Polymer Characterization

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Analysis and Characterization".

Deadline for manuscript submissions: closed (30 June 2018) | Viewed by 38637

Special Issue Editor

Institute for Polymer Research, Waterloo Institute of Nanotechnology, Department of Chemistry, University of Waterloo, Waterloo, ON N2L 3G1, Canada
Interests: fluorescence; polymer science; polypeptides; polysaccharides; polymeric bottle brushes
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Under its many forms, fluorescence has become an essential tool for the structural and dynamic characterization of synthetic and biological macromolecules in solution and in a solid state. Its extreme sensitivity enables one to probe macromolecules under conditions that are so dilute (sub-mg/L concentrations can be easily achieved) that they prevent intermacromolecular interactions during that short time window (a few tens of nanoseconds) where the fluorescent probe remains excited, in essence allowing the study of isolated macromolecules. Furthermore, novel living radical polymerization techniques have provided scientists with means to incorporate dyes in well-defined synthetic macromolecules of ever more complex architectures and at positions of which specificity was once believed to be solely available to biological macromolecules. The length scales probed by fluorescence, ranging from several angstroms up to ten nanometers, are also ideally suited for the study of macromolecules, being themselves a few nanometers in size. Due to its long scientific history, some might believe that fluorescence has nothing new to offer. Nothing would be further from the truth however as new instrumental, theoretical, and synthetic developments continue to push the applicability of fluorescence to ever newer areas of research. For instance, FRET, introduced in 1967 as a spectroscopic ruler, is now applied to probe the dynamics and conformations of individual biological macromolecules in cells. The discovery in 2001 that hexaphenylsilole could undergo aggregation induced emission has been rapidly harnessed to characterize macromolecular systems. In summary, the many scientific advances being currently achieved by using fluorescence as an essential analytical technique for the characterization of macromolecules provides a particularly appealing opportunity to review the exciting developments happening in this constantly evolving field in the upcoming Special Issue of Polymers and I look forward to your contributions on this topic.

Prof. Dr. Jean Duhamel
Guest Editor

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Keywords

  • Fluorescence
  • Macromolecules
  • Structure
  • Dynamics
  • Association
  • Confinement

Published Papers (9 papers)

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Research

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13 pages, 2361 KiB  
Article
Self-Assembled Nanostructures of Red Fluorescent Amphiphilic Block Copolymers as Both Imaging Probes and Drug Carriers
by Shuo Huang, Xin Wei and Mingfeng Wang
Polymers 2018, 10(10), 1120; https://doi.org/10.3390/polym10101120 - 10 Oct 2018
Cited by 7 | Viewed by 3574
Abstract
We report a red-fluorescent drug delivery system formed by biodegradable and biocompatible amphiphilic A-B-A block copolymers. Each polymer consists of a red fluorescent dye covalently bonded in the middle of hydrophobic block (B) of polylactone, tethered at both ends with poly[(oligo ethylene glycol) [...] Read more.
We report a red-fluorescent drug delivery system formed by biodegradable and biocompatible amphiphilic A-B-A block copolymers. Each polymer consists of a red fluorescent dye covalently bonded in the middle of hydrophobic block (B) of polylactone, tethered at both ends with poly[(oligo ethylene glycol) methyl ether methacrylate] (POEGMA) as the hydrophilic block. Two types of polylactones, i.e., semicrystalline poly(ε-caprolactone) (PCL) and amorphous poly(δ-decalactone) (PDL), respectively, were incorporated as the hydrophobic segment in the block copolymers. Using transmission electron microscopy, we characterized the self-assembled nanostructures formed by these amphiphilic block copolymers in mixtures of water/tetrahydrofuran or water/dimethylformamide. All of these polymers remained highly fluorescent in water, although some extent of aggregation-induced fluorescence quenching was still observed. Among the three types of polymers presented here, the polymer (RPO-3) containing an amorphous block of PDL showed the highest drug-loading capacity and the largest extent of drug release in acidic media. RPO-3 micelles loaded with doxorubicin as a model of anticancer drug showed sustainable intracellular release and cytotoxicity against HeLa cells. Full article
(This article belongs to the Special Issue Polymer Characterization)
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15 pages, 2064 KiB  
Article
Two Orders of Magnitude Variation of Diffusion-Enhanced Förster Resonance Energy Transfer in Polypeptide Chains
by Maik H. Jacob, Indrajit Ghosh, Roy N. D’Souza and Werner M. Nau
Polymers 2018, 10(10), 1079; https://doi.org/10.3390/polym10101079 - 29 Sep 2018
Cited by 2 | Viewed by 3356
Abstract
A flexible peptide chain displays structural and dynamic properties that correspond to its folding and biological activity. These properties are mirrored in intrachain site-to-site distances and diffusion coefficients of mutual site-to-site motion. Both distance distribution and diffusion determine the extent of Förster resonance [...] Read more.
A flexible peptide chain displays structural and dynamic properties that correspond to its folding and biological activity. These properties are mirrored in intrachain site-to-site distances and diffusion coefficients of mutual site-to-site motion. Both distance distribution and diffusion determine the extent of Förster resonance energy transfer (FRET) between two sites labeled with a FRET donor and acceptor. The relatively large Förster radii of traditional FRET methods (R0 > 20 Å) lead to a fairly low contribution of diffusion. We introduced short-distance FRET (sdFRET) where Dbo, an asparagine residue conjugated to 2,3-diazabicyclo[2.2.2]octane, acts as acceptor paired with donors, such as naphtylalanine (NAla), tryptophan, 5-l-fluorotryptophan, or tyrosine. The Förster radii are always close to 10 Å, which makes sdFRET highly sensitive to diffusional motion. We recently found indications that the FRET enhancement caused by diffusion depends symmetrically on the product of the radiative fluorescence lifetime of the donor and the diffusion coefficient. In this study, we varied this product by two orders of magnitude, using both donors of different lifetime, NAla and FTrp, as well as a varying viscogen concentration, to corroborate this statement. We demonstrate the consequences of this relationship in evaluating the impact of viscogenic coadditives on peptide dimensions. Full article
(This article belongs to the Special Issue Polymer Characterization)
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10 pages, 2024 KiB  
Article
Conformational Transitions of Polymer Chains in Solutions Characterized by Fluorescence Resonance Energy Transfer
by Linlin Qin, Linling Li, Ye Sha, Ziyu Wang, Dongshan Zhou, Wei Chen and Gi Xue
Polymers 2018, 10(9), 1007; https://doi.org/10.3390/polym10091007 - 10 Sep 2018
Cited by 10 | Viewed by 4297
Abstract
The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and [...] Read more.
The critical overlap concentration C* is an important concept in polymer solutions and is defined as the boundary between dilute and semidilute regimes. In this study, the chain conformational changes of polystyrene (PS) with both high (Mn = 200,000 Da) and low (Mn = 13,000 Da) molecular weights in cis-decalin were compared by intrachain fluorescence resonance energy transfer (FRET). The random labeling of donor and acceptor chromophores strategy was employed for long PS chains, whereas chain-end labeling was used for short PS chains. By monitoring the spectroscopic intensity ratio between acceptor and donor, the concentration dependence on chain conformation from dilute to semidilute solutions was determined. Both long and short chains exhibit a conformational transition concentration, above which the polymer chains begin to collapse with concentration significantly. Interestingly, for randomly labeled polymer long chains, such concentration is consistent with C* determined from the viscosity result, below which only slight conformational change of polymer chain takes place. However, for the chain-end labeled short chain, the conformational transition concentration takes place earlier than C*, below which no significant polymer conformation change is observed. Full article
(This article belongs to the Special Issue Polymer Characterization)
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8 pages, 850 KiB  
Communication
Intrinsic Fluorescence of PAMAM Dendrimers—Quenching Studies
by Malgorzata Konopka, Anna Janaszewska and Barbara Klajnert-Maculewicz
Polymers 2018, 10(5), 540; https://doi.org/10.3390/polym10050540 - 17 May 2018
Cited by 17 | Viewed by 3949
Abstract
Intrinsic, non-traditional fluorescence of polyamidoamine (PAMAM) dendrimers that do not possess classical fluorophores has been attracting considerable interest for the last decade. Many hypotheses regarding the source of the fluorescence have appeared, but some of them are still disputable. In order to shed [...] Read more.
Intrinsic, non-traditional fluorescence of polyamidoamine (PAMAM) dendrimers that do not possess classical fluorophores has been attracting considerable interest for the last decade. Many hypotheses regarding the source of the fluorescence have appeared, but some of them are still disputable. In order to shed new light on the nature of the phenomenon, we applied quenchers that are normally used to study intrinsic fluorescence of proteins (i.e., KI, CsCl, and acrylamide). KI and acrylamide efficiently quenched steady state fluorescence of PAMAM G2, PAMAM G3, and PAMAM G4 dendrimers. Stern-Volmer plots exhibited a downward curvature that has been elucidated by heterogenous emission. We assume that there are two distinct fluorescent moieties in the dendrimer structure that are characterized by different accessibility to the quenchers. Full article
(This article belongs to the Special Issue Polymer Characterization)
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15 pages, 3663 KiB  
Article
Long Range Polymer Chain Dynamics of Highly Flexible Polysiloxane in Solution Probed by Pyrene Excimer Fluorescence
by Janine L. Thoma, Jean Duhamel, Michael J. Bertocchi and Richard G. Weiss
Polymers 2018, 10(4), 345; https://doi.org/10.3390/polym10040345 - 21 Mar 2018
Cited by 10 | Viewed by 5425
Abstract
A poly(dimethylsiloxane-co-(3-aminopropyl)methylsiloxane) polymer (PDMS with 20.3 mol % of (3-aminopropyl)methyl siloxane monomer) has been labeled randomly with 1-pyreneacetyl groups to generate a series of polysiloxanes (Py-PDMS) with pyrenyl contents ranging from 0.7 mol % to 5.2 mol % of the total [...] Read more.
A poly(dimethylsiloxane-co-(3-aminopropyl)methylsiloxane) polymer (PDMS with 20.3 mol % of (3-aminopropyl)methyl siloxane monomer) has been labeled randomly with 1-pyreneacetyl groups to generate a series of polysiloxanes (Py-PDMS) with pyrenyl contents ranging from 0.7 mol % to 5.2 mol % of the total number of structural units. The remainder of the amino groups were acetylated to avoid intra-chain quenching of the excited singlet states of pyrene via exciplex formation with free amino groups while allowing the formation of excimers to proceed. The fluorescence spectra and temporal decays of the Py-PDMS samples were acquired in tetrahydrofuran (THF), N,N-dimethylformamide (DMF), and dioxane. <kMF>blob, the average rate constant for intra-chain pyrene excimer formation, was determined from the analysis of the fluorescence decays. <kMF>blob was found to equal 1.16 (±0.13) × 109, 1.14 (±0.12) × 109, and 0.99 (±0.10) × 109 s−1 in THF, DMF, and dioxane, respectively, at room temperature. They are the largest values found to date for any polymeric backbone in these solvents. The qualitative relationship found here between <kMF>blob and the chemical structures of the polymers indicates that the luminescence characteristics of randomly labeled polymers is a very useful method to probe the long range dynamics of chains of almost any polymer that is amenable to substitution by a lumophore. Full article
(This article belongs to the Special Issue Polymer Characterization)
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4069 KiB  
Article
A Cationic Smart Copolymer for DNA Binding
by Tânia Ribeiro, Ana Margarida Santiago, Jose Manuel Gaspar Martinho and Jose Paulo Farinha
Polymers 2017, 9(11), 576; https://doi.org/10.3390/polym9110576 - 04 Nov 2017
Cited by 1 | Viewed by 5063
Abstract
A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethylene [...] Read more.
A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT) polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA), with the ratio DEGMA/OEGMA being used to choose the volume phase transition temperature of the polymer in water, tunable from ca. 25 to above 90 °C. The second block, of trimethyl-2-methacroyloxyethylammonium chloride (TMEC), is positively charged at physiological pH values and is used for DNA binding. The coacervate complexes between the block copolymer and a model single strand DNA are characterized by fluorescence correlation spectroscopy and fluorescence spectroscopy. The new materials offer good prospects for biomedical application, for example in controlled gene delivery. Full article
(This article belongs to the Special Issue Polymer Characterization)
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6809 KiB  
Article
Poly(tris(4-carbazoyl-9-ylphenyl)amine)/Three Poly(3,4-ethylenedioxythiophene) Derivatives in Complementary High-Contrast Electrochromic Devices
by Chung-Wen Kuo, Jeng-Kuei Chang, Yuan-Chung Lin, Tzi-Yi Wu, Po-Ying Lee and Tsung-Han Ho
Polymers 2017, 9(10), 543; https://doi.org/10.3390/polym9100543 - 23 Oct 2017
Cited by 16 | Viewed by 5017
Abstract
A carbazole-based polymer (poly(tris(4-carbazoyl-9-ylphenyl)amine) (PtCz)) is electrosynthesized on an indium tin oxide (ITO) electrode. PtCz film displays light yellow at 0.0 V, earthy yellow at 1.3 V, grey at 1.5 V, and dark grey at 1.8 V in 0.2 M LiClO4/ACN/DCM [...] Read more.
A carbazole-based polymer (poly(tris(4-carbazoyl-9-ylphenyl)amine) (PtCz)) is electrosynthesized on an indium tin oxide (ITO) electrode. PtCz film displays light yellow at 0.0 V, earthy yellow at 1.3 V, grey at 1.5 V, and dark grey at 1.8 V in 0.2 M LiClO4/ACN/DCM (ACN/DCM = 1:3, by volume) solution. The ΔT and coloration efficiency (η) of PtCz film are 30.5% and 54.8 cm2∙C−1, respectively, in a solution state. Three dual-type electrochromic devices (ECDs) are fabricated using the PtCz as the anodic layer, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3,3-dimethyl-3,4-dihydro-thieno[3,4-b][1,4]dioxepine) (PProDOT-Me2), and poly(3,4-(2,2-diethylpropylenedioxy)thiophene) (PProDOT-Et2) as the cathodic layers. PtCz/PProDOT-Me2 ECD shows high ΔTmax (36%), high ηmax (343.4 cm2·C−1), and fast switching speed (0.2 s) at 572 nm. In addition, PtCz/PEDOT, PtCz/PProDOT-Me2, and PtCz/PProDOT-Et2 ECDs show satisfactory open circuit memory and long-term stability. Full article
(This article belongs to the Special Issue Polymer Characterization)
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Review

Jump to: Research

24 pages, 7124 KiB  
Review
Energy Transfer in Dendritic Systems Having Pyrene Peripheral Groups as Donors and Different Acceptor Groups
by Pasquale Porcu, Mireille Vonlanthen, Andrea Ruiu, Israel González-Méndez and Ernesto Rivera
Polymers 2018, 10(10), 1062; https://doi.org/10.3390/polym10101062 - 25 Sep 2018
Cited by 15 | Viewed by 3763
Abstract
In this feature article, a specific overview of resonance energy transfer (FRET) in dendritic molecules was performed. We focused mainly on constructs bearing peripheral pyrene groups as donor moieties using different acceptor groups, such as porphyrin, fullerene C60, ruthenium-bipyridine complexes, and [...] Read more.
In this feature article, a specific overview of resonance energy transfer (FRET) in dendritic molecules was performed. We focused mainly on constructs bearing peripheral pyrene groups as donor moieties using different acceptor groups, such as porphyrin, fullerene C60, ruthenium-bipyridine complexes, and cyclen-core. We have studied the effect of all the different donor-acceptor pairs in the energy transfer efficiency (FRET). In all cases, high FRET efficiency values were observed. Full article
(This article belongs to the Special Issue Polymer Characterization)
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14 pages, 5763 KiB  
Review
A Radio-Fluorogenic Polymer-Gel Makes Fixed Fluorescent Images of Complex Radiation Fields
by John M. Warman, Matthijs P. De Haas, Leonard H. Luthjens, Antonia G. Denkova and Tiantian Yao
Polymers 2018, 10(6), 685; https://doi.org/10.3390/polym10060685 - 20 Jun 2018
Cited by 8 | Viewed by 3267
Abstract
We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., [...] Read more.
We review the development and application of an organic polymer-gel capable of producing fixed, three-dimensional fluorescent images of complex radiation fields. The gel consists for more than 99% of γ-ray-polymerized (~15% conversion) tertiary-butyl acrylate (TBA) containing ~100 ppm of a fluorogenic compound, e.g., maleimido-pyrene (MPy). The radio-fluorogenic effect depends on copolymerization of the MPy into growing chains of TBA on radiation-induced polymerization. This converts the maleimido residue, which quenches the pyrene fluorescence, into a succinimido moeity (SPy), which does not. The intensity of the fluorescence is proportional to the yield of free-radicals formed and hence to the local dose deposited. Because the SPy moieties are built into the polymer network, the image is fixed. The method of preparing the gel and imaging the radiation-induced fluorescence are presented and discussed. The effect is illustrated with fluorescent images of the energy deposited in the gel by beams of X-rays, electrons, and protons as well as a radioactive isotope. Full article
(This article belongs to the Special Issue Polymer Characterization)
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