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Real-time tracking of intracellular carbohydrates remains challenging. While click chemistry allows bio-orthogonal tagging with fluorescent probes, the reaction permanently alters the target molecule and only allows a single snapshot. Here, we demonstrate click-free mid-infrared photothermal (MIP) imaging of azide-tagged carbohydrates in live cells. Leveraging the micromolar detection sensitivity for 6-azido-trehalose (TreAz) and the 300-nm spatial resolution of MIP imaging, the trehalose recycling pathway in single mycobacteria, from cytoplasmic uptake to membrane localization, is directly visualized. A peak shift of azide in MIP spectrum further uncovers interactions between TreAz and intracellular protein. MIP mapping of unreacted azide after click reaction reveals click chemistry heterogeneity within a bacterium. Broader applications of azido photothermal probes to visualize the initial steps of the Leloir pathway in yeasts and the newly synthesized glycans in mammalian cells are demonstrated.
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http://dx.doi.org/10.1101/2024.03.08.584185 | DOI Listing |
RSC Chem Biol
September 2025
Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet 17165 Solna Sweden
Labeling the plasma membrane for advanced imaging remains a significant challenge. For time-lapse live cell imaging, probe internalization and photobleaching are major limitations affecting most membrane-specific dyes. In fixed or permeabilized cells, many membrane probes either lose signal after fixation or fail to remain localized to the plasma membrane.
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September 2025
Gynaecology and Obstetrics, The Second Affiliated Hospital of Harbin Medical University, Harbin Medical University, Heilongjiang 150081, PR China. Electronic address:
Single-cell surface-enhanced Raman scattering (SERS) has emerged as a powerful tool for precision medicine owing to its label-free detection, ultrasensitivity, and unique molecular fingerprinting. Unlike conventional bulk analysis, it enables detailed characterization of cellular heterogeneity, with particular promise in circulating tumor cell (CTC) identification, tumor microenvironment (TME) metabolic profiling, subcellular imaging, and drug sensitivity assessment. Coupled with microfluidic droplet systems, SERS supports high-throughput single-cell analysis and multiparametric screening, while integration with complementary modalities such as fluorescence microscopy and mass spectrometry enhances temporal and spatial resolution for monitoring live cells.
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September 2025
Institute of Anatomy, University of Bern, 3012 Bern, Switzerland. Electronic address:
Cryo-electron tomography (cryoET) provides 3D datasets of organelles and proteins at nanometer and sub-nanometer resolution. However, locating target proteins in live cells remains a significant challenge. Conventional labeling methods, such as fluorescent protein tagging and immunogold labeling, are unsuitable for small structures in vitrified samples at molecular resolution.
View Article and Find Full Text PDFPLoS Comput Biol
September 2025
Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
Ubiquity of cancer across the tree of life yields opportunities to understand variation in cancer defences across species. Peto's paradox, the finding that large-bodied species do not suffer from more cancer despite having more cells at risk of oncogenic mutations compared to small species, can be explained if large size selects for better cancer defences. Since birds live longer than non-flying mammals of equivalent size, and are descendants of moderate-sized dinosaurs, we ask whether ancestral cancer defences are retained if body size shrinks in a lineage.
View Article and Find Full Text PDFSTAR Protoc
September 2025
Laboratory of Genome Integrity, CCR, NCI, NIH, Bethesda, MD, USA. Electronic address:
Tracking the translocation of fluorescent-based reporters at the single-cell level in living mouse embryos requires specialized expertise in mouse embryology and deep computational skills. Here, we detail an approach to quantify cyclin-dependent kinase (CDK) activity levels in single cells throughout different stages of the pre-implantation embryo. We discuss in vitro culture strategies that enable efficient live fluorescent confocal image acquisition and subsequent cell tracking.
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