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Biocompatible quantum dot-antibody conjugate for cell imaging, targeting and fluorometric immunoassay: crosslinking, characterization and applications
摘要： Quantum dots (QDs) are important fluorescent probes that offer great promise for bio-imaging research due to their superior optical properties. However, QDs for live cell imaging and the tracking of cells need improving labeling efficiency, and reducing more investigation to simplify processing procedures, chronic toxicity. In this study, QDs were functionalized with bovine serum albumin (BSA) via a chemical linker. Anti-human immunoglobulin antibodies were oxidized by sodium periodate to create reactive aldehyde groups for a spontaneous reaction with the amine groups of BSA-modified QDs. An antibody-labeled QD bioconjugate was characterized using agarose gel electrophoresis, dynamic light scattering, and zeta potential. Using fluorescence spectroscopy, we found that the fluorescence of QDs was retained after multiple conjugation steps. The cell-labeling function of the QD bioconjugate was confirmed using an image analyzer and confocal microscopy. The QD bioconjugate specifically targeted the human immunoglobulin on the membrane surface of recombinant cells. The QD bioconjugate applied in fluorometric immunoassay was effective for the quantitative analysis of human immunoglobulin in an enzyme-linked immunosorbent assay. The developed QD bioconjugate may offer a promising platform to develop biocompatible tools to label cells and quantify antibodies in the immunoassay.
关键词： Quantum dots,Bio-imaging,Fluorescent probes,Cell labeling,Fluorometric immunoassay
更新于2025-09-16 10:30:52
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Biodegradable and Photostable Nb2C MXene Quantum Dots as Promising Nanofluorophores for Metal Ions Sensing and Fluorescence Imaging
摘要： Conventional fluorescent probes are either easily photobleached or non-biodegradable, which often leads to the unstable fluorescence signal output and long-term biological toxicity. Therefore, the development of novel fluorescent materials with both excellent photostability and biodegradability is of great significance for further broadening their application in numerous research fields. In this work, Nb2C quantum dots (Nb2C QDs) with pristine crystallographic structures of Nb2C MXene phases and surface oxygen-containing species are synthesized by an ultrasound assisted physicochemical exfoliation in tetrapropylammonium hydroxide. Detailed analyses indicate that the Nb2C QDs not only possess excellent chemical- and photo-stable fluorescence emission but also achieve successful application in fluorescence sensing of heavy metal ions and fluorescence imaging. More importantly, it is confirmed that the Nb2C QDs present high biocompatibility and unique biodegradation property responsive to human myeloperoxidase, implying the application safety of Nb2C QDs in vivo. Under the background of ever-growing and stringent requirements for biosafety and technical stability, the biocompatibility, biodegradability, and most importantly the promising fluorescence sensing/imaging characteristic of the obtained Nb2C QDs may argue well for their future applications in environmental monitoring, biomedical diagnosis, visual display, and anti-counterfeiting.
关键词： MXene quantum dots,biodegradation,fluorescent probes,fluorescence imaging,photobleaching resistance
更新于2025-09-16 10:30:52
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Protein-specific, multi-color and 3D STED imaging in cells with DNA-labeled antibodies
摘要： Photobleaching is a major challenge in fluorescence microscopy, in particular if high excitation light intensities are used. Signal-to-noise and spatial resolution may be compromised, which limits the amount of information that can be extracted from an image. Photobleaching can be bypassed with exchangeable labels, which transiently bind to and off a target and thereby replenish destroyed labels by intact ones from a reservoir. Here, we demonstrate confocal and STED microscopy with short, fluorophore-labeled oligonucleotides that transiently bind to complementary oligonucleotides attached to protein-specific antibodies. The constant exchange of fluorophore labels in DNA-based STED imaging bypasses photobleaching that occurs with covalent labels. We show that this concept is suitable for targeted, two-color STED imaging of whole cells.
关键词： multicolor imaging,STED microscopy,fluorescent probes,DNA-PAINT,fluorescence
更新于2025-09-11 14:15:04
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Coumarin-based Fluorescent Probes for Super-resolution and Dynamic Tracking of Lipid Droplets
摘要： Visualizing and dynamic tracking lipid droplets (LDs) are of great importance to biological research. Herein, two-photon absorption fluorescent small bio-probes based on lipophilic coumarin were developed, which exhibited high selectivity towards LDs in Hela cells. Owing to the good biocompatibility and excellent photo-stability, the probes were applied to realize specific super-resolution visualization of the intracellular LDs in Hela cells, offering us the quantitative results of the amount and diameters of LDs as well. Furthermore, the bio-probes were capable of monitoring the movements of the LDs in real-time. We believe that the bio-probes would provide new avenues to designing bio-imaging and biological diagnosis.
关键词： Fluorescent Probes,Super-resolution,Lipid Droplets,Coumarin-based,Dynamic Tracking
更新于2025-09-10 09:29:36
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Fast 3D Microscopy Imaging of Contacts Between Surfaces Using a Fluorescent Liquid
摘要： A novel method is presented for the rapid direct 3D visualization of the contact between two surfaces by means of fluorescence microscopy using a fluorescent liquid. Distances between the surfaces of up to several hundred nanometers can be determined with sub-nanometer accuracy in 3D and within seconds of measurement time. The method opens new possibilities for research in the areas of contact mechanics, friction, wear and lubrication.
关键词： fluorescent probes,mechanical properties,3D imaging,Interfaces
更新于2025-09-10 09:29:36
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A Fluorescent Probe with Aggregation-Induced Emission for Detecting Alkaline Phosphatase and Cell Imaging
摘要： Alkaline phosphatase (ALP) is associated with many diseases, and its accurate detection is of great significance. Fluorescent compounds with aggregation-induced emission (AIE) feature show beneficial advantages for serving as fluorescent probes. Herein, an AIE-active “turn on” probe for ALP detection was synthesized through incorporating a strong electron-withdrawing group (cyano) in the middle and the recognition moiety phosphate group at the end, thereby rendering a D–A–D structure with a relatively high conjugation degree and good water solubility. It was found that the probe TPE-CN-pho is highly sensitive to ALP in aqueous solution. In the presence of ALP, the hydrophilic phosphate group on the probe is rapidly removed, resulting in a decrease in water solubility and subsequent formation of aggregates, thereby achieving aggregation-induced emission. Moreover, the probe TPE-CN-pho has also been successfully applied to imaging ALP in living cells.
关键词： alkaline phosphatase,aggregation-induced emission,fluorescent probes,cell imaging,biosensors
更新于2025-09-10 09:29:36
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Photochemistry and Photophysics - Fundamentals to Applications || Tailoring the Photophysical Signatures of BODIPY Dyes: Toward Fluorescence Standards across the Visible Spectral Region
摘要： The modern synthetic routes in organic chemistry, as well as the recent advances in high-resolution spectroscopic and microscopic techniques, have awakened a renewable interest in the development of organic fluorophores. In this regard, boron-dipyrrin (BODIPY) dyes are ranked at the top position as luminophores to be applied in photonics or biophotonics. This chromophore outstands not only by its excellent and tunable photophysical signatures, but also by the chemical versatility of its core, which is readily available to a myriad of functionalization routes. In this chapter, we show that, after a rational design, bright and photostable BODIPYs can be achieved along the whole visible spectral region, being suitable as molecular probes or active media of lasers. Alternatively, the selective functionalization of the dipyrrin core, mainly at meso position, can induce new photophysical phenomena (such as charge transfer) paving the way to the development of fluorescent sensors, where the fluorescent response is sensitive to a specific environmental property.
关键词： fluorescent probes,laser dyes,charge transfer,organic synthesis,BODIPY,fluorescent sensors
更新于2025-09-09 09:28:46
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Ratiometric Fluorescence Sensing of Cu(II): Elucidation of FRET Mechanism and Bio‐Imaging Application
摘要： Rhodamine-formylaniline conjugate RFA has been developed as a Cu2+-selective ratiometric fluorescent probe. The probe shows high selectivity towards Cu2+ ion through both its absorption and emission properties; and has been characterized by 1H NMR, FTIR, ESI-MS spectroscopy. Sensing of Cu2+ proceed through FRET process which is nicely depicted from steady-state and fluorescence lifetime studies. From the measurement of fluorescence lifetime, the FRET mechanism has been established undoubtedly. The important parameters regarding FRET, namely the energy transfer efficiency (ΦEt) and the F?rster distance (R0) have also been calculated by fluorescence measurement. The origin of different emission bands has been distinguished by recording excitation spectra. The lowest detection limit (DL) for Cu2+ ion was 4.2 × 10?7 M in Tris-HCl buffered MeCN: H2O (10 mM, 1:1 v/v).
关键词： Time-resolved experiment,Confocal Bioimaging,Energy Transfer Efficiency,FRET,Fluorescent probes
更新于2025-09-09 09:28:46
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Photochemically Active Dyes for Super-Resolution Microscopy
摘要： The development of super-resolved optical microscopies has revolutionized the way we visualize cell biology. These techniques strongly rely on the use of photochemically active fluorophores that display changes in their photophysical properties upon irradiation with light. Many reversible and irreversible photochemical transformations have been explored for this purpose, and different imaging techniques require specific mechanisms of photoconversion. In this review, we provide an overview of the most common strategies used for the development of fluorophores for super-resolution microscopy and give specific examples of state-of-the-art fluorogenic probes. Furthermore, we discuss their main field of application and possible directions for future developments.
关键词： Live-cell imaging,Photoswitchable,Super-resolution microscopy,Fluorescent probes,Photoactivatable
更新于2025-09-09 09:28:46
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Imaging flow cytometry and confocal microscopy-based examination of F-actin and phosphoinositide dynamics during leukocyte immune-type receptor-mediated phagocytic events
摘要： Cells of the innate immune system rapidly detect and eliminate invading microbes using surface-expressed immunoregulatory receptors that translate extracellular binding events into potent effector responses. Channel catfish (Ictalurus punctatus) leukocyte immune-type receptors (IpLITRs) are a family of immunoregulatory proteins that have been shown to regulate several innate immune cell effector responses including the phagocytic process. The mechanisms by which these receptors regulate phagocytosis are not entirely understood but we have previously shown that different IpLITR-types use ITAM-dependent as well as ITAM-independent pathways for controlling target engulfment. The main objective of this study was to develop and use imaging flow cytometry and confocal microscopy-based assays to further examine both F-actin and phosphoinositide dynamics that occur during the different IpLITR-mediated phagocytic pathways. Results show that the ITAM-dependent IpLITR-induced phagocytic response promotes canonical changes in F-actin polymerization and PI(4,5)P2 redistributions. However, the ITAM-independent IpLITR phagocytic response induced unique patterns of F-actin and PI(4,5)P2 redistributions, which are likely due to its ability to regulate alternative signaling pathways. Additionally, both IpLITR-induced phagocytic pathways induced target internalization into PI(3)P-enriched phagosomes indicative of a maturing phagosome compartment. Overall, this imaging-based platform can be further applied to monitor the recruitment and distribution of signaling molecules during IpLITR-mediated phagocytic processes and may serve as a useful strategy for functional examinations of other immunoregulatory receptor-types in fish.
关键词： Cytoskeletal dynamics,Teleost,Phosphoinositides,Leukocyte immune-type receptors,Imaging,Phagocytosis,Innate immunity,Fluorescent probes,F-actin,Flow cytometry
更新于2025-09-04 15:30:14