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Special Issue "Fluorescent Probes"

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Organic Synthesis".

Deadline for manuscript submissions: closed (30 April 2014)

Special Issue Editor

Guest Editor
Prof. Dr. Kevin D. Belfield (Website)

College of Science and Liberal Arts, New Jersey Institute of Technology, 504 Cullimore Hall, 323 Dr. Martin Luther King Jr. Blvd Newark, NJ 07102
Phone: +1 973-596-3676
Fax: +1 973-596-6063
Interests: multiphoton absorbing materials; two-photon photochemistry; in vivo and ex vivo two-photon fluorescence bioimaging; magnetic polymeric and sol-gel nanocomposites; site-specific fluorophore labeling; fluorescent-based sensors and bioimaging probes; photodynamic therapy agents; nanostructured functional organic and polymeric materials; two-photon based 3D high density optical data storage

Special Issue Information

Dear Colleagues,

The use of fluorescent probes in biological imaging and diagnosis along environmental sensing has become ubiquitous, with numerous standard protocols that have become broadly adopted. Due to its sensitivity, environmental dependence, and quantitative ability fluorescence provides unsurpassed advantages in many applications. Fluorescent probes have become increasingly used in time-dependent studies, ranging from cell, organelles, and protein trafficking to monitoring the fate and persistence of environmental contaminants, imposing ever-increasing demands on probes, such as photochemical stability. The rapidly emerging area of two-photon absorption (2PA) based techniques for bioimaging relies heavily on the development of new, efficient, stable, and highly target-selective fluorescent probes and bioconjugates. A particular focus for fluorescent probes has been in the area of in vivo imaging and optimization of not only photophysical parameters but biological activity and targeting characteristics, such as cytotoxicity, biomarker affinity, and circulatory retention. Novel materials and methods in three-dimensional optical data storage have also been facilitated by the development of new fluorescent probes. Research papers dealing with all aspects of fluorescent probes and bioconjugates, including new compounds, photophysical studies, imaging and sensing results for particularly challenging targets, and new fluorescence-based imaging and sensing techniques to advance the field, including multiphoton and super resolution technology, are welcomed for inclusion into this Special Issue of Molecules. Review articles, particularly those dealing with retrospective analyses of prior successes in biological imaging and environmental sensing, are also welcomed for inclusion.

Prof. Dr. Kevin D. Belfield
Guest Editor

Submission

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are refereed through a peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed Open Access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs).

Keywords

  • fluorescent probes
  • fluorescence imaging
  • confocal imaging
  • confocal microscopy
  • fluorescence microscopy
  • fluorescence sensors
  • multiphoton microscopy
  • two-photon fluorescence
  • two-photon fluorescent probes
  • ion sensors

Published Papers (9 papers)

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Research

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Open AccessArticle Secondary Metabolite Localization by Autofluorescence in Living Plant Cells
Molecules 2015, 20(3), 5024-5037; doi:10.3390/molecules20035024
Received: 3 June 2014 / Revised: 9 February 2015 / Accepted: 25 February 2015 / Published: 19 March 2015
Cited by 8 | PDF Full-text (3125 KB) | HTML Full-text | XML Full-text
Abstract
Autofluorescent molecules are abundant in plant cells and spectral images offer means for analyzing their spectra, yielding information on their accumulation and function. Based on their fluorescence characteristics, an imaging approach using multiphoton microscopy was designed to assess localization of the endogenous [...] Read more.
Autofluorescent molecules are abundant in plant cells and spectral images offer means for analyzing their spectra, yielding information on their accumulation and function. Based on their fluorescence characteristics, an imaging approach using multiphoton microscopy was designed to assess localization of the endogenous fluorophores in living plant cells. This method, which requires no previous treatment, provides an effective experimental tool for discriminating between multiple naturally-occurring fluorophores in living-tissues. Combined with advanced Linear Unmixing, the spectral analysis extends the possibilities and enables the simultaneous detection of fluorescent molecules reliably separating overlapping emission spectra. However, as with any technology, the possibility for artifactual results does exist. This methodological article presents an overview of the applications of tissular and intra-cellular localization of these intrinsic fluorophores in leaves and fruits (here for coffee and vanilla). This method will provide new opportunities for studying cellular environments and the behavior of endogenous fluorophores in the intracellular environment. Full article
(This article belongs to the Special Issue Fluorescent Probes)
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Open AccessArticle Photobleaching Kinetics and Time-Integrated Emission of Fluorescent Probes in Cellular Membranes
Molecules 2014, 19(8), 11096-11130; doi:10.3390/molecules190811096
Received: 10 April 2014 / Revised: 4 July 2014 / Accepted: 10 July 2014 / Published: 29 July 2014
Cited by 3 | PDF Full-text (3686 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often hampered [...] Read more.
Since the pioneering work of Hirschfeld, it is known that time-integrated emission (TiEm) of a fluorophore is independent of fluorescence quantum yield and illumination intensity. Practical implementation of this important result for determining exact probe distribution in living cells is often hampered by the presence of autofluorescence. Using kinetic modelling of photobleaching combined with pixel-wise bleach rate fitting of decay models with an updated plugin to the ImageJ program, it is shown that the TiEm of a fluorophore in living cells can be determined exactly from the product of bleaching amplitude and time constant. This applies to mono-exponential bleaching from the first excited singlet and/or triplet state and to multi-exponential combinations of such processes. The TiEm can be used to correct for illumination shading and background autofluorescence without the need for fluorescent test layers or separate imaging of non-stained cells. We apply the method to simulated images and to images of cells, whose membranes were labelled with fluorescent sterols and sphingolipids. Our bleaching model can be extended to include a probability density function (PDF) of intrinsic bleach rate constants with a memory kernel. This approach results in a time-dependent bleach rate coefficient and is exemplified for fluorescent sterols in restricted intracellular environments, like lipid droplets. We show that for small deviations from the classical exponential bleaching, the TiEm of decay functions with rate coefficients remains largely independent of fluorescence lifetime and illumination, and thereby represents a faithful measure of probe distribution. Full article
(This article belongs to the Special Issue Fluorescent Probes)
Open AccessArticle Fluorescent Lectins for Local in Vivo Visualization of Peripheral Nerves
Molecules 2014, 19(7), 9876-9892; doi:10.3390/molecules19079876
Received: 7 May 2014 / Revised: 19 June 2014 / Accepted: 1 July 2014 / Published: 8 July 2014
Cited by 2 | PDF Full-text (1944 KB) | HTML Full-text | XML Full-text
Abstract
Damage to peripheral nerves caused during a surgical intervention often results in function loss. Fluorescence imaging has the potential to improve intraoperative identification and preservation of these structures. However, only very few nerve targeting agents are available. This study describes the in [...] Read more.
Damage to peripheral nerves caused during a surgical intervention often results in function loss. Fluorescence imaging has the potential to improve intraoperative identification and preservation of these structures. However, only very few nerve targeting agents are available. This study describes the in vivo nerve staining capabilities of locally administered fluorescent lectin-analogues. To this end WGA, PNA, PHA-L and LEL were functionalized with Cy5 (λex max 640 nm; λem max 680 nm). Transfer of these imaging agents along the sciatic nerve was evaluated in Thy1-YFP mice (n = 12) after intramuscular injection. Migration from the injection site was assessed in vivo using a laboratory fluorescence scanner and ex vivo via fluorescence confocal microscopy. All four lectins showed retrograde movement and staining of the epineurium with a signal-to-muscle ratio of around two. On average, the longest transfer distance was obtained with WGA-Cy5 (0.95 cm). Since WGA also gave minimal uptake in the lymphatic system, this lectin type revealed the highest potential as a migration imaging agent to visualize nerves. Full article
(This article belongs to the Special Issue Fluorescent Probes)
Open AccessArticle Evaluation of a Triple-Helical Peptide with Quenched Fluorophores for Optical Imaging of MMP-2 and MMP-9 Proteolytic Activity
Molecules 2014, 19(6), 8571-8588; doi:10.3390/molecules19068571
Received: 18 April 2014 / Revised: 5 June 2014 / Accepted: 11 June 2014 / Published: 23 June 2014
Cited by 3 | PDF Full-text (2155 KB) | HTML Full-text | XML Full-text
Abstract
Matrix metalloproteinases (MMP) 2 and 9, the gelatinases, have consistently been associated with tumor progression. The development of gelatinase-specific probes will be critical for identifying in vivo gelatinoic activity to understand the molecular role of the gelatinases in tumor development. Recently, a [...] Read more.
Matrix metalloproteinases (MMP) 2 and 9, the gelatinases, have consistently been associated with tumor progression. The development of gelatinase-specific probes will be critical for identifying in vivo gelatinoic activity to understand the molecular role of the gelatinases in tumor development. Recently, a self-assembling homotrimeric triple-helical peptide (THP), incorporating a sequence from type V collagen, with high substrate specificity to the gelatinases has been developed. To determine whether this THP would be suitable for imaging protease activity, 5-carboxyfluorescein (5FAM) was conjugated, resulting in 5FAM3-THP and 5FAM6-THP, which were quenched up to 50%. 5FAM6-THP hydrolysis by MMP-2 and MMP-9 displayed kcat/KM values of 1.5 × 104 and 5.4 × 103 M−1 s−1, respectively. Additionally 5FAM6-THP visualized gelatinase activity in gelatinase positive HT-1080 cells, but not in gelatinase negative MCF-7 cells. Furthermore, the fluorescence in the HT-1080 cells was greatly attenuated by the addition of a MMP-2 and MMP-9 inhibitor, SB-3CT, indicating that the observed fluorescence release was mediated by gelatinase proteolysis and not non-specific proteolysis of the THPs. These results demonstrate that THPs fully substituted with fluorophores maintain their substrate specificity to the gelatinases in human cancer cells and may be useful in in vivo molecular imaging of gelatinase activity. Full article
(This article belongs to the Special Issue Fluorescent Probes)
Open AccessArticle Organic Liquids-Responsive β-Cyclodextrin-Functionalized Graphene-Based Fluorescence Probe: Label-Free Selective Detection of Tetrahydrofuran
Molecules 2014, 19(6), 7459-7479; doi:10.3390/molecules19067459
Received: 1 April 2014 / Revised: 3 June 2014 / Accepted: 4 June 2014 / Published: 6 June 2014
Cited by 10 | PDF Full-text (5968 KB) | HTML Full-text | XML Full-text
Abstract
In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD) was firstly grafted on reduced graphene surfaces effectively and uniformly, [...] Read more.
In this study, a label-free graphene-based fluorescence probe used for detection of volatile organic liquids was fabricated by a simple, efficient and low-cost method. To fabricate the probe, a bio-based β-cyclodextrin (β-CD) was firstly grafted on reduced graphene surfaces effectively and uniformly, as evidenced by various characterization techniques such as Ultraviolet/Visible spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. The subsequent inclusion of Rhodamine B (RhB) into the inner cavities of the β-CD grafted on the graphene surfaces was achieved easily by a solution mixing method, which yielded the graphene-based fluorescent switch-on probe. In addition, the gradual and controllable quenching of RhB by Fluorescence Resonance Energy Transfer from RhB to graphene during the process of stepwise accommodation of the RhB molecules into the β-CD-functionalized graphene was investigated in depth. A wide range of organic solvents was examined using the as-fabricated fluorescence probe, which revealed the highest sensitivity to tetrahydrofuran with the detection limit of about 1.7 μg/mL. Some insight into the mechanism of the different responsive behaviors of the fluorescence sensor to the examined targets was also described. Full article
(This article belongs to the Special Issue Fluorescent Probes)
Figures

Open AccessArticle 2,5-PRODAN Derivatives as Highly Sensitive Sensors of Low Solvent Acidity
Molecules 2014, 19(5), 6415-6427; doi:10.3390/molecules19056415
Received: 2 April 2014 / Revised: 8 May 2014 / Accepted: 12 May 2014 / Published: 20 May 2014
Cited by 2 | PDF Full-text (1061 KB) | HTML Full-text | XML Full-text
Abstract
Two 5-acyl-2-dimethylaminonaphthalene derivatives, one with a propionyl group and the other with a fused cyclohexanone ring, are investigated as sensors of H-bond-donating ability in protic solvents of low solvent acidity. Their fluorescence is highly quenched in protic solvents, and the quenching order [...] Read more.
Two 5-acyl-2-dimethylaminonaphthalene derivatives, one with a propionyl group and the other with a fused cyclohexanone ring, are investigated as sensors of H-bond-donating ability in protic solvents of low solvent acidity. Their fluorescence is highly quenched in protic solvents, and the quenching order of magnitude is linearly related to the H-bond-donating ability of the solvent as quantified by the solvent acidity (SA) scale. As the solvent acidity increases from 0.15 to 0.40, the fluorescence for both is quenched by more than a factor of ten; thus, they are extremely sensitive sensors of the hydrogen-bond-donating ability in this weakly acidic range. Preferential solvation studies suggest that quenching occurs from a doubly H-bonded excited state. Full article
(This article belongs to the Special Issue Fluorescent Probes)
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Open AccessArticle Turn-on Type Chemical Sensing of Vitamin K4 by Fluorene Dendrimers with Naphthalene Segments
Molecules 2014, 19(4), 4135-4144; doi:10.3390/molecules19044135
Received: 7 March 2014 / Revised: 27 March 2014 / Accepted: 28 March 2014 / Published: 2 April 2014
PDF Full-text (474 KB) | HTML Full-text | XML Full-text
Abstract
G1 and G2 fluorene dendrimers with naphthalene termini were synthesized as a fluorescence turn-on type chemical sensor for vitamin K4. The fluorene dendrimers were prepared by Williamson ether reaction between the fluorene core with dihydroxy groups and dendritic naphthalene segments with methylene [...] Read more.
G1 and G2 fluorene dendrimers with naphthalene termini were synthesized as a fluorescence turn-on type chemical sensor for vitamin K4. The fluorene dendrimers were prepared by Williamson ether reaction between the fluorene core with dihydroxy groups and dendritic naphthalene segments with methylene chloride by a convergent method. We investigated the relationship between the dendrimer generation and vitamin K4 recognition of fluorene dendrimer with naphthalene termini in CHCl3. Addition of vitamin K4 enhanced the fluorescence intensity of the fluorene dendrimer. Especially, the G2 fluorene dendrimer was found to be an effective chemical sensor for vitamin K4 and better than the G1 fluorene dendrimer. Full article
(This article belongs to the Special Issue Fluorescent Probes)
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Open AccessCommunication Saccharide Substituted Zinc Phthalocyanines: Optical Properties, Interaction with Bovine Serum Albumin and Near Infrared Fluorescence Imaging for Sentinel Lymph Nodes
Molecules 2014, 19(1), 525-537; doi:10.3390/molecules19010525
Received: 20 November 2013 / Revised: 24 December 2013 / Accepted: 24 December 2013 / Published: 3 January 2014
Cited by 4 | PDF Full-text (1986 KB) | HTML Full-text | XML Full-text
Abstract
Saccharide-substituted zinc phthalocyanines, [2,9(10),16(17),23(24)-tetrakis((1-(β-D-glucose-2-yl)-1H-1,2,3-triazol-4-yl)methoxy)phthalocyaninato]zinc(II) and [2,9(10), 16(17),23(24)-tetrakis((1-(β-D-lactose-2-yl)-1H-1,2,3-triazol-4-yl)methoxy)phthalocyaninato] zinc(II), were evaluated as novel near infrared fluorescence agents. Their interaction with bovine serum albumin was investigated by fluorescence and circular dichroism spectroscopy and isothermal titration calorimetry. Near infrared imaging for [...] Read more.
Saccharide-substituted zinc phthalocyanines, [2,9(10),16(17),23(24)-tetrakis((1-(β-D-glucose-2-yl)-1H-1,2,3-triazol-4-yl)methoxy)phthalocyaninato]zinc(II) and [2,9(10), 16(17),23(24)-tetrakis((1-(β-D-lactose-2-yl)-1H-1,2,3-triazol-4-yl)methoxy)phthalocyaninato] zinc(II), were evaluated as novel near infrared fluorescence agents. Their interaction with bovine serum albumin was investigated by fluorescence and circular dichroism spectroscopy and isothermal titration calorimetry. Near infrared imaging for sentinel lymph nodes in vivo was performed using nude mice as models. Results show that saccharide- substituted zinc phthalocyanines have favourable water solubility, good optical stability and high emission ability in the near infrared region. The interaction of lactose-substituted phthalocyanine with bovine serum albumin displays obvious differences to that of glucose- substituted phthalocyanine. Moreover, lactose-substituted phthalocyanine possesses obvious imaging effects for sentinel lymph nodes in vivo. Full article
(This article belongs to the Special Issue Fluorescent Probes)

Review

Jump to: Research

Open AccessReview Fluorescent Probes for Exploring Plant Cell Wall Deconstruction: A Review
Molecules 2014, 19(7), 9380-9402; doi:10.3390/molecules19079380
Received: 25 April 2014 / Revised: 27 June 2014 / Accepted: 27 June 2014 / Published: 3 July 2014
Cited by 5 | PDF Full-text (2403 KB) | HTML Full-text | XML Full-text
Abstract
Plant biomass is a potential resource of chemicals, new materials and biofuels that could reduce our dependency on fossil carbon, thus decreasing the greenhouse effect. However, due to its chemical and structural complexity, plant biomass is recalcitrant to green biological transformation by [...] Read more.
Plant biomass is a potential resource of chemicals, new materials and biofuels that could reduce our dependency on fossil carbon, thus decreasing the greenhouse effect. However, due to its chemical and structural complexity, plant biomass is recalcitrant to green biological transformation by enzymes, preventing the establishment of integrated bio-refineries. In order to gain more knowledge in the architecture of plant cell wall to facilitate their deconstruction, many fluorescent probes bearing various fluorophores have been devised and used successfully to reveal the changes in structural motifs during plant biomass deconstruction, and the molecular interactions between enzymes and plant cell wall polymers. Fluorescent probes are thus relevant tools to explore plant cell wall deconstruction. Full article
(This article belongs to the Special Issue Fluorescent Probes)
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