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A conjugated polymer‐liposome complex: A contiguous water‐stable, electronic, and optical interface. VIEW 2020. [DOI: 10.1002/viw.20200081] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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2
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Fernandez Oropeza N, Zurek NA, Galvan-De La Cruz M, Fabry-Wood A, Fetzer JM, Graves SW, Shreve AP. Multiplexed Lipid Bilayers on Silica Microspheres for Analytical Screening Applications. Anal Chem 2017; 89:6440-6447. [PMID: 28558200 PMCID: PMC6342469 DOI: 10.1021/acs.analchem.7b00296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most druggable targets are membrane components, including membrane proteins and soluble proteins that interact with ligands or receptors embedded in membranes. Current target-based screening and intermolecular interaction assays generally do not include the lipid membrane environment in presenting these targets, possibly altering their native structure and leading to misleading or incorrect results. To address this issue, an ideal assay involving membrane components would (1) mimic the natural membrane environment, (2) be amenable to high-throughput implementation, and (3) be easily multiplexed. In a step toward developing such an ideal target-based analytical assay for membrane components, we present fluorescently indexed multiplexed biomimetic membrane assays amenable to high-throughput flow cytometric detection. We build fluorescently multiplexed biomimetic membrane assays by using varying amounts of a fluorescently labeled lipid, NBD-DOPE [1,2-dioleoyl-sn-glycero-3-phosphoethanolamine-N-(7-nitro-2-1,3-benzoxadiazol-4-yl)], incorporated into a phospholipid membrane bilayer supported on 3 μm silica microspheres. Using flow cytometry, we demonstrate this multiplexed approach by measuring specific affinity of two well-characterized systems, the fluorescently labeled soluble proteins cholera toxin B subunit-Alexa 647 and streptavidin-PE/Cy5, to membranes containing different amounts of ligand targets of these proteins, GM1 and biotin-DOPE, respectively. This work will enable future efforts in developing highly efficient biomimetic assays for interaction analysis and drug screening involving membrane components.
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Affiliation(s)
| | | | | | | | | | - Steven W. Graves
- Center for Biomedical Engineering
- Department of Chemical and Biological Engineering University of New Mexico Albuquerque, NM 87131
| | - Andrew P. Shreve
- Center for Biomedical Engineering
- Department of Chemical and Biological Engineering University of New Mexico Albuquerque, NM 87131
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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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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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Li Q, Zhang J, Sun W, Yu J, Wu C, Qin W, Chiu DT. Europium-complex-grafted polymer dots for amplified quenching and cellular imaging applications. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:8607-8614. [PMID: 24976495 DOI: 10.1021/la501876m] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We report on a europium-complex-grafted polymer for preparing stable nanoparticle probes with high luminescence brightness, narrow emission bandwidth, and long luminescence lifetimes. A Eu complex bearing an amino group was used to react with a functional copolymer poly(styrene-co-maleic anhydride) by the spontaneous amidation reaction, producing the polymer grafted with Eu complexes in the side chains. The Eu-complex-grafted polymer was further used to prepare Eu-complex-grafted polymer dots (Pdots) and Eu-complex-blended poly(9-vinylcarbazole) composite Pdots, which showed improved colloidal stability as compared to those directly doped with Eu-complex molecules. Both types of Pdots can be efficiently quenched by a nile blue dye, exhibiting much lower detection limit and higher quenching sensitivity as compared to free Eu-complex molecules. Steady-state spectroscopy and time-resolved decay dynamics suggest the quenching mechanism is via efficient fluorescence resonance energy transfer from the Eu complex inside a Pdot to surface dye molecules. The amplified quenching in Eu-complex Pdots, together with efficient cell uptake and specific cell surface labeling observed in mammalian cells, suggests their potential applications in time-resolved bioassays and cellular imaging.
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Affiliation(s)
- Qiong Li
- State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University , Changchun, Jilin 130012, China
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Chen X, Shojaei-Zadeh S, Gilchrist ML, Maldarelli C. A lipobead microarray assembled by particle entrapment in a microfluidic obstacle course and used for the display of cell membrane receptors. LAB ON A CHIP 2013; 13:3041-3060. [PMID: 23748734 DOI: 10.1039/c3lc50083g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Platforms which can display cell membrane ligands and receptors as a microarray library of probes for screening against a target are essential tools in drug discovery, biomarker identification, and pathogen detection. Membrane receptors and ligands require their native bilayer environment to retain their selectivity and binding affinity, and this complicates displaying them in a microarray platform. In this study, a design is developed in which the probes are first incorporated in supported lipid bilayers formed around micron-sized particles (lipobeads), and the microbeads themselves are then arrayed on a surface by hydrodynamic capture in a microfluidic obstacle course of traps. The traps are "V" shaped open enclosures, which are arranged in a wide channel of a microfluidic device, and capture the lipobeads (slightly smaller than the channel height) as they are streamed through the course. Screening assays are undertaken directly in the device after assembly, by streaming a fluorescently labeled target through the device and detecting the bead fluorescence. Conditions are first established for which the supported bilayers on the bead surface remain intact during the capture and assay steps, using fluorescent tags in the bilayer to infer bilayer integrity. Numerical calculations of the hydrodynamic drag coefficient on the entrapped beads are presented in conjunction with the stability experiments to develop criteria for the bilayer stability as a function of the screening assay perfusion rate. Simulations of the flow streamlines are also presented to quantify the trapping efficiency of the obstacle course. Screening assays are illustrated, assaying fluorescently labeled NeutrAvidin with biotin, and labeled cholera toxin with its ganglioside binding ligand, GM1. Sequential capturing of sets of lipobeads (one at a time, and with each set bearing a different probe), followed by indexing the bead positions after each set is entrapped, allows for the construction of an indexed array of multiple probes without the need for particle encoding and is illustrated using the NeutrAvidin-biotin pair. Finally, the lipobead platform is used for quantitatively measuring the kinetic rate constants for the binding of a probe (biotin) to a target (NeutrAvidin).
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Affiliation(s)
- Xiaoxiao Chen
- Levich Institute and Department of Chemical Engineering, The City College of the City University of New York, New York, New York 10031, USA
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Piper-Feldkamp AR, Wegner M, Brzezinski P, Reed SM. Mixtures of supported and hybrid lipid membranes on heterogeneously modified silica nanoparticles. J Phys Chem B 2013; 117:2113-22. [PMID: 23387352 PMCID: PMC3935798 DOI: 10.1021/jp308305y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Simple supported lipid bilayers do not accurately reflect the complex heterogeneity of cellular membranes; however, surface modification makes it possible to tune membrane properties to better mimic biological systems. Here, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (DETAS), a silica modifier, facilitated formation of supported lipid bilayers on silica nanoparticles. Evidence for a stable supported bilayer came from the successful entrapment of a soluble fluorophore within an interstitial water layer. A fluorescence-quenching assay that utilized a pore-forming peptide was used to demonstrate the existence of two separate lipid leaflets. In this assay, fluorescence was quenched by dithionite in roughly equal proportions prior to and after addition of melittin. When a hydrophobic modifier, octadecyltriethoxysilane, was codeposited on the nanoparticles with DETAS, there was a decrease in the amount of supported bilayer on the nanoparticles and an increase in the quantity of hybrid membrane. This allowed for a controlled mixture of two distinct types of membranes on a single substrate, one separated by a water cushion and the other anchored directly on the surface, thereby providing a new mimic of cellular membranes.
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Affiliation(s)
- Aundrea R. Piper-Feldkamp
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217 3364, Office: 303.556.6260, Fax: 303.556.4776,
| | - Maria Wegner
- Department of Biochemistry and Biophysics, Stockholm Univ., Svante Arrhenius väg 16, SE-106 91, Stockholm, Sweden
| | - Peter Brzezinski
- Department of Biochemistry and Biophysics, Stockholm Univ., Svante Arrhenius väg 16, SE-106 91, Stockholm, Sweden
| | - Scott M. Reed
- Department of Chemistry, University of Colorado Denver, Campus Box 194, P.O. Box 173364, Denver, CO 80217 3364, Office: 303.556.6260, Fax: 303.556.4776,
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Liu HW, Ngo AT, Cosa G. Enhancing the Emissive Properties of Poly(p-phenylenevinylene)-Conjugated Polyelectrolyte-Coated SiO2 Nanoparticles. J Am Chem Soc 2012; 134:1648-52. [DOI: 10.1021/ja208437e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Hsiao-Wei Liu
- Department
of Chemistry and Centre for Self-Assembled
Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke
Street West, Montreal, Quebec H3A 2K6, Canada
| | - An Thien Ngo
- Department
of Chemistry and Centre for Self-Assembled
Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke
Street West, Montreal, Quebec H3A 2K6, Canada
| | - Gonzalo Cosa
- Department
of Chemistry and Centre for Self-Assembled
Chemical Structures (CSACS/CRMAA), McGill University, 801 Sherbrooke
Street West, Montreal, Quebec H3A 2K6, Canada
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Liu Q, Lü X, Geng L, Lü C. A new insight into the mechanism of influence of different inorganic salts on optical properties of water-soluble cationic conjugated polymers. POLYM INT 2011. [DOI: 10.1002/pi.3110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Aili D, Mager M, Roche D, Stevens MM. Hybrid nanoparticle-liposome detection of phospholipase activity. NANO LETTERS 2011; 11:1401-1405. [PMID: 20795711 DOI: 10.1021/nl1024062] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A flexible nanoparticle-based phospholipase (PL) assay is demonstrated in which the enzymatic substrate is decoupled from the nanoparticle surface. Liposomes are loaded with a polypeptide that is designed to heteroassociate with a second polypeptide immobilized on gold nanoparticles. Release of this polypeptide from the liposomes, triggered by PL, induces a folding-dependent nanoparticle bridging aggregation. The colorimetric response from this aggregation enables straightforward and continuous detection of PL in the picomolar range. The speed, specificity, and flexibility of this assay make it appropriate for a range of applications, from point of care diagnostics to high-throughput pharmaceutical screening.
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Affiliation(s)
- Daniel Aili
- Department of Materials and Institute of Biomedical Engineering, Imperial College London, SW7 2AZ London, UK
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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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Martínez-Máñez R, Sancenón F, Biyikal M, Hecht M, Rurack K. Mimicking tricks from nature with sensory organic–inorganic hybrid materials. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm11210d] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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Ding L, Chi EY, Schanze KS, Lopez GP, Whitten DG. Insight into the mechanism of antimicrobial conjugated polyelectrolytes: lipid headgroup charge and membrane fluidity effects. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:5544-5550. [PMID: 20000327 DOI: 10.1021/la9038045] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The interactions of antimicrobial cationic conjugated polyelectrolytes (CPEs) with two model membranes, liposomes and lipid monolayers at the air-water interface, have been investigated by fluorescence emission, fluorescence quenching, pressure-area isotherm, and dynamic light scattering measurements. This study continues the evaluation of the antimicrobial mechanism of a cationic poly(phenylene ethynylene) (PPE)-based CPE (polymer 1), which contains a 2,5-thienylene moiety in the repeat unit. To this end, the interactions of polymer 1 with lipids with varying headgroup charge and acyl chain length have been examined. Our results show that the cationic polymer 1 can efficiently associate with and insert into anionic phosphatidylglycerol (PG) membranes. However, polymer 1 does not exhibit any interactions with zwitterionic lipid membranes composed of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids. Polymer 1's selective affinity toward anionic lipids over zwitterionic lipids makes it an attractive antimicrobial agent with low toxicity. The interactions of polymer 1 with lipid membranes of different fluidity were studied by varying the surface pressure of lipid monolayers and by adjusting the temperature of liposomes. We observe that increasing membrane fluidity enhances both the conformational changes of polymer 1 upon associating with lipid membranes and the extent of polymer 1 insertion into lipid monolayers. We also find that the thickness of the lipid bilayers, modulated by acyl chain length, affects the extent of polymer 1 incorporation into the lipid bilayer.
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Affiliation(s)
- Liping Ding
- Center for Biomedical Engineering, Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131-1341, USA
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Chemburu S, Fenton K, Lopez GP, Zeineldin R. Biomimetic silica microspheres in biosensing. Molecules 2010; 15:1932-57. [PMID: 20336023 PMCID: PMC6257317 DOI: 10.3390/molecules15031932] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Revised: 03/16/2010] [Accepted: 03/17/2010] [Indexed: 11/16/2022] Open
Abstract
Lipid vesicles spontaneously fuse and assemble into a lipid bilayer on planar or spherical silica surfaces and other substrates. The supported lipid bilayers (SLBs) maintain characteristics of biological membranes, and are thus considered to be biomembrane mimetic systems that are stable because of the underlying substrate. Examples of their shared characteristics with biomembranes include lateral fluidity, barrier formation to ions and molecules, and their ability to incorporate membrane proteins into them. Biomimetic silica microspheres consisting of SLBs on solid or porous silica microspheres have been utilized for different biosensing applications. The advantages of such biomimetic microspheres for biosensing include their increased surface area to volume ratio which improves the detection limits of analytes, and their amenability for miniaturization, multiplexing and high throughput screening. This review presents examples and formats of using such biomimetic solid or porous silica microspheres in biosensing.
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Affiliation(s)
- Sireesha Chemburu
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - Kyle Fenton
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM 87131, USA
| | - Gabriel P. Lopez
- Center for Biomedical Engineering, University of New Mexico, Albuquerque, NM 87131, USA
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Mechanical Engineering & Materials Science, Duke University, Durham, NC 27708, USA
| | - Reema Zeineldin
- Department of Pharmaceutical Sciences, Massachusetts College of Pharmacy and Health Sciences, 19 Foster Street, Worcester, MA 01608, USA
- Author to whom correspondence should be addressed; E-Mail: ; Tel.: +1-508-373-5762; Fax: +1- 508-890-5618
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Ruan YB, Li AF, Zhao JS, Shen JS, Jiang YB. Specific Hg2+-mediated perylene bisimide aggregation for highly sensitive detection of cysteine. Chem Commun (Camb) 2010; 46:4938-40. [DOI: 10.1039/c0cc00630k] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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Ding L, Chi EY, Chemburu S, Ji E, Schanze KS, Lopez GP, Whitten DG. Insight into the mechanism of antimicrobial poly(phenylene ethynylene) polyelectrolytes: interactions with phosphatidylglycerol lipid membranes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:13742-51. [PMID: 20560549 DOI: 10.1021/la901457t] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The interactions of antimicrobial poly(phenylene ethynylene) (PPE)-based cationic conjugated polyelectrolytes (CPEs) with lipid membranes were investigated to gain insight into the mechanism of their biocidal activity. Three model membrane systems comprising negatively charged phosphatidylglycerol (PG) lipids were used to mimic the bacterial cell membrane, including unilamellar lipid vesicles in aqueous solution, lipid bilayer coated silica microspheres, and lipid monolayers at the air-water interface. Two PPE CPEs, one containing a thiophene moiety on the PPE repeat unit and the second containing a diazabicyclooctane (DABCO) moiety on the pendant side chain, were chosen, since the former exhibits distinct dark biocidal activity and the latter shows strong light-activated antimicrobial activity but little dark biocidal activity. The interactions of these two PPE polymers with lipid membranes were characterized in detail by CPE fluorescence spectral changes, fluorescence resonance energy transfer (FRET), fluorescence quenching, monolayer insertion, and dynamic light scattering assays. Both PPE polymers exhibit affinity for the anionic lipid membrane systems. Their concomitant association and insertion into the membrane leads to conformational changes of the PPE polymer from an aggregated state to a more extended state, as evidenced by the polymer's enhanced fluorescence and FRET between the polymer and rhodamine incorporated in the lipid membrane. In comparison, the thiophene polymer exhibits stronger interactions with PG lipid membranes than the DABCO-containing polymer. The former induces a larger fluorescence enhancement, shows faster transfer across the lipid membrane, and inserts more readily and to a higher extent into lipid monolayers. The observed differences between the two PPE polymers in their interactions with the lipid membrane may stem from their structural differences, as the DABCO-containing polymer has a much bulkier and larger pendant group on its side chain. The higher degree of membrane interaction and insertion, and subsequent membrane disorganization, of the thiophene polymer may account for its dark biocidal activity.
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Affiliation(s)
- Liping Ding
- Center for Biomedical Engineering, Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131-0001, USA
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Chemburu S, Corbitt TS, Ista LK, Ji E, Fulghum J, Lopez GP, Ogawa K, Schanze KS, Whitten DG. Light-induced biocidal action of conjugated polyelectrolytes supported on colloids. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2008; 24:11053-62. [PMID: 18729335 DOI: 10.1021/la8016547] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A series of water soluble, cationic conjugated polyelectrolytes (CPEs) with backbones based on a poly(phenylene ethynylene) repeat unit structure and tetraakylammonium side groups exhibit a profound light-induced biocidal effect. The present study examines the biocidal activity of the CPEs, correlating this activity with the photophysical properties of the polymers. The photophysical properties of the CPEs are studied in solution, and the results demonstrate that direct excitation produces a triplet excited-state in moderate yield, and the triplet is shown to be effective at sensitizing the production of singlet oxygen. Using the polymers in a format where they are physisorbed or covalently grafted to the surface of colloidal silica particles (5 and 30 microm diameter), we demonstrate that they exhibit light-activated biocidal activity, effectively killing Cobetia marina and Pseudomonas aeruginosa. The light-induced biocidal activity is also correlated with a requirement for oxygen suggesting that interfacial generation of singlet oxygen is the crucial step in the light-induced biocidal activity.
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Affiliation(s)
- Sireesha Chemburu
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131-1341, USA
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Chemburu S, Ji E, Casana Y, Wu Y, Buranda T, Schanze KS, Lopez GP, Whitten DG. Conjugated polyelectrolyte supported bead based assays for phospholipase A2 activity. J Phys Chem B 2008; 112:14492-9. [PMID: 18808092 DOI: 10.1021/jp803358j] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A fluorescence based assay for human serum-derived phospholipase activity has been developed in which cationic conjugated polyelectrolytes are supported on silica microspheres. The polymer-coated beads are overcoated with an anionic phospholipid (1,2-dimyristoyl-sn-glycero-3-[phospho- rac-(1-glycerol)) (DMPG) to provide "lipobeads" that serve as a sensor for PLA2. The lipid serves a dual role as a substrate for PLA2 and an agent to attenuate quenching of the polymer fluorescence by the external electron transfer quencher 9,10-anthraquinone-2,6-disulfonic acid (AQS). In this case quenching of the polymer fluorescence by AQS increases as the PLA2 digests the lipid. The lipid can also be used itself as a quencher and substrate by employing a small amount of energy transfer quencher substituted lipid in the DMPG. In this case the fluorescence of the polymer is quenched when the lipid layer is intact; as the enzyme digests the lipid, the fluorescence of the polymer is restored. The sensing of PLA2 activity has been studied both by monitoring fluorescence changes in a multiwell plate reader and by flow cytometry. The assay exhibits good sensitivity with EC50 values in the nanomolar range.
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Affiliation(s)
- Sireesha Chemburu
- Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA
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