Research

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13 pages, 3492 KiB

Open AccessArticle

The Preparation of Golgi Apparatus-Targeted Polymer Dots Encapsulated with Carbon Nanodots of Bright Near-Infrared Fluorescence for Long-Term Bioimaging

by Yiping Lu, Wei Song, Zhiquan Tang, Wenru Shi, Shumei Gao, Jun Wu, Yuan Wang, Hu Pan, Yangang Wang and Hong Huang

Molecules 2023, 28(17), 6366; https://doi.org/10.3390/molecules28176366 - 31 Aug 2023

Cited by 2 | Viewed by 910

Abstract

As a vital organelle in eukaryotic cells, the Golgi apparatus is responsible for processing and transporting proteins in cells. Precisely monitoring the status of the Golgi apparatus with targeted fluorescence imaging technology is of enormous importance but remains a dramatically challenging task. In [...] Read more.

As a vital organelle in eukaryotic cells, the Golgi apparatus is responsible for processing and transporting proteins in cells. Precisely monitoring the status of the Golgi apparatus with targeted fluorescence imaging technology is of enormous importance but remains a dramatically challenging task. In this study, we demonstrate the construction of the first Golgi apparatus-targeted near-infrared (NIR) fluorescent nanoprobe, termed Golgi-Pdots. As a starting point of our investigation, hydrophobic carbon nanodots (CNDs) with bright NIR fluorescence at 674 nm (fluorescence quantum yield: 12.18%), a narrow emission band of 23 nm, and excellent stability were easily prepared from Magnolia Denudata flowers using an ultrasonic method. Incorporating the CNDs into a polymer matrix modified with Golgi-targeting molecules allowed for the production of the water-soluble Golgi-Pdots, which showed high colloidal stability and similar optical properties compared with pristine CNDs. Further studies revealed that the Golgi-Pdots showed good biocompatibility and Golgi apparatus-targeting capability. Based on these fascinating merits, utilizing Golgi-Pdots for the long-term tracking of the Golgi apparatus inside live cells was immensely successful. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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22 pages, 8222 KiB

Open AccessArticle

Interaction of Hoechst 33342 with POPC Membranes at Different pH Values

by Margarida M. Cordeiro, Hugo A. L. Filipe, Patrícia dos Santos, Jaime Samelo, João P. Prates Ramalho, Luís M. S. Loura and Maria J. Moreno

Molecules 2023, 28(15), 5640; https://doi.org/10.3390/molecules28155640 - 25 Jul 2023

Cited by 1 | Viewed by 2520

Abstract

Hoechst 33342 (H33342) is a fluorescent probe that is commonly used to stain the DNA of living cells. To do so, it needs to interact with and permeate through cell membranes, despite its high overall charge at physiological pH values. In this work, [...] Read more.

Hoechst 33342 (H33342) is a fluorescent probe that is commonly used to stain the DNA of living cells. To do so, it needs to interact with and permeate through cell membranes, despite its high overall charge at physiological pH values. In this work, we address the effect of pH in the association of H33342 with lipid bilayers using a combined experimental and computational approach. The partition of H33342 to 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) lipid membranes was experimentally quantified using fluorescence spectroscopy and isothermal titration calorimetry (ITC) measurements. Quantum chemical calculations were performed to select the most stable isomer of H33342 for the overall charges 0, +1, and +2, expected to predominate across the 5 < pH < 10 range. The interaction of these isomers with POPC bilayers was then studied by both unrestrained and umbrella sampling molecular dynamics (MD) simulations. Both experimental results and computational free energy profiles indicate that the partition coefficient of H33342 displays a small variation over a wide pH range, not exceeding one order of magnitude. The enthalpy variation upon partition to the membrane suggests efficient hydrogen bonding between the probe and the lipid, namely, for the protonated +2 form, which was confirmed in the MD simulation studies. The relatively high lipophilicity obtained for the charged species contrasts with the decrease in their general hydrophobicity as estimated from octanol/water partition. This highlights the distinction between lipophilicity and hydrophobicity, as well as the importance of considering the association with lipid bilayers when predicting the affinity for biomembranes. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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15 pages, 7453 KiB

Open AccessArticle

Quantitation of Tissue Amyloid via Fluorescence Spectroscopy Using Controlled Concentrations of Thioflavin-S

by Tatiana P. MacKeigan, Megan L. Morgan and Peter K. Stys

Molecules 2023, 28(11), 4483; https://doi.org/10.3390/molecules28114483 - 01 Jun 2023

Viewed by 2423

Abstract

Amyloids are misfolded proteins that aggregate into fibrillar structures, the accumulation of which is associated with the pathogenesis of many neurodegenerative diseases, such as Alzheimer’s disease (AD). Early, sensitive detection of these misfolded aggregates is of great interest to the field, as amyloid [...] Read more.

Amyloids are misfolded proteins that aggregate into fibrillar structures, the accumulation of which is associated with the pathogenesis of many neurodegenerative diseases, such as Alzheimer’s disease (AD). Early, sensitive detection of these misfolded aggregates is of great interest to the field, as amyloid deposition begins well before the presentation of clinical symptoms. Thioflavin-S (ThS) is a fluorescent probe commonly used to detect amyloid pathology. Protocols for ThS staining vary, but they often use high staining concentrations followed by differentiation, which causes varying levels of non-specific staining and potentially leaves more subtle amyloid deposition unidentified. In this study, we developed an optimized ThS staining protocol for the sensitive detection of β-amyloids in the widely used 5xFAD Alzheimer’s mouse model. Controlled dye concentrations together with fluorescence spectroscopy and advanced analytical methods enabled not only the visualization of plaque pathology, but also the detection of subtle and widespread protein misfolding throughout the 5xFAD white matter and greater parenchyma. Together, these findings demonstrate the efficacy of a controlled ThS staining protocol and highlight the potential use of ThS for the detection of protein misfolding that precedes clinical manifestation of disease. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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11 pages, 1987 KiB

Open AccessArticle

Visualization and Comparison of the Level of Apurinic/Apyrimidinic Endonuclease 1 in Live Normal/Cancerous and Neuron Cells with a Fluorescent Nanoprobe

by Peng Lu, Xiangjian Cao, Jinghui Zheng, Ying Sun, Ziyu Tang and Meiping Zhao

Molecules 2023, 28(9), 3935; https://doi.org/10.3390/molecules28093935 - 07 May 2023

Cited by 5 | Viewed by 1612

Abstract

As a major apurinic/apyrimidinic endonuclease and a redox signaling protein in human cells, APE1 plays a crucial role in cellular function and survival. The relationship between alterations of APE1 expression and subcellular localization and the initiation, development and treatment of various cancers has [...] Read more.

As a major apurinic/apyrimidinic endonuclease and a redox signaling protein in human cells, APE1 plays a crucial role in cellular function and survival. The relationship between alterations of APE1 expression and subcellular localization and the initiation, development and treatment of various cancers has received extensive attention. However, comparing the in-vivo activity of APE1 in normal and cancerous breast live cells remains challenging due to the low efficiency of commonly used liposome transfection methods in delivering DNA substrate probes into human normal breast epithelial cells (MCF-10A). In this work, we develop a DNA/RNA hybrid-based small magnetic fluorescent nanoprobe (25 ± 3 nm) that can be taken up by various live cells under magnetic transfection. The D₀/R-nanoprobe demonstrates an outstanding specificity toward APE1 and strong resistance to the cellular background interference. Using this nanoprobe, we are not only able to visualize the intracellular activity of APE1 in breast ductal carcinoma (MCF-7) live cells, but also demonstrate the APE1 activity in MCF-10A live cells for the first time. The method is then extended to observe the changes in APE1 levels in highly metabolically active neuroendocrine cells under normal conditions and severe attacks by reactive oxygen species in real-time. The fluorescent nanoprobe provides a useful tool for studying the dynamic changes of intracellular APE1 in normal or cancerous live cells. It also displays the potential for visible and controllable release of miRNA drugs within live cells for therapeutic purposes. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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11 pages, 3835 KiB

Open AccessArticle

Endoplasmic Reticulum-Targeting Two-Photon Fluorescent Probe for CYP1A Activity and Its Imaging Application in Endoplasmic Reticulum Stress

by Chao Shi, Yan Wang, Xiangge Tian, Xia Lv, Yue An, Jing Ning, Xiulan Xin, Li Dai, Xiaochi Ma and Lei Feng

Molecules 2023, 28(8), 3472; https://doi.org/10.3390/molecules28083472 - 14 Apr 2023

Cited by 2 | Viewed by 1139

Abstract

Cytochrome P450 1A is one of the vital subfamilies of heme-containing cytochrome P450 enzymes belonging to an important exogenous metabolizing CYP in human. The abnormal of endoplasmic reticulum (ER) may directly affect the functional activity of ER-located CYP1A and be associated with the [...] Read more.

Cytochrome P450 1A is one of the vital subfamilies of heme-containing cytochrome P450 enzymes belonging to an important exogenous metabolizing CYP in human. The abnormal of endoplasmic reticulum (ER) may directly affect the functional activity of ER-located CYP1A and be associated with the occurrence and development of various diseases. In the present study, we constructed a selective two-photon fluorescent probe ERNM for rapid and visual detection of endogenous CYP1A that was localized in the ER. ERNM could target the ER and detect the enzymatically active CYP1A in living cells and tissues. The monitoring ability of ERNM for the fluctuations in functionality level of CYP1A was confirmed using ER stressed A549 cell. Based on the ER-targeting two-photon probe for CYP1A, the close association of ER state and the functional activity of ER-locating CYP1A was confirmed, which would promote the deep understanding of the biofunction of CYP1A in various ER-related diseases. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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14 pages, 2368 KiB

Open AccessArticle

Ascorbic Acid-Caused Quenching Effect of Protein Clusteroluminescence Probe: The Fast Fluorescent Detection of Ascorbic Acid in Vegetables

by Jiying Song, Xinyan Guo, Haiying Chen, Yunge Tang and Lei Han

Molecules 2023, 28(5), 2162; https://doi.org/10.3390/molecules28052162 - 25 Feb 2023

Cited by 3 | Viewed by 1380

Abstract

It is interesting and meaningful to explore fluorescent probes for novel rapid detection methods. In this study, we discovered a natural fluorescence probe, bovine serum albumin (BSA), for the assay of ascorbic acid (AA). Due to clusterization-triggered emission (CTE), BSA has the character [...] Read more.

It is interesting and meaningful to explore fluorescent probes for novel rapid detection methods. In this study, we discovered a natural fluorescence probe, bovine serum albumin (BSA), for the assay of ascorbic acid (AA). Due to clusterization-triggered emission (CTE), BSA has the character of clusteroluminescence. AA shows an obvious fluorescence quenching effect on BSA, and the quenching effect increases with increasing concentrations of AA. After optimization, a method for the rapid detection of AA is established by the AA-caused fluorescence quenching effect. The fluorescence quenching effect reaches saturation after 5 min of incubation time and the fluorescence is stable within more than one hour, suggesting a rapid and stable fluorescence response. Moreover, the proposed assay method shows good selectivity and a wide linear range. To further study the mechanisms of AA-caused fluorescence quenching effect, some thermodynamic parameters are calculated. The main intermolecular force between BSA and AA is electrostatic, presumably leading to the inhibiting CTE process of BSA. This method also shows acceptable reliability for the real vegetable sample assay. In summary, this work will not only provide an assay strategy for AA, but also open an avenue for the application expansion of CTE effect of natural biomacromolecules. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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9 pages, 6066 KiB

Open AccessArticle

An Imidazo[1,5-a]pyridine Benzopyrylium-Based NIR Fluorescent Probe with Ultra-Large Stokes Shifts for Monitoring SO₂

by Renle Cui, Caihong Liu, Ping Zhang, Kun Qin and Yanqing Ge

Molecules 2023, 28(2), 515; https://doi.org/10.3390/molecules28020515 - 05 Jan 2023

Cited by 1 | Viewed by 1555

Abstract

A mitochondria-targeted NIR probe based on the FRET mechanism was developed. It shows ultra-large Stokes shifts (460 nm) and emission shifts (285 nm). Furthermore, we also realized the imaging of SO₂ in living SKOV-3 cells, zebrafish and living mice which may be [...] Read more.

A mitochondria-targeted NIR probe based on the FRET mechanism was developed. It shows ultra-large Stokes shifts (460 nm) and emission shifts (285 nm). Furthermore, we also realized the imaging of SO₂ in living SKOV-3 cells, zebrafish and living mice which may be useful for understanding the biological roles of SO₂ in mitochondria and in vivo. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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10 pages, 2457 KiB

Open AccessFeature PaperArticle

Theoretical Investigations on the Sensing Mechanism of Phenanthroimidazole Fluorescent Probes for the Detection of Selenocysteine

by Zhe Tang, Xiaochen Wang, Runze Liu and Panwang Zhou

Molecules 2022, 27(23), 8444; https://doi.org/10.3390/molecules27238444 - 02 Dec 2022

Cited by 3 | Viewed by 1372

Abstract

The level of selenocysteine (Sec) in the human body is closely related to a variety of pathophysiological states, so it is important to study its fluorescence sensing mechanism for designing efficient fluorescent probes. Herein, we used time-dependent density functional theory to investigate the [...] Read more.

The level of selenocysteine (Sec) in the human body is closely related to a variety of pathophysiological states, so it is important to study its fluorescence sensing mechanism for designing efficient fluorescent probes. Herein, we used time-dependent density functional theory to investigate the fluorescence sensing mechanism of phenanthroimidazole derivates A4 and B4 for the detection of Sec, which are proposed to be designed based on excited state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) mechanisms. The calculation results show that the fluorescence quenching mechanism of A4 and B4 is due to the photo-induced electron transfer (PET) process with the sulfonate group acts as the electron acceptor. Subsequently, A4 and B4 react with Sec, the sulfonate group is substituted by hydroxyl groups, PET is turned off, and significant fluorescence enhancement of the formed A3 and B3 is observed. The theoretical results suggest that the fluorescence enhancement mechanism of B3 is not based on ICT mechanism, and the charge transfer phenomenon was not observed by calculating the frontier molecular orbitals, and proved to be a local excitation mode. The reason for the fluorescence enhancement of A3 based on ESIPT is also explained by the calculated potential energy curves. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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12 pages, 2302 KiB

Open AccessArticle

Identification of an IGF2BP2-Targeted Peptide for Near-Infrared Imaging of Esophageal Squamous Cell Carcinoma

by Wenbin Shu, Yitai Xiao, Lizhu Wang, Mingzhu Liang, Zhihong Li, Xiangwen Wu and Qingdong Cao

Molecules 2022, 27(21), 7609; https://doi.org/10.3390/molecules27217609 - 06 Nov 2022

Cited by 1 | Viewed by 1527

Abstract

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies globally. Peptide-based tumor-targeted imaging is critical for ESCC imaging. In this study, we aim to identify a peptide-targeting IGF2BP2 that specifically binds to human ESCC for near-infrared imaging of esophageal cancer. [...] Read more.

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal malignancies globally. Peptide-based tumor-targeted imaging is critical for ESCC imaging. In this study, we aim to identify a peptide-targeting IGF2BP2 that specifically binds to human ESCC for near-infrared imaging of esophageal cancer. Applying phage display techniques, we identified a peptide target for IGF2BP2 which was confirmed to be highly expressed in ESCC cell lines or tumor tissue and may serve as an imaging target for ESCC. We conjugated the peptide to the NIRF group, Cy5, and further evaluated the targeting efficacy of the probe at a cellular level and in animal tumor models. The Cy5 conjugated peptide (P12-Cy5) showed a high binding affinity to human ESCC cells in vitro. In vivo, optical imaging also validated the tumor-targeting ability of P12-Cy5 in KYSE-30-bearing subcutaneous ESCC tumor models. Furthermore, the results of biodistribution showed a significantly higher fluorescence intensity in tumors compared to scrambled peptide, which is consistent with in vivo observations. In summary, an IGF2BP2-targeted peptide was successfully identified. In vitro and in vivo experiments confirmed that P12-Cy5 has high affinity, specificity and tumor-targeting properties. Thus, P12-Cy5 is a prospective NIR probe for the imaging of ESCC. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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13 pages, 3344 KiB

Open AccessArticle

A Hydroxytricyanopyrrole-Based Fluorescent Probe for Sensitive and Selective Detection of Hypochlorous Acid

by Chunhua Zeng, Zhengjun Chen, Mingyan Yang, Jiajia Lv, Hongyu Li, Jie Gao and Zeli Yuan

Molecules 2022, 27(21), 7237; https://doi.org/10.3390/molecules27217237 - 25 Oct 2022

Cited by 4 | Viewed by 2097

Abstract

Hypochlorous acid (HOCl) is a reactive substance that reacts with most biomolecules and is essential in physiological and pathological processes. Abnormally elevated HOCl levels may cause inflammation and other disease responses. To further understand its key role in inflammation, HOCl must be detected [...] Read more.

Hypochlorous acid (HOCl) is a reactive substance that reacts with most biomolecules and is essential in physiological and pathological processes. Abnormally elevated HOCl levels may cause inflammation and other disease responses. To further understand its key role in inflammation, HOCl must be detected in situ. Here, we designed a hydroxytricyanopyrrole-based small-molecule fluorescent probe (HTCP-NTC) to monitor and identify trace amounts of HOCl in biological systems. In the presence of HOCl, HTCP-NTC released hydroxyl groups that emit strong fluorescence covering a wide wavelength range from the visible to near-infrared region owing to the resumption of the intramolecular charge transfer process. Additionally, HTCP-NTC demonstrated a 202-fold fluorescence enhancement accompanied by a large Stokes shift and a low detection limit (21.7 nM). Furthermore, HTCP-NTC provided a rapid response to HOCl within 18 s, allowing real-time monitoring of intracellular HOCl. HTCP-NTC exhibited rapid kinetics and biocompatibility, allowing effective monitoring of the exogenous and endogenous HOCl fluctuations in living cells. Finally, based on fluorescence imaging, HTCP-NTC is a potential method for understanding the relationship between inflammation and HOCl. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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Review

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18 pages, 5769 KiB

Open AccessReview

Recent Development of Lysosome-Targeted Organic Fluorescent Probes for Reactive Oxygen Species

by Van-Nghia Nguyen and Haidong Li

Molecules 2023, 28(18), 6650; https://doi.org/10.3390/molecules28186650 - 15 Sep 2023

Cited by 1 | Viewed by 1265

Abstract

Reactive oxygen species (ROS) are extremely important for various biological functions. Lysosome plays key roles in cellular metabolism and has been known as the stomach of cells. The abnormalities and malfunctioning of lysosomal function are associated with many diseases. Accordingly, the quantitative monitoring [...] Read more.

Reactive oxygen species (ROS) are extremely important for various biological functions. Lysosome plays key roles in cellular metabolism and has been known as the stomach of cells. The abnormalities and malfunctioning of lysosomal function are associated with many diseases. Accordingly, the quantitative monitoring and real-time imaging of ROS in lysosomes are of great interest. In recent years, with the advancement of fluorescence imaging, fluorescent ROS probes have received considerable interest in the biomedical field. Thus far, considerable efforts have been undertaken to create synthetic fluorescent probes for sensing ROS in lysosomes; however, specific review articles on this topic are still lacking. This review provides a general introduction to fluorescence imaging technology, the sensing mechanisms of fluorescent probes, lysosomes, and design strategies for lysosome-targetable fluorescent ROS probes. In addition, the latest advancements in organic small-molecule fluorescent probes for ROS detection within lysosomes are discussed. Finally, the main challenges and future perspectives for developing effective lysosome-targetable fluorescent ROS probes for biomedical applications are presented. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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17 pages, 3921 KiB

Open AccessReview

Enzyme-Instructed Aggregation/Dispersion of Fluorophores for Near-Infrared Fluorescence Imaging In Vivo

by Zhipeng Zhang, Peiyao Chen and Yao Sun

Molecules 2023, 28(14), 5360; https://doi.org/10.3390/molecules28145360 - 12 Jul 2023

Cited by 5 | Viewed by 1254

Abstract

Near-infrared (NIR) fluorescence is a noninvasive, highly sensitive, and high-resolution modality with great potential for in vivo imaging. Compared with “Always-On” probes, activatable NIR fluorescent probes with “Turn-Off/On” or “Ratiometric” fluorescent signals at target sites exhibit better signal-to-noise ratio (SNR), wherein enzymes are [...] Read more.

Near-infrared (NIR) fluorescence is a noninvasive, highly sensitive, and high-resolution modality with great potential for in vivo imaging. Compared with “Always-On” probes, activatable NIR fluorescent probes with “Turn-Off/On” or “Ratiometric” fluorescent signals at target sites exhibit better signal-to-noise ratio (SNR), wherein enzymes are one of the ideal triggers for probe activation, which play vital roles in a variety of biological processes. In this review, we provide an overview of enzyme-activatable NIR fluorescent probes and concentrate on the design strategies and sensing mechanisms. We focus on the aggregation/dispersion state of fluorophores after the interaction of probes and enzymes and finally discuss the current challenges and provide some perspective ideas for the construction of enzyme-activatable NIR fluorescent probes. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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16 pages, 1969 KiB

Open AccessReview

Recent Advances of Diketopyrrolopyrrole Derivatives in Cancer Therapy and Imaging Applications

by Lingyun Wang, Bihong Lai, Xueguang Ran, Hao Tang and Derong Cao

Molecules 2023, 28(10), 4097; https://doi.org/10.3390/molecules28104097 - 15 May 2023

Cited by 5 | Viewed by 1553

Abstract

Cancer is threatening the survival of human beings all over the world. Phototherapy (including photothermal therapy (PTT) and photodynamic therapy (PDT)) and bioimaging are important tools for imaging–mediated cancer theranostics. Diketopyrrolopyrrole (DPP) dyes have received more attention due to their high thermal and [...] Read more.

Cancer is threatening the survival of human beings all over the world. Phototherapy (including photothermal therapy (PTT) and photodynamic therapy (PDT)) and bioimaging are important tools for imaging–mediated cancer theranostics. Diketopyrrolopyrrole (DPP) dyes have received more attention due to their high thermal and photochemical stability, efficient reactive oxygen species (ROS) generation and thermal effects, easy functionalization, and tunable photophysical properties. In this review, we outline the latest achievements of DPP derivatives in cancer therapy and imaging over the past three years. DPP-based conjugated polymers and small molecules for detection, bioimaging, PTT, photoacoustic imaging (PAI)-guided PTT, and PDT/PTT combination therapy are summarized. Their design principles and chemical structures are highlighted. The outlook, challenges, and future opportunities for the development of DPP derivatives are also presented, which will give a future perspective for cancer treatment. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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23 pages, 7936 KiB

Open AccessReview

Recent Advances in Excimer-Based Fluorescence Probes for Biological Applications

by Yi Chen

Molecules 2022, 27(23), 8628; https://doi.org/10.3390/molecules27238628 - 06 Dec 2022

Cited by 7 | Viewed by 2099

Abstract

The fluorescent probe is a powerful tool for biological sensing and optical imaging, which can directly display analytes at the molecular level. It provides not only direct visualization of biological structures and processes, but also the capability of drug delivery systems regarding the [...] Read more.

The fluorescent probe is a powerful tool for biological sensing and optical imaging, which can directly display analytes at the molecular level. It provides not only direct visualization of biological structures and processes, but also the capability of drug delivery systems regarding the target therapy. Conventional fluorescent probes are mainly based on monomer emission which has two distinguishing shortcomings in practice: small Stokes shifts and short lifetimes. Compared with monomer-based emission, excimer-based fluorescent probes have large Stokes shifts and long lifetimes which benefit biological applications. Recent progress in excimer-based fluorescent sensors (organic small molecules only) for biological applications are highlighted in this review, including materials and mechanisms as well as their representative applications. The progress suggests that excimer-based fluorescent probes have advantages and potential for bioanalytical applications. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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18 pages, 3173 KiB

Open AccessReview

Research Progress in Fluorescent Probes for Arsenic Species

by Yunliang Qiu, Shuaibing Yu and Lianzhi Li

Molecules 2022, 27(23), 8497; https://doi.org/10.3390/molecules27238497 - 02 Dec 2022

Cited by 3 | Viewed by 2094

Abstract

Arsenic is a toxic non-metallic element that is widely found in nature. In addition, arsenic and arsenic compounds are included in the list of Group I carcinogens and toxic water pollutants. Therefore, rapid and efficient methods for detecting arsenic are necessary. In the [...] Read more.

Arsenic is a toxic non-metallic element that is widely found in nature. In addition, arsenic and arsenic compounds are included in the list of Group I carcinogens and toxic water pollutants. Therefore, rapid and efficient methods for detecting arsenic are necessary. In the past decade, a variety of small molecule fluorescent probes have been developed, which has been widely recognized for their rapidness, efficiency, convenience and sensitivity. With the development of new nanomaterials (AuNPs, CDs and QDs), organic molecules and biomolecules, the conventional detection of arsenic species based on fluorescence spectroscopy is gradually transforming from the laboratory to the portable kit. Therefore, in view of the current research status, this review introduces the research progress of both traditional and newly developed fluorescence spectrometry based on novel materials for arsenic detection, and discusses the potential of this technology in the rapid screening and field testing of water samples contaminated with arsenic. The review also discusses the problems that still exist in this field, as well as the expectations. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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12 pages, 2477 KiB

Open AccessReview

Development of Small-Molecule Fluorescent Probes Targeting Enzymes

by Yuan-Xiang Li, Dong-Tai Xie, Ya-Xi Yang, Zhao Chen, Wu-Yingzheng Guo and Wen-Chao Yang

Molecules 2022, 27(14), 4501; https://doi.org/10.3390/molecules27144501 - 14 Jul 2022

Cited by 10 | Viewed by 2958

Abstract

As biological catalysts, enzymes are vital in controlling numerous metabolic reactions. The regulation of enzymes in living cells and the amount present are indicators of the metabolic status of cell, whether in normal condition or disease. The small-molecule fluorescent probes are of interest [...] Read more.

As biological catalysts, enzymes are vital in controlling numerous metabolic reactions. The regulation of enzymes in living cells and the amount present are indicators of the metabolic status of cell, whether in normal condition or disease. The small-molecule fluorescent probes are of interest because of their high sensitivity and selectivity, as well as their potential for automated detection. Fluorescent probes have been useful in targeting particular enzymes of interest such as proteases and caspases. However, it is difficult to develop an ideal fluorescent probe for versatile purposes. In the future, the design and synthesis of enzyme-targeting fluorescent probes will focus more on improving the selectivity, sensitivity, penetration ability and to couple the fluorescent probes with other available imaging molecules/technologies. Full article

(This article belongs to the Special Issue Fluorescent Probes for Imaging and Diagnostics)

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