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Tong QB, Du C, Wei Z, Du M, Wu ZL, Zheng Q. Synergic influences of network topologies and associative interactions on the microstructures and bulk performances of hydrogels. J Mater Chem B 2021; 9:9863-9873. [PMID: 34849519 DOI: 10.1039/d1tb02114a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Revealing the relationship between network topologies and mechanical properties of hydrogels is fundamental yet challenging in the design of tough soft materials. Here, we report a series of hydrogels using N-isopropyl acrylamide (NIPAm) and acrylic acid (AAc) as the basic units to form a single network of the copolymer, a semi-interpenetrated network of two homopolymers, and a grafted network with homopolymer chains anchored on another homopolymer network, to investigate the influence of network architectures on the mechanical properties and thermal responses of the gels. We found that the properties of the gels are also significantly influenced by the formation of hydrogen bonds between poly(N-isopropyl acrylamide) (PNIPAm) and poly(acrylic acid) (PAAc) segments. The gels with the single network of poly(NIPAm-co-AAc) are mechanically weak due to the low efficiency for forming robust hydrogen bonds, while micro-segregated domains are formed in the hydrogels with a semi-interpenetrated network structure due to the formation of inter-chain hydrogen bonds that favors energy dissipation and toughening of the gels. On the other hand, dense hydrogen bonds form between the grafted PNIPAm chains and the PAAc network, resulting in nano-segregated domains and excellent mechanical properties of the gels. The hydrogels with the grafted network structure exhibit a more repeatable response to temperature than those with the semi-interpenetrated network structure due to the relatively stable hydrogen-bond network. The comparison of the mechanical properties and thermal stability of the hydrogels with the same composition but different topological networks should be informative for engineering hydrogel properties or functions by tailoring the network structures.
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Affiliation(s)
- Qing Bo Tong
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Cong Du
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Zhou Wei
- Hangzhou Toka Ink Co., Ltd., Hangzhou 310018, China
| | - Miao Du
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Zi Liang Wu
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
| | - Qiang Zheng
- Ministry of Education Key Laboratory of Macromolecular Synthesis and Functionalization, Department of Polymer Science and Engineering, Zhejiang University, Hangzhou 310027, China.
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2
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Zhou C, Chen Y, Huang M, Ling Y, Yang L, Zhao G, Chen J. A new type of dual temperature sensitive triblock polymer (P(AM- co-AN)- b-PDMA- b-PNIPAM) and its self-assembly and gel behavior. NEW J CHEM 2021. [DOI: 10.1039/d0nj06153k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
A dual-action polymer (P(AM-co-AN)-b-PDMA-b-PNIPAM) and its sol–gel behavior only through simple temperature changes.
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Affiliation(s)
- Cheng Zhou
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yan Chen
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Mingjun Huang
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Yi Ling
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Liming Yang
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
| | - Guochen Zhao
- Shandong Provincial Key Laboratory of High Strength Lightweight Metallic Materials
- Advanced Materials Institute
- Qilu University of Technology (Shandong Academy of Sciences)
- Jinan 250014
- China
| | - Jie Chen
- Department of Chemical Engineering and technology
- School of Environmental and Chemical Engineering
- Shanghai University
- Shanghai 200444
- P. R. China
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3
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Cazares-Cortes E, Baker BC, Nishimori K, Ouchi M, Tournilhac F. Polymethacrylic Acid Shows Thermoresponsivity in an Organic Solvent. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b00412] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Esther Cazares-Cortes
- Molecular, Macromolecular Chemistry, and Materials Laboratory, CNRS, ESPCI-Paris, PSL Research University, 10 Rue Vauquelin, 75005 Paris, France
| | - Benjamin C. Baker
- Molecular, Macromolecular Chemistry, and Materials Laboratory, CNRS, ESPCI-Paris, PSL Research University, 10 Rue Vauquelin, 75005 Paris, France
| | - Kana Nishimori
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Nishikyo-ku, 615-8510 Kyoto, Japan
| | - Makoto Ouchi
- Department of Polymer Chemistry, Graduate School of Engineering, Kyoto University, Katsura Nishikyo-ku, 615-8510 Kyoto, Japan
| | - François Tournilhac
- Molecular, Macromolecular Chemistry, and Materials Laboratory, CNRS, ESPCI-Paris, PSL Research University, 10 Rue Vauquelin, 75005 Paris, France
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4
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Swift T, Seaton CC, Rimmer S. Poly(acrylic acid) interpolymer complexes. SOFT MATTER 2017; 13:8736-8744. [PMID: 29119179 DOI: 10.1039/c7sm01787a] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Interpolymer complex formation of poly(acrylic acid) with other macromolecules can occur via several mechanisms that vary depending on the pH. At low pH the protonated acid functional group can form bonds with both donor and acceptor moieties, resulting in desolvated structures consisting of two polymers. Complexes were formed in dilute solutions of PAA, functionalised with acenaphthylene, with a range of other polymers including: poly(NIPAM); poly(ethylene oxide) (PEO); poly(dimethylacrylamide) (PDMA); poly(diethyl acrylamide) (PDEAM) poly(vinyl alcohol) (PVA) and poly(vinyl pyrolidinone) (PVP). Fluorescence anisotropy was used to demonstrate complex formation in each case by monitoring the reductions in segmental motion of the chain as the complexes formed. Considerations of the molecular structures of the complexing moieties suggest that solvation energies and pKas play an important role in complex formation.
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Affiliation(s)
- Thomas Swift
- School of Chemistry and Biosciences, University of Bradford, Bradford, West Yorkshire BD7 1DP, UK.
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5
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Swift T, Paul N, Swanson L, Katsikogianni M, Rimmer S. Förster Resonance Energy Transfer across interpolymer complexes of poly(acrylic acid) and poly(acrylamide). POLYMER 2017. [DOI: 10.1016/j.polymer.2017.06.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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6
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Asadujjaman A, Kent B, Bertin A. Phase transition and aggregation behaviour of an UCST-type copolymer poly(acrylamide-co-acrylonitrile) in water: effect of acrylonitrile content, concentration in solution, copolymer chain length and presence of electrolyte. SOFT MATTER 2017; 13:658-669. [PMID: 27995248 DOI: 10.1039/c6sm02262f] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
An UCST-type copolymer of acrylamide (AAm) and acrylonitrile (AN) (poly(AAm-co-AN)) was prepared by reversible addition fragmentation chain transfer (RAFT) polymerization and its temperature-induced phase transition and aggregation behaviour studied by turbidimetry, static and dynamic light scattering, small angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM) measurements. The phase transition temperature was found to increase with increasing AN content in the copolymer, concentration of the solutions and copolymer chain length. A significant effect was observed onto the phase transition temperature by addition of different electrolytes into the copolymer solution. The copolymer chains were aggregated below the phase transition temperature and disaggregated above it. The size of the aggregates increases with increasing AN contents and concentration of the copolymer solutions below the phase transition temperature. The copolymer chains were expanded and weekly associated in solution above the phase transition temperature. A model is proposed to explain such association-aggregation behaviour of poly(AAm-co-AN) copolymers depending on AN contents and concentration of the copolymer solutions as a function of temperature.
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Affiliation(s)
- Asad Asadujjaman
- Federal Institute for Materials Research and Testing (BAM), Unter den Eichen 87, 12205 Berlin, Germany.
| | - Ben Kent
- Helmholtz-Zentrum Berlin (HZB), Hanhn-Meitner-Platz 1, 14109 Berlin, Germany
| | - Annabelle Bertin
- Federal Institute for Materials Research and Testing (BAM), Unter den Eichen 87, 12205 Berlin, Germany. and Freie Universität Berlin, Institute of Chemistry and Biochemistry-Organic Chemistry, Takustr. 3, 14195 Berlin, Germany
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7
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Alvarado AG, Cortés J, Pérez-Carrillo LA, Rabelero M, Arellano J, Sánchez-Díaz JC, Puig JE, Arellano M. Temperature and pH-Responsive Polyacrylamide/Poly(Acrylic Acid) Interpenetrating Polymer Network Nanoparticles. J MACROMOL SCI B 2016. [DOI: 10.1080/00222348.2016.1238436] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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8
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Fu W, Zhao B. Thermoreversible physically crosslinked hydrogels from UCST-type thermosensitive ABA linear triblock copolymers. Polym Chem 2016. [DOI: 10.1039/c6py01517d] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Moderately concentrated aqueous solutions of UCST-type thermosensitive ABA linear triblock copolymers undergo cooling-induced, reversible sol–gel transitions.
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Affiliation(s)
- Wenxin Fu
- Department of Chemistry
- University of Tennessee
- Knoxville
- USA
| | - Bin Zhao
- Department of Chemistry
- University of Tennessee
- Knoxville
- USA
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9
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Hou L, Wu P. Understanding the UCST-type transition of P(AAm-co-AN) in H2O and D2O: dramatic effects of solvent isotopes. SOFT MATTER 2015; 11:7059-7065. [PMID: 26249207 DOI: 10.1039/c5sm01745a] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The UCST-type transition of poly(acrylamide-co-acrylonitrile) (P(AAm-co-AN)) (molar fraction of AN: 13.3%; PDI = 3.2) in H2O and D2O is explored and compared by applying turbidity, DLS as well as FTIR measurements. The transition temperature of P(AAm-co-AN) in D2O is observed to be almost 10 °C higher than that in H2O at the same concentration, demonstrating a dramatic solvent isotope effect. Such a phenomenon could be rooted from a stronger interaction among polymer chains in D2O than in H2O, as indicated from DLS results. It is also observed in second-derivative analysis of FTIR spectra in the ν(C=O) region, where all C=O groups participate in the formation of inter-/intra-chain hydrogen bonds (C=O···H-N) in D2O while there is still part of relatively "free" C=O groups in H2O. Moreover, we find in the temperature-dependent FTIR spectra that C≡N groups exhibit hydrating behavior while C=O groups present increased inter-/intra-molecular hydrogen bonding interaction (C=O···H-N) upon cooling, revealing the later process to be the driving force of the UCST-type transition.
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Affiliation(s)
- Lei Hou
- The State Key Laboratory of Molecular Engineering of Polymers, Collaborative Innovation Center of Polymers and Polymer Composite Materials, Department of Macromolecular Science, and Laboratory of Advanced Materials, Fudan University, Shanghai 200433, China.
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Slaughter BV, Blanchard AT, Maass KF, Peppas NA. Dynamic swelling behavior of interpenetrating polymer networks in response to temperature and pH. J Appl Polym Sci 2015; 132:42076. [PMID: 26405349 PMCID: PMC4577068 DOI: 10.1002/app.42076] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Temperature responsive hydrogels based on ionic polymers exhibit swelling transitions in aqueous solutions as a function of shifting pH and ionic strength, in addition to temperature. Applying these hydrogels to useful applications, particularly for biomedical purposes such as drug delivery and regenerative medicine, is critically dependent on understanding the hydrogel solution responses as a function of all three parameters together. In this work, interpenetrating polymer network (IPN) hydrogels of polyacrylamide and poly(acrylic acid) were formulated over a broad range of synthesis variables using a fractional factorial design, and were examined for equilibrium temperature responsive swelling in a variety of solution conditions. Due to the acidic nature of these IPN hydrogels, usable upper critical solution temperature (UCST) responses for this system occur in mildly acidic environments. Responses were characterized in terms of maximum equilibrium swelling and temperature-triggered swelling using turbidity and gravimetric measurements. Additionally, synthesis parameters critical to achieving optimal overall swelling, temperature-triggered swelling, and sigmoidal temperature transitions for this IPN system were analyzed based on the fractional factorial design used to formulate these hydrogels.
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Affiliation(s)
- Brandon V. Slaughter
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Aaron T. Blanchard
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Katie F. Maass
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
| | - Nicholas A. Peppas
- Department of Biomedical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
- Department of Chemical Engineering, The University of Texas at Austin, Austin, Texas 78712, USA
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11
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Feldstein MM, Dormidontova EE, Khokhlov AR. Pressure sensitive adhesives based on interpolymer complexes. Prog Polym Sci 2015. [DOI: 10.1016/j.progpolymsci.2014.10.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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12
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Wang L, Shan G, Pan P. Highly enhanced toughness of interpenetrating network hydrogel by incorporating poly(ethylene glycol) in first network. RSC Adv 2014. [DOI: 10.1039/c4ra11494a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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13
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Swift T, Swanson L, Rimmer S. Poly(acrylic acid) interpolymer complexation: use of a fluorescence time resolved anisotropy as a poly(acrylamide) probe. RSC Adv 2014. [DOI: 10.1039/c4ra07263d] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A poly(acrylamide) sensor has been developed which uses the segmental mobility of another polymer poly(acrylic acid) with an attached fluorescent marker. The system uses interpolymer complexation, which leads to reduced segmental mobility.
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Affiliation(s)
- Thomas Swift
- Polymer and Biomaterials Chemistry Laboratories
- Department of Chemistry
- University of Sheffield
- Sheffield, UK
| | - Linda Swanson
- Polymer and Biomaterials Chemistry Laboratories
- Department of Chemistry
- University of Sheffield
- Sheffield, UK
| | - Stephen Rimmer
- Polymer and Biomaterials Chemistry Laboratories
- Department of Chemistry
- University of Sheffield
- Sheffield, UK
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Li Z, Amado E, Kressler J. Self-assembly behavior of fluorocarbon-end-capped poly(glycerol methacrylate) in aqueous solution. Colloid Polym Sci 2012. [DOI: 10.1007/s00396-012-2803-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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15
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Irmukhametova GS, Fraser BJ, Keddie JL, Mun GA, Khutoryanskiy VV. Hydrogen-bonding-driven self-assembly of PEGylated organosilica nanoparticles with poly(acrylic acid) in aqueous solutions and in layer-by-layer deposition at solid surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:299-306. [PMID: 22106883 DOI: 10.1021/la2038735] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
PEGylated organosilica nanoparticles have been synthesized through self-condensation of (3-mercaptopropyl)trimethoxysilane in dimethyl sulfoxide into thiolated nanoparticles with their subsequent reaction with methoxypoly(ethylene glycol) maleimide. The PEGylated nanoparticles showed excellent colloidal stability over a wide range of pH in contrast to the parent thiolated nanoparticles, which have a tendency to aggregate irreversibly under acidic conditions (pH < 3.0). Due to the presence of a poly(ethylene glycol)-based corona, the PEGylated nanoparticles are capable of forming hydrogen-bonded interpolymer complexes with poly(acrylic acid) in aqueous solutions under acidic conditions, resulting in larger aggregates. The use of hydrogen-bonding interactions allows more efficient attachment of the nanoparticles to surfaces. The alternating deposition of PEGylated nanoparticles and poly(acrylic acid) on silicon wafer surfaces in a layer-by-layer fashion leads to multilayered coatings. The self-assembly of PEGylated nanoparticles with poly(acrylic acid) in aqueous solutions and at solid surfaces was compared to the behavior of linear poly(ethylene glycol). The nanoparticle system creates thicker layers than the poly(ethylene glycol), and a thicker layer is obtained on a poly(acrylic acid) surface than on a silica surface, because of the effects of hydrogen bonding. Some implications of these hydrogen-bonding-driven interactions between PEGylated nanoparticles and poly(acrylic acid) for pharmaceutical formulations are discussed.
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Affiliation(s)
- Galiya S Irmukhametova
- Reading School of Pharmacy, University of Reading, Whiteknights, P.O. Box 224, RG6 6AD Reading, United Kingdom
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Sudre G, Tran Y, Creton C, Hourdet D. pH/Temperature control of interpolymer complexation between poly(acrylic acid) and weak polybases in aqueous solutions. POLYMER 2012. [DOI: 10.1016/j.polymer.2011.11.055] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
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17
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Mashat A, Deng L, Altawashi A, Sougrat R, Wang G, Khashab NM. Zippered release from polymer-gated carbon nanotubes. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm30454f] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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18
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Zhou J, Ke F, Liang D. Kinetic study on the reentrant condensation of oligonucleotide in trivalent salt solution. J Phys Chem B 2011; 114:13675-80. [PMID: 20936839 DOI: 10.1021/jp1074187] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reentrant condensation of 21-bp oligonucleotide in the presence of spermidine was investigated by laser light scattering and capillary electrophoresis. 21-bp oligonucleotide showed a bimodal distribution in 1 × TE buffer, with the slow mode being the characteristic diffusion of polyelectrolyte in solution without enough salt. At the fixed spermidine concentration, the reentry of oligonucleotide underwent aggregation, phase separation, and disassociation in sequence with time, and the kinetics was extremely slow. For example, it took more than 1200 h (50 days) for the reentry to complete at 21 mM spermidine. Higher spermidine concentration led to faster kinetics. After reentry, the slow mode disappeared, and the charges of oligonucleotide were at least partially neutralized. No prominent charge inversion was observed. The kinetics of oligonucleotide reentry in the presence of spermidine gained insight in the interactions of polyelectrolyte in aqueous solution.
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Affiliation(s)
- Jihan Zhou
- Beijing National Laboratory for Molecular Sciences and the Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, China, 100871
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Xia Y, Chen E, Liang D. Recognition of single- and double-stranded oligonucleotides by bovine serum albumin via nonspecific interactions. Biomacromolecules 2010; 11:3158-66. [PMID: 20873766 DOI: 10.1021/bm100969z] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The complexes formed by bovine serum albumin (BSA) with single-stranded oligonucleotide (ss-oligo) or double-stranded oligonucleotide (ds-oligo) were investigated by laser light scattering, zeta potential analysis, and atomic force microscopy. It was found that BSA was able to recognize ss-oligo and ds-oligo upon forming complexes in HCOOH-HCOONa buffer at pH 3.0. When oligonucleotide was added dropwise to BSA, BSA formed a complex with ss-oligo but not with ds-oligo in the studied charge ratio. When BSA was added to oligonucleotides, BSA formed complexes with both ss-oligo and ds-oligo but via different paths: the BSA/ds-oligo underwent two processes, heavy precipitation followed by reentry, with increasing BSA/oligo charge ratio, whereas BSA/ss-oligo underwent only aggregation process, but with a charge reversal occurred at BSA/oligo charge ratio about 0.1. Moreover, the complex formed by BSA and ds-oligo showed a kinetics much slower than that of BSA and ss-oligo. We attributed the big difference upon complexation to the physical nature of oligonucleotides as well as the conformational change of BSA under severe conditions. The differentiation of ss-oligo from ds-oligo by BSA via nonspecific interactions gained insight in the recognition of DNA or RNA by specific protein (enzyme) under physiological conditions.
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Affiliation(s)
- Yuqiong Xia
- Beijing National Laboratory for Molecular Sciences and the Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, College of Chemistry and Molecular Engineering, Peking University, Beijing, China 100871
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