Imaging Macrophage Phagocytosis Using AIE Luminogen‐Labeled <i>E. coli</i>

Gu, Meijia; Zeng, Zi-Xuan; Wu, Mingyu; Leung, Jong‐Kai; Zhao, Engui; Wang, Shidong; Chen, Sijie

doi:10.1002/asia.201801859

Cited by 12 publications

(11 citation statements)

References 21 publications

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“…However, particles sticking to the cell membrane of a phagocyte are difficult to distinguish from those which are completely internalized by the cell. Therefore pH-sensitive dyes (CypHer5E, TPE-Cy and pHrodo ® ) have been developed, which have a low fluorescence intensity at neutral pH, but upon acidification in the lysosome start to emit a several-fold higher fluorescence [7][8][9][10]. Thus, nonphagocytosed particles sticking to the outer cell membrane will not be detected, whereas internalized, lysosomal particles are highly fluorescent.…”

Section: Methods Summarymentioning

confidence: 99%

Phagocytosis Assays with Different pH-Sensitive Fluorescent Particles and Various Readouts

2020

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Phagocytosis is a fundamental mechanism of innate immunity and its impairment is associated with severe chronic diseases, for example, chronic obstructive pulmonary disease. Investigating phagocytosis requires flexible tools and assay conditions, such as different fluorescent particle types, detection colors and readouts. We comprehensively evaluated and optimized phagocytosis assays using particles labeled with fluorescent pH-sensitive pHrodo® dyes, facilitating the specific detection of phagocytosed particles. Beads, bacterial and yeast particles labeled with pHrodo red and green were tested for their uptake by THP-1 cells and primary human macrophages by flow cytometry and high-content imaging. Whereas the latter allowed kinetic phagocytosis measurement, the former demonstrated the feasibility of using cell sorting for periods of up to 6 h, enabling downstream applications such as pooled genetic screens.

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Section: Methods Summarymentioning

confidence: 99%

Phagocytosis Assays with Different pH-Sensitive Fluorescent Particles and Various Readouts

2020

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“…Given that ideal fluorescent agents for fluorescence imaging should possess large Stokes shift, excellent photostability, highly efficient emission, and free of ACQ effect, AIEgens are good candidates. In fact, AIEgens have been widely applied for monitoring biological processes,19c such as osteogenic differentiation, droplet‐lysosome interplay, autophagy, mitophagy, apoptosis, cancer cell progression, tumor growth,49b,61 macrophage phagocytosis, embryonic development, and lipid metabolism . Herein, we discuss some other recent examples that were performed in small animal models.…”

Section: Monitoring Biological Processesmentioning

confidence: 99%

Promising Applications of AIEgens in Animal Models

Situ

Zhao

et al. 2019

Small Methods

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organisms cannot be achieved from these static findings. Therefore, gaining in-depth insights into biological and physiological functions at the in vivo level is of great significance, and various imaging techniques have been explored for this purpose. [1] In addition to the clinically available magnetic resonance imaging (MRI), ultrasonic imaging, computed tomography (CT), positron emission tomography (PET), and single-photon emission computed tomography, fluorescence imaging (another distinct type of optical imaging [1c] from bioluminescence imaging [2] ) has attracted increasing attention, owing to its advantages of high temporal-spatial resolution and sensitivity, noninvasive, and real-time applications, and the ability to provide dynamic information for basic research and (pre-)clinical settings at cellular and subcellular levels. [3] Fluorescent probes or contrast agents are essential for fluorescence imaging. Compared with fluorescent proteins, [4] inorganic nanoparticles (NPs), [5] such as quantum dots, [6] upconversion NPs, [7] and metallic NPs, [8] and organic dyes [9] (e.g., U.S. Food and Drug Administration (FDA)-approved 5-ALA, indocyanine green (ICG), and methylene blue), organic NPs [10] have obvious advantages, such as easy preparation and good biocompatibility. However, many organic NPs show weak fluorescence because they are made with conventional organic dyes, which suffer from the aggregation-caused quenching (ACQ) effect, i.e., their fluorescence is partially or completely quenched in the aggregated state.The advent of the aggregation-induced emission (AIE) concept offers a new strategy to deal with ACQ. [11] AIE refers to the interesting photophysical phenomenon that luminogens are weakly fluorescent or nonfluorescent in solution but show greatly enhanced emission in the aggregated state, primarily because of restricted intramolecular motion. [12] The past 19 years have witnessed spectacular advances of AIEgens, [13] due to their advantages of structural variety, easy functionalization, strong luminescence, large Stokes shift, high photobleaching-resistance, and so on. In particular, various AIE bioprobes have been designed: [14] (i) water-soluble AIEgens, which are comprised of a hydrophobic AIE core and hydrophilic units (e.g., ionic groups, peptides, carbohydrates, DNA, aptamers, antibodies, and poly(ethylene glycol) (PEG)); (ii) bare AIEgen dots (nanoaggregates); iii) AIEgen/biopolymer dots, which can be obtained by loading AIEgens onto biopolymer matrixes covalently (e.g., chitosan, dextran, and starch) or noncovalently (e.g., bovine serum albumin, human serum albumin (HSA), and fetal bovine serum (FBS)); (iv)In vivo investigations using small animal models are of great significance for the comprehensive understanding of biological and physiological functions-seeing is believing. Fluorescence imaging can provide real-time and dynamic information of living systems. During the past few years, aggregation-induced emission luminogens (AIEgens) are widely and rapidly developed for biolog...

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“…Therefore, TPE‐Cy can be applied as a cell biosensor with a wide pH‐response window, as it overcomes the limitation of the ACQ effects and the small Stokes shift (less than 20 nm) that characterizes Cy. Further, 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium bromide (MTT) assays confirmed that TPE‐Cy has few cytotoxic effects at the range of concentrations used for staining . However, the MTT assay does not reflect the genetic cytotoxicity induced by the molecule, which still needs to be determined.…”

Section: Tpe‐cymentioning

confidence: 99%

“…Recently, Gu et al. demonstrated the feasibility of employing TPE‐Cy stained bacteria as an environmental biosensor and in cellular imaging systems . By observing the varied fluorescence of stained Escherichia coli (E. coli) , the changes in pH could be simply monitored.…”

Section: Tpe‐cymentioning

confidence: 99%

“…Confocal microscopic imaging and flow cytometry data further confirmed the enormous potential for the super‐resolution and high‐throughput analysis of intracellular microenvironments through the use of TPE‐Cy. All of these processes are expected to promote the development of biological and medical applications in disease diagnosis and drug screening …”

Section: Tpe‐cymentioning

confidence: 99%

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The Biological Applications of Two Aggregation‐Induced Emission Luminogens

Zeng

Mai

et al. 2019

Biotechnology Journal

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Fluorescence imaging, as a commonly used scientific tool, is widely applied in various biomedical and material structures through visualization technology. Highly selective and sensitive luminescent biological probes, as well as those with good water solubility, are urgently needed for biomedical research. In contrast to the traditional aggregation‐caused quenching of fluorescence, in the unique phenomenon of aggregation‐induced emission (AIE), the individual luminogens have extremely weak or no emissivity because they each have free intramolecular motion; however, when they form aggregates, these components immediately “light up”. Since the discovery of “turn‐on” mechanism, researchers have been studying and applying AIE in a variety of fields to develop more sensitive, selective, and efficient strategies for the AIE dyes. There are numerous advantages to the use of AIE‐based methods, including low background interference, strong contrast, high performance in intracellular imaging, and the ability for long‐term monitoring in vivo. In this review, two typical examples of AIEgens, TPE‐Cy and TPE‐Ph‐In, are described, including their structure properties and applications. Recent progress in the biological applications is mainly focused on. Undoubtedly, in the near future, an increasing number of encouraging and practical ideas will promote the development of more AIEgens for broad use in biomedical applications.

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Imaging Macrophage Phagocytosis Using AIE Luminogen‐Labeled E. coli

Cited by 12 publications

References 21 publications

Phagocytosis Assays with Different pH-Sensitive Fluorescent Particles and Various Readouts

Phagocytosis Assays with Different pH-Sensitive Fluorescent Particles and Various Readouts

Promising Applications of AIEgens in Animal Models

The Biological Applications of Two Aggregation‐Induced Emission Luminogens

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