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Moreau H, Zimmermann SD, Gaillard I, Paris N. pH biosensing in the plant apoplast-a focus on root cell elongation. PLANT PHYSIOLOGY 2021; 187:504-514. [PMID: 35237817 PMCID: PMC8491080 DOI: 10.1093/plphys/kiab313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 06/19/2021] [Indexed: 05/24/2023]
Abstract
The pH parameter of soil plays a key role for plant nutrition as it is affecting the availability of minerals and consequently determines plant growth. Although the mechanisms by which root perceive the external pH is still unknown, the impact of external pH on tissue growth has been widely studied especially in hypocotyl and root. Thanks to technological development of cell imaging and fluorescent sensors, we can now monitor pH in real time with at subcellular definition. In this focus, fluorescent dye-based, as well as genetically-encoded pH indicators are discussed especially with respect to their ability to monitor acidic pH in the context of primary root. The notion of apoplastic subdomains is discussed and suggestions are made to develop fluorescent indicators for pH values below 5.0.
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Affiliation(s)
- Hortense Moreau
- BPMP, Univ Montpellier, CNRS, INRAE, Montpellier SupAgro, Montpellier, France
| | | | - Isabelle Gaillard
- BPMP, Univ Montpellier, CNRS, INRAE, Montpellier SupAgro, Montpellier, France
| | - Nadine Paris
- BPMP, Univ Montpellier, CNRS, INRAE, Montpellier SupAgro, Montpellier, France
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2
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Improving the efficiency of CO 2 electrolysis by using a bipolar membrane with a weak-acid cation exchange layer. Nat Chem 2020; 13:33-40. [PMID: 33288894 DOI: 10.1038/s41557-020-00602-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 11/04/2020] [Indexed: 11/08/2022]
Abstract
The efficient conversion of electricity to chemicals is needed to mitigate the intermittency of renewable energy sources. Driving these electrochemical conversions at useful rates requires not only fast electrode kinetics, but also rapid mass and ion transport. However, little is known about the effect of local environments on ionic flows in solid polymer electrolytes. Here, we show that it is possible to measure and manipulate the local pH in membrane electrolysers with a resolution of tens of nanometres. In bipolar-membrane-based gas-fed CO2 electrolysers, the acidic environment of the cation exchange layer results in low CO2 reduction efficiency. By using ratiometric indicators and layer-by-layer polyelectrolyte assembly, the local pH was measured and controlled within an ~50-nm-thick weak-acid layer. The weak-acid layer suppressed the competing hydrogen evolution reaction without affecting CO2 reduction. This method of probing and controlling the local membrane environment may be useful in devices such as electrolysers, fuel cells and flow batteries, as well as in operando studies of ion distributions within polymer electrolytes.
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3
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Skvortsov IA, Zimcik P, Stuzhin PA, Novakova V. pH-Sensitive subphthalocyanines and subazaphthalocyanines. Dalton Trans 2020; 49:11090-11098. [PMID: 32582891 DOI: 10.1039/d0dt01703e] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Although subphthalocyanines (SubPcs) possess advantageous fluorescence properties and serve as an amazing tool to attach a recognition sensor moiety to the axial position, a limited number of switchable SubPcs have been described so far. Isosteric aza-replacement is known to improve sensing properties in closely related phthalocyanine families; however, pyrazino[2,3-b,g,l]subporphyrazines (SubPyzPzs) have not yet been investigated for use in sensing applications. Therefore, this project focuses on the synthesis and sensing abilities of pH-sensitive SubPcs and SubPyzPzs on the principle of photoinduced electron transfer (PET). 4-Dimethylaminophenoxy (for acidic pH) or 4-hydroxyphenoxy (for basic pH) groups were employed as pH-sensitive axial ligands. Electrochemical studies revealed improvements in the electron-accepting properties of SubPyzPzs (Ered-0.56 V vs. SCE) in comparison to those of SubPcs (Ered-1.0 V vs. SCE). Hydroxy groups on the axial phenoxy ligands of SybPyzPzs and SubPcs have been found to act as donors for PET. The sensing properties under basic conditions could not be studied, since all the SubPcs and SubPyzPzs decomposed under basic conditions, SubPyzPzs were more susceptible to this process. On the other hand, compounds with 4-dimethylaminophenoxy groups as axial ligands showed great potential for sensing applications. These compounds were nonfluorescent (ΦF < 0.01) in acetone due to efficient PET, while their fluorescence steeply increased by two orders of magnitude upon the addition of trifluoroacetic acid, reaching a ΦF value of up to 0.17 (λem range of 563-590 nm). These compounds maintained their sensing properties in aqueous medium after incorporation into microemulsions. The most basic derivative showed pKA = 2.95 with ΦF = 0.10 in the ON state (fluorescence enhancement factor = 46, λem = 577 nm).
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Affiliation(s)
- Ivan A Skvortsov
- Research Institute of Macroheterocycles, Ivanovo State University of Chemistry and Technology, Sheremetevsky Avenue 7, Ivanovo RF-153000, Russia.
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4
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Fulaz S, Hiebner D, Barros CHN, Devlin H, Vitale S, Quinn L, Casey E. Ratiometric Imaging of the in Situ pH Distribution of Biofilms by Use of Fluorescent Mesoporous Silica Nanosensors. ACS APPLIED MATERIALS & INTERFACES 2019; 11:32679-32688. [PMID: 31418546 DOI: 10.1021/acsami.9b09978] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Biofilms are communities of microorganisms enclosed in a self-generated matrix of extracellular polymeric substances. While biofilm recalcitrance and persistence are caused by several factors, a reduction in antimicrobial susceptibility has been closely associated with the generation of pH gradients within the biofilm structure. Cells embedded within the biofilm create a localized acidic microenvironment, which is unaffected by the external pH. Therefore, pH monitoring is a promising approach for understanding the complexities of a three-dimensional heterogeneous biofilm. A fluorescent pH nanosensor was designed through the synthesis of mesoporous silica nanoparticles (47 ± 5 nm diameter) conjugated to a pH-sensitive dye (fluorescein) and a pH-insensitive dye (rhodamine B) as an internal standard (dye-MSNs). The fluorescence intensity of fluorescein (IF) reduced significantly as the pH was decreased from 8.5 to 3.5. In contrast, the fluorescence intensity of rhodamine B (IR) remained constant at any pH. The ratio of IF/IR produced a sigmoidal curve with respect to the pH, in a working pH range between 4.5 and 7.5. Dye-MSNs enabled the measurement of pH gradients within Pseudomonas fluorescens WCS 365 biofilm microcolonies. The biofilms showed spatially distinct low-pH regions that were enclosed into large clusters corresponding to high-cell-density areas. Also present were small low-pH areas that spread indistinctly throughout the microcolony caused by the mass transfer effect. The lowest detected pH within the inner core of the microcolonies was 5.1, gradually increasing to a neutral pH toward the exterior of the microcolonies. The dye-MSNs were able to fully penetrate the biofilm matrix and allowed a quantitative ratiometric analysis of pH gradients and distribution throughout the biofilm, which was independent of the nanoparticle concentration.
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Affiliation(s)
- Stephanie Fulaz
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Dishon Hiebner
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Caio H N Barros
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Henry Devlin
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Stefania Vitale
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Laura Quinn
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
| | - Eoin Casey
- UCD School of Chemical and Bioprocess Engineering , University College Dublin , Belfield, Dublin 4 Dublin , Ireland
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5
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Dalfen I, Dmitriev RI, Holst G, Klimant I, Borisov SM. Background-Free Fluorescence-Decay-Time Sensing and Imaging of pH with Highly Photostable Diazaoxotriangulenium Dyes. Anal Chem 2018; 91:808-816. [PMID: 30518209 DOI: 10.1021/acs.analchem.8b02534] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Novel fluorescent diazaoxatriangulenium (DAOTA) pH indicators for lifetime-based self-referenced pH sensing are reported. The DAOTA dyes were decorated with phenolic-receptor groups inducing fluorescence quenching via a photoinduced-electron-transfer mechanism. Electron-withdrawing chlorine substituents ensure response in the most relevant pH range (apparent p Ka' values of ∼5 and 7.5 for the p, p-dichlorophenol- and p-chlorophenol-substituted dyes, respectively). The dyes feature long fluorescence lifetimes (17-20 ns), high quantum yields (∼60%), and high photostabilities. Planar optodes are prepared upon immobilization of the dyes into polyurethane hydrogel D4. Apart from the response in the fluorescence intensity, the optodes show pH-dependent lifetime behavior, which makes them suitable for studying 2D pH distributions with the help of fluorescence-lifetime-imaging techniques. The lifetime response is particularly pronounced for the sensors with high dye concentrations (0.5-1 wt % with respect to the polymer) and is attributed to the efficient homo-FRET mechanism.
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Affiliation(s)
- Irene Dalfen
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Ruslan I Dmitriev
- School of Biochemistry and Cell Biology , University College Cork , T12 K8AF Cork , Ireland.,Institute for Regenerative Medicine , I.M. Sechenov First Moscow State University , 119146 Moscow , Russian Federation
| | | | - Ingo Klimant
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
| | - Sergey M Borisov
- Institute of Analytical Chemistry and Food Chemistry , Graz University of Technology , Stremayrgasse 9 , 8010 Graz , Austria
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Hwang JY, Lee JY, Cho CW, Choi W, Lee Y, Shim S, Hwang GT. 5-Bromo-4',5'-bis(dimethylamino)fluorescein: Synthesis and Photophysical Studies. Molecules 2018; 23:E219. [PMID: 29361711 PMCID: PMC6017165 DOI: 10.3390/molecules23010219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/10/2018] [Accepted: 01/16/2018] [Indexed: 11/17/2022] Open
Abstract
In this study, three new fluorescein derivatives-5-bromo-4',5'-dinitrofluorescein (BDNF), 5-bromo-4',5'-diaminofluorescein (BDAF), and 5-bromo-4',5'-bis(dimethylamino)fluorescein (BBDMAF)-were synthesized and their pH-dependent protolytic equilibria were investigated. In particular, BBDMAF exhibited pH-dependent fluorescence, showing strong emission only at pH 3-6. BBDMAF bears a bromine moiety and thus, can be used in various cross-coupling reactions to prepare derivatives and take advantage of its unique emission properties. To confirm this, the Suzuki and Sonogashira reactions of BBDMAF with phenylboronic acid and phenylacetylene, respectively, were performed, and the desired products were successfully obtained.
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Affiliation(s)
- Jun Yeon Hwang
- Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea; (J.Y.H.); (J.-Y.L.); (C.-W.C.)
| | - Jung-Yean Lee
- Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea; (J.Y.H.); (J.-Y.L.); (C.-W.C.)
| | - Chang-Woo Cho
- Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea; (J.Y.H.); (J.-Y.L.); (C.-W.C.)
| | - Wonjun Choi
- Department of Chemistry, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam 57922, Korea; (W.C.); (Y.L.)
| | - Yejin Lee
- Department of Chemistry, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam 57922, Korea; (W.C.); (Y.L.)
| | - Sangdeok Shim
- Department of Chemistry, Sunchon National University, 255 Jungang-ro, Sunchon, Jeonnam 57922, Korea; (W.C.); (Y.L.)
| | - Gil Tae Hwang
- Department of Chemistry and Green-Nano Materials Research Center, Kyungpook National University, Daegu 41566, Korea; (J.Y.H.); (J.-Y.L.); (C.-W.C.)
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7
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Leavesley SJ, Sweat B, Abbott C, Favreau P, Rich TC. A theoretical-experimental methodology for assessing the sensitivity of biomedical spectral imaging platforms, assays, and analysis methods. JOURNAL OF BIOPHOTONICS 2018; 11:10.1002/jbio.201600227. [PMID: 28485093 PMCID: PMC5680159 DOI: 10.1002/jbio.201600227] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Revised: 04/07/2017] [Accepted: 04/09/2017] [Indexed: 05/21/2023]
Abstract
Spectral imaging technologies have been used for many years by the remote sensing community. More recently, these approaches have been applied to biomedical problems, where they have shown great promise. However, biomedical spectral imaging has been complicated by the high variance of biological data and the reduced ability to construct test scenarios with fixed ground truths. Hence, it has been difficult to objectively assess and compare biomedical spectral imaging assays and technologies. Here, we present a standardized methodology that allows assessment of the performance of biomedical spectral imaging equipment, assays, and analysis algorithms. This methodology incorporates real experimental data and a theoretical sensitivity analysis, preserving the variability present in biomedical image data. We demonstrate that this approach can be applied in several ways: to compare the effectiveness of spectral analysis algorithms, to compare the response of different imaging platforms, and to assess the level of target signature required to achieve a desired performance. Results indicate that it is possible to compare even very different hardware platforms using this methodology. Future applications could include a range of optimization tasks, such as maximizing detection sensitivity or acquisition speed, providing high utility for investigators ranging from design engineers to biomedical scientists.
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Affiliation(s)
- Silas J. Leavesley
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- Department of Pharmacology, University of South Alabama
- Center for Lung Biology, University of South Alabama
| | - Brenner Sweat
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- IT Security & Governance, AM/NS Calvert
| | - Caitlyn Abbott
- Department of Chemical and Biomolecular Engineering, University of South Alabama
| | - Peter Favreau
- Department of Chemical and Biomolecular Engineering, University of South Alabama
- Basic Medical Sciences, University of South Alabama
- Morgridge Institute for Research, University of Wisconsin - Madison
| | - Thomas C. Rich
- Department of Pharmacology, University of South Alabama
- Center for Lung Biology, University of South Alabama
- College of Engineering, University of South Alabama
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8
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Hwang JY, Shim S, Hwang GT. 4′,5′-Bis(dimethylamino)fluorescein Exhibits pH-Dependent Emission Behavior Distinct From That of Fluorescein. ASIAN J ORG CHEM 2017. [DOI: 10.1002/ajoc.201700577] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Jun Yeon Hwang
- Department of Chemistry; Kyungpook National University; 80 Daehakro Bukgu Daegu 41566 Republic of Korea
| | - Sangdeok Shim
- Department of Chemistry; Sunchon National University; 255 Jungang-ro Sunchon Jeonnam 57922 Republic of Korea
| | - Gil Tae Hwang
- Department of Chemistry; Kyungpook National University; 80 Daehakro Bukgu Daegu 41566 Republic of Korea
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9
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Hwang DI, Kim HJ. An Optical pH Sensor with Extended Dynamic Range for Acidic pH Based on 2-(4 H
-Pyran-4-ylidene)malononitrile. B KOREAN CHEM SOC 2017. [DOI: 10.1002/bkcs.11181] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Do Ik Hwang
- School of Chemical Engineering; Chonnam National University; Gwangju 61186 Republic of Korea
| | - Hyung Jin Kim
- School of Chemical Engineering; Chonnam National University; Gwangju 61186 Republic of Korea
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10
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Di W, Czarny RS, Fletcher NA, Krebs MD, Clark HA. Comparative Study of Poly (ε-Caprolactone) and Poly(Lactic-co-Glycolic Acid) -Based Nanofiber Scaffolds for pH-Sensing. Pharm Res 2016; 33:2433-44. [PMID: 27380188 PMCID: PMC5007178 DOI: 10.1007/s11095-016-1987-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Accepted: 06/27/2016] [Indexed: 01/12/2023]
Abstract
PURPOSE This study aims to develop biodegradable and biocompatible polymer-based nanofibers that continuously monitor pH within microenvironments of cultured cells in real-time. In the future, these fibers will provide a scaffold for tissue growth while simultaneously monitoring the extracellular environment. METHODS Sensors to monitor pH were created by directly electrospinning the sensor components within a polymeric matrix. Specifically, the entire fiber structure is composed of the optical equivalent of an electrode, a pH-sensitive fluorophore, an ionic additive, a plasticizer, and a polymer to impart mechanical stability. The resulting poly(ε-caprolactone) (PCL) and poly(lactic-co-glycolic acid) (PLGA) based sensors were characterized by morphology, dynamic range, reversibility and stability. Since PCL-based nanofibers delivered the most desirable analytical response, this matrix was used for cellular studies. RESULTS Electrospun nanofiber scaffolds (NFSs) were created directly out of optode material. The resulting NFS sensors respond to pH changes with a dynamic range centered at 7.8 ± 0.1 and 9.6 ± 0.2, for PCL and PLGA respectively. NFSs exhibited multiple cycles of reversibility with a lifetime of at least 15 days with preservation of response characteristics. By comparing the two NFSs, we found PCL-NFSs are more suitable for pH sensing due to their dynamic range and superior reversibility. CONCLUSION The proposed sensing platform successfully exhibits a response to pH and compatibility with cultured cells. NSFs will be a useful tool for creating 3D cellular scaffolds that can monitor the cellular environment with applications in fields such as drug discovery and tissue engineering.
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Affiliation(s)
- Wenjun Di
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, 02115, USA
| | - Ryan S Czarny
- Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, 80401, USA
| | - Nathan A Fletcher
- Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, 80401, USA
| | - Melissa D Krebs
- Chemical and Biological Engineering, Colorado School of Mines, Golden, Colorado, 80401, USA
| | - Heather A Clark
- Department of Pharmaceutical Sciences, Northeastern University, Boston, Massachusetts, 02115, USA.
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11
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Kim YH, Kim H, Kim HJ. Synthesis and pH-sensing Properties of a Push-Pull Conjugated Fluorophore Based on Dicyanomethylene-1,4-dihydropyridine. B KOREAN CHEM SOC 2016. [DOI: 10.1002/bkcs.10711] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Young Hyun Kim
- School of Chemical Engineering; Chonnam National University; Gwangju 61186 Republic of Korea
| | - Heemoon Kim
- School of Chemical Engineering; Chonnam National University; Gwangju 61186 Republic of Korea
| | - Hyung Jin Kim
- School of Chemical Engineering; Chonnam National University; Gwangju 61186 Republic of Korea
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12
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Schäferling M. Nanoparticle-based luminescent probes for intracellular sensing and imaging of pH. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2015; 8:378-413. [PMID: 26395962 DOI: 10.1002/wnan.1366] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Revised: 07/06/2015] [Accepted: 07/22/2015] [Indexed: 12/13/2022]
Abstract
Fluorescence imaging microscopy is an essential tool in biomedical research. Meanwhile, various fluorescent probes are available for the staining of cells, cell membranes, and organelles. Though, to monitor intracellular processes and dysfunctions, probes that respond to ubiquitous chemical parameters determining the cellular function such as pH, pO2 , and Ca(2+) are required. This review is focused on the progress in the design, fabrication, and application of photoluminescent nanoprobes for sensing and imaging of pH in living cells. The advantages of using nanoprobes carrying fluorescent pH indicators compared to single molecule probes are discussed as well as their limitations due to the mostly lysosomal uptake by cells. Particular attention is paid to ratiometric dual wavelength nanosensors that enable intrinsic referenced measurements. Referencing and proper calibration procedures are basic prerequisites to carry out reliable quantitative pH determinations in complex samples such as living cells. A variety of examples will be presented that highlight the diverseness of nanocarrier materials (polymers, micelles, silica, quantum dots, carbon dots, gold, photon upconversion nanocrystals, or bacteriophages), fluorescent pH indicators for the weak acidic range, and referenced sensing mechanisms, that have been applied intracellularly up to now. WIREs Nanomed Nanobiotechnol 2016, 8:378-413. doi: 10.1002/wnan.1366 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Michael Schäferling
- Division 1.10 Biophotonics, Federal Institute for Materials Research and Testing, Berlin, Germany
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13
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Qi J, Liu D, Liu X, Guan S, Shi F, Chang H, He H, Yang G. Fluorescent pH Sensors for Broad-Range pH Measurement Based on a Single Fluorophore. Anal Chem 2015; 87:5897-904. [DOI: 10.1021/acs.analchem.5b00053] [Citation(s) in RCA: 85] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jing Qi
- Department
of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, P.R. China
| | - Daying Liu
- Department
of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, P.R. China
| | - Xiaoyan Liu
- Department
of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, P.R. China
| | - Shiquan Guan
- Heowns Biochem Technologies LLC, 6 Lanyuan Road, Tianjin 300384, P.R. China
| | - Fengli Shi
- Heowns Biochem Technologies LLC, 6 Lanyuan Road, Tianjin 300384, P.R. China
| | - Hexi Chang
- Heowns Biochem Technologies LLC, 6 Lanyuan Road, Tianjin 300384, P.R. China
| | - Huarui He
- Heowns Biochem Technologies LLC, 6 Lanyuan Road, Tianjin 300384, P.R. China
| | - Guangming Yang
- Department
of Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, P.R. China
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14
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Cardona MA, Magri DC. Synthesis and spectrophotometric studies of water-soluble amino[bis(ethanesulfonate)] azobenzene pH indicators. Tetrahedron Lett 2014. [DOI: 10.1016/j.tetlet.2014.06.079] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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15
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Harris MA, Jiang J, Niedzwiedzki DM, Jiao J, Taniguchi M, Kirmaier C, Loach PA, Bocian DF, Lindsey JS, Holten D, Parkes-Loach PS. Versatile design of biohybrid light-harvesting architectures to tune location, density, and spectral coverage of attached synthetic chromophores for enhanced energy capture. PHOTOSYNTHESIS RESEARCH 2014; 121:35-48. [PMID: 24604033 DOI: 10.1007/s11120-014-9993-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/22/2014] [Indexed: 06/03/2023]
Abstract
Biohybrid antennas built upon chromophore-polypeptide conjugates show promise for the design of efficient light-capturing modules for specific purposes. Three new designs, each of which employs analogs of the β-polypeptide from Rhodobacter sphaeroides, have been investigated. In the first design, amino acids at seven different positions on the polypeptide were individually substituted with cysteine, to which a synthetic chromophore (bacteriochlorin or Oregon Green) was covalently attached. The polypeptide positions are at -2, -6, -10, -14, -17, -21, and -34 relative to the 0-position of the histidine that coordinates bacteriochlorophyll a (BChl a). All chromophore-polypeptides readily formed LH1-type complexes upon combination with the α-polypeptide and BChl a. Efficient energy transfer occurs from the attached chromophore to the circular array of 875 nm absorbing BChl a molecules (denoted B875). In the second design, use of two attachment sites (positions -10 and -21) on the polypeptide affords (1) double the density of chromophores per polypeptide and (2) a highly efficient energy-transfer relay from the chromophore at -21 to that at -10 and on to B875. In the third design, three spectrally distinct bacteriochlorin-polypeptides were prepared (each attached to cysteine at the -14 position) and combined in an ~1:1:1 mixture to form a heterogeneous mixture of LH1-type complexes with increased solar coverage and nearly quantitative energy transfer from each bacteriochlorin to B875. Collectively, the results illustrate the great latitude of the biohybrid approach for the design of diverse light-harvesting systems.
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Affiliation(s)
- Michelle A Harris
- Department of Chemistry, Washington University, St. Louis, MO, 63130-4889, USA
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Kim DY, Kim JN, Kim HJ. 2-{2-[4-(Dimethylamino)phenyl]-6-methyl-4H-pyran-4-ylidene}malononitrile: a colorimetric and fluorescent chemosensor for low pH values. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 122:304-308. [PMID: 24316545 DOI: 10.1016/j.saa.2013.11.035] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 11/01/2013] [Indexed: 06/02/2023]
Abstract
For developing intramolecular charge transfer (ICT) chemosensors for low pH values, 2-{2-[4-(dimethylamino)phenyl]-6-methyl-4H-pyran-4-ylidene}malononitrile (DPM) was designed and synthesized. The spectroscopic and pH-sensing properties of DPM were investigated by UV-Vis and fluorescence spectroscopy. This sensor exhibited a pH-dependent ratiometric absorption property in the range of pH 0-3, along with a reversible color change from yellow to colorless with increasing acid concentration. The fluorescence intensity of the sensor was increased with increasing pH within the pH range of 0-2.
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Affiliation(s)
- Dae-Young Kim
- School of Applied Chemical Engineering, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Jae Nyoung Kim
- Department of Chemistry and Institute of Basic Science, Chonnam National University, Gwangju 500-757, Republic of Korea
| | - Hyung Jin Kim
- School of Applied Chemical Engineering, Chonnam National University, Gwangju 500-757, Republic of Korea.
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Han Y, Shchukin D, Schneider J, Möhwald H. Fluorescence indicative pH drop in sonication. Colloids Surf A Physicochem Eng Asp 2014. [DOI: 10.1016/j.colsurfa.2013.12.061] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Wadhavane PD, Izquierdo MÁ, Lutters D, Burguete MI, Marín MJ, Russell DA, Galindo F, Luis SV. Fluorescent macrocyclic probes with pendant functional groups as markers of acidic organelles within live cells. Org Biomol Chem 2014; 12:823-31. [DOI: 10.1039/c3ob41773e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Best QA, Liu C, van Hoveln PD, McCarroll ME, Scott CN. Anilinomethylrhodamines: pH sensitive probes with tunable photophysical properties by substituent effect. J Org Chem 2013; 78:10134-43. [PMID: 24050117 DOI: 10.1021/jo401323g] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
A series of pH dependent rhodamine analogues possessing an anilino-methyl moiety was developed and shown to exhibit a unique photophysical response to pH. These anilinomethylrhodamines (AnMR) maintain a colorless, nonfluorescent spirocyclic structure at high pH. The spirocyclic structures open in mildly acidic conditions and are weakly fluorescent; however, at very low pH, the fluorescence is greatly enhanced. The equilibrium constants of these processes show a linear response to substituent effects, which was demonstrated by the Hammett equation.
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Affiliation(s)
- Quinn A Best
- Department of Chemistry & Biochemistry, Southern Illinois University , Carbondale, Illinois 62901-4409, United States
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20
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Criscitiello MF, Dickman MB, Samuel JE, de Figueiredo P. Tripping on acid: trans-kingdom perspectives on biological acids in immunity and pathogenesis. PLoS Pathog 2013; 9:e1003402. [PMID: 23874196 PMCID: PMC3715416 DOI: 10.1371/journal.ppat.1003402] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Affiliation(s)
- Michael F Criscitiello
- Comparative Immunogenetics Laboratory, Texas A&M University, College Station, Texas, United States of America.
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21
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Hwang JY, Wachsmann-Hogiu S, Ramanujan VK, Ljubimova J, Gross Z, Gray HB, Medina-Kauwe LK, Farkas DL. A multimode optical imaging system for preclinical applications in vivo: technology development, multiscale imaging, and chemotherapy assessment. Mol Imaging Biol 2012; 14:431-42. [PMID: 21874388 DOI: 10.1007/s11307-011-0517-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
PURPOSE Several established optical imaging approaches have been applied, usually in isolation, to preclinical studies; however, truly useful in vivo imaging may require a simultaneous combination of imaging modalities to examine dynamic characteristics of cells and tissues. We developed a new multimode optical imaging system designed to be application-versatile, yielding high sensitivity, and specificity molecular imaging. PROCEDURES We integrated several optical imaging technologies, including fluorescence intensity, spectral, lifetime, intravital confocal, two-photon excitation, and bioluminescence, into a single system that enables functional multiscale imaging in animal models. RESULTS The approach offers a comprehensive imaging platform for kinetic, quantitative, and environmental analysis of highly relevant information, with micro-to-macroscopic resolution. Applied to small animals in vivo, this provides superior monitoring of processes of interest, represented here by chemo-/nanoconstruct therapy assessment. CONCLUSIONS This new system is versatile and can be optimized for various applications, of which cancer detection and targeted treatment are emphasized here.
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Affiliation(s)
- Jae Youn Hwang
- Minimally Invasive Surgical Technologies Institute and Department of Surgery, Cedars-Sinai Medical Center, 8700 Beverly Blvd. D6061, Los Angeles, CA 90048, USA.
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22
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Xu J, Sun L, Li J, Liang J, Zhang H, Yang W. FITC and Ru(phen)32+ co-doped silica particles as visualized ratiometric pH indicator. NANOSCALE RESEARCH LETTERS 2011; 6:561. [PMID: 22027093 PMCID: PMC3220666 DOI: 10.1186/1556-276x-6-561] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2011] [Accepted: 10/25/2011] [Indexed: 05/29/2023]
Abstract
The performance of fluorescein isothiocyanate (FITC) and tris(1, 10-phenanathroline) ruthenium ion (Ru(phen)32+) co-doped silica particles as pH indicator was evaluated. The emission intensity ratios of the pH sensitive dye (FITC) and the reference dye (Ru(phen)32+) in the particles were dependent on pH of the environment. The changes in emission intensity ratios of the two dyes under different pH could be measured under single excitation wavelength and readily visualized by naked eye under a 365-nm UV lamp. In particular, such FITC and Ru(phen)32+ co-doped silica particles were identified to show high sensitivity to pH around the pKa of FITC (6.4), making them be potential useful as visualized pH indicator for detection of intracellular pH micro-circumstance.
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Affiliation(s)
- Jianquan Xu
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China
| | - Lei Sun
- College of Public Health, Jilin University, Changchun, Jilin, 130021, People's Republic of China
| | - Jun Li
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China
| | - Jinglun Liang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China
| | - Huimao Zhang
- China-Japan Union Hospital, Jilin University, Changchun 130033, People's Republic of China
| | - Wensheng Yang
- State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun 130012, People's Republic of China
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23
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Martínez-Otero A, González-Monje P, Maspoch D, Hernando J, Ruiz-Molina D. Multiplexed arrays of chemosensors by parallel dip-pen nanolithography. Chem Commun (Camb) 2011; 47:6864-6. [DOI: 10.1039/c0cc03838e] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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24
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Yuan L, Lin W, Feng Y. A rational approach to tuning the pKa values of rhodamines for living cell fluorescence imaging. Org Biomol Chem 2011; 9:1723-6. [DOI: 10.1039/c0ob01045f] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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25
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Tian Y, Su F, Weber W, Nandakumar V, Shumway BR, Jin Y, Zhou X, Holl MR, Johnson RH, Meldrum DR. A series of naphthalimide derivatives as intra and extracellular pH sensors. Biomaterials 2010; 31:7411-22. [PMID: 20619451 PMCID: PMC2940253 DOI: 10.1016/j.biomaterials.2010.06.023] [Citation(s) in RCA: 86] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2010] [Accepted: 06/15/2010] [Indexed: 10/19/2022]
Abstract
A series of new naphthalimide derivatives were synthesized and studied. Three of the materials (SM1, SM2, and SM3) possess methacrylate(s) moieties as pH sensor monomers, enabling these compounds to be polymerized with other monomers for thin film preparation for extracellular pH sensing. Herein, poly(2-hydroxyethyl methacrylate)-co-poly(acrylamide) (PHEMA-co-PAM) was chosen as the polymer matrix. Structure influences on pH responses and pK(a) values were studied. The film P3 composed of the sensing moiety SM3 has a pK(a) close to the usual biological environmental pH of approximately 7. It was used as an extracellular pH sensor to monitor pH change during the metabolism of prokaryotic Escherichia coli (E. coil). On the other hand, the three sensor monomers are new intracellular biomarkers to sense lysosomes of eukaryotic cells since (1) their pK(a) values are in a range of 5.9-6.8; (2) their emission intensities at acidic conditions (such as at pH 5) are much stronger than those at a neutral condition of pH 7; (3) lysosomes range in size from 0.1 to 1.2 mum in diameter with pH ranging from 4.5 to 5.0, which is much more acidic than the pH value of the cytoplasm (usually with a pH value of approximately 7.2); and (4) the acidity of lysosomes enables a protonation of the amino groups of the pH probes making the sensors emit brightly in acidic organelles by inhibiting the photo-induced electron transfer from the amino groups to the fluorophores. Lysosome sensing was demonstrated using live human brain glioblastoma U87MG cell line, human cervical cancer HeLa cell line, and human esophagus premalignant CP-A and CP-D cell lines by observations of small acidic spherical organelles (lysosomes) and significant colocalizations (82-95%) of the sensors with a commercially available lysosome-selective staining probe LysoTracker Red under confocal fluorescence microscopy.
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Affiliation(s)
- Yanqing Tian
- Center for Biosignatures Discovery Automation, Biodesign Institute, Arizona State University, 1001 McAllister Ave, Tempe, AZ 85287, USA.
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26
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Affiliation(s)
- Junyan Han
- Department of Chemistry, Texas A&M University, Box 30012, College Station, Texas 77841, USA
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27
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Hermida LG, Sabés-Xamaní M, Barnadas-Rodríguez R. Combined strategies for liposome characterization during in vitro digestion. J Liposome Res 2009; 19:207-19. [PMID: 19548842 DOI: 10.1080/08982100902740847] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Three types of pyranine (HPTS)-containing liposomes were prepared by high-pressure homogenization under optimized conditions. At 37 degrees C, they were 1) fluid-state vesicles made from soybean phosphatidylcholine (SPC), 2) gel-state liposomes made from hydrogenated SPC (HSPC), and 3) solid-disordered membranes obtained from HSPC and cholesterol (HSPC-Chol). These liposome formulations were characterized before, during, and after in vitro digestion, which involved the presence of pH gradients, enzymes, and bile salts. Mean sizes and size distributions of the vesicles were determined by DLS; (31)P-NMR (nuclear magnetic resonance) was used to quantify lyso-PC forms; internal pH was monitored throughout digestion with two different fluorescent pH probes; and changes in bilayer permeability and HPTS encapsulation were determined by size-exclusion chromatography and fluorimetry. Differential scanning calorimetry analysis was also performed in order to study the effect of digestion on HSPC vesicles. SPC liposomes were physically stable during digestion; they presented 8% lyso-forms and an HPTS encapsulation around 85% after in vitro digestion. However, they were extremely permeable to ions, so that the internal pH immediately equilibrated with the bulk pH. HSPC liposomes were the most affected by the digestive process. Even though they were chemically stable, as inferred from the low lyso-PC content, very important changes in their size distribution were observed. A final 50% HPTS leakage was quantified after in vitro digestion. Nevertheless, they were the least permeable to protons under pH gradients. HSPC-Chol vesicles presented intermediate permeability to protons, having their internal pH decreased from approximately 6.8 to 4.6 after 1 hour of incubation at pH 2. This was the most chemically stable formulation and showed the highest encapsulation, even after in vitro digestion. Therefore, HSPC-Chol liposomes would be the most adequate choice for the design of lipid products for oral administration.
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Affiliation(s)
- Laura G Hermida
- Centro de Investigación y Desarrollo en Química, Instituto Nacional de Tecnología Industrial, Buenos Aires, Argentina
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28
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Quentmeier S, Quentmeier CC, Walla PJ, Gericke KH. Two-color two-photon excitation of intrinsic protein fluorescence: label-free observation of proteolytic digestion of bovine serum albumin. Chemphyschem 2009; 10:1607-13. [PMID: 19156800 DOI: 10.1002/cphc.200800586] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Two-color two-photon (2c2p) excitation fluorescence is used to monitor the enzymatic cleavage of bovine serum albumin (BSA) by subtilisin. Fluorescence is generated by irradiation with spatially and temporally overlapping femtosecond laser beams resulting in simultaneous absorption of an 800 and a 400 nm photon. Thereby, excitation of the fluorescent amino acid tryptophan present in BSA corresponds to an effective one-photon wavelength of 266 nm. The progress of protein cleavage is monitored by time-resolved fluorescence analysis. The fluorescence lifetime of tryptophan decreases during the reaction. This demonstrates a novel label-free multiphoton observation technique for conformational changes of proteins containing tryptophan. Due to the strong 2c2p fluorescence signal it is suitable for fast evaluation and monitoring of protein reactions. The course of the reaction is monitored simultaneously by gel electrophoresis. In contrast to conventional one-photon techniques, 2c2p excitation enables label-free protein fluorescence studies without irradiating the sample with UV light. Due to the dependence of the excitation on the power of both laser beams, excitation is limited to a relatively small focal volume. This results in dramatically reduced overall photodamage compared to direct UV irradiation. This method can be easily extended to microscopy imaging techniques.
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Affiliation(s)
- Stefan Quentmeier
- Institut für Physikalische und Theoretische Chemie, Technische Universität Braunschweig, Hans-Sommer-Str. 10, 38106 Braunschweig, Germany
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29
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Berghuis BA, Spruijt RB, Koehorst RBM, van Hoek A, Laptenok SP, van Oort B, van Amerongen H. Exploring the structure of the N-terminal domain of CP29 with ultrafast fluorescence spectroscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2009; 39:631-8. [PMID: 19639311 PMCID: PMC2841283 DOI: 10.1007/s00249-009-0519-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Revised: 06/26/2009] [Accepted: 07/05/2009] [Indexed: 11/17/2022]
Abstract
A high-throughput Förster resonance energy transfer (FRET) study was performed on the approximately 100 amino acids long N-terminal domain of the photosynthetic complex CP29 of higher plants. For this purpose, CP29 was singly mutated along its N-terminal domain, replacing one-by-one native amino acids by a cysteine, which was labeled with a BODIPY fluorescent probe, and reconstituted with the natural pigments of CP9, chlorophylls and xanthophylls. Picosecond fluorescence experiments revealed rapid energy transfer (~20–70 ps) from BODIPY at amino-acid positions 4, 22, 33, 40, 56, 65, 74, 90, and 97 to Chl a molecules in the hydrophobic part of the protein. From the energy transfer times, distances were estimated between label and chlorophyll molecules, using the Förster equation. When the label was attached to amino acids 4, 56, and 97, it was found to be located very close to the protein core (~15 Å), whereas labels at positions 15, 22, 33, 40, 65, 74, and 90 were found at somewhat larger distances. It is concluded that the entire N-terminal domain is in close contact with the hydrophobic core and that there is no loop sticking out into the stroma. Most of the results support a recently proposed topological model for the N-terminus of CP29, which was based on electron-spin-resonance measurements on spin-labeled CP29 with and without its natural pigment content. The present results lead to a slight refinement of that model.
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Affiliation(s)
- Bojk A Berghuis
- Laboratory of Biophysics, Wageningen University, 6700 ET Wageningen, The Netherlands
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30
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Hynes J, O'Riordan TC, Zhdanov AV, Uray G, Will Y, Papkovsky DB. In vitro analysis of cell metabolism using a long-decay pH-sensitive lanthanide probe and extracellular acidification assay. Anal Biochem 2009; 390:21-8. [PMID: 19379702 DOI: 10.1016/j.ab.2009.04.016] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2008] [Revised: 03/31/2009] [Accepted: 04/11/2009] [Indexed: 10/20/2022]
Abstract
Metabolic perturbations play a critical role in a variety of disease states and toxicities. Therefore, knowledge of the interplay between the two main cellular ATP generating pathways, glycolysis and oxidative phosphorylation, is particularly informative when examining such perturbations. Here we describe a new fluorescence-based screening assay for the assessment of glycolytic flux and demonstrate the value of such analysis in assessing the cellular "energy budget." The assay employs a long-decay pH-sensitive lanthanide probe to monitor extracellular acidification (ECA) in standard 96- or 384-well plates on a time-resolved fluorescence plate reader. The simple mix-and-measure procedure and fluorescence lifetime-based pH sensing allow the use of standard adherent cell culture techniques, providing high sample throughput and excellent assay performance. The assay also facilitates multiplexed or parallel analysis with existing oxygen consumption and ATP assays, thereby providing a detailed multiparametric assessment of cell metabolism. Data on cellular CO(2) production can also be obtained by comparing sealed and unsealed samples. The utility of the approach in assessing perturbed cell metabolism is demonstrated using a panel of metabolic effectors with known mechanisms of action. More complex metabolic stimuli, such as G protein-coupled receptor (GPCR) activation and perturbed ion homeostasis, are also examined.
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Affiliation(s)
- James Hynes
- Luxcel Biosciences, BioInnovation Center, University College Cork, Ireland
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31
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A method for imaging of low pH in live cells based on excited state saturation. J Microbiol Methods 2009; 77:98-101. [DOI: 10.1016/j.mimet.2009.01.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Accepted: 01/16/2009] [Indexed: 11/18/2022]
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32
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van Oort B, Murali S, Wientjes E, Koehorst RB, Spruijt RB, van Hoek A, Croce R, van Amerongen H. Ultrafast resonance energy transfer from a site-specifically attached fluorescent chromophore reveals the folding of the N-terminal domain of CP29. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2008.10.052] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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33
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Chemin C, Péan JM, Bourgaux C, Pabst G, Wüthrich P, Couvreur P, Ollivon M. Supramolecular organization of S12363-liposomes prepared with two different remote loading processes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1788:926-35. [PMID: 19101501 DOI: 10.1016/j.bbamem.2008.11.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 10/27/2008] [Accepted: 11/11/2008] [Indexed: 11/17/2022]
Abstract
The S12363 anticancer drug was encapsulated into liposomes in an attempt to increase its therapeutic index. Loading of S12363 was achieved using two different processes based on the formation of either a pH gradient or an ammonium gradient between the acidic inner liposomal compartment and the basic outer phase. High encapsulation yields (>90%) were obtained using both processes for sphingomyelin/cholesterol/cholesterol-PEG vesicles. Spectrofluorimetry measurements have shown that liposomes were characterized by an internal pH around 4 for both loading processes. This internal pH was stable over a period of at least 20 days. Differential scanning calorimetry coupled with time-resolved synchrotron X-ray diffraction was used to study the drug/carrier supramolecular organization. In ammonium sulfate, S12363 was inserted into the bilayer in the vicinity of the polar headgroup. In citrate buffer, S12363 was mainly adsorbed at the water-lipid interface. The drug partitioning into the membrane was inhomogeneous and led to the formation of drug-rich and drug-poor domains. This effect was enhanced in the presence of cholesterol, especially in ammonium sulfate. To conclude, for both processes, the encapsulated drug was found inside the liposome aqueous core but strongly interacting with the membrane.
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Affiliation(s)
- Caroline Chemin
- Université Paris-Sud 11, UMR CNRS 8612, 5 rue J.B. Clément, 92290 Châtenay-Malabry, France.
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34
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Gao F, Tang L, Dai L, Wang L. A fluorescence ratiometric nano-pH sensor based on dual-fluorophore-doped silica nanoparticles. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2007; 67:517-21. [PMID: 16965933 DOI: 10.1016/j.saa.2006.08.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2006] [Revised: 08/05/2006] [Accepted: 08/07/2006] [Indexed: 05/11/2023]
Abstract
We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors.
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Affiliation(s)
- Feng Gao
- College of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000, PR China
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35
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Burns A, Sengupta P, Zedayko T, Baird B, Wiesner U. Core/Shell fluorescent silica nanoparticles for chemical sensing: towards single-particle laboratories. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2006; 2:723-6. [PMID: 17193111 DOI: 10.1002/smll.200600017] [Citation(s) in RCA: 144] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Affiliation(s)
- Andrew Burns
- Department of Materials Science & Engineering, 330 Bard Hall, Cornell University, Ithaca, NY 14853, USA
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36
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Hayward R, Saliba KJ, Kirk K. The pH of the digestive vacuole of Plasmodium falciparum is not associated with chloroquine resistance. J Cell Sci 2006; 119:1016-25. [PMID: 16492710 DOI: 10.1242/jcs.02795] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Chloroquine resistance in the human malaria parasite, Plasmodium falciparum, arises from decreased accumulation of the drug in the ;digestive vacuole' of the parasite, an acidic compartment in which chloroquine exerts its primary toxic effect. It has been proposed that changes in the pH of the digestive vacuole might underlie the decreased accumulation of chloroquine by chloroquine-resistant parasites. In this study we have investigated the digestive vacuole pH of a chloroquine-sensitive and a chloroquine-resistant strain of P. falciparum, using a range of dextran-linked pH-sensitive fluorescent dyes. The estimated digestive vacuole pH varied with the concentration and pK(a) of the dye, ranging from approximately 3.7-6.5. However, at low dye concentrations the estimated digestive vacuole pH of both the chloroquine-resistant and chloroquine-sensitive strains converged in the range 4.5-4.9. The results suggest that there is no significant difference in digestive vacuole pH of chloroquine-sensitive and chloroquine-resistant parasites, and that digestive vacuole pH does not play a primary role in chloroquine resistance.
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Affiliation(s)
- Rhys Hayward
- School of Biochemistry and Molecular Biology, Faculty of Science, The Australian National University, Canberra ACT 0200, Australia
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37
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Li CY, Zhang XB, Han ZX, Akermark B, Sun L, Shen GL, Yu RQ. A wide pH range optical sensing system based on a sol–gel encapsulated amino-functionalised corrole. Analyst 2006; 131:388-93. [PMID: 16496047 DOI: 10.1039/b514510d] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of a new compound, 10-(4-aminophenyl)-5,15-dimesitylcorrole, and its application for the preparation of optical chemical pH sensors is described. The dye materials were immobilized in a sol-gel glass matrix and characterised upon exposure to aqueous buffer solutions. The response of the sensor is based on the fluorescence intensity changing of corrole owing to multiple steps of protonation and deprotonation. Due to its containing several proton sensitive centers, the 10-(4-aminophenyl)-5,15-dimesitylcorrole based optode shows a wider response range toward pH than that of tetraphenylporphyrin (TPPH(2)) and 5,10,15-tris(pentafluorophenyl)corrole (H(3)(tpfc)). It shows a linear pH response in the range of 2.17-10.30. The effect of the composition of the sensor membrane has been studied and the experimental conditions were optimized. The optode showed good reproducibility and reversibility, and common co-existing inorganic ions did not show obvious interference to its pH measurement.
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Affiliation(s)
- Chun-Yan Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China
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38
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Hassler K, Anhut T, Lasser T. Time-resolved Hadamard fluorescence imaging. APPLIED OPTICS 2005; 44:7564-72. [PMID: 16363781 DOI: 10.1364/ao.44.007564] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
We present a new concept for fluorescence lifetime imaging (FLIM) based on time-resolved Hadamard imaging (HI). HI allows image acquisition by use of one single-point detector without requiring a moving scanning stage. Moreover, it reduces the influence of detector noise compared with raster scanning. By use of Monte Carlo simulations it could be confirmed that Hadamard transformation may decrease the error in lifetime estimation and in general in fluorescence parameter estimation when the signal-to-noise ratio is low and detector dark noise is high. This concept may find applications whenever the performance of FLIM or similar methods is limited by high dark-count rates and when the use of a single-point detector is preferable.
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Affiliation(s)
- Kai Hassler
- Ecole Polytechnique Fédérale de Lausanne, Laboratoire d'Optique Biomédicale, CH-1015 Lausanne, Switzerland.
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39
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Niu CG, Gui XQ, Zeng GM, Yuan XZ. A ratiometric fluorescence sensor with broad dynamic range based on two pH-sensitive fluorophores. Analyst 2005; 130:1551-6. [PMID: 16222379 DOI: 10.1039/b504882f] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This paper describes a novel ratiometric fluorescence sensor for pH measurement. Two pH-sensitive fluorophores, N-allyl-4-(4'-methyl-piperazinyl)-1,8-naphthalimide (AMPN) and meso-5,10,15,20-tetra-(4-allyloxyphenyl)porphyrin (TAPP), which served as referencing indicators for each other, were co-polymerized with acrylamide, hydroxyethyl methacrylate and triethylene glycol dimethacrylate on the silanized glass surface. The proposed sensor is based on the pH-dependent fluorescence intensities of the two fluorophores in different pH ranges. The sensor covers a broad dynamic range of pH 1.5-9.0. It exhibits satisfactory analytical performance in terms of selectivity, reproducibility and stability. The successful fabrication of the proposed sensor provides an alternative concept to utilizing two or more fluorophores for the development of ratiometric sensors covering a broad range of pH.
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Affiliation(s)
- Cheng-Gang Niu
- College of Environmental Science and Engineering, State Key Laboratory for Chemo/Biosensing and Chemometrics, Hunan University, Changsha 410082, P. R. China.
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Gannot I, Ron I, Hekmat F, Chernomordik V, Gandjbakhche A. Functional optical detection based on pH dependent fluorescence lifetime. Lasers Surg Med 2005; 35:342-8. [PMID: 15611954 DOI: 10.1002/lsm.20101] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND AND OBJECTIVES Detection of possible alterations of physiological parameters (e.g., pH and temperature), resulting from malignant transformation of initially healthy tissue, can be a powerful diagnostic tool for earlier cancer detection. Such variations can be observed by comparing these parameters with those of healthy tissue surrounding the abnormality. Time-resolved spectroscopy of specifically targeted fluorescent labeled antibodies can be sensitive to such variations and provide a high resolution functional image of the region of interest. The goal of this study was to establish a forward experimental setup for calibration of the lifetime dependencies of near-IR fluorescent dyes on physiological parameters, and to develop analytical solutions, taking into account the effects of light propagation in turbid media (e.g., tissue), that was able to extract an original lifetime fluorescence signal from time-of-flight intensity distributions, measured in vivo from a deeply embedded live organ for further analysis. STUDY DESIGN/MATERIALS AND METHODS Tissue-like phantoms with embedded fluorescent dyes and background optical properties simulating those of live tissues were designed and created. Fluorescence decay curves were measured for different fluorophore positions, and pH values. Those measurements were made with a system based on a time-correlated single photon counting (TCSPC) instrument and a tunable femtosecond Ti-Sapphire system built by our group. RESULTS Decay curves were recorded for fluorophore depths of up to 5 mm and source-detector separation of 7 mm. It was shown that a forward model, based on the random walk theory, adequately described the experimental data. Measured pH dependencies of the fluorescence lifetime were characterized for two different dyes. CONCLUSIONS Good correlation between experimental data and predictions of the theoretical model allows the use of close-form analytical solutions to separate the effects of photon time delays due to multiple scattering in tissues from the original intensity fluorescence time decay curve, determined by the fluorophore itself and its immediate surroundings. It is the latter dependence that can be diagnostically important. Experimentally obtained scaling between lifetime and a parameter of interest can be used in vivo to obtain a map of physiological parameter changes which can serve as a base for an in vivo specific diagnostic system.
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Affiliation(s)
- Israel Gannot
- Lasers and Optics in Medicine Laboratory, Department of Biomedical Engineering, Faculty of Engineering Tel-Aviv University, Tel-Aviv 69978, Israel.
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Mela P, Onclin S, Goedbloed MH, Levi S, Garcia-Parajo MF, van Hulst NF, Ravoo BJ, Reinhoudt DN, van den Berg A. Monolayer-functionalized microfluidics devices for optical sensing of acidity. LAB ON A CHIP 2005; 5:163-170. [PMID: 15672130 DOI: 10.1039/b409978h] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
This paper describes the integration of opto-chemosensors in microfluidics networks. Our technique exploits the internal surface of the network as a platform to build a sensing system by coating the surface with a self-assembled monolayer and subsequently binding a fluorescent sensing molecule to the monolayer. Fluorescent molecules were used that can switch between a fluorescent and a non-fluorescent state, depending on the acidity of the surrounding solution. Two systems were investigated. The first employs surface confinement of a Rhodamine B dye in a glass micro channel that serves as a molecular switch in organic solutions. Upon rinsing the micro channels with acidic or basic solutions it was possible to switch between the fluorescent and non-fluorescent forms reversibly. Moreover, this system could be used to monitor the mixing of two solutions of different acidity along the micro channel. To widen the scope of optical sensing in micro channels an Oregon Green dye derivative was immobilized, which functions as a sensing molecule for pH differences in aqueous solutions. In this case, a hybrid system was used consisting of a glass slide and PDMS channels. The fluorescence intensity was found to be directly correlated to the pH of the solution in contact, indicating the possibility of using such a system as a pH sensor. These systems allow real-time measurements and can be easily implemented in micro- and nanofluidics systems thus enabling analysis of extremely small sample volumes in a fast and reproducible manner.
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Affiliation(s)
- P Mela
- Applied Optics Group, MESA+ Institute for Nanotechnology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands
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Gale PA, Light ME, McNally B, Navakhun K, Sliwinski KE, Smith BD. Co-transport of H+/Cl– by a synthetic prodigiosin mimic. Chem Commun (Camb) 2005:3773-5. [PMID: 16041412 DOI: 10.1039/b503906a] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An amidopyrrole with appended imidazole group can bind and co-transport H+/Cl- across vesicle membranes much more effectively than an analogue with an appended pyridyl group.
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Affiliation(s)
- Philip A Gale
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
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Wang Y, Zhang Z, Mu LX, Mao HS, Wang YF, Jin WJ. Phosphorescent pH sensors and switches with substitutionally tunable response range based on photo-induced electron transfer. LUMINESCENCE 2005; 20:339-46. [PMID: 16134222 DOI: 10.1002/bio.832] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
According to the principle of photo-induced electron transfer (PET), five aminomethyl-bromonaphthalene phosphoroionophores with long lifetimes (to ms) were synthesized, all of them working well in beta-cyclodextrin (beta-CD) aqueous solutions. They form a family of phosphorescent sensors with pH-dependent spectral properties. For all the compounds, the fully protonated form exhibits the highest phosphorescence emission intensity and the proton-free form of the sensor is weakly emissive, due to the designed PET process. The sensors also show the expected pH dependence of phosphorescence quantum yields. Responses of the sensors are tuned by variation of substituent. The pH response ranges for 1-5 were 4.3-6.5, 3.5-10.5, 3.4-10.5, 3.4-10.5 and 3.4-6.1, respectively.
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Affiliation(s)
- Yu Wang
- School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, People's Republic of China
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Abstract
Amidopyrroles have been employed in a variety of anion receptors and sensors. 2,5-Bisamidopyrroles show selective oxo-anion complexation properties in organic solution whilst bis-amides containing dipyrrolylmethane groups form strong complexes with dihydrogen phosphate anions in mixtures of DMSO-d6 and water. Deprotonation of the 2,5-bisamidopyrrole unit can lead to interesting solid-state structures including the formation of orthogonal hydrogen bonded dimers. Amidopyrrole groups have also been employed in receptors for ion-pairs and in membrane transport agents for HCl.
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Affiliation(s)
- Philip A Gale
- School of Chemistry, University of Southampton, Southampton SO17 1BJ, UK.
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Fu Y, Collinson MM, Higgins DA. Single-molecule spectroscopy studies of microenvironmental acidity in silicate thin films. J Am Chem Soc 2004; 126:13838-44. [PMID: 15493944 DOI: 10.1021/ja046527j] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Single-molecule (SM) spectroscopic methods were employed to study single site variations in the acidity properties of sol-gel-derived silicate films. The pH-sensitive dye Carboxy SNARF-1 (C.SNARF-1) was used to sense film acidity. Its concentration in the films was maintained at nanomolar levels to allow for SMs to be spectroscopically interrogated. The ratio of C.SNARF-1 fluorescence at 580 nm (protonated form) and 640 nm (deprotonated form) was used to characterize local film pH. SM data were acquired both for "untreated" films and for those treated by immersion for either 1 or 8 h in phosphate solutions of different pH. The SM results prove that the spectral variability observed is dominated by static variations in the local matrix acidity. Shorter immersion times lead to relatively broad histograms and broad "titration" curves, providing clear evidence for kinetic limitations to access of certain film environments by the immersion solutions. Films subjected to longer immersion times generally exhibit narrower histograms. Particularly narrow distributions were obtained for films treated near pH 8-9, while much broader histograms were produced near pH 7. These results are attributed to the buffering effects of surface silanols near pH 9 and enhanced pH sensitivity of the dye near pH 7.
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Affiliation(s)
- Yi Fu
- Department of Chemistry, Kansas State University, Manhattan, Kansas 66506, USA
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Fan L, Neumann PM. The spatially variable inhibition by water deficit of maize root growth correlates with altered profiles of proton flux and cell wall pH. PLANT PHYSIOLOGY 2004; 135:2291-300. [PMID: 15286291 PMCID: PMC520798 DOI: 10.1104/pp.104.041426] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2004] [Revised: 04/23/2004] [Accepted: 04/27/2004] [Indexed: 05/18/2023]
Abstract
Growth of elongating primary roots of maize (Zea mays) seedlings was approximately 50% inhibited after 48 h in aerated nutrient solution under water deficit induced by polyethylene glycol 6000 at -0.5 MPa water potential. Proton flux along the root elongation zone was assayed by high resolution analyses of images of acid diffusion around roots contacted for 5 min with pH indicator gel. Profiles of root segmental elongation correlated qualitatively and quantitatively (r(2) = 0.74) with proton flux along the surface of the elongation zone from water-deficit and control treatments. Proton flux and segmental elongation in roots under water deficit were remarkably well maintained in the region 0 to 3 mm behind the root tip and were inhibited from 3 to 10 mm behind the tip. Associated changes in apoplastic pH inside epidermal cell walls were measured in three defined regions along the root elongation zone by confocal laser scanning microscopy using a ratiometric method. Finally, external acidification of roots was shown to specifically induce a partial reversal of growth inhibition by water deficit in the central region of the elongation zone. These new findings, plus evidence in the literature concerning increases induced by acid pH in wall-extensibility parameters, lead us to propose that the apparently adaptive maintenance of growth 0 to 3 mm behind the tip in maize primary roots under water deficit and the associated inhibition of growth further behind the tip are related to spatially variable changes in proton pumping into expanding cell walls.
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Affiliation(s)
- Ling Fan
- Plant Physiology Laboratory, Department of Environmental, Water and Agricultural Engineering, Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Fan L, Neumann PM. The spatially variable inhibition by water deficit of maize root growth correlates with altered profiles of proton flux and cell wall pH. PLANT PHYSIOLOGY 2004. [PMID: 15286291 DOI: 10.1104/pp.104.041426.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Growth of elongating primary roots of maize (Zea mays) seedlings was approximately 50% inhibited after 48 h in aerated nutrient solution under water deficit induced by polyethylene glycol 6000 at -0.5 MPa water potential. Proton flux along the root elongation zone was assayed by high resolution analyses of images of acid diffusion around roots contacted for 5 min with pH indicator gel. Profiles of root segmental elongation correlated qualitatively and quantitatively (r(2) = 0.74) with proton flux along the surface of the elongation zone from water-deficit and control treatments. Proton flux and segmental elongation in roots under water deficit were remarkably well maintained in the region 0 to 3 mm behind the root tip and were inhibited from 3 to 10 mm behind the tip. Associated changes in apoplastic pH inside epidermal cell walls were measured in three defined regions along the root elongation zone by confocal laser scanning microscopy using a ratiometric method. Finally, external acidification of roots was shown to specifically induce a partial reversal of growth inhibition by water deficit in the central region of the elongation zone. These new findings, plus evidence in the literature concerning increases induced by acid pH in wall-extensibility parameters, lead us to propose that the apparently adaptive maintenance of growth 0 to 3 mm behind the tip in maize primary roots under water deficit and the associated inhibition of growth further behind the tip are related to spatially variable changes in proton pumping into expanding cell walls.
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Affiliation(s)
- Ling Fan
- Plant Physiology Laboratory, Department of Environmental, Water and Agricultural Engineering, Faculty of Civil and Environmental Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
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Edelson BS, Best TP, Olenyuk B, Nickols NG, Doss RM, Foister S, Heckel A, Dervan PB. Influence of structural variation on nuclear localization of DNA-binding polyamide-fluorophore conjugates. Nucleic Acids Res 2004; 32:2802-18. [PMID: 15155849 PMCID: PMC419610 DOI: 10.1093/nar/gkh609] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2004] [Revised: 04/22/2004] [Accepted: 04/22/2004] [Indexed: 11/14/2022] Open
Abstract
A pivotal step forward in chemical approaches to controlling gene expression is the development of sequence-specific DNA-binding molecules that can enter live cells and traffic to nuclei unaided. DNA-binding polyamides are a class of programmable, sequence-specific small molecules that have been shown to influence a wide variety of protein-DNA interactions. We have synthesized over 100 polyamide-fluorophore conjugates and assayed their nuclear uptake profiles in 13 mammalian cell lines. The compiled dataset, comprising 1300 entries, establishes a benchmark for the nuclear localization of polyamide-dye conjugates. Compounds in this series were chosen to provide systematic variation in several structural variables, including dye composition and placement, molecular weight, charge, ordering of the aromatic and aliphatic amino-acid building blocks and overall shape. Nuclear uptake does not appear to be correlated with polyamide molecular weight or with the number of imidazole residues, although the positions of imidazole residues affect nuclear access properties significantly. Generally negative determinants for nuclear access include the presence of a beta-Ala-tail residue and the lack of a cationic alkyl amine moiety, whereas the presence of an acetylated 2,4-diaminobutyric acid-turn is a positive factor for nuclear localization. We discuss implications of these data on the design of polyamide-dye conjugates for use in biological systems.
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Affiliation(s)
- Benjamin S Edelson
- Division of Chemistry and Chemical Engineering and The Beckman Institute, California Institute of Technology, Pasadena, CA 91125, USA
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Abstract
Acidification of some organelles, including the Golgi complex, lysosomes, secretory granules, and synaptic vesicles, is important for many of their biochemical functions. In addition, acidic pH in some compartments is also required for the efficient sorting and trafficking of proteins and lipids along the biosynthetic and endocytic pathways. Despite considerable study, however, our understanding of how pH modulates membrane traffic remains limited. In large part, this is due to the diversity of methods to perturb and monitor pH, as well as to the difficulties in isolating individual transport steps within the complex pathways of membrane traffic. This review summarizes old and recent evidence for the role of acidification at various steps of biosynthetic and endocytic transport in mammalian cells. We describe the mechanisms by which organelle pH is regulated and maintained, as well as how organelle pH is monitored and quantitated. General principles that emerge from these studies as well as future directions of interest are discussed.
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Affiliation(s)
- Ora A Weisz
- Renal-Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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Niu CG, Zeng GM, Chen LX, Shen GL, Yu RQ. Proton "off-on" behaviour of methylpiperazinyl derivative of naphthalimide: a pH sensor based on fluorescence enhancement. Analyst 2003; 129:20-4. [PMID: 14737578 DOI: 10.1039/b309594k] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In a search for new type pH sensing fluorophores, the possibility of using the proton "off-on" switch behaviour of naphthalimide derivatives for optical pH sensor preparation has been explored. A new compound, N-allyl-4-(4[prime or minute]-methyl-piperazinyl)-1,8-naphthalimide (AMPN), was synthesized. The enhancement of fluorescence of AMPN with the increase of hydrogen ion concentration is based on arresting photo-induced electron transfer to the naphthalimide fluorophore from aliphatic amine group after its protonation. The Stokes Shift of the proposed type of pH sensing fluorophore is significantly larger than that of the fluorescein counterparts. To avoid the leakage of the fluorophore, AMPN was photo-copolymerized with 2-hydroxyethyl methacrylate and acrylamide on the glass surface. The fluorescence intensity of membrane contacted with a pH 3.50 buffer is 4.7 times of that for pH 12.00 buffer solutions. The proposed pH sensor is not susceptible to ionic strength and shows good selectivity, repeatability and short response time. The membrane shows a good stability with a lifetime over two months. The sensor can be used for the determination of pH in the range of pH 4.5-9.0, without interference of most commonly co-existing inorganic ions and some organic species. The sensor has been applied to the analysis of urine samples.
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Affiliation(s)
- Cheng-Gang Niu
- State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, P. R. China.
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