Analytical chemistry

  • Article
    | Open Access

    Detection of the tumour boundary in prostate cancer is required for surgery. Here the authors present a fluorescent molecular rotor probe to target a prostate cancer marker, prostate-specific membrane antigen (PSMA), which they use in a xenograft mouse model to show it can be used for in vivo imaging.

    • Jingming Zhang
    • , Anastasia Rakhimbekova
    •  & Xing Yang
  • Article
    | Open Access

    Here, the authors use solid-state NMR and EPR measurements to characterise the ATP hydrolysis transition state of the oligomeric bacterial DnaB helicase from Helicobacter pylori, which was trapped by using aluminium fluoride as a chemical mimic. They identify protein protons that coordinate to the phosphate groups of ADP and DNA and observe that the aluminium fluoride unit is highly mobile and fast-rotating.

    • Alexander A. Malär
    • , Nino Wili
    •  & Thomas Wiegand
  • Article
    | Open Access

    Sustainable strategies for shepherding active particles are at the heart of many prospective applications. Here, Palacios et al. use the emerging topological properties of a microfluidic maze array to passively guide self-propelled colloids from the interior to the edges of the device.

    • Lucas S. Palacios
    • , Serguei Tchoumakov
    •  & Adolfo G. Grushin
  • Article
    | Open Access

    Ligand-oligonucleotide interactions can integrate both small molecules and proteins into nucleic acid-based circuits. Here the authors design ligand-aptamer complexes to control strand-displacement reactions for versatile ligand transduction.

    • Qiu-Long Zhang
    • , Liang-Liang Wang
    •  & Liang Xu
  • Article
    | Open Access

    Many current immunoassays require multiple washing, incubation and optimization steps. Here the authors present Ratiometric Plug-and-Play Immunodiagnostics (RAPPID), a generic assay platform that uses ratiometric bioluminescent detection to allow sandwich immunoassays to be performed directly in solution.

    • Yan Ni
    • , Bas J. H. M. Rosier
    •  & Maarten Merkx
  • Article
    | Open Access

    Finding durable, high-density media for data storage is necessary to support the ever-expanding generation of digital data. Here, the authors use peptide sequences to store digital data and retrieve them using tandem mass spectrometry, proving that peptides can be used as a storage medium.

    • Cheuk Chi A. Ng
    • , Wai Man Tam
    •  & Zhong-Ping Yao
  • Article
    | Open Access

    The electron-withdrawing target (EWT)-induced fluorescence quenching is an unsolved issue in intramolecular charge transfer (ICT) fluorophores that limits their applicability. Here, the authors report a simple and generalizable strategy to reverse the EWT-induced quenching mode into light-up mode, by introducing an indazole building block between the π-bridge and the donor in the ICT scaffold.

    • Chenxu Yan
    • , Zhiqian Guo
    •  & Wei-Hong Zhu
  • Article
    | Open Access

    A large number of mass spectra from different samples have been collected, and to identify small molecules from these spectra, database searches are needed, which is challenging. Here, the authors report molDiscovery, a mass spectral database search method that uses an algorithm to generate mass spectrometry fragmentations and learns a probabilistic model to match small molecules with their mass spectra.

    • Liu Cao
    • , Mustafa Guler
    •  & Hosein Mohimani
  • Article
    | Open Access

    Several scenarios exist to explain the origins of the organic matter found in carbonaceous chondrites. Here, the authors show laboratory experiments confirming that a significant portion of the soluble organic matter can originate from organic ices inherited from the dense molecular cloud.

    • G. Danger
    • , V. Vinogradoff
    •  & P. Schmitt-Kopplin
  • Article
    | Open Access

    SERS assays have potential for multiplexed detection of biomarkers but differentiation of SERS tags remains a challenge. Here, the authors report the creation of 14 distinct geometrically controlled metal carbonyl tags and demonstrate multiplexed detection of nasopharyngeal carcinoma biomarkers from patient blood.

    • Duo Lin
    • , Chang-Lin Hsieh
    •  & Kien Voon Kong
  • Article
    | Open Access

    Here, the authors present a method for quantifying molecular interactions on a glass surface, based on measuring surface refractive index changes via the reflectivity near the critical angle. They demonstrate tunable sensitivity and dynamic range, deep vertical sensing range, also for intracellular signals.

    • Guangzhong Ma
    • , Runli Liang
    •  & Shaopeng Wang
  • Article
    | Open Access

    Determining the structure of amorphous solids is important for optimization of pharmaceutical formulations, but direct relation of molecular dynamics (MD) simulations and NMR to achieve this is challenging. Here, the authors use a machine learning model of chemical shifts to solve the atomic-level structure of the hydrated amorphous drug AZD5718 by combining dynamic nuclear polarization-enhanced solid-state NMR with predicted shifts for MD simulations of large systems.

    • Manuel Cordova
    • , Martins Balodis
    •  & Lyndon Emsley
  • Article
    | Open Access

    Analyzing the lipidomes of single cells remains a challenge. Here, the authors present a strategy to identify class, fatty acyl-chain, C=C locations and sn-positions of lipids in single cells, and use their method to identify individual gefitinib-resistant cells in a wild-type lung cancer cell population.

    • Zishuai Li
    • , Simin Cheng
    •  & Zheng Ouyang
  • Article
    | Open Access

    Though there is a long archaeological record of the use of honey, beeswax and other bee products, there are few known records from Africa. Here Dunne et al. analyse lipid residues from pottery from the Nok culture, Nigeria, dating to ~3500 years ago and find evidence of the collection and processing of bee products, likely honey.

    • Julie Dunne
    • , Alexa Höhn
    •  & Richard P. Evershed
  • Article
    | Open Access

    Investigation of spatial organization and relationships of biomolecules in cellular nanoenvironments is necessary to understand essential biological processes, but methodologically challenging. Here, the authors report cellular macromolecules-tethered DNA walking indexing (Cell-TALKING) to probe the nanoenvironments of DNA modifications around histone post-translational modifications, and explore the nanoenvironments in different cancer cell lines and clinical specimens.

    • Feng Chen
    • , Min Bai
    •  & Yongxi Zhao
  • Article
    | Open Access

    Studies of metabolites in neurodegeneration have not yet used sebum as a source fluid. Here the authors demonstrate the potential of metabolomics of sebum samples from individuals with Parkinson’s disease and controls.

    • Eleanor Sinclair
    • , Drupad K. Trivedi
    •  & Perdita Barran
  • Article
    | Open Access

    It is currently challenging to identify protein structures at low concentrations. Here the authors report optical tweezers-coupled Raman spectroscopy to generate tunable and reproducible SERS enhancements with single-molecule level sensitivity and use the method to detect protein structural features.

    • Xin Dai
    • , Wenhao Fu
    •  & Jinqing Huang
  • Article
    | Open Access

    Glycolipids are glycoconjugates with important biological functions, but techniques for their analysis are deficient. Here, the authors report the use of cryogenic gas-phase infrared spectroscopy to investigate isomerism in a set of immunologically relevant glycolipids, and show that their structural features can be accurately resolved based on a narrow spectral fingerprint region.

    • Carla Kirschbaum
    • , Kim Greis
    •  & Kevin Pagel
  • Article
    | Open Access

    Currently the most common method of COVID-19 diagnosis is by qRT-PCR which is slow and requires expensive instrumentation. Here the authors report an electrochemical biosensor based on isothermal rolling circle amplification for rapid detection of SARS-CoV-2 in clinical samples.

    • Thanyarat Chaibun
    • , Jiratchaya Puenpa
    •  & Benchaporn Lertanantawong
  • Article
    | Open Access

    Microbial symbionts can help their hosts metabolise diverse diets. A study on herbivorous turtle ants identifies the cuticular components which are nitrogen-enriched by gut bacteria, highlighting the role of symbionts in insect evolution.

    • Christophe Duplais
    • , Vincent Sarou-Kanian
    •  & Corrie S. Moreau
  • Article
    | Open Access

    The charging of Fe and Mn oxide anodes in lithium-ion batteries are believed to form rocksalt phases via reconstructive conversion reactions. Here, the authors show that MxOy (M = Fe, Mn) transform into non-native body-centred cubic FeO and zincblende MnO via topotactic displacement-like pathways.

    • Xiao Hua
    • , Phoebe K. Allan
    •  & Andrew L. Goodwin
  • Article
    | Open Access

    Dynamic kinetic resolution is a common approach for the preparation of optically pure amino acids using enzymes. Here the authors report an alternative method based on enantioselective extraction coupled with racemization, in which a bulky extractant affords hydrophobic extractable imines with amino acids rapidly, reversibly and enantioselectively.

    • Haofei Huang
    • , Yingji Jin
    •  & Kwan Mook Kim
  • Article
    | Open Access

    N-phosphorylation plays a critical role in central metabolism and signaling processes, however, enrichment methods for N-phosphopeptides are limited by the P-N bond lability. Here, the authors report the synthesis and use of silica microspheres functionalized with bis(zinc(II)-dipicolylamine) in N-phosphopeptides effective enrichment.

    • Yechen Hu
    • , Bo Jiang
    •  & Yukui Zhang
  • Article
    | Open Access

    Currently available mitochondria-targeted fluorescent dyes emit only one color in the visible or NIR-I and their applications are limited. Here, the authors develop upconversion mitochondria-targeted NIR-II fluorophores for synchronous upconversion-mitochondria-targeted cell imaging, in vivo NIR-II osteosarcoma imaging and photothermal efficiency

    • Hui Zhou
    • , Xiaodong Zeng
    •  & Yuling Xiao
  • Article
    | Open Access

    XylE is a bacterial xylose transporter and homologue of human glucose transporters GLUTs 1-4. HDX-MS, mutagenesis and MD simulations suggest that protonation of a conserved aspartate triggers conformational transition from outward- to inward facing state only in the presence of substrate xylose. In contrast, inhibitor glucose locks the transporter in the outward facing state.

    • Ruyu Jia
    • , Chloe Martens
    •  & Argyris Politis
  • Article
    | Open Access

    Myo-Inositol phosphates (InsPs) and pyrophosphates (PP-InsPs) are important second messengers but their analysis remains challenging. Here, the authors develop a capillary electrophoresis-mass spectrometry method for the identification and quantitation of InsP and PP-InsP isomers in cells and tissues.

    • Danye Qiu
    • , Miranda S. Wilson
    •  & Henning J. Jessen
  • Article
    | Open Access

    Fast and specific detection of pathogenic bacteria is needed to combat infections. Here the authors generate an array of near-infrared biosensors based on carbon nanotubes to detect released metabolites and virulence factors and use them to distinguish pathogens such as S. aureus and P. aeruginosa.

    • Robert Nißler
    • , Oliver Bader
    •  & Sebastian Kruss
  • Article
    | Open Access

    Existing high-dimensional optical imaging techniques that record space and polarization cannot detect the photon’s time of arrival due to the limited speeds of electronic sensors. Here, the authors develop a single-shot ultrafast imaging modality to record light-speed high-dimensional events with picosecond resolution.

    • Mohammad A. Almajhadi
    • , Syed Mohammad Ashab Uddin
    •  & H. Kumar Wickramasinghe
  • Article
    | Open Access

    Membrane-less organelles or compartments are considered to be dynamic reaction centers for spatiotemporal control of diverse cellular processes. Here authors report quantitative measurements of changes in protein interactions for the proteins recruited into membrane-less compartments (termed client proteins) in living cells.

    • Daesun Song
    • , Yongsang Jo
    •  & Yongwon Jung
  • Article
    | Open Access

    On-chip synthesis and screening has been used to automate drug discovery but on-chip analysis still remains a major limitation. Here, the authors report on a dendrimer-based surface patterning method to create nanodroplet arrays on materials which allow for on-chip high-throughput analysis.

    • Maximilian Benz
    • , Arndt Asperger
    •  & Pavel A. Levkin
  • Article
    | Open Access

    Directly linked porphyrin dimers show intriguing electronic features but emphasis has been placed on planar monomeric units. Here, the authors report a Twisted-Planar-Twisted framework which can undergo a cis-trans transformation accompanied by a colour change in presence of methanol, making this framework applicable as a methanol sensor.

    • Qizhao Li
    • , Chengjie Li
    •  & Yongshu Xie
  • Article
    | Open Access

    Protein identification at the single-molecule level is the ultimate goal for biological research and disease diagnosis. Here, the authors identify the size, charge, mobility, and binding of individual protein molecules by measuring the optical and electrical responses of each protein molecule tethered to a surface.

    • Guangzhong Ma
    • , Zijian Wan
    •  & Nongjian Tao
  • Article
    | Open Access

    Due to the pulsed nature of X-ray free electron laser (XFEL) instruments the majority of protein crystals, which are injected using continuous jet injection techniques are wasted. Here, the authors present a microfluidic device to deliver aqueous protein crystal laden droplets segmented with an immiscible oil and demonstrate that with this device an approx. 60% reduction in sample waste was achieved for data collection of 3-deoxy-D-manno-octulosonate 8-phosphate synthase crystals at the EuXFEL.

    • Austin Echelmeier
    • , Jorvani Cruz Villarreal
    •  & Alexandra Ros
  • Article
    | Open Access

    Determination of 3D molecular structures remains challenging for natural products or organic compounds available in minute amounts. Here, the authors determine the structure of complex molecules, including few micrograms of briarane B-3 isolated from Briareum asbestinums, through measurement of 1H residual chemical shift anisotropy.

    • Nilamoni Nath
    • , Juan Carlos Fuentes-Monteverde
    •  & Christian Griesinger
  • Article
    | Open Access

    Conventional bioluminescence imaging usually operates in the visible region and its performance is limited by strong tissue absorption and scattering. Here, the authors present bioluminescence probes (BPs) with emission in the second near infrared (NIR-II) region, and show the NIR-II-BPs could sensitively recognize tumor metastasis with a high tumor-to-normal tissue ratio.

    • Lingfei Lu
    • , Benhao Li
    •  & Fan Zhang
  • Article
    | Open Access

    Programmed cell death or apoptosis is an essential biological process that is impaired in some diseases and can be used to assess the effectiveness of drugs. Here the authors design Apo-15 as a fluorogenic peptide for the detection and real-time imaging of apoptotic cells.

    • Nicole D. Barth
    • , Ramon Subiros-Funosas
    •  & Marc Vendrell
  • Article
    | Open Access

    The use of one dimensional devices in nanomechanical mass spectrometry leads to a trade-off between analysis time and resolution. Here, the authors report single-particle mass spectrometry using integrated optomechanical resonators, impervious to particle position, stiffness or shape.

    • Marc Sansa
    • , Martial Defoort
    •  & Sébastien Hentz
  • Article
    | Open Access

    The authors demonstrate wafer-scale, graphene-based ion sensitive field effect transistors arrays for simultaneous concentration measurement of K+, Na+, NH4+, NO3, SO42−, HPO42− and Cl, and use their technology for real-time ion concentration measurements in an aquarium with lemnoideae lemna over a period of three weeks.

    • Ibrahim Fakih
    • , Oliver Durnan
    •  & Thomas Szkopek
  • Article
    | Open Access

    Atomic force microscopy-infrared (AFM-IR) spectroscopic imaging techniques offer a non-perturbative, molecular contrast for characterization of nanomaterials; however, data are often complicated by the measurement apparatus, sample preparation conditions and low signal-to-noise ratio. Here, the authors demonstrate a closed-loop controlled AFM-IR instrument design to address measurement artifacts and reduce noise up to 5x compared to previous methods.

    • Seth Kenkel
    • , Shachi Mittal
    •  & Rohit Bhargava
  • Article
    | Open Access

    Analysis of exchange processes is time consuming by two-dimensional exchange NMR spectroscopy. Here the authors demonstrate a single-scan ultrafast Laplace NMR approach based on spatial encoding to measure molecular diffusion, with an increase by a factor six in the sensitivity per unit time.

    • Otto Mankinen
    • , Vladimir V. Zhivonitko
    •  & Ville-Veikko Telkki
  • Article
    | Open Access

    The monitoring of nitric oxide is important to a number of disease states and biomedical applications. Here, the authors report on a single nickel atom catalyst based sensor for detecting nitric oxide production from cells.

    • Min Zhou
    • , Ying Jiang
    •  & Lanqun Mao