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Eslami M, Zeglio E, Alosaimi G, Yan Y, Ruprai H, Macmillan A, Seidel J, Lauto A, Joukhdar H, Rnjak-Kovacina J, Mawad D. A One Step Procedure toward Conductive Suspensions of Liposome-Polyaniline Complexes. Macromol Biosci 2020; 20:e2000103. [PMID: 32537900 DOI: 10.1002/mabi.202000103] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 05/21/2020] [Indexed: 11/07/2022]
Abstract
Interaction of conjugated polymers with liposomes is an attractive approach that benefits from both systems' characteristics such as electroactivity and enhanced interaction with cells. Conjugated polymer-liposome complexes have been investigated for bioimaging, drug delivery, and photothermal therapy. Their fabrication has largely been achieved by multistep procedures that require first the synthesis and processing of the conjugated polymer. Here, a new one step fabrication approach is reported based on in situ polymerization of a conjugated monomer precursor around liposomes. Polyaniline (PANI) doped with phytic acid is synthesized via oxidative polymerization in the presence of 1,2-dioleoyl-sn-glycero-3-phosphatidylcholine (DOPC) vesicles to produce a conductive aqueous suspension of Liposome-PANI complexes. PANI interacts with liposomes without disrupting the bilayer as shown using differential scanning calorimetry and fluorescence quenching studies of the hydrophobic Nile red probe. The electronic conductivity of the Liposome-PANI complexes, which stems from the doped PANI accessible on the liposome surface, is confirmed using conductive atomic force microscopy and electrochemical impedance spectroscopy. Further, short-term in vitro cell studies show that the complexes colocalize with the cell membrane without reducing cell proliferation. This study presents a novel fabrication route to conductive suspensions of conjugated polymer-liposome complexes suitable for potential applications at the biointerface.
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Affiliation(s)
- Minoo Eslami
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Centre for Advanced Macromolecular Design, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Erica Zeglio
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Centre for Advanced Macromolecular Design, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Division of Micro and Nanosystems, KTH Royal Institute of Technology, Stockholm, 10044, Sweden
| | - Ghaida Alosaimi
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- School of Chemistry, Taif University, Taif, 26571, Kingdom of Saudi Arabia
| | - Yihan Yan
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Centre for Advanced Macromolecular Design, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Herleen Ruprai
- School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Alexander Macmillan
- Biomedical Imaging Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Jan Seidel
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Antonio Lauto
- School of Science, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Habib Joukhdar
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Jelena Rnjak-Kovacina
- Graduate School of Biomedical Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
| | - Damia Mawad
- School of Materials Science and Engineering, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Centre for Advanced Macromolecular Design, UNSW Sydney, Sydney, New South Wales, 2052, Australia
- Australian Centre for Nano Medicine and ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, UNSW Sydney, Sydney, New South Wales, 2052, Australia
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2
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Hassoun S, Karam P. Fluorescent-Based Thermal Sensing in Lipid Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:1221-1226. [PMID: 31941281 DOI: 10.1021/acs.langmuir.9b03128] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Thermal mapping in biological membranes could unlock and help us understand many chemical and physical processes that do not only pertain to localized membrane phenomena but also extend to many other intra- and extracellular pathways. In this manuscript, we report the development of a ratiometric thermal fluorescent probe based on the Förster resonance energy transfer between a lipid-embedded conjugated polyelectrolyte and a lyophilic acceptor dye. We showed that the Förster resonance energy transfer (FRET) pair is sensitive within the relevant physiological temperature window (20.0-50.0 °C). The signal was also shielded from an external pH and stable when cycled multiple times. The probe was also sensitive to the membrane composition and could, therefore, be further developed to probe the membrane composition and viscosity.
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Affiliation(s)
- Sarriah Hassoun
- Chemistry Department , American University of Beirut , P.O. Box 11-0236, Riad El-Solh , 1107 2020 Beirut , Lebanon
| | - Pierre Karam
- Chemistry Department , American University of Beirut , P.O. Box 11-0236, Riad El-Solh , 1107 2020 Beirut , Lebanon
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3
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Sarkar Y, Roy S, Majumder R, Das S, Bhalani DV, Ray A, Jewrajka SK, Parui PP. Protonation-induced pH increase at the triblock copolymer micelle interface for transient membrane permeability at neutral pH. SOFT MATTER 2020; 16:798-809. [PMID: 31834342 DOI: 10.1039/c9sm01002e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Achieving controlled membrane permeability using pH-responsive block copolymers is crucial for selective intercellular uptake. We have shown that the pH at the triblock-copolymer micelle interface as compared to its bulk pH can help regulate membrane permeability. The pH-dependent acid/base equilibriums of two different interface-interacting pH probes were determined in order to measure the interfacial pH for a pH-responsive triblock copolymer (TBP) micelle under a wide range of bulk pH (4.5-9.0). According to 1H NMR studies, both pH probes provided interfacial pH at a similar interfacial depth. We revealed that the protonation of the amine moiety at the micelle interface and the subsequent formation of a positive charge caused the interface to become relatively less acidic than that of the bulk as well as an increase in the bulk-to-interfacial pH deviation (ΔpH) from ∼0.9 to 1.9 with bulk pH reducing from 8.0 to 4.5. From the ΔpH vs. interface and bulk pH plots, the apparent and intrinsic protonations or positive charge formation pKa values for the micelle were estimated to be ∼7.3 and 6.0, respectively. When the TBP micelle interacted with an anionic large unilamellar vesicle (LUV) of a binary lipid (neutral and anionic) system at the bulk pH of 7.0, fluorescence leakage studies revealed that the pH increase at the micelle interface from that of the LUV interface (pH ∼ 5.5) made the micelle interface partially protonated/cationic, thereby exhibiting transient membrane permeability. Although the increasing interface protonation causes the interface to become relatively less acidic than the bulk at any bulk pH below 6.5, the pH increase at the micelle interface may not be sufficiently large to maintain the threshold for the amine-protonated condition for effecting transient leakage and therefore, a continuous leakage was observed due to the slow disruption of the lipid bilayer.
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Affiliation(s)
- Yeasmin Sarkar
- Department of Chemistry, Jadavpur University, Kolkata 700032, India.
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4
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Yassine SR, Hassoun SA, Karam P. Fluorescent thermal sensing using conjugated polyelectrolytes in thin polymer films. Anal Chim Acta 2019; 1077:249-254. [PMID: 31307716 DOI: 10.1016/j.aca.2019.05.046] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2018] [Revised: 04/20/2019] [Accepted: 05/20/2019] [Indexed: 01/23/2023]
Abstract
Thermal sensing in thin films polymers has been a significant limitation towards optimizing the heat dissipation in micro- and nano-electronic devices as well as many other thin film-based technologies. In this work, we report on poly (phenylene ethynylene) fluorescent-based conjugated polyelectrolyte capable of detecting thermal fluctuations in polymer films prepared from polyvinylpyrrolidone-co-vinyl acetate. The sensor was first optimized in solution by testing two polyvinylpyrrolidone (PVP) copolymers (co-vinyl acetate (VA) and co-polystyrene (PS)) before it was spun cast onto quartz slides and imaged using a DSLR camera at different temperatures. The images were analyzed and showed a change in color with the increase in temperature. When not illuminated, the polymer thin film is clear and transparent.
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Affiliation(s)
- Sarah R Yassine
- Chemistry Department, American University of Beirut, P.O.Box 11-0236, Riad El-Solh, 1107 2020, Beirut, Lebanon
| | - Sarriah A Hassoun
- Chemistry Department, American University of Beirut, P.O.Box 11-0236, Riad El-Solh, 1107 2020, Beirut, Lebanon
| | - Pierre Karam
- Chemistry Department, American University of Beirut, P.O.Box 11-0236, Riad El-Solh, 1107 2020, Beirut, Lebanon.
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5
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Zhang B, Wang F, Zhou H, Gao D, Yuan Z, Wu C, Zhang X. Polymer Dots Compartmentalized in Liposomes as a Photocatalyst for In Situ Hydrogen Therapy. Angew Chem Int Ed Engl 2019; 58:2744-2748. [DOI: 10.1002/anie.201813066] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Indexed: 11/06/2022]
Affiliation(s)
- Boyu Zhang
- Faculty of Health SciencesUniversity of Macau Macau SAR China
- College of Medical LaboratoryDalian Medical University Dalian Liaoning 116044 China
| | - Fei Wang
- Department of Biomedical EngineeringSouthern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Hua Zhou
- Faculty of Health SciencesUniversity of Macau Macau SAR China
| | - Duyang Gao
- Paul C. Lauterbur Research Center for Biomedical ImagingInstitute of Biomedical and Health EngineeringShenzhen Institute of Advanced TechnologyChinese Academy of Science Shenzhen 518055 China
| | - Zhen Yuan
- Faculty of Health SciencesUniversity of Macau Macau SAR China
| | - Changfeng Wu
- Department of Biomedical EngineeringSouthern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Xuanjun Zhang
- Faculty of Health SciencesUniversity of Macau Macau SAR China
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6
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Zhang B, Wang F, Zhou H, Gao D, Yuan Z, Wu C, Zhang X. Polymer Dots Compartmentalized in Liposomes as a Photocatalyst for In Situ Hydrogen Therapy. Angew Chem Int Ed Engl 2019. [DOI: 10.1002/ange.201813066] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Boyu Zhang
- Faculty of Health SciencesUniversity of Macau Macau SAR China
- College of Medical LaboratoryDalian Medical University Dalian Liaoning 116044 China
| | - Fei Wang
- Department of Biomedical EngineeringSouthern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Hua Zhou
- Faculty of Health SciencesUniversity of Macau Macau SAR China
| | - Duyang Gao
- Paul C. Lauterbur Research Center for Biomedical ImagingInstitute of Biomedical and Health EngineeringShenzhen Institute of Advanced TechnologyChinese Academy of Science Shenzhen 518055 China
| | - Zhen Yuan
- Faculty of Health SciencesUniversity of Macau Macau SAR China
| | - Changfeng Wu
- Department of Biomedical EngineeringSouthern University of Science and Technology Shenzhen Guangdong 518055 China
| | - Xuanjun Zhang
- Faculty of Health SciencesUniversity of Macau Macau SAR China
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7
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Calver CF, Schanze KS, Cosa G. Biomimetic Light-Harvesting Antenna Based on the Self-Assembly of Conjugated Polyelectrolytes Embedded within Lipid Membranes. ACS NANO 2016; 10:10598-10605. [PMID: 27934088 DOI: 10.1021/acsnano.6b07111] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Here we report a biomimetic light-harvesting antenna based on negatively charged poly(phenylene ethynylene) conjugated polyelectrolytes assembled within a positively charged lipid membrane scaffold constructed by the lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). Light harvested by the polymers was transferred via through-space mechanisms to a lipophilic energy acceptor (the cyanine dye DiI) whose effective molar absorption was enhanced by up to 18-fold due to the antenna effect. Absorption amplification of DiI was found to be due primarily to direct energy transfer from polymers. The efficiency of homoenergy transfer among polymers was next probed by the membrane embedding fullerene derivative phenyl-C61-butryic acid methyl ester (PCBM) acting as an electron acceptor. PCBM was able to quench the emission of up to five polymers, consistent with a modest amount of homotransfer. The ability of the membrane to accommodate a high density of polymer donors without self-quenching was crucial to the success of electronic energy harvesting achieved. This work highlights the potential of lipid membranes as a platform to organize light-harvesting molecules on the nanoscale toward achieving efficient energy transfer to a target chromophore/trap.
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Affiliation(s)
- Christina F Calver
- Department of Chemistry and Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
| | - Kirk S Schanze
- Department of Chemistry, University of Texas at San Antonio , One UTSA Way, San Antonio, Texas 78023, United States
| | - Gonzalo Cosa
- Department of Chemistry and Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Quebec H3A 0B8, Canada
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8
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Zeglio E, Schmidt MM, Thelakkat M, Gabrielsson R, Solin N, Inganäs O. Conjugated Polyelectrolyte Blend as Photonic Probe of Biomembrane Organization. ChemistrySelect 2016. [DOI: 10.1002/slct.201600920] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Erica Zeglio
- Department of Physics, Chemistry and Biology; Linköping University; SE-581 83 Linköping Sweden
| | - Martina M. Schmidt
- Chemistry I-Applied Functional Polymers; University of Bayreuth; Universitätsstrasse 30 95440 Bayreuth Germany
| | - Mukundan Thelakkat
- Chemistry I-Applied Functional Polymers; University of Bayreuth; Universitätsstrasse 30 95440 Bayreuth Germany
| | - Roger Gabrielsson
- Department of Science and Technology; Linköping University, Campus Norrköping; S-60174 Norrköping Sweden
| | - Niclas Solin
- Department of Physics, Chemistry and Biology; Linköping University; SE-581 83 Linköping Sweden
| | - Olle Inganäs
- Department of Physics, Chemistry and Biology; Linköping University; SE-581 83 Linköping Sweden
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9
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Houston JE, Kraft M, Mooney I, Terry AE, Scherf U, Evans RC. Charge-Mediated Localization of Conjugated Polythiophenes in Zwitterionic Model Cell Membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:8141-8153. [PMID: 27434827 DOI: 10.1021/acs.langmuir.6b01828] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The selective engineering of conjugated polyelectrolyte (CPE)-phospholipid interfaces is poised to play a key role in the design of advanced biomedical and biotechnological devices. Herein, we report a strategic study to investigate the relationship between the charge of the CPE side group and their association with zwitterionic phospholipid bilayers. The interaction of dipalmitoylphosphatidylcholine (DPPC) phospholipid vesicles with a series of poly(thiophene)s bearing zwitterionic, cationic, or anionic terminal groups (P3Zwit, P3TMAHT and P3Anionic, respectively) has been probed. Although all CPEs showed an affinity for the zwitterionic vesicles, the calculated partition coefficients determined using photoluminescence spectroscopy suggested preferential incorporation within the lipid bilayer in the order P3Zwit > P3Anionic ≫ P3TMAHT. The polarity probe Prodan was used to further qualify the position of the CPE inside the vesicle bilayers via Förster resonance energy transfer (FRET) studies. The varying proximity of the CPEs to Prodan was reflected in the Stern-Volmer quenching constants and decreased in the order P3Anionic > P3TMAHT ≫ P3Zwit. Dynamic light scattering measurements showed an increase in the hydrodynamic diameter of the DPPC vesicles upon addition of each poly(thiophene), but to the greatest extent for P3Anionic. Small-angle neutron scattering studies also revealed that P3Anionic specifically increased the thickness of the headgroup region of the phospholipid bilayer. Epifluorescence and atomic force microscopy imaging showed that P3TMAHT formed amorphous agglomerates on the vesicle surface, P3Zwit was buried throughout the bilayer, and P3Anionic formed a shell of protruding chains around the surface, which promoted vesicle fusion. The global data indicate three distinctive modes of interaction for the poly(thiophene)s within DPPC vesicles, whereby the nature of the association is ultimately controlled by the pendant charge group on each CPE chain. Our results suggest that charge-mediated self-assembly may provide a simple and effective route to design luminescent CPE probes capable of specific localization within phospholipid membranes.
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Affiliation(s)
- Judith E Houston
- School of Chemistry and CRANN, University of Dublin, Trinity College , College Green, Dublin 2, Ireland
| | - Mario Kraft
- Macromolecular Chemistry Group (Buwmakro) and Institute for Polymer Technology, Bergische Universität Wuppertal , Gauss-Str. 20, D-42119 Wuppertal, Germany
| | - Ian Mooney
- School of Chemistry and CRANN, University of Dublin, Trinity College , College Green, Dublin 2, Ireland
| | - Ann E Terry
- ISIS, STFC, Rutherford Appleton Laboratory, Didcot, Oxon OX11 0QX, U.K
| | - Ullrich Scherf
- Macromolecular Chemistry Group (Buwmakro) and Institute for Polymer Technology, Bergische Universität Wuppertal , Gauss-Str. 20, D-42119 Wuppertal, Germany
| | - Rachel C Evans
- School of Chemistry and CRANN, University of Dublin, Trinity College , College Green, Dublin 2, Ireland
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10
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Chen Z, Wu P, Cong R, Xu N, Tan Y, Tan C, Jiang Y. Sensitive Conjugated-Polymer-Based Fluorescent ATP Probes and Their Application in Cell Imaging. ACS APPLIED MATERIALS & INTERFACES 2016; 8:3567-74. [PMID: 26393287 DOI: 10.1021/acsami.5b06935] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Three cationic conjugated polyelectrolytes (CPEs) with a common poly(p-phenylene ethynylene terthiophene) backbone and side chains of different lengths, named as PPET3-N1, PPET3-N2, and PPET3-N3, were designed and synthesized. The UV-vis absorption and fluorescence spectra of the polymers vary strongly with solvent composition, suggesting that the polymers are strongly aggregated in H2O. In addition, the spectroscopic properties of the polymers are affected by small-molecule ATP, characterized by significant fluorescence intensity decreases and red shifts of their absorption bands. Further application of these polymers in cell imaging was studied by confocal fluorescence microscopy, which demonstrated that all of the polymers were localized on the cell membrane and partially inside of cells and that the staining effect gradually increased with the length of the polymer side chains. On the basis of the low cytotoxicity and efficient quenching of PPET3-N2 by ATP, the dose and time effects of ATP on PPET3-N2 imaging were studied, and the results indicated that this polymer might have potential in cell imaging for ATP semiquantification in vivo.
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Affiliation(s)
- Zhifang Chen
- Department of Chemistry, Tsinghua University , Beijing 100084, P. R. China
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
| | - Pan Wu
- Department of Chemistry, Tsinghua University , Beijing 100084, P. R. China
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
| | - Rong Cong
- Cranbrook Kingswood Upper School , Bloomfield Hills, Michigan 48304, United States
| | - Naihan Xu
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
| | - Ying Tan
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
| | - Chunyan Tan
- Department of Chemistry, Tsinghua University , Beijing 100084, P. R. China
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
| | - Yuyang Jiang
- The Ministry-Province Jointly Constructed Base for State Key Lab, Shenzhen Key Laboratory of Chemical Biology, Graduate School at Shenzhen, Tsinghua University , Shenzhen 518055, P. R. China
- Department of Pharmacology and Pharmaceutical Sciences, School of Medicine, Tsinghua University , Beijing 100084, P. R. China
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11
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Chan K, Yik-Sham Chung C, Wing-Wah Yam V. Parallel folding topology-selective label-free detection and monitoring of conformational and topological changes of different G-quadruplex DNAs by emission spectral changes via FRET of mPPE-Ala-Pt(ii) complex ensemble. Chem Sci 2016; 7:2842-2855. [PMID: 30090278 PMCID: PMC6055111 DOI: 10.1039/c5sc04563k] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2015] [Accepted: 01/05/2016] [Indexed: 12/28/2022] Open
Abstract
The formation of supramolecular assemblies between [Pt(bzimpy-Et){C[triple bond, length as m-dash]CC6H4(CH2NMe3-4)}]Cl2 (1) and mPPE-Ala and the FRET properties of the ensemble have been revealed from the UV-vis absorption, steady-state emission and time-resolved emission decay studies. The two-component mPPE-Ala-1 ensemble has been employed in a "proof-of-principle" concept for label-free detection of G-quadruplex DNAs with the intramolecular propeller parallel folding topology, such as c-myc, in aqueous buffer solution. By the modulation of the aggregation/deaggregation of the polymer-metal complex aggregates and hence the FRET from the mPPE-Ala donor to the aggregated 1 as acceptor, the ensemble has been demonstrated for sensitive and selective label-free detection of c-myc via the monitoring of emission spectral changes of the ensemble. Ratiometric emission of the ensemble at 461 and 662 nm has been shown to distinguish the intramolecular propeller parallel G-quadruplex folding topology of c-myc from other G-quadruplex-forming sequences of different folding topologies, owing to the strong and specific interactions between c-myc and 1 as suggested by the UV-vis absorption and UV melting studies. In addition, the formation of high-order intermolecular multimeric G-quadruplexes from c-myc under molecular crowding conditions has been successfully probed by the ratiometric emission of the ensemble. The conformational and topological transition of human telomeric DNA from the mixed-hybrid form to the intramolecular propeller parallel form, as observed from the circular dichroism spectroscopy, has also been monitored by the ratiometric emission of the ensemble. The ability of the ensemble to detect these conformational and topological transitions of G-quadruplex DNAs has been rationalized by the excellent selectivity and sensitivity of the ensemble towards the intramolecular propeller parallel G-quadruplex DNAs and their high-order intermolecular multimers, which are due to the extra stabilization gained from Pt···Pt and π-π interactions in addition to the electrostatic and hydrophobic interactions found in the polymer-metal complex aggregates.
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Affiliation(s)
- Kevin Chan
- Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee (Hong Kong)) , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , P. R. China .
| | - Clive Yik-Sham Chung
- Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee (Hong Kong)) , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , P. R. China .
| | - Vivian Wing-Wah Yam
- Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee (Hong Kong)) , Department of Chemistry , The University of Hong Kong , Pokfulam Road , Hong Kong , P. R. China .
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12
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Darwish GH, Koubeissi A, Shoker T, Abou Shaheen S, Karam P. Turning the heat on conjugated polyelectrolytes: an off–on ratiometric nanothermometer. Chem Commun (Camb) 2016; 52:823-6. [DOI: 10.1039/c5cc08541a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
A ratiometric single component nanothermometer fluorescent probe.
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Affiliation(s)
| | - Ali Koubeissi
- The Department of Chemistry
- American University of Beirut
- Lebanon
| | | | | | - Pierre Karam
- The Department of Chemistry
- American University of Beirut
- Lebanon
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13
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Calver CF, Liu HW, Cosa G. Exploiting Conjugated Polyelectrolyte Photophysics toward Monitoring Real-Time Lipid Membrane-Surface Interaction Dynamics at the Single-Particle Level. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:11842-11850. [PMID: 25955885 DOI: 10.1021/acs.langmuir.5b00979] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Herein we report the real-time observation of the interaction dynamics between cationic liposomes flowing in solution and a surface-immobilized charged scaffolding formed by the deposition of conjugated polyanion poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene (MPS-PPV) onto 100-nm-diameter SiO2 nanoparticles (NPs). Contact of the freely floating liposomes with the polymer-coated surfaces led to the formation of supported lipid bilayers (SLBs). The interaction of the incoming liposomes with MPS-PPV adsorbed on individual SiO2 nanoparticles promoted the deaggregation of the polymer conformation and led to large emission intensity enhancements. Single-particle total internal reflection fluorescence microscopy studies exploited this phenomenon as a way to monitor the deformation dynamics of liposomes on surface-immobilized NPs. The MPS-PPV emission enhancement (up to 25-fold) reflected on the extent of membrane contact with the surface of the NP and was correlated with the size of the incoming liposome. The time required for the MPS-PPV emission to reach a maximum (ranging from 400 to 1000 ms) revealed the dynamics of membrane deformation and was also correlated with the liposome size. Cryo-TEM experiments complemented these results by yielding a structural view of the process. Immediately following the mixing of liposomes and NPs the majority of NPs had one or more adsorbed liposomes, yet the presence of a fully formed SLB was rare. Prolonged incubation of liposomes and NPs showed completely formed SLBs on all of the NPs, confirming that the liposomes eventually ruptured to form SLBs. We foresee that the single-particle studies we report herein may be readily extended to study membrane dynamics of other lipids including cellular membranes in live cell studies and to monitor the formation of polymer-cushioned SLBs.
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Affiliation(s)
- Christina F Calver
- Department of Chemistry and Centre for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Hsiao-Wei Liu
- Department of Chemistry and Centre for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
| | - Gonzalo Cosa
- Department of Chemistry and Centre for Self Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, QC H3A 0B8, Canada
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14
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Darwish GH, Karam P. Nanohybrid conjugated polyelectrolytes: highly photostable and ultrabright nanoparticles. NANOSCALE 2015; 7:15149-15158. [PMID: 26255590 DOI: 10.1039/c5nr03299g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We present a general and straightforward one-step approach to enhance the photophysical properties of conjugated polyelectrolytes. Upon complexation with an amphiphilic polymer (polyvinylpyrrolidone), an anionic conjugated polyelectrolyte (poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene]) was prepared into small nanoparticles with exceptional photostability and brightness. The polymer fluorescence intensity was enhanced by 23 -fold and could be easily tuned by changing the order of addition. Single molecule experiments revealed a complete suppression of blinking. In addition, after only losing 18% of the original intensity, a remarkable amount of photons were emitted per particle (∼10(9), on average). This number is many folds greater than popular organic fluorescent dyes. We believe that an intimate contact between the two polymers is shielding the conjugated polyelectrolyte from the destructive photooxidation. The prepared nanohybrid particles will prove instrumental in single particle based fluorescent assays and can serve as a probe for the current state-of-the-art bioimaging fluorescence techniques.
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Affiliation(s)
- Ghinwa H Darwish
- Department of Chemistry, American University of Beirut, P.O. Box 11-0236, Beirut, Lebanon.
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15
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Elacqua E, Weck M. Fabrication of Supramolecular Semiconductor Block Copolymers by Ring-Opening Metathesis Polymerization. Chemistry 2015; 21:7151-8. [DOI: 10.1002/chem.201406204] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Indexed: 11/06/2022]
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16
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Tapia MJ, Monteserín M, Burrows HD, Almeida JAS, Pais AACC, Pina J, Seixas de Melo JS, Jarmelo S, Estelrich J. From molecular modelling to photophysics of neutral oligo- and polyfluorenes incorporated into phospholipid bilayers. SOFT MATTER 2015; 11:303-317. [PMID: 25411076 DOI: 10.1039/c4sm02145b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The combination of various experimental techniques with theoretical simulations has allowed elucidation of the mode of incorporation of fluorene based derivatives into phospholipid bilayers. Molecular dynamics (MD) simulations on a fully hydrated 1,2-dimyristoyl-sn-glycero-3-phosphatidylcholine (DMPC) bilayer, with benzene (B), biphenyl (BP), fluorene (F) and tri-(9,9-di-n-octylfluorenyl-2,7-diyl), TF, have provided insights into the topography of these molecules when they are present in the phospholipid bilayer, and suggest marked differences between the behavior of the small molecules and the oligomer. Further information on the interaction of neutral fluorenes within the phospholipid bilayer was obtained by an infrared (IR) spectroscopic study of films of DMPC and of the phospholipid with PFO deuterated specifically on its alkyl chains (DMPC-PFO-d34). This was complemented by measurements of the effect of F, TF and two neutral polymers: polyfluorene poly(9,9-di-n-octylfluorenyl-2,7-diyl), PFO, and poly(9,9-di-n-dodecylfluorenyl-2,7-diyl), PFD, on the phospholipid phase transition temperature using differential scanning calorimetry (DSC). Changes in liposome size upon addition of F and PFO were followed by dynamic light scattering. In addition, the spectroscopic properties of F, TF, PFO and PFD solubilised in DMPC liposomes (absorption, steady-state and time-resolved fluorescence) were compared with those of the same probes in typical organic solvents (chloroform, cyclohexane and ethanol). Combining the insight from MD simulations with the results at the molecular level from the various experimental techniques suggests that while the small molecules have a tendency to be located in the phospholipid head group region, the polymers are incorporated within the lipid bilayers, with the backbone predominantly orthogonal to the phospholipid alkyl chains and with interdigitation of them and the PFO alkyl chains.
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Affiliation(s)
- M J Tapia
- Departamento de Química, Universidad de Burgos, Plaza Misael Bañuelos s/n, 09001 Burgos, Spain.
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17
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Karam P, Hariri AA, Calver CF, Zhao X, Schanze KS, Cosa G. Interaction of anionic phenylene ethynylene polymers with lipids: from membrane embedding to liposome fusion. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:10704-10711. [PMID: 25115171 DOI: 10.1021/la502572u] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Here we report spectroscopic studies on the interaction of negatively charged, amphiphilic polyphenylene ethynylene (PPE) polymers with liposomes prepared either from negative, positive or zwitterionic lipids. Emission spectra of PPEs of 7 and 49 average repeat units bearing carboxylate terminated side chains showed that the polymer embeds within positively charged lipids where it exists as free chains. No interaction was observed between PPEs and negatively charged lipids. Here the polymer remained aggregated giving rise to broad emission spectra characteristic of the aggregate species. In zwitterionic lipids, we observed that the majority of the polymer remained aggregated yet a small fraction readily embedded within the membrane. Titration experiments revealed that saturation of zwitterionic lipids with polymer typically occurred at a polymer repeat unit to lipid mole ratio close to 0.05. No further membrane embedding was observed above that point. For liposomes prepared from positively charged lipids, saturation was observed at a PPE repeat unit to lipid mole ratio of ∼0.1 and liposome precipitation was observed above this point. FRET studies showed that precipitation was preceded by lipid mixing and liposome fusion induced by the PPEs. This behavior was prominent for the longer polymer and negligible for the shorter polymer at a repeat unit to lipid mole ratio of 0.05. We postulate that fusion is the consequence of membrane destabilization whereby the longer polymer gives rise to more extensive membrane deformation than the shorter polymer.
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Affiliation(s)
- Pierre Karam
- Department of Chemistry and Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University , 801 Sherbrooke Street West, Montreal, Québec H3A 0B8, Canada
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18
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Interaction between oxidized polyaniline and oppositely charged amphiphilic assemblies in an aqueous/organic biphasic system. J Colloid Interface Sci 2013; 407:516-23. [DOI: 10.1016/j.jcis.2013.06.038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 06/13/2013] [Accepted: 06/14/2013] [Indexed: 11/20/2022]
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19
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Costa T, Garner LE, Knaapila M, Thomas AW, Rogers SE, Bazan GC, Burrows HD. Aggregation properties of p-phenylene vinylene based conjugated oligoelectrolytes with surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:10047-10058. [PMID: 23822142 DOI: 10.1021/la401871x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The amphiphilic properties of conjugated oligoelectrolytes (COE) and their sensitivity to the polarity of their microenvironment lead to interesting aggregation behavior, in particular in their interaction with surfactants. Photoluminescence (PL) spectroscopy, liquid-phase atomic force microscopy, small-angle neutron scattering, small-angle X-ray scattering, and grazing-incidence X-ray diffraction were used to examine interactions between cationic p-phenylene vinylene based oligoelectrolytes and surfactants. These techniques indicate the formation of COE/surfactant aggregates in aqueous solution, and changes in the photophysical properties are observed when compared to pure aqueous solutions. We evaluate the effect of the charge of the surfactant polar headgroup, the size of the hydrophobic chain, and the role of counterions. At low COE concentrations (micromolar), it was found that these COEs display larger emission quantum efficiencies upon incorporation into micelles, along with marked blue-shifts of the PL spectra. This effect is most pronounced in the series of anionic surfactants, and the degree of blue shifts as a function of surfactant charge is as follows: cationic < nonionic < anionic surfactants. In anionic surfactants, such as sodium dodecyl sulfate (SDS), the PL spectra show vibronic resolution above the critical micelle concentration of the surfactant, suggesting more rigid structures. Scattering data indicate that in aqueous solutions, trimers appear as essentially 3-dimensional particles, while tetra- and pentamers form larger, cylindrical particles. When the molar ratio of nonionic C12E5 surfactant to 1,4-bis(4-{N,N-bis-[(N,N,N-trimethylammonium)hexyl]amino}-styryl)benzene tetraiodide (DSBNI) is close to one, the size of the formed DSBNI-C12E5 particles corresponds to the full coverage of individual oligomers. When these particles are transferred into thin films, they organize into a cubic in-plane pattern. If anionic SDS is added, the formed DSBNI-SDS particles are larger than expected for full surfactant coverage, and particles may thus contain several oligomers. This tendency is attributed to the merging of DSBNI oligomers due to the charge screening and, thus, reduced water solubility.
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Affiliation(s)
- Telma Costa
- Chemistry Department, University of Coimbra, Coimbra 3004-535, Portugal.
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20
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Kahveci Z, Martínez-Tomé MJ, Mallavia R, Mateo CR. Use of the Conjugated Polyelectrolyte Poly{[9,9-bis(6′-N,N,N-trimethylammonium)hexyl]fluorene-phenylene} Bromide (HTMA-PFP) as a Fluorescent Membrane Marker. Biomacromolecules 2013; 14:1990-8. [DOI: 10.1021/bm400348n] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Zehra Kahveci
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | | | - Ricardo Mallavia
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
| | - C. Reyes Mateo
- Instituto de Biología Molecular
y Celular, Universidad Miguel Hernández, 03202 Elche, Spain
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21
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Sasaki DY, Zawada N, Gilmore SF, Narasimmaraj P, Sanchez MAA, Stachowiak JC, Hayden CC, Wang HL, Parikh AN, Shreve AP. Lipid membrane domains for the selective adsorption and surface patterning of conjugated polyelectrolytes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:5214-5221. [PMID: 23544969 DOI: 10.1021/la400454c] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Conjugated polyelectrolytes (CPEs) are promising materials for generating optoelectronics devices under environmentally friendly processing conditions, but challenges remain to develop methods to define lateral features for improved junction interfaces and direct optoelectronic pathways. We describe here the potential to use a bottom-up approach that employs self-assembly in lipid membranes to form structures to template the selective adsorption of CPEs. Phase separation of gel phase anionic lipids and fluid phase phosphocholine lipids allowed the formation of negatively charged domain assemblies that selectively adsorb a cationic conjugated polyelectrolyte (P2). Spectroscopic studies found the adsorption of P2 to negatively charged membranes resulted in minimal structural change of the solution phase polymer but yielded an enhancement in fluorescence intensity (~50%) due to loss of quenching pathways. Fluorescence microscopy, dynamic light scattering, and AFM imaging were used to characterize the polymer-membrane interaction and the polymer-bound domain structures of the biphasic membranes. In addition to randomly formed circular gel phase domains, we also show that predefined features, such as straight lines, can be directed to form upon etched patterns on the substrate, thus providing potential routes toward the self-organization of optoelectronic architectures.
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Affiliation(s)
- Darryl Y Sasaki
- Sandia National Laboratories, Livermore, California 94550, USA.
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22
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Dutta K, Mahale RY, Arulkashmir A, Krishnamoorthy K. Reversible assembly and disassembly of micelles by a polymer that switches between hydrophilic and hydrophobic wettings. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:10097-10104. [PMID: 22690803 DOI: 10.1021/la301760a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Supramolecular complexes involving nanoscopic amphiphilic assemblies (AAs) and polyelectrolytes have been used to prepare a variety of materials, wherein the dynamic AAs retain the structural features, but the polyelectrolytes undergo conformational changes. Here we show that a charge bearing rigid conjugated polymer can alter the structural features and disassemble AAs. We also demonstrate reversible assembly and disassembly of AAs by controlling the number of charges on the rigid polymer. During the disassembly, the guest molecules sequestered in the AAs are released. The rate of release has been modulated by changing the morphology of the charge bearing polymer. Concomitant to the AAs disassembly, the polymer surface becomes hydrophobic due to the binding of the amphiphiles on the charges of the polymer backbone. By controlling the charges on the polymer, the surface wettability was varied gradually from hydrophilic to hydrophobic.
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Affiliation(s)
- Kingshuk Dutta
- Polymers and Advanced Materials Laboratory, CSIR-National Chemical Laboratory-Pune, Pune, Maharashtra, India
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23
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Brasch M, Cornelissen JJLM. Relative size selection of a conjugated polyelectrolyte in virus-like protein structures. Chem Commun (Camb) 2011; 48:1446-8. [PMID: 22121498 DOI: 10.1039/c1cc13185k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A conjugated polyelectrolyte poly[(2-methoxy-5-propyloxy sulfonate)-phenyl-ene vinylene] (MPS-PPV) drives the assembly of virus capsid proteins to form single virus-like particles (VLPs) and aggregates with more than two VLPs, with a relative selection of high molecular weight polymer in the latter.
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Affiliation(s)
- Melanie Brasch
- Laboratory for Biomolecular Nanotechnology, MESA+ Institute, University of Twente, PO Box 207, 7500 AE Enschede, The Netherlands
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Ngo AT, Lau KL, Quesnel JS, Aboukhalil R, Cosa G. Deposition of anionic conjugated poly(phenylenevinylene) onto silica nanoparticles via electrostatic interactions — Assembly and single-particle spectroscopy. CAN J CHEM 2011. [DOI: 10.1139/v10-141] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Fluorescent nanoparticles were prepared via adsorption of the conjugated polyelectrolyte poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] (MPS-PPV) onto 50 and 100 nm aminosilane functionalized silica beads. The particles were investigated via ensemble and single-molecule or -particle spectroscopy techniques to quantify the effect of the silica bead core on the exciton migration efficiency within the polymer. Ensemble emission spectra and ensemble fluorescence quenching studies with methyl viologen are consistent with good exciton migration along the polymer in the polymer-coated bead. The silica nanobead scaffolding preserves the sensitivity of the free polymer and provides a controllable architecture that minimizes nonspecific interactions. Single-particle spectroscopy studies were conducted on particles immobilized onto the positively charged surface of glass cover slips. Particle immobilization enabled us to monitor the effect of oxygen scavenger solutions on individual particles by changing the surrounding solution. The intensity–time trajectories of individual beads provide a mechanism of signal transduction with potential applications in multiplexing studies. Hundreds of individual beads can be imaged in a rapid parallel fashion.
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Affiliation(s)
- An T. Ngo
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Bldg, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Kai L. Lau
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Bldg, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Jeffrey S. Quesnel
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Bldg, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Robert Aboukhalil
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Bldg, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
| | - Gonzalo Cosa
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
- Centre for Self-Assembled Chemical Structures (CSACS/CRMAA), McGill University, Otto Maass Bldg, 801 Sherbrooke Street West, Montreal, QC H3A 2K6, Canada
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Karam P, Ngo AT, Rouiller I, Cosa G. Unraveling electronic energy transfer in single conjugated polyelectrolytes encapsulated in lipid vesicles. Proc Natl Acad Sci U S A 2010; 107:17480-5. [PMID: 20876146 PMCID: PMC2955115 DOI: 10.1073/pnas.1008068107] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
A method for the study of conjugated polyelectrolyte (CPE) photophysics in solution at the single-molecule level is described. Extended observation times of single polymer molecules are enabled by the encapsulation of the CPEs within 200-nm lipid vesicles, which are in turn immobilized on a surface. When combined with a molecular-level visualization of vesicles and CPE via cryo-transmission electron microscopy, these single-molecule spectroscopy studies on CPEs enable us to directly correlate the polymer conformation with its spectroscopic features. These studies are conducted with poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylene-vinylene] (MPS-PPV, a negatively charged CPE), when encapsulated in neutral and in negatively charged lipid vesicles. MPS-PPV exists as a freely diffusing polymer when confined in negatively charged vesicles. Individual MPS-PPV molecules adopt a collapsed-chain conformation leading to efficient energy migration over multiple chromophores. Both the presence of stepwise photobleaching in fluorescence intensity-time trajectories and emission from low-energy chromophores along the chain are observed. These results correlate with the amplified sensing potential reported for MPS-PPV in aqueous solution. When confined within neutral vesicles, single MPS-PPV molecules adopt an extended conformation upon insertion in the lipid bilayer. In this case emission arises from multiple chromophores within the isolated polymer chains, leading to an exponential decay of the intensity over time and a broad blue-shifted emission spectrum.
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Affiliation(s)
- Pierre Karam
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6
- Centre for Self-Assembled Chemical Structures; and
| | - An Thien Ngo
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6
- Centre for Self-Assembled Chemical Structures; and
| | - Isabelle Rouiller
- Department of Anatomy and Cell Biology, McGill University, Strathcona Anatomy and Dentistry Building, Room 115, 3640 University Street, Montreal, QC, Canada H3A 2B2
| | - Gonzalo Cosa
- Department of Chemistry, McGill University, 801 Sherbrooke Street West, Montreal, QC, Canada H3A 2K6
- Centre for Self-Assembled Chemical Structures; and
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