A Theme Issue in Honor of Dr. Richard Horobin—Cell or Organelle Selective Fluorescent Probes: Their Design, Mechanism, Modeling and Application

A special issue of Chemosensors (ISSN 2227-9040).

Deadline for manuscript submissions: 31 August 2024 | Viewed by 30053

Special Issue Editors


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Guest Editor
Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang 37673, Republic of Korea
Interests: cell selective fluorescent probes and sensors

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Guest Editor
Department of Chemistry, School of Natural Sciences (SNS), Shiv Nadar University, Delhi, Uttar Pradesh, India
Interests: activity based chemosensors and fluorescent probes for environmental monitoring and cellular imaging

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Guest Editor
Department of Chemistry and Biology, Faculty of Environment and Life, Beijing University of Technology, Beijing 100124, China
Interests: fluorescence imaging; small-molecule fluorescent probe; nanoprobe; accurate diagnosis; organic synthesis
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Special Issue Information

Dear Colleagues,

Dr. Richard W. Horobin is the pioneer of QSAR modelling of organelle selectivity of dyes in cell staining. After a PhD apprenticeship in chemistry at the University of Sheffield, England, he jumped ship—being re-socialised as a cell biologist in Prof Robert Barer’s multidisciplinary microscopy development group. His task was to produce novel “stains”—substances giving visual contrast to biological materials being viewed in microscopes. Initially this concerned non-living biopsies, and electron or light microscopes. Consequently, he became involved with dyestuff chemistry, which enthusiasm has proved lifelong. Finally, he arrived at small-molecule fluorescent probes used to report on the structure, content and functions of living cells and organisms. That his knowledge and skills base were not confined to a single academic compartment now became significant. Typically, chemists consider probe chemistry, biologists cell structure and physiology—very few study the details of probe-cell interactions, even fewer the implications for staining protocols. His fascination with staining processes led to QSAR models relating probe structure to cellular sites of probe accumulation, and eventually to accumulation models for all common cell organelles. In parallel, he clarified and emphasised the role of “protocol effects”—factors such as probe purity; probe stability outside or inside the cell; choice of excitation and emission wavelengths; and other technical variables influencing what occurs and can be observed. These perspectives did not emerge from a social vacuum. Richard Horobin’s life in science has not tracked the conventional academic career, instead he became a player in a globally distributed invisible college. Key to his achievements are collaborators across disciples, from anatomy to zoology; and organisations with expertise regarding purity, application and understanding of dyes and their interactions. Hence his involvement with the Biological Stain Commission, the Royal Microscopical Society, and the Society of Dyers and Colourists. Plus smart, hard-working and critical students—working directly with him or with his collaborators—doing much leg-work and challenging many assumptions. Finally, research workers who ask “Why isn’t this method working?” or “What is the best probe to identify organelle Z?” This combination of viewpoints provided the foundation of his long, post-conventional, research life. For more than two decades he has been an Honorary Research Fellow at the University of Glasgow, Scotland, presently in the Chemical Biology Group in the School of Chemistry. His current investigation seeks to understand probes selectively staining lipid droplets in living cells—and hence to obtain a general protocol for designing an optimum probe for the job.

This special issue is dedicated to celebrating the career of Dr. Richard Horobin in honour of his contribution in the field of cell staining dyes. It will cover recent research on subjects of cell selective and organelle selective dyes in their design, mechanism, modelling and application.

Cell and organelle selective probes, especially for live cells, provide the window to look at the inside of body in real time. The probes are playing the critical roles to monitor the biological system and also provide the clues to understand and elucidate new mechanism of biological process. This special issue aims to provide an overview and current development in the field of cell and organelle probes. Potential topics include, but are not limited to:

  • Reviews on selective probes for organelle visualization or cell distinction    
  • Innovations of new sensor and probe development for biological study
  • New design of optical sensor and bioprobes
  • QSAR prediction model for organelle or cell selectivity
  • Application of sensor and probes in biological study

Prof. Dr. Young-Tae Chang
Dr. Animesh Samanta
Prof. Dr. Dongdong Su
Guest Editors

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Published Papers (15 papers)

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Research

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13 pages, 3888 KiB  
Article
Updating Ortho- and Metachromatic Acridine Orange Fluorescence in Cytochemical Chromosome Staining: A Proposal for Understanding Its Differential Fluorescence on Double- and Single-Stranded Nucleic Acids Substrates Based on Intercalation
by Juan C. Stockert and Alfonso Blázquez-Castro
Chemosensors 2023, 11(10), 540; https://doi.org/10.3390/chemosensors11100540 - 16 Oct 2023
Viewed by 1749
Abstract
Many fluorophores display interesting features that make them useful biological labels and chemosensors, in particular in Cell Biology. Changes in the absorption-emission spectra (ortho- and metachromasia) are accounted among them. Acridine orange (AO) is one such fluorochromes that shows a prototypical orthochromatic vs. [...] Read more.
Many fluorophores display interesting features that make them useful biological labels and chemosensors, in particular in Cell Biology. Changes in the absorption-emission spectra (ortho- and metachromasia) are accounted among them. Acridine orange (AO) is one such fluorochromes that shows a prototypical orthochromatic vs. metachromatic behavior depending on its concentration and binding mode to different cellular substrates. Here, we revisit the differential AO fluorescence that occurs in selected biological examples, which allows for the identification of single-stranded or double-stranded nucleic acids. Although known for long, the ultimate reason for this phenomenon has not been properly advanced. We provide a potential molecular mechanism that adequately accounts for the different aspects of the phenomenon. This theoretical mechanism implies a difference in the degree of overlap of excited state orbitals whenever AO molecules are interacting with a single-stranded or a double-stranded nucleic acid. In the first case, massive π-electron overlapping between bases and intercalated AO leads to a metachromatic red emission. On the contrary, no excited-state orbital overlapping in AO-intercalated DNA duplexes is possible due to excessive separation between AO molecules and compliancy to the nearest neighbor exclusion principle, which manifests as orthochromatic green fluorescence. Full article
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14 pages, 11184 KiB  
Article
Synthesis of Photoluminescent Carbon Dots Using Hibiscus Tea Waste and Heteroatom Doping for Multi-Metal Ion Sensing: Applications in Cell imaging and Environmental Samples
by Sonaimuthu Mohandoss, Naushad Ahmad, Kuppu Sakthi Velu, Mohammad Rizwan Khan, Subramanian Palanisamy, SangGuan You and Yong Rok Lee
Chemosensors 2023, 11(9), 474; https://doi.org/10.3390/chemosensors11090474 - 24 Aug 2023
Cited by 3 | Viewed by 1286
Abstract
Novel photoluminescent carbon dots (CDs) were synthesized through a facile hydrothermal method using Hibiscus tea extract as a natural carbon source and boric acid as a boron source. The optical and physicochemical properties of the as-synthesized nitrogen- and boron-doped CDs (NB-CDs) were characterized [...] Read more.
Novel photoluminescent carbon dots (CDs) were synthesized through a facile hydrothermal method using Hibiscus tea extract as a natural carbon source and boric acid as a boron source. The optical and physicochemical properties of the as-synthesized nitrogen- and boron-doped CDs (NB-CDs) were characterized using UV–Visible (UV–Vis), photoluminescence (PL) spectroscopy, Fourier-transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The as-synthesized NB-CDs showed spherical morphology of approximately 6.2 ± 0.5 nm with quantum yield (9.2%), high aqueous solubility, strong photo-stability, and excitation-dependent PL behavior. The obtained NB-CDs exhibited high stability over a wide pH range and high ionic strength. Additionally, NB-CDs exhibited PL enhancement response with excellent sensitivity toward multi-metal ions, including Ag+, Cd2+, and Cr3+ ions, with very low detection limits of 44.5, 164.4, and 54.6 nM, respectively, with a wide concentration range of 0–10 μM. Upon testing the cytotoxicity of the NB-CDs at a concentration of 20 μg/mL for 24 h, we found no obvious inhibition of cell viability. Therefore, the proposed sensor method can be successfully applied to detect Ag+, Cd2+, and Cr3+ ions in cell imaging as well as in real water environmental samples. Full article
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12 pages, 2595 KiB  
Article
Applicability and Limitations of Fluorescence Intensity-Based Thermometry Using a Palette of Organelle Thermometers
by Takeru Yamazaki, Xiao Liu, Young-Tae Chang and Satoshi Arai
Chemosensors 2023, 11(7), 375; https://doi.org/10.3390/chemosensors11070375 - 4 Jul 2023
Viewed by 1379
Abstract
Fluorescence thermometry is a microscopy technique in which a fluorescent temperature sensor records temperature changes as alterations of fluorescence signals. Fluorescence lifetime imaging (FLIM) is a promising method for quantitative analysis of intracellular temperature. Recently, we developed small-molecule thermometers, termed Organelle Thermo Greens, [...] Read more.
Fluorescence thermometry is a microscopy technique in which a fluorescent temperature sensor records temperature changes as alterations of fluorescence signals. Fluorescence lifetime imaging (FLIM) is a promising method for quantitative analysis of intracellular temperature. Recently, we developed small-molecule thermometers, termed Organelle Thermo Greens, that target various organelles and achieved quantitative temperature mapping using FLIM. Despite its highly quantitative nature, FLIM-based thermometry cannot be used widely due to expensive instrumentation. Here, we investigated the applicability and limitations of fluorescence intensity (FI)-based analysis, which is more commonly used than FLIM-based thermometry. Temperature gradients generated by artificial heat sources and physiological heat produced by brown adipocytes were visualized using FI- and FLIM-based thermometry. By comparing the two thermometry techniques, we examined how the shapes of organelles and cells affect the accuracy of the temperature measurements. Based on the results, we concluded that FI-based thermometry could be used for “qualitative”, rather than quantitative, thermometry under the limited condition that the shape change and the dye leakage from the target organelle were not critical. Full article
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14 pages, 3848 KiB  
Article
Gold Nanocluster-Based Fluorescent Sensor Array for Antibiotic Sensing and Identification
by Mengjiao Mo, Haoyi Yuan, Jingyu Zhang, Jian Wang, Ying Liu, Juanjuan Peng and Lingzhi Zhao
Chemosensors 2023, 11(6), 330; https://doi.org/10.3390/chemosensors11060330 - 3 Jun 2023
Cited by 4 | Viewed by 1255
Abstract
Antibiotic contamination has become a serious global problem due to abuse and misuse. Therefore, it is important to develop an efficient detection method to monitor the rational use of antibiotics. In this study, fluorescent gold nanoclusters with 11-mercaptoundecanoic acid as ligands (MUA-AuNCs) were [...] Read more.
Antibiotic contamination has become a serious global problem due to abuse and misuse. Therefore, it is important to develop an efficient detection method to monitor the rational use of antibiotics. In this study, fluorescent gold nanoclusters with 11-mercaptoundecanoic acid as ligands (MUA-AuNCs) were synthesized by a one-step method firstly. Rare earth ions (Re3+) can enhance the fluorescence of MUA-AuNCs through inducing the aggregation of MUA-AuNCs, but antibiotics decrease the fluorescence of the Re3+-MUA-AuNCs to different degrees through coordination with Re3+ and competitive absorption with AuNCs. Therefore, a sensor array was obtained on the basis of the above mechanism, which can detect and discriminate six different antibiotics with a detection range from 40 to 300 μM. A 100% correct classification was achieved. The fluorescent sensor array showed high selectivity for tetracycline antibiotics and good anti-interference performance was demonstrated. Combined with pattern recognition methods, the proposed sensor array can be used for the discrimination of different antibiotics and binary antibiotic mixtures. Furthermore, the excellent performance of this sensor array in quantitation and blind sample recognition further validates its potential for practical applications. Full article
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12 pages, 2245 KiB  
Article
Near-Infrared Fluorescence Probe for Visualizing Fluctuations of Peroxynitrite in Living Cells and Inflammatory Mouse Models
by Shuchun Qin, Yiming Ran, Yitian He, Xiaoyan Lu, Jiamin Wang, Weili Zhao and Jian Zhang
Chemosensors 2023, 11(6), 316; https://doi.org/10.3390/chemosensors11060316 - 24 May 2023
Cited by 1 | Viewed by 1299
Abstract
Inflammation is a vital protective response in living systems and closely related to various diseases. As a member of the reactive oxygen species (ROS) family, peroxynitrite (ONOO) is involved in the organism’s inflammatory process and considered as an important biomarker of [...] Read more.
Inflammation is a vital protective response in living systems and closely related to various diseases. As a member of the reactive oxygen species (ROS) family, peroxynitrite (ONOO) is involved in the organism’s inflammatory process and considered as an important biomarker of inflammation. Therefore, the construction of a simple, rapid, and sensitive tool for detecting ONOO is of great importance for the diagnosis of inflammation. In this study, we constructed the new near-infrared fluorescence probe BDP-ENE-S-Py+ based on BODIPY dye, which has the advantages of fast response speed (2 min), good selectivity, and a high signal-to-noise ratio. Moreover, the probe had a good linear relationship (LOD = 120 nM) when the ONOO concentration was 10–35 µM. In addition, BDP-ENE-S-Py+ could detect exogenous ONOO in liver cancer cells without interference from other reactive oxygen species and visualize the fluctuations in ONOO concentrations in cells. More importantly, BDP-ENE-S-Py+ was able to track the upregulation of ONOO content in a mouse model of peritonitis induced by LPS. This work demonstrated that the near-infrared fluorescent probe for visualizing ONOO level fluctuations could provide a promising tool for inflammation-related studies. Full article
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10 pages, 1796 KiB  
Communication
Quantitative Structure-Activity Relationship of Fluorescent Probes and Their Intracellular Localizations
by Seong-Hyeon Park, Hong-Guen Lee, Xiao Liu, Sung Kwang Lee and Young-Tae Chang
Chemosensors 2023, 11(5), 310; https://doi.org/10.3390/chemosensors11050310 - 22 May 2023
Cited by 3 | Viewed by 1575
Abstract
The development of organelle-specific fluorescent probes has been impeded by the absence of a comprehensive understanding of the relationship between the physicochemical properties of fluorescent probes and their selectivity towards specific organelles. Although a few machine learning models have suggested several physicochemical parameters [...] Read more.
The development of organelle-specific fluorescent probes has been impeded by the absence of a comprehensive understanding of the relationship between the physicochemical properties of fluorescent probes and their selectivity towards specific organelles. Although a few machine learning models have suggested several physicochemical parameters that control the target organelle of the probes and have attempted to predict the target organelles, they have been challenged by low accuracy and a limited range of applicable organelles. Herein, we report a multi-organelle prediction QSAR model that is capable of predicting the destination of probes among nine categories, including cytosol, endoplasmic reticulum, Golgi body, lipid droplet, lysosome, mitochondria, nucleus, plasma membrane, and no entry. The model is trained using the Random Forest algorithm with a dataset of 350 organelle-specific fluorescent probes and 786 descriptors, and it is able to predict the target organelles of fluorescent probes with an accuracy of 75%. The MDI analysis of the model identifies 38 key parameters that have a significant impact on the organelle selectivity of the probes, including LogD, pKa, hydrophilic-lipophilic balance (HLB), and topological polar surface area (TPSA). This prediction model may be useful in developing new organelle-specific fluorescent probes by providing crucial variables that determine the destination of the probes. Full article
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14 pages, 2240 KiB  
Article
A Highly Sensitive and Selective Near-Infrared Fluorescent Probe for Detecting Peroxynitrite in Living Cells and Drosophila Brains
by Wei Wang, Jian-Bin Deng, Long Jin and Bai-Ou Guan
Chemosensors 2023, 11(5), 286; https://doi.org/10.3390/chemosensors11050286 - 11 May 2023
Viewed by 1806
Abstract
Peroxynitrite (ONOO) is a highly reactive nitrogen species (RNS) that is closely associated with many physiological and pathological processes. In this study, we construct a near-infrared (NIR) fluorescent probe, NAF-BN, that utilizes benzyl boronic acid ester for fluorescence quenching of [...] Read more.
Peroxynitrite (ONOO) is a highly reactive nitrogen species (RNS) that is closely associated with many physiological and pathological processes. In this study, we construct a near-infrared (NIR) fluorescent probe, NAF-BN, that utilizes benzyl boronic acid ester for fluorescence quenching of naphthofluorescein cores. NAF-BN has been thoroughly evaluated for reliable imaging of exogenous ONOO in living cells. Further, NAF-BN can be applied effectively to visualize ONOO in Drosophila brains, confirming the hypothesis that neonicotinoid pesticides increase neurological damage and oxidative stress. The probe NAF-BN offers exciting potential to reveal the role of ONOO in various biological and medical fields. Full article
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14 pages, 5302 KiB  
Article
Distinctive Labeling of Live Monocytes and Neutrophils with a Single Fluorescent Molecule
by Songhui Kim, Masahiro Fukuda, Jung Yeol Lee, Young-Tae Chang, H. Shawn Je and Beomsue Kim
Chemosensors 2023, 11(5), 265; https://doi.org/10.3390/chemosensors11050265 - 29 Apr 2023
Viewed by 1251
Abstract
(1) Background: a small-molecule fluorescent chemosensor, CDr20, tracks the resident macrophages based on the UGT1A7C activity in the brain, raising the possibility that additional immune cells expressing the UGT1A7C can be labeled with CDr20. (2) Methods: we applied CDr20 to various types of [...] Read more.
(1) Background: a small-molecule fluorescent chemosensor, CDr20, tracks the resident macrophages based on the UGT1A7C activity in the brain, raising the possibility that additional immune cells expressing the UGT1A7C can be labeled with CDr20. (2) Methods: we applied CDr20 to various types of blood cells derived from hematopoietic organs (spleen and bone marrow) as well as peripheral blood to test the degree and selectivity of labeling of CDr20 in these cell types; (3) Results: CDr20 fluorescently labels monocytes/macrophages and neutrophils as a result of glucuronidation reaction (CDr20-Gluc), which is mediated with UGT1A7C. The selectivity of CDr20 labeling highly correlates with the Ugt1a7c expression level in immune cells. Moreover, CDr20-Gluc is exported from cells by a mechanism of how glucuronides within cells are excreted into extracellular space. Interestingly, the exportation of CDr20-Gluc is mainly observed in monocytes, potentially due to the monocyte-specific expression of ABCC transporters and this resulted in large differences in the degree of fluorescence retention in neutrophils (CDr20bright), compared to monocytes (CDr20dim) upon one hour of CDr20 incubation; (4) Conclusions: CDr20 can differentially label monocytes and neutrophils due to the variance in two different cellular enzymatic activities of UGT1A7C and ABCC. By using this property, CDr20 can be used to distinguish specific cell types within blood. Full article
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18 pages, 5130 KiB  
Article
Detection of Lysosomal Hg2+ Using a pH-Independent Naphthalene Monoimide-Based Fluoroprobe
by Rupam Roy, Tanoy Dutta, Shruti Nema and Apurba Lal Koner
Chemosensors 2023, 11(3), 184; https://doi.org/10.3390/chemosensors11030184 - 10 Mar 2023
Cited by 3 | Viewed by 1992
Abstract
The development of fluorometric detection methods for toxic metal ions in real samples and inside cellular environments using fluorescent dyes has gained tremendous research interest. This work represents the design and synthesis of a 1,8-naphthalimide-based visible light absorbing fluorescence probe His-NMI-Bu showing an [...] Read more.
The development of fluorometric detection methods for toxic metal ions in real samples and inside cellular environments using fluorescent dyes has gained tremendous research interest. This work represents the design and synthesis of a 1,8-naphthalimide-based visible light absorbing fluorescence probe His-NMI-Bu showing an intramolecular charge transfer (ICT) feature. Photophysical properties of the fluoroprobe are investigated in-depth through a combination of steady-state, time-resolved spectroscopic techniques, and DFT calculation. The probe displays outstanding pH tolerance in the pH range of 5–10 as evident from UV–Vis. and fluorescence measurements. The fluoroprobe exhibits chelation with Hg2+-induced fluorescence attenuation via PET in the solution, thus acting as a suitable fluorescence sensor for mercury ions with LOD 0.52 µM. The high sensitivity and selectivity of the probe towards Hg2+ are validated from fluorescence titration with various metal ions. Banking on its intriguing solid-state emissive properties, dye-loaded filter paper-based sensing of Hg2+ is also developed demonstrating the sensitivity in the micromolar range. Finally, His-NMI-Bu fluorophore depicts its selective localization inside the lysosomal compartment of live cells which assists further to monitor the presence of mercury ions inside the lysosome showing similar Hg2+-induced fluorescence depletion. Full article
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12 pages, 2080 KiB  
Article
An Aptamer-Array-Based Sample-to-Answer Biosensor for Ochratoxin A Detection via Fluorescence Resonance Energy Transfer
by Yongning Li, Zhenfei Peng, Yaxi Li, Min Xiao, Gongjun Tan, Wenlian Wang, Yu Wang, Min Fang, Shu Zhang, Chenling Tang, Bowen Yang and Tianfu Wu
Chemosensors 2021, 9(11), 309; https://doi.org/10.3390/chemosensors9110309 - 30 Oct 2021
Cited by 9 | Viewed by 2296
Abstract
Food toxins are a hidden threat that can cause cancer and tremendously impact human health. Therefore, the detection of food toxins in a timely manner with high sensitivity is of paramount importance for public health and food safety. However, the current detection methods [...] Read more.
Food toxins are a hidden threat that can cause cancer and tremendously impact human health. Therefore, the detection of food toxins in a timely manner with high sensitivity is of paramount importance for public health and food safety. However, the current detection methods are relatively time-consuming and not practical for field tests. In the present work, we developed a novel aptamer-chip-based sample-to-answer biosensor (ACSB) for ochratoxin A (OTA) detection via fluorescence resonance energy transfer (FRET). In this system, a cyanine 3 (Cy3)-labeled OTA-specific biotinylated aptamer was immobilized on an epoxy-coated chip via streptavidin-biotin binding. A complementary DNA strand to OTA aptamer at the 3′-end was labeled with a black hole quencher 2 (BHQ2) to quench Cy3 fluorescence when in proximity. In the presence of OTA, the Cy3-labeled OTA aptamer bound specifically to OTA and led to the physical separation of Cy3 and BHQ2, which resulted in an increase of fluorescence signal. The limit of detection (LOD) of this ACSB for OTA was 0.005 ng/mL with a linearity range of 0.01–10 ng/mL. The cross-reactivity of ACSB against other mycotoxins, ochratoxin B (OTB), aflatoxin B1 (AFB1), zearalenone (ZEA), or deoxynilvalenol (DON), was less than 0.01%. In addition, this system could accurately detect OTA in rice samples spiked with OTA, and the mean recovery rate of the spiked-in OTA reached 91%, with a coefficient of variation (CV) of 8.57–9.89%. Collectively, the ACSB may represent a rapid, accurate, and easy-to-use platform for OTA detection with high sensitivity and specificity. Full article
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8 pages, 1729 KiB  
Communication
Nanometre-Scale Visualization of Chemical Parameter Changes by T1-Weighted ODMR Imaging Using a Fluorescent Nanodiamond
by Takahiro Fujisaku, Ryuji Igarashi and Masahiro Shirakawa
Chemosensors 2020, 8(3), 68; https://doi.org/10.3390/chemosensors8030068 - 11 Aug 2020
Cited by 1 | Viewed by 3545
Abstract
The dynamics of physical parameters in cells is strongly related to life phenomena; thus, a method to monitor and visualize them on a single-organelle scale would be useful to reveal unknown biological processes. We demonstrate real-time nanometre-scale T1-weighted imaging using a [...] Read more.
The dynamics of physical parameters in cells is strongly related to life phenomena; thus, a method to monitor and visualize them on a single-organelle scale would be useful to reveal unknown biological processes. We demonstrate real-time nanometre-scale T1-weighted imaging using a fluorescent nanodiamond. We explored optically detected magnetic resonance (ODMR) contrast at various values of interval laser pulse (τ), showing that sufficient contrast is obtained by appropriate selection of τ. By this method, we visualized nanometre-scale pH changes using a functionalized nanodiamond whose T1 has a dependence on pH conditions. Full article
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Review

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29 pages, 7762 KiB  
Review
Recent Advances in Design Strategies and Imaging Applications of Fluorescent Probes for ATP
by Qing-Song Gu, Ting Li, Ting Liu, Guo Yu, Guo-Jiang Mao, Fen Xu and Chun-Yan Li
Chemosensors 2023, 11(7), 417; https://doi.org/10.3390/chemosensors11070417 - 24 Jul 2023
Cited by 7 | Viewed by 1732
Abstract
Adenosine 5′-triphosphate (ATP) is the energy currency in cells. It is involved in numerous cellular life activities and exhibits a close association with the development of certain diseases. Thus, the precise detection of ATP within cells holds immense significance in understanding cell biological [...] Read more.
Adenosine 5′-triphosphate (ATP) is the energy currency in cells. It is involved in numerous cellular life activities and exhibits a close association with the development of certain diseases. Thus, the precise detection of ATP within cells holds immense significance in understanding cell biological events and related disease development. Fluorescent probes have obvious advantages in imaging ATP in cells and in vivo due to their high sensitivity, good selectivity, real-time imaging, and good biocompatibility. Thus far, an extensive array of fluorescent probes targeting ATP has been formulated to enable the visualization of ATP within cells and in vivo. This review summarizes the recent advances in ATP fluorescent probes according to different design strategies, mainly including those based on organic small molecules, metal complexes, and water-soluble conjugated polymers. In addition, the practical applications of ATP fluorescent probes in the imaging of target organelles, cell biological events, and disease markers are highlighted. Finally, the challenges and future trends of ATP detection based on fluorescent probes are discussed. Full article
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19 pages, 11372 KiB  
Review
Recent Progress in Fluorescent Probes for the Detection and Research of Hydrogen Sulfide in Cells
by Weier Liang, Yong Zhang, Shaoqing Xiong and Dongdong Su
Chemosensors 2023, 11(6), 333; https://doi.org/10.3390/chemosensors11060333 - 4 Jun 2023
Cited by 1 | Viewed by 1985
Abstract
Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays an important role in regulating various physiological activities in biological systems. As the fundamental structural and functional unit of organisms, cells are closely related to the homeostasis of their internal environment. [...] Read more.
Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays an important role in regulating various physiological activities in biological systems. As the fundamental structural and functional unit of organisms, cells are closely related to the homeostasis of their internal environment. The levels of H2S in different organelles maintain a certain balance, and any disruption of this balance will lead to various functional abnormalities that affect the health of organisms. Fluorescent imaging technology provides unique merits, such as simplicity, non-invasiveness, and real-time monitoring, and has become a powerful approach for the detection of molecules in biological systems. Based on the special physicochemical properties of H2S, numerous H2S-specific fluorogenic probes have been designed with different recognition mechanisms that enable rapid and accurate detection of H2S in cells. Therefore, this review briefly illustrates the design strategies, response principles, and biological applications of H2S-specific fluorescent probes and aims to provide relevant researchers with insight for future research. Full article
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33 pages, 6253 KiB  
Review
Fluorescent Sensors for Detecting and Imaging Metal Ions in Biological Systems: Recent Advances and Future Perspectives
by Yang Shi, Wenxian Zhang, Yi Xue and Jingjing Zhang
Chemosensors 2023, 11(4), 226; https://doi.org/10.3390/chemosensors11040226 - 6 Apr 2023
Cited by 3 | Viewed by 4304
Abstract
Metal ions play a crucial role in many biochemical processes, and when in a state of scarcity or surplus, they can lead to various diseases. Therefore, the development of a selective, sensitive, cost-effective, and fast-responding sensor to detect metal ions is critical for [...] Read more.
Metal ions play a crucial role in many biochemical processes, and when in a state of scarcity or surplus, they can lead to various diseases. Therefore, the development of a selective, sensitive, cost-effective, and fast-responding sensor to detect metal ions is critical for in vitro medical diagnostics. In recent years, fluorescent sensors have been extensively investigated as potent kits for the effective assessment of metal ions in living systems due to their high sensitivity, selectivity, ability to perform real-time, non-invasive monitoring, and versatility. This review is an overview of recent advances in fluorescent sensors for the detection and imaging of metal ions in biosystems from 2018 to date. Specifically, we discuss their application in detecting essential metal ions and non-essential metal ions for in vitro diagnostics, living cell imaging, and in vivo imaging. Finally, we summarize remaining challenges and offer a future outlook on the above topics. Full article
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Other

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15 pages, 1109 KiB  
Viewpoint
Chemists Focus on Probes, Biologists on Cells—But Who Talks about Probe-Cell Interactions? A Critical Account of the Suboptimal Reporting of Novel Fluorescent Imaging Probes, Using Lipid Droplet Stains as a Case Study
by Richard W. Horobin
Chemosensors 2023, 11(5), 282; https://doi.org/10.3390/chemosensors11050282 - 8 May 2023
Viewed by 1058
Abstract
Many current reports in the scientific literature describe novel fluorescent probes intended to provide information on various structures or properties of live cells by using microscopic imaging. Unfortunately, many such reports fail to provide key information regarding the staining process. It is often [...] Read more.
Many current reports in the scientific literature describe novel fluorescent probes intended to provide information on various structures or properties of live cells by using microscopic imaging. Unfortunately, many such reports fail to provide key information regarding the staining process. It is often the case that neither the necessary minimum technical detail (probe concentration, solvent and cosolute, temperature and time of staining, and details of post-staining washes) nor a discussion of the proposed staining mechanism are provided. Such omissions make it unnecessarily difficult for biomedical end-users to try out reported novel probes in their own laboratories. The validity of these criticisms is explored and demonstrated by a detailed analysis of 75 non-cherry-picked articles describing novel fluorescent probes for the detection of lipid droplets in live cells. This dataset also suggests that papers from journals with high journal impact factors or from better-known research groups are no more likely to provide better protocol information or discussion of the mechanism than papers from less prestigious sources. Comments on possible reasons for this suboptimal reporting are offered. The use of a suitable information/feature checklist, following best practice in many leading chemical and biological journals, is suggested as a mechanism for ameliorating this situation, with a draft checklist being provided. Full article
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