analytes for sensing applications. Such customizable platforms represent promising alternatives to conventional electrodes for a wide range of sensing applications.

The exploration of new physical and chemical properties of materials and their innovative application in different fields are of great importance to advance analytical chemistry, material science, and other important fields. Herein, we, for the first time, discovered the photothermal effect of an iron oxide nanoparticles (NPs)-mediated TMB (3,3′,5,5′-tetramethylbenzidine)-H 2 O 2 colorimetric system, and applied it toward the development of a new NP-mediated photothermal immunoassay platform for visual quantitative biomolecule detection using a thermometer as the signal reader. Using a sandwich-type proof-of-concept immunoassay, we found that the charge transfer complex of the iron oxide NPs-mediated one-electron oxidation product of TMB (oxidized TMB) exhibited not only color changes, but also a strong near-infrared (NIR) laser-driven photothermal effect. Hence, oxidized TMB was explored as a new sensitive photothermal probe to convert the immunoassay signal into heat through the near-infrared laser-driven photothermal effect, enabling simple photothermal immunoassay using a…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTRecent Advances in Body-on-a-Chip SystemsJong Hwan SungJong Hwan SungDepartment of Chemical Engineering, Hongik University, Seoul, 04066, Republic of KoreaMore by Jong Hwan SungView Biographyhttp://orcid.org/0000-0002-4019-866X, Ying I. WangYing I. WangNancy E. and Peter C. Meinig School of Biomedical Engineering, Cornell University, Ithaca, New York 14853, United StatesMore by Ying I. WangView Biographyhttp://orcid.org/0000-0003-0236-5962, Narasimhan Narasimhan SriramNarasimhan Narasimhan SriramHesperos, Inc. Orlando, Florida 32836, United StatesMore by Narasimhan Narasimhan SriramView Biography, Max JacksonMax JacksonHesperos, Inc. Orlando, Florida 32836, United StatesMore by Max JacksonView Biography, Christopher LongChristopher LongHesperos, Inc. Orlando, Florida 32836, United StatesMore by Christopher LongView Biographyhttp://orcid.org/0000-0002-2333-7576, James J. HickmanJames J. HickmanHesperos, Inc. Orlando, Florida 32836, United StatesNanoScience Technology Center, University of Central Florida, Orlando, Florida 32828, United…

High Resolution Image Download MS PowerPoint Slide N 1-methyladenosine (m 1 A) is an important post-transcriptional modification in RNA; however, the exact biological role of m 1 A remains to be determined. By employing a quantitative proteomics method, we identified multiple putative protein readers of m 1 A in RNA, including several YTH domain family proteins. We showed that YTHDF1-3 and YTHDC1, but not YTHDC2, could bind directly to m 1 A in RNA. We also found that Trp 432 in YTHDF2, a conserved residue in the hydrophobic pocket of the YTH domain that is necessary for its binding to N 6 -methyladenosine (m 6 A), is required for its recognition of m 1 A. An analysis of previously published data revealed transcriptome-wide colocalization of YTH domain-containing proteins and m 1 A sites in HeLa cells, suggesting that YTH domain-containing proteins can bind to m 1 A in cells. Together, our results uncovered YTH domain-containing proteins as readers for m 1 A in RNA and provided new insight into the functions of m 1 A in RNA biology.

Molecular networking (MN) is becoming a standard bioinformatics tool in the metabolomic community. Its paradigm is based on the observation that compounds with a high degree of chemical similarity share comparable MS 2 fragmentation pathways. To afford a clear separation between MS 2 spectral clusters, only the most relevant similarity scores are selected using dedicated filtering steps requiring time-consuming parameter optimization. Depending on the filtering values selected, some scores are arbitrarily deleted and a part of the information is ignored. The problem of creating a reliable representation of MS 2 spectra data sets can be solved using algorithms developed for dimensionality reduction and pattern recognition purposes, such as t-distributed stochastic neighbor embedding (t-SNE). This multivariate embedding method pays particular attention to local details by using nonlinear outputs to represent the entire data space. To overcome the limitations inherent to the GNPS workflow and the networking architecture, we developed MetGem. Our software allows the parallel…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTUpconversion Nanoprobes: Recent Advances in Sensing ApplicationsZhiming ZhangZhiming ZhangSchool of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, 200444, Shanghai, ChinaMore by Zhiming ZhangView Biography, Swati ShikhaSwati ShikhaDepartment of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117583, SingaporeMore by Swati ShikhaView Biography, Jinliang LiuJinliang LiuSchool of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, 200444, Shanghai, ChinaMore by Jinliang LiuView Biography, Jing Zhang*Jing ZhangSchool of Environmental and Chemical Engineering, Shanghai University, 99 Shangda Road, 200444, Shanghai, China*E-mail: [email protected]More by Jing ZhangView Biography, Qingsong Mei*Qingsong MeiDepartment of Biomedical Engineering, Faculty of Engineering, National University of Singapore, Singapore 117583, Singapore*E-mail: [email protected]More by Qingsong MeiView Biographyhttp://orcid.org/0000-0003-4327-6931, and Yong Zhang*Yong…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTAdvances of Ionic Liquids in Analytical ChemistryMaría J. Trujillo-RodríguezMaría J. Trujillo-RodríguezDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United StatesMore by María J. Trujillo-RodríguezView Biography, He NanHe NanDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United StatesMore by He NanView Biography, Marcelino VaronaMarcelino VaronaDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United StatesMore by Marcelino VaronaView Biography, Miranda N. EmausMiranda N. EmausDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United StatesMore by Miranda N. EmausView Biography, Israel D. SouzaIsrael D. SouzaDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United StatesMore by Israel D. SouzaView Biography, and Jared L. Anderson*Jared L. AndersonDepartment of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, Iowa 50011, United States*E-mail: [email…

Lipid coverage is crucial in comprehensive lipidomics studies challenged by high diversity in lipid structures and wide dynamic range in lipid levels. Current state-of-the-art lipidomics technologies are mostly based on mass spectrometry (MS), including direct-infusion MS, chromatography-MS, and matrix-assisted laser desorption ionization (MALDI) imaging MS, each with its pros and cons. Due to the need or favorability for measurement of isomers and isobars, chromatography-MS is preferable for lipid profiling. The ultra-high performance liquid chromatography-high resolution mass spectrometry (UHPLC-HRMS)-based nontargeted lipidomics approach and UHPLC-tandem MS (UHPLC-MS/MS)-based targeted approach are two representative methodological platforms for chromatography-MS. In the present study, we developed a high coverage pseudotargeted lipidomics method combining the advantages of nontargeted and targeted lipidomics approaches. The high coverage of lipids was achieved by integration of the detected lipids derived from nontargeted UHPLC-HRMS lipidomics analysis of multiple matrices…

The detection of phosphates and their enzymatic hydrolysis is of great importance because of their essential roles in various biological processes and numerous diseases. Compared with individual sensors for detecting one given phosphate at a time, sensor arrays are able to discriminate multiple phosphates simultaneously. Although nanomaterial-based sensor arrays have shown great promise for the discrimination of phosphates, very few of them have been explored for probing phosphates involved enzymatic hydrolysis. To fill this gap, herein we fabricated two-dimensional-metal-organic-framework (2D-MOF)-nanozyme-based sensor arrays by modulating their peroxidase-mimicking activity with various phosphates, including AMP, ADP, ATP, pyrophosphate (PPi), and phosphate (Pi). The sensor arrays were used to successfully discriminate the five phosphates not only in aqueous solutions but also in biological samples. The practical application of the sensor arrays was then validated with blind samples, where 30 unknown samples containing phosphates were accurately identified. Moreover, the sensor…

van Krevelen diagrams (O/C vs H/C ratios of elemental formulas) have been widely used in studies to obtain an estimation of the main compound categories present in environmental samples. However, the limits defining a specific compound category based solely on O/C and H/C ratios of elemental formulas have never been accurately listed or proposed to classify metabolites in biological samples. Furthermore, while O/C vs H/C ratios of elemental formulas can provide an overview of the compound categories, such classification is inefficient because of the large overlap among different compound categories along both axes. We propose a more accurate compound classification for biological samples analyzed by high-resolution mass spectrometry based on an assessment of the C/H/O/N/P stoichiometric ratios of over 130 000 elemental formulas of compounds classified in 6 main categories: lipids, peptides, amino sugars, carbohydrates, nucleotides, and phytochemical compounds (oxy-aromatic compounds). Our multidimensional stoichiometric compound classification (MSCC) constraints showed a highly…

The peroxidase-like catalytic activity of gold nanoclusters (Au-NCs) is quite low around physiological pH, which greatly limits their biological applications. Herein, we found heparin can greatly accelerate the peroxidase-like activity of Au-NCs at neutral pH. The catalytic activity of Au-NCs toward the peroxidase substrate 3,3′,5,5′-tetramethylbenzidine (TMB) oxidation by H 2 O 2 was 25-fold increased in the presence of heparin at pH 7. The addition of heparin not only accelerated the initial catalytic rate of Au-NCs but also prevented the Au-NCs from catalyst deactivation. This allows the sensitive colorimetric detection of heparin at neutral pH. In the presence of heparinase, heparin was hydrolyzed into small fragments, weakening the enhancement effect of catalytic activity. On the basis of this phenomenon, the colorimetric determination of heparinase in the range from 0.1 to 3 μg·mL –1 was developed with a detection limit of 0.06 μg·mL –1 . Finally, the detection of heparin and heparinase activity in diluted serum samples was also demonstrated.

Diffusion-ordered NMR spectroscopy (DOSY) is increasingly widely used for the analysis of mixtures by NMR spectroscopy, dispersing the signals of different species according to their diffusion coefficients. DOSY is used primarily to distinguish between the signals of different species, with the interpretation of the diffusion coefficients observed usually being purely qualitative, for example to deduce whether one species is bigger or smaller than another. In principle, the actual values of diffusion coefficient obtained carry important information about the sizes of different species and on interactions between species, but the relationship between diffusion coefficient and molecular mass is in general a very complex one. Here a recently proposed analytical relationship between diffusion coefficient and molecular mass for the restricted case of small organic molecules is tested against a wide range of data from the scientific literature and generalized to cover a range of solvents and temperatures.

We report an extensive 600 MHz NMR trial of quantitative lipoprotein and small-molecule measurements in human blood serum and plasma. Five centers with eleven 600 MHz NMR spectrometers were used to analyze 98 samples including 20 quality controls (QCs), 37 commercially sourced, paired serum and plasma samples, and two National Institute of Science and Technology (NIST) reference material 1951c replicates. Samples were analyzed using rigorous protocols for sample preparation and experimental acquisition. A commercial lipoprotein subclass analysis was used to quantify 105 lipoprotein subclasses and 24 low molecular weight metabolites from the NMR spectra. For all spectrometers, the instrument specific variance in measuring internal QCs was lower than the percentage described by the National Cholesterol Education Program (NCEP) criteria for lipid testing [triglycerides <2.7%; cholesterol <2.8%; low-density lipoprotein (LDL) cholesterol <2.8%; high-density lipoprotein (HDL) cholesterol <2.3%], showing exceptional reproducibility for direct quantitation of lipoproteins in both matrixes.…

Single cell proteomic analysis provides crucial information on cellular heterogeneity in biological systems. Herein, we describe a nanoliter-scale oil-air-droplet (OAD) chip for achieving multistep complex sample pretreatment and injection for single cell proteomic analysis in the shotgun mode. By using miniaturized stationary droplet microreaction and manipulation techniques, our system allows all sample pretreatment and injection procedures to be performed in a nanoliter-scale droplet with minimum sample loss and a high sample injection efficiency (>99%), thus substantially increasing the analytical sensitivity for single cell samples. We applied the present system in the proteomic analysis of 100 ± 10, 50 ± 5, 10, and 1 HeLa cell(s), and protein IDs of 1360, 612, 192, and 51 were identified, respectively. The OAD chip-based system was further applied in single mouse oocyte analysis, with 355 protein IDs identified at the single oocyte level, which demonstrated its special advantages of high enrichment of sequence coverage, hydrophobic proteins, and enzymatic digestion efficiency…

The contamination of micro- and nanoplastics in marine systems and freshwater is a global issue. Determination of micro- and nanoplastics in the aqueous environment is of high priority to fully assess the risk that plastic particles will pose. Although microplastics have been detected in a variety of aquatic ecosystems, the analysis of nanoplastics remains an unsolved challenge. Herein, for the first time, a Triton X-45 (TX-45)-based cloud-point extraction (CPE) was proposed to preconcentrate trace nanoplastics in environmental waters. Under the optimum extraction conditions, an enrichment factor of 500 was obtained for two types of nanoplastics with different compositions, polystyrene (PS) and poly(methyl methacrylate) (PMMA), without disturbing their original morphology and sizes. Additionally, following thermal treatment at 190 °C for 3 h, the CPE-obtained extract could be submitted to pyrolysis gas chromatography-mass spectrometry (Py-GC/MS) analysis for mass quantification of nanoplastics. Taking 66.2 nm PS nanoplastics and 86.2 nm PMMA nanoplastics as examples, the proposed…

Abstract Intracellular viscosity is an essential microenvironmental parameter and H2S is a critical gaseous signaling molecule, which are both related to various physiological processes. It is reported that the change of viscosity and an imbalance of H2S production in the mitochondria are both associated with overexpression of amyloid betapeptide (Aβ), which is thought to play a central role in the pathogenesis of Alzheimer’s disease (AD). However, to our best knowledge, no fluorescent probe is found for dual detection of mitochondrial viscosity and H2S. Herein, a dual-response fluorescent probe (Mito-VS) is designed and synthesized to monitor the level of viscosity and H2S, respectively. Mito-VS itself is nonfluorescent due to a free intramolecular rotation between dimethylaniline and pyridine. After the increase of viscosity, the rotation is prohibited and an intense red fluorescence is released. Upon the addition of H2S, the probe can react with H2S to form compound 3 and a strong green fluorescence can be observed. Moreover, the probe possesses a good mitochondrion-targeting…

Sensitive and specific detection of tumor exosomes is of great significance for early cancer diagnosis. In this paper, we report an aptamer strategy for exosome detection based on aptamer recognition-induced multi-DNA release and cyclic enzymatic amplification. First, we use aptamer–magnetic bead bioconjugates to capture tumor exosomes derived from LNCaP cells, leading to the release of three kinds of messenger DNAs (mDNAs). After magnetic separation, the released mDNAs hybridized with the probe DNAs immobilized on a gold electrode. Electroactive Ru(NH 3 ) 6 3+ was used as the signal reporter because of its electrostatic attraction to DNA. Subsequent Exo III cyclic digestion caused the electrochemical signal to “turn off”. Because the electrochemical signal reflects the concentration of Ru(NH 3 ) 6 3+ and the concentration of Ru(NH 3 ) 6 3+ is correlated with the mDNA concentration, which is correlated with the exosome concentration, the tumor exosomes can be detected by examining the decrease in the peak current of Ru(NH 3 ) 6 3+ . In this paper, the signal was amplified by the…

Abstract A new analytical all-solid-state platform for intradermal potentiometric detection of potassium in interstitial fluid is presented here. Solid microneedles are modified with different coatings and polymeric membranes to prepare both the potassium-selective electrode and reference electrode needed for the potentiometric readout. These microneedle-based electrodes are fixed in an epidermal patch suitable for insertion into the skin. The analytical performances observed for the potentiometric cell (Nernstian slope, limit of detection of 10–4.9 potassium activity, linear range of 10–4.2 to 10–1.1, drift of 0.35 ± 0.28 mV h–1), together with a fast response time, adequate selectivity, and excellent reproducibility and repeatability, are appropriate for potassium analysis in interstitial fluid within both clinical and harmful levels. The potentiometric response is maintained after several insertions into animal skin, confirming the resiliency of the microneedle-based sensor. Ex vivo tests based on the intradermal detection of potassium in chicken and porcine skin demonstrate that…

Rapid and sensitive foodborne pathogen detection assay, which can be applied in multiple fields, is essential to timely diagnosis. Herein, we proposed a multisignal readout lateral flow immunoassay for Salmonella typhimurium ( S. typhi ) detection. The assay employs colorimetric-fluorescent-magnetic nanospheres (CFMNs) as labels, which possess multifunctional target separation and enrichment, multisignal readout, and two formats of quantitation. The assay for S. typhi detection involves magnetic separation and chromatography. First, the S. typhi were separated and enriched from matrix by antibody labeled CFMNs, and then the S. typhi -containing suspension is added onto the sample pad to flow up the test strip. The introduction of magnetic separation enhances anti-interference ability and 10-fold sensitivity, making the assay possible for practical application. The assay has realized naked eye detection of 1.88 × 10 4 CFU/mL S. typhi, and 3.75 × 10 3 CFU/mL S. typhi can be detected with a magnetic assay reader, which is 2–4 orders of magnitude lower than other label-based LFIAs, with…

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTPorous Silicon-Based Photonic Biosensors: Current Status and Emerging ApplicationsSofia Arshavsky-GrahamSofia Arshavsky-GrahamDepartment of Biotechnology and Food Engineering, Technion − Israel Institute of Technology, Haifa 3200003, IsraelInstitute of Technical Chemistry, Leibniz Universität Hannover, Callinstrasse 5, 30167 Hanover, GermanyMore by Sofia Arshavsky-GrahamView Biography, Naama Massad-IvanirNaama Massad-IvanirDepartment of Biotechnology and Food Engineering, Technion − Israel Institute of Technology, Haifa 3200003, IsraelMore by Naama Massad-IvanirView Biographyhttp://orcid.org/0000-0001-8964-9997, Ester Segal*Ester SegalDepartment of Biotechnology and Food Engineering, Technion − Israel Institute of Technology, Haifa 3200003, IsraelThe Russell Berrie Nanotechnology Institute, Technion − Israel Institute of Technology, Haifa 3200003, Israel*E.S. e-mail: [email protected]More by Ester SegalView Biographyhttp://orcid.org/0000-0001-9472-754X, and Sharon Weiss*Sharon WeissDepartment of Electrical Engineering and Computer Science,…

Abstract The use of plastic materials in daily life, industry, and agriculture can cause soil pollution with plastic fragments down to the micrometer scale, i.e., microplastics. Quantitative assessment of microplastics in soil has been limited so far. Until now, microplastic analyses in soil require laborious sample cleanup and are mostly restricted to qualitative assessments. In this study, we applied thermogravimetry–mass spectrometry (TGA–MS) to develop a method for the direct quantitative analysis of poly­(ethylene terephthalate) (PET) without further sample pretreatment. For this, soil samples containing 1.61 ± 0.15 wt % organic matter were spiked with 0.23–4.59 wt % PET bottle recyclate microplastics. dl-Cysteine was used as the internal standard (IS). Sample mixtures were pyrolyzed with a 5 K min–1 ramp (40–1000 °C), while sample mass loss and MS signal intensity of typical PET pyrolysis products were recorded. We found MS signal intensities linearly responding to microplastic concentrations. The most-promising results were obtained with the IS-corrected PET pyrolysis product…

Tumor exosomes that inherit molecular markers from their parent cells are emerging as cellular “surrogates” in cancer diagnostics. Molecular profiling and detection of exosomes offer a noninvasive access to the state of cancer progression, yet are still technically challenging. Here we report an exosome-oriented, aptamer nanoprobe-based profiling (ExoAPP) assay to phenotype surface proteins and quantify cancerous exosomes in a facile mix-and-detect format. Our ExoAPP interfaces graphene oxide (GO) with target-responsive aptamers to profile exosomal markers across five cell types by complementing with enzyme-assisted exosome recycling, revealing a heterogeneous pattern.This assay achieves a detection limit down to 1.6 × 10 5 particles/mL, lowered by several orders of magnitude over other homogeneous protocols. Such a sensitive ExoAPP assay allows for monitoring epithelial-mesenchymal transition through heterogeneous exosomes without involving cellular internalization that often occurs in GO-based cargo delivery. Using ExoAPP to analyze blood samples from prostate cancer patients, we…

Nanozymes have emerged as promising alternatives to overcome the high cost and low stability of natural enzymes. Nanozymes with peroxidase-like activities have been studied to construct versatile biosensors by using specific biorecognition ligands (such as enzymes, antibodies, and aptamers) or molecularly imprinted polymers (MIPs). However, the use of bioligands compromises the high stability and low cost promise of nanozymes, while the MIPs may not be applicable to multiplex detection. To address these limitations, here we constructed the nanozyme sensor arrays based on peroxidase-like Pt, Ru, and Ir nanozymes. The cross-reactive nanozyme sensor arrays were successfully used for the detection of biothiols and proteins as well as the discrimination of cancer cells because of the differential nonspecific interactions between the components of the sensor arrays and the analytes. The usefulness of the nanozyme sensor arrays was further validated by the detection of blind unknown samples, where 28 of 30 biothiols and 42 of 45 proteins were correctly identified. Moreover, the practical…

Abstract Peroxynitrite (ONOO–), a reactive and short-lived biological oxidant, is closely related with many pathological conditions such as cancer. However, real-time in vivo imaging of ONOO– in tumors remains to be challenging. Herein, we develop a near-infrared fluorescence (NIRF) and photoacoustic dual-modal molecular probe (CySO3CF3) composed of a water-soluble hemicyanine dye caged with a trifluoromethyl ketone moiety for in vivo imaging of ONOO–. The trifluoromethyl ketone moiety can undergo a series of ONOO–-induced cascade oxidation-elimination reactions, leading to sensitive and specific fluorescence and photoacoustic turn-on responses toward ONOO–; whereas, a zwitterionic structure of the hemicyanine component ensures good water-solubility. Thus, CySO3CF3 not only specifically detects ONOO– in solution and cells with the limit of detection down to 53 nM but also allows for NIRF and photoacoustic dual-modal imaging of ONOO– in the tumors of living mice.

Surfaces and interfaces, of both practical and fundamental interest, have long been recognized to be complex, yet while there are many microscopy and spectroscopy methods for imaging structure, topography and surface chemical composition at high spatial resolution, there are relatively few techniques for mapping associated chemical fluxes in the near-interface region. In this regard, scanning electrochemical probe microscopy (SEPM), which utilizes a small scale electrode probe as an imaging device, has had a unique place in the scanning probe microscopy (SPM) family of techniques, in being able to map chemical fluxes and interfacial reactivity. For a long time, techniques such as scanning electrochemical microscopy (SECM) were largely stuck at the micron –or larger –scale in terms of spatial resolution, but recent years have seen spectacular progress, such that a variety of different types of SEPM technique are now available and 10sof nm spatial resolution is becoming increasingly accessible. This step-change in capability is opening many new opportunities for the characterization…

The development of a sensitive and practical electrochemiluminescence (ECL) bioassay relies on the use of ECL signal tags whose signal intensity is high and stable. In this work, strong ECL emission was achieved from metal organic framework (MOF) accelerator enriched quantum dots (CdTe), which were applied as an efficient ECL signal tag for trace biomarker detection. It is particularly noteworthy that a novel mechanism to drastically enhance the ECL intensity of CdTe is established because isoreticular metal organic framework-3 (IRMOF-3) with 2-amino terephthalic acid (2-NH 2 -BDC) as the organic ligand not only allows for loading a large amount of CdTe via the encapsulating effect and internal/external decoration but also functions as a novel coreactant accelerator for promoting the conversion of coreactant S 2 O 8 2– into the sulfate radical anion (SO 4 •– ), further boosting the ECL emission of CdTe. On the basis of the simple sandwich immunoreaction approach, cardiac troponin-I antigen (cTnI), a kind of biomarker related with myocardial infarction, was chosen as a detection…

In this study, we first present rotational paper-based microfluidic chips (RPADs) combined with a molecular-imprinting (MIP) technique to detect phenolic pollutants. The proposed rotational paper-based microfluidic chips could implement qualitative and quantitative analysis of two different phenolic contaminants, 4-nitrophenol (4-NP) and 2,4,6-trinitrophenol (TNP), simultaneously. Qualitative and quantitative analysis could be implemented simultaneously through fluorescence-intensity changes depending on the structures of quantum dots combined with a molecular-imprinting technique. Moreover, the rotational paper-based microfluidic chips provide a low cost, flexible, and easy way to operate the entire process conveniently. Under the optimal conditions, the proposed sensors showed high sensitivity and selectivity. Our final experimental results illustrated that the detection limits of 4-NP and TNP in the paper-based quantum-dot MIP (PQ-MIP) RPADs ranged from 0.5 to 20.0 mg/L, with detection limits of 0.097 and 0.071 mg/L, respectively. This novel rotational paper-based microfluidic…

This Feature addresses the analysis of the reactive species generated by nonthermal atmospheric pressure plasmas, which are widely employed in industrial and biomedical research, as well as first clinical applications. We summarize the progress in detection of plasma-generated short-lived reactive oxygen and nitrogen species in aqueous solutions, discuss the potential and limitations of various analytical methods in plasma-liquid systems, and provide an outlook on the possible future research goals in development of short-lived reactive species analysis methods for a general nonspecialist audience.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTADDITION / CORRECTIONThis article has been corrected. View the notice.Nonlinear MicrofluidicsDaniel StoeckleinDaniel StoeckleinDepartment of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, United StatesMore by Daniel Stoecklein and Dino Di Carlo*Dino Di CarloDepartment of Bioengineering, University of California, Los Angeles, Los Angeles, California 90095, United States*E-mail: [email protected]. Phone: +1-310-983-3235. Fax: +1-310-794-5956.More by Dino Di Carlohttp://orcid.org/0000-0003-3942-4284Cite this: Anal. Chem. 2019, 91, 1, 296–314Publication Date (Web):December 3, 2018Publication History Published online3 December 2018Published inissue 2 January 2019https://pubs.acs.org/doi/10.1021/acs.analchem.8b05042https://doi.org/10.1021/acs.analchem.8b05042review-articleACS PublicationsCopyright © 2018 American Chemical SocietyRequest reuse permissionsArticle Views6024Altmetric-Citations133LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November…