Publications by year, excluding conference proceedings.
Complete CV Google Scholar Page
2022
Zhang, Wengang; Starr, Francis W.; Beers, Kathryn L.; Douglas, Jack F.
Reactive Molecular Dynamics Simulations of the Depolymerization of Polyethylene Using Graphene-Oxide-Supported Platinum Nanoparticles Journal Article
In: The Journal of Physical Chemistry A, vol. 126, no. 20, pp. 3167-3173, 2022, (PMID: 35533406).
BibTeX | Tags: Nanotechnology, Polymers | Links:
@article{zsbd22,
title = {Reactive Molecular Dynamics Simulations of the Depolymerization of Polyethylene Using Graphene-Oxide-Supported Platinum Nanoparticles},
author = {Wengang Zhang and Francis W. Starr and Kathryn L. Beers and Jack F. Douglas},
url = {https://fstarr.wescreates.wesleyan.edu/publications/zsbd22.pdf},
doi = {10.1021/acs.jpca.2c01167},
year = {2022},
date = {2022-05-26},
urldate = {2022-01-01},
journal = {The Journal of Physical Chemistry A},
volume = {126},
number = {20},
pages = {3167-3173},
note = {PMID: 35533406},
keywords = {Nanotechnology, Polymers},
pubstate = {published},
tppubtype = {article}
}
2021
McKenzie-Smith, Thomas Q.; Douglas, Jack F.; Starr, Francis W.
Explaining the Sensitivity of Polymer Segmental Relaxation to Additive Size Based on the Localization Model Journal Article
In: Phys. Rev. Lett., vol. 127, pp. 277802, 2021.
BibTeX | Tags: Glass Formation, Nanocomposites, Nanotechnology | Links:
@article{mds21,
title = {Explaining the Sensitivity of Polymer Segmental Relaxation to Additive Size Based on the Localization Model},
author = {Thomas Q. McKenzie-Smith and Jack F. Douglas and Francis W. Starr},
url = {https://fstarr.wescreates.wesleyan.edu/publications/mds21.pdf},
doi = {10.1103/PhysRevLett.127.277802},
year = {2021},
date = {2021-12-30},
journal = {Phys. Rev. Lett.},
volume = {127},
pages = {277802},
publisher = {American Physical Society},
keywords = {Glass Formation, Nanocomposites, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
Zhang, Wengang; Starr, Francis W.; Douglas, Jack F.
Activation free energy gradient controls interfacial mobility gradient in thin polymer films Journal Article
In: The Journal of Chemical Physics, vol. 155, no. 17, pp. 174901, 2021.
BibTeX | Tags: Dynamic Heterogeneity, Glass Formation, Nanotechnology, Thin Films | Links:
@article{zsd21,
title = {Activation free energy gradient controls interfacial mobility gradient in thin polymer films},
author = {Wengang Zhang and Francis W. Starr and Jack F. Douglas},
url = {https://fstarr.wescreates.wesleyan.edu/publications/zsd21.pdf},
doi = {10.1063/5.0064866},
year = {2021},
date = {2021-11-07},
journal = {The Journal of Chemical Physics},
volume = {155},
number = {17},
pages = {174901},
keywords = {Dynamic Heterogeneity, Glass Formation, Nanotechnology, Thin Films},
pubstate = {published},
tppubtype = {article}
}
Emamy, Hamed; Starr, Francis W.; Kumar, Sanat K.
Detecting bound polymer layers in attractive polymeranoparticle hybrids Journal Article
In: Nanoscale, vol. 13, pp. 12910-12915, 2021.
BibTeX | Tags: Glass Formation, Nanocomposites, Nanotechnology | Links:
@article{esk21,
title = {Detecting bound polymer layers in attractive polymeranoparticle hybrids},
author = {Hamed Emamy and Francis W. Starr and Sanat K. Kumar},
url = {https://https://fstarr.wescreates.wesleyan.edu/publications/esk21.pdf},
doi = {10.1039/D1NR02395K},
year = {2021},
date = {2021-07-01},
journal = {Nanoscale},
volume = {13},
pages = {12910-12915},
publisher = {The Royal Society of Chemistry},
keywords = {Glass Formation, Nanocomposites, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
Zhang, Wengang; Douglas, Jack F.; Chremos, Alexandros; Starr, Francis W.
Structure and Dynamics of Star Polymer Films from Coarse-Grained Molecular Simulations Journal Article
In: Macromolecules, vol. 54, no. 12, pp. 5344-5353, 2021.
BibTeX | Tags: Glass Formation, Nanotechnology, Thin Films | Links:
@article{zdcs21,
title = {Structure and Dynamics of Star Polymer Films from Coarse-Grained Molecular Simulations},
author = {Wengang Zhang and Jack F. Douglas and Alexandros Chremos and Francis W. Starr},
url = {https://https://fstarr.wescreates.wesleyan.edu/publications/zdcs21.pdf},
doi = {10.1021/acs.macromol.1c00504},
year = {2021},
date = {2021-06-04},
journal = {Macromolecules},
volume = {54},
number = {12},
pages = {5344-5353},
keywords = {Glass Formation, Nanotechnology, Thin Films},
pubstate = {published},
tppubtype = {article}
}
Liu, Ari Y.; Emamy, Hamed; Douglas, Jack F.; Starr, Francis W.
Effects of Chain Length on the Structure and Dynamics of Semidilute Nanoparticle-Polymer Composites Journal Article
In: Macromolecules, vol. 54, no. 7, pp. 3041-3051, 2021.
BibTeX | Tags: Glass Formation, Nanocomposites, Nanotechnology | Links:
@article{leds21,
title = {Effects of Chain Length on the Structure and Dynamics of Semidilute Nanoparticle-Polymer Composites},
author = {Ari Y. Liu and Hamed Emamy and Jack F. Douglas and Francis W. Starr},
url = {http://fstarr.wescreates.wesleyan.edu/publications/leds21.pdf},
doi = {10.1021/acs.macromol.0c02500},
year = {2021},
date = {2021-03-23},
journal = {Macromolecules},
volume = {54},
number = {7},
pages = {3041-3051},
keywords = {Glass Formation, Nanocomposites, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
2019
Emamy, Hamed; Gang, Oleg; Starr, Francis W
The Stability of a Nanoparticle Diamond Lattice Linked by DNA Journal Article
In: Nanomaterials, vol. 9, no. 5, 2019, ISSN: 2079-4991.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{egs19,
title = {The Stability of a Nanoparticle Diamond Lattice Linked by DNA},
author = {Hamed Emamy and Oleg Gang and Francis W Starr},
url = {http://fstarr.web.wesleyan.edu/publications/egs19.pdf},
doi = {10.3390/nano9050661},
issn = {2079-4991},
year = {2019},
date = {2019-04-26},
journal = {Nanomaterials},
volume = {9},
number = {5},
abstract = {The functionalization of nanoparticles (NPs) with DNA has proven to be an effective strategy for self-assembly of NPs into superlattices with a broad range of lattice symmetries. By combining this strategy with the DNA origami approach, the possible lattice structures have been expanded to include the cubic diamond lattice. This symmetry is of particular interest, both due to the inherent synthesis challenges, as well as the potential valuable optical properties, including a complete band-gap. Using these lattices in functional devices requires a robust and stable lattice. Here, we use molecular simulations to investigate how NP size and DNA stiffness affect the structure, stability, and crystallite shape of NP superlattices with diamond symmetry. We use the Wulff construction method to predict the equilibrium crystallite shape of the cubic diamond lattice. We find that, due to reorientation of surface particles, it is possible to create bonds at the surface with dangling DNA links on the interior, thereby reducing surface energy. Consequently, the crystallite shape depends on the degree to which such surface reorientation is possible, which is sensitive to DNA stiffness. Further, we determine dependence of the lattice stability on NP size and DNA stiffness by evaluating relative Gibbs free energy. We find that the free energy is dominated by the entropic component. Increasing NP size or DNA stiffness increases free energy, and thus decreases the relative stability of lattices. On the other hand, increasing DNA stiffness results in a more precisely defined lattice structure. Thus, there is a trade off between structure and stability of the lattice. Our findings should assist experimental design for controlling lattice stability and crystallite shape.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
The functionalization of nanoparticles (NPs) with DNA has proven to be an effective strategy for self-assembly of NPs into superlattices with a broad range of lattice symmetries. By combining this strategy with the DNA origami approach, the possible lattice structures have been expanded to include the cubic diamond lattice. This symmetry is of particular interest, both due to the inherent synthesis challenges, as well as the potential valuable optical properties, including a complete band-gap. Using these lattices in functional devices requires a robust and stable lattice. Here, we use molecular simulations to investigate how NP size and DNA stiffness affect the structure, stability, and crystallite shape of NP superlattices with diamond symmetry. We use the Wulff construction method to predict the equilibrium crystallite shape of the cubic diamond lattice. We find that, due to reorientation of surface particles, it is possible to create bonds at the surface with dangling DNA links on the interior, thereby reducing surface energy. Consequently, the crystallite shape depends on the degree to which such surface reorientation is possible, which is sensitive to DNA stiffness. Further, we determine dependence of the lattice stability on NP size and DNA stiffness by evaluating relative Gibbs free energy. We find that the free energy is dominated by the entropic component. Increasing NP size or DNA stiffness increases free energy, and thus decreases the relative stability of lattices. On the other hand, increasing DNA stiffness results in a more precisely defined lattice structure. Thus, there is a trade off between structure and stability of the lattice. Our findings should assist experimental design for controlling lattice stability and crystallite shape.
Zhang, Wengang; Emamy, Hamed; Betancourt, Beatriz A Pazmiño; Vargas-Lara, Fernando; Starr, Francis W; Douglas, Jack F
The interfacial zone in thin polymer films and around nanoparticles in polymer nanocomposites Journal Article
In: The Journal of Chemical Physics, vol. 151, no. 12, pp. 124705, 2019.
BibTeX | Tags: Dynamic Heterogeneity, Glass Formation, Nanocomposites, Nanotechnology | Links:
@article{zepvsd19,
title = {The interfacial zone in thin polymer films and around nanoparticles in polymer nanocomposites},
author = {Wengang Zhang and Hamed Emamy and Beatriz A Pazmiño Betancourt and Fernando Vargas-Lara and Francis W Starr and Jack F Douglas},
url = {http://fstarr.web.wesleyan.edu/publications/zepvsd19.pdf},
doi = {10.1063/1.5119269},
year = {2019},
date = {2019-01-01},
journal = {The Journal of Chemical Physics},
volume = {151},
number = {12},
pages = {124705},
keywords = {Dynamic Heterogeneity, Glass Formation, Nanocomposites, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
2017
Rivera, Jose L.; Villanueva-Mejia, Francisco; Navarro-Santos, Pedro; Starr, Francis W.
Desalination by dragging water using a low-energy nano-mechanical device of porous graphene Journal Article
In: RSC Adv., vol. 7, pp. 53729-53739, 2017.
Abstract | BibTeX | Tags: Nanotechnology, Thin Films, Water | Links:
@article{rvns17,
title = {Desalination by dragging water using a low-energy nano-mechanical device of porous graphene},
author = { Jose L. Rivera and Francisco Villanueva-Mejia and Pedro Navarro-Santos and Francis W. Starr},
url = {http://fstarr.web.wesleyan.edu/publications/rvns17.pdf},
doi = {10.1039/C7RA09847B},
year = {2017},
date = {2017-01-01},
journal = {RSC Adv.},
volume = {7},
pages = {53729-53739},
publisher = {The Royal Society of Chemistry},
abstract = {We propose a nano-structured suction system based on graphene sheets for water desalination processes. The desalination system modeled in this work is an alternative process to the commonly employed but energy intensive reverse osmosis process. The nano-structured system generates drag forces, which pull water molecules from the saline solution into a chamber. Our molecular simulations consist of two rigid walls of graphene: one wall with 5 A pores permeable to water molecules forms the membrane, while the other wall acts as a plunger to induce and control the transfer of desalinated water molecules, which accumulate in a chamber between the two walls. Prior to the desalination process, the chamber is saturated with one monolayer of water molecules. The desalination occurs when the plunger moves to create unsaturated space inside the chamber. At plunger speeds up to 10 cm s-1, the system desalinates saltwater films in the open part of the membrane. At higher plunger speeds, the desalination chamber expands faster than molecules can fill the chamber, resulting in cavitation and poor desalination. At plunger speeds of 0.5 cm s-1, the desalination occurs via a quasi-equilibrium process, which minimizes the energy necessary to drive desalination. Our findings suggest that the desalination process requires less energy than reverse osmosis methods at plunger speeds up to 0.15 cm s-1 (for the chosen pore density). The filling profile of desalinated water molecules inside the chamber occurs via three distinct regimes: the first two regimes correspond to the formation of one and then two monolayers adsorbed to the chamber's walls. The third regime corresponds to the filling of molecules between the adsorbed layers, which approaches a density close to the density of bulk liquid water. Including flexibility in the graphene sheets does not affect the energy consumption for desalination processes occurring after the formation of the second monolayer, but flexible membranes require a slightly larger pore diameter (7 A) than rigid membranes.},
keywords = {Nanotechnology, Thin Films, Water},
pubstate = {published},
tppubtype = {article}
}
We propose a nano-structured suction system based on graphene sheets for water desalination processes. The desalination system modeled in this work is an alternative process to the commonly employed but energy intensive reverse osmosis process. The nano-structured system generates drag forces, which pull water molecules from the saline solution into a chamber. Our molecular simulations consist of two rigid walls of graphene: one wall with 5 A pores permeable to water molecules forms the membrane, while the other wall acts as a plunger to induce and control the transfer of desalinated water molecules, which accumulate in a chamber between the two walls. Prior to the desalination process, the chamber is saturated with one monolayer of water molecules. The desalination occurs when the plunger moves to create unsaturated space inside the chamber. At plunger speeds up to 10 cm s-1, the system desalinates saltwater films in the open part of the membrane. At higher plunger speeds, the desalination chamber expands faster than molecules can fill the chamber, resulting in cavitation and poor desalination. At plunger speeds of 0.5 cm s-1, the desalination occurs via a quasi-equilibrium process, which minimizes the energy necessary to drive desalination. Our findings suggest that the desalination process requires less energy than reverse osmosis methods at plunger speeds up to 0.15 cm s-1 (for the chosen pore density). The filling profile of desalinated water molecules inside the chamber occurs via three distinct regimes: the first two regimes correspond to the formation of one and then two monolayers adsorbed to the chamber's walls. The third regime corresponds to the filling of molecules between the adsorbed layers, which approaches a density close to the density of bulk liquid water. Including flexibility in the graphene sheets does not affect the energy consumption for desalination processes occurring after the formation of the second monolayer, but flexible membranes require a slightly larger pore diameter (7 A) than rigid membranes.
2016
Liu, Wenyan; Tagawa, Miho; Xin, Huolin L.; Wang, Tong; Emamy, Hamed; Li, Huilin; Yager, Kevin G.; Starr, Francis W.; Tkachenko, Alexei V.; Gang, Oleg
Diamond family of nanoparticle superlattices Journal Article
In: SCIENCE, vol. 351, no. 6273, pp. 582-586, 2016, ISSN: 0036-8075.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{science16,
title = {Diamond family of nanoparticle superlattices},
author = {Liu, Wenyan and Tagawa, Miho and Xin, Huolin L. and Wang, Tong and Emamy, Hamed and Li, Huilin and Yager, Kevin G. and Starr, Francis W. and Tkachenko, Alexei V. and Gang, Oleg},
url = {http://fstarr.web.wesleyan.edu/publications/science16.pdf},
doi = {10.1126/science.aad2080},
issn = {0036-8075},
year = {2016},
date = {2016-02-01},
journal = {SCIENCE},
volume = {351},
number = {6273},
pages = {582-586},
abstract = {Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via self-assembly and demonstrate its experimental realization by assembling two variant diamond lattices, one with and one without atomic analogs. Our approach relies on the association between anisotropic particles with well-defined tetravalent binding topology and isotropic particles. The constrained packing of triangular binding footprints of truncated tetrahedra on a sphere defines a unique three-dimensional lattice. Hence, the diamond self-assembly problem is solved via its mapping onto two-dimensional triangular packing on the surface of isotropic spherical particles.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
Diamond lattices formed by atomic or colloidal elements exhibit remarkable functional properties. However, building such structures via self-assembly has proven to be challenging because of the low packing fraction, sensitivity to bond orientation, and local heterogeneity. We report a strategy for creating a diamond superlattice of nano-objects via self-assembly and demonstrate its experimental realization by assembling two variant diamond lattices, one with and one without atomic analogs. Our approach relies on the association between anisotropic particles with well-defined tetravalent binding topology and isotropic particles. The constrained packing of triangular binding footprints of truncated tetrahedra on a sphere defines a unique three-dimensional lattice. Hence, the diamond self-assembly problem is solved via its mapping onto two-dimensional triangular packing on the surface of isotropic spherical particles.
2014
Ko, Seung Hyeon; Vargas-Lara, Fernando; Patrone, Paul N.; Stavis, Samuel M.; Starr, Francis W.; Douglas, Jack F.; Liddle, J. Alexander
High-speed, high-purity separation of gold nanoparticle-DNA origami constructs using centrifugation Journal Article
In: SOFT MATTER, vol. 10, no. 37, pp. 7370-7378, 2014, ISSN: 1744-683X.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology | Links:
@article{kvpssdl14,
title = {High-speed, high-purity separation of gold nanoparticle-DNA origami constructs using centrifugation},
author = {Ko, Seung Hyeon and Vargas-Lara, Fernando and Patrone, Paul N. and Stavis, Samuel M. and Starr, Francis W. and Douglas, Jack F. and Liddle, J. Alexander},
url = {http://fstarr.web.wesleyan.edu/publications/kvpssdl14.pdf},
doi = {10.1039/c4sm01071j},
issn = {1744-683X},
year = {2014},
date = {2014-01-01},
journal = {SOFT MATTER},
volume = {10},
number = {37},
pages = {7370-7378},
abstract = {DNA origami is a powerful platform for assembling gold nanoparticle constructs, an important class of nanostructure with numerous applications. Such constructs are assembled by the association of complementary DNA oligomers. These association reactions have yields of <100%, requiring the development of methods to purify the desired product. We study the performance of centrifugation as a separation approach by combining optical and hydrodynamic measurements and computations. We demonstrate that bench-top microcentrifugation is a simple and efficient method of separating the reaction products, readily achieving purities of >90%. The gold nanoparticles play a number of critical roles in our system, functioning not only as integral components of the purified products, but also as hydrodynamic separators and optical indicators of the reaction products during the purification process. We find that separation resolution is ultimately limited by the polydispersity in the mass of the gold nanoparticles and by structural distortions of DNA origami induced by the gold nanoparticles. Our study establishes a methodology for determining the design rules for nanomanufacturing DNA origami-nanoparticle constructs.},
keywords = {Biophysics, DNA, Nanotechnology},
pubstate = {published},
tppubtype = {article}
}
DNA origami is a powerful platform for assembling gold nanoparticle constructs, an important class of nanostructure with numerous applications. Such constructs are assembled by the association of complementary DNA oligomers. These association reactions have yields of <100%, requiring the development of methods to purify the desired product. We study the performance of centrifugation as a separation approach by combining optical and hydrodynamic measurements and computations. We demonstrate that bench-top microcentrifugation is a simple and efficient method of separating the reaction products, readily achieving purities of >90%. The gold nanoparticles play a number of critical roles in our system, functioning not only as integral components of the purified products, but also as hydrodynamic separators and optical indicators of the reaction products during the purification process. We find that separation resolution is ultimately limited by the polydispersity in the mass of the gold nanoparticles and by structural distortions of DNA origami induced by the gold nanoparticles. Our study establishes a methodology for determining the design rules for nanomanufacturing DNA origami-nanoparticle constructs.
2011
Padovan-Merhar, Olivia; Vargas Lara, Fernando; Starr, Francis W.
Stability of DNA-linked nanoparticle crystals: Effect of number of strands, core size, and rigidity of strand attachment Journal Article
In: JOURNAL OF CHEMICAL PHYSICS, vol. 134, no. 24, pp. 244701, 2011, ISSN: 0021-9606.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{pvs11,
title = {Stability of DNA-linked nanoparticle crystals: Effect of number of strands, core size, and rigidity of strand attachment},
author = {Padovan-Merhar, Olivia and Vargas Lara, Fernando and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/pvs11.pdf},
doi = {10.1063/1.3596745},
issn = {0021-9606},
year = {2011},
date = {2011-06-01},
journal = {JOURNAL OF CHEMICAL PHYSICS},
volume = {134},
number = {24},
pages = {244701},
abstract = {Three-dimensional ordered lattices of nanoparticles (NPs) linked by DNA have potential applications in novel devices and materials, but most experimental attempts to form crystals result in amorphous packing. Here we use a coarse-grained computational model to address three factors that impact the stability of bcc and fcc crystals formed by DNA-linked NPs : (i) the number of attached strands to the NP surface, (ii) the size of the NP core, and (iii) the rigidity of the strand attachment. We find that allowing mobility in the attachment of DNA strands to the core NP can very slightly increase or decrease melting temperature T(M). Larger changes to T(M) result from increasing the number of strands, which increases T(M), or by increasing the core NP diameter, which decreases T(M). Both results are consistent with experimental findings. Moreover, we show that the behavior of T(M) can be quantitatively described by the model introduced previously [F. Vargas Lara and F. W. Starr, Soft Matter, 7, 2085 (2011)]. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3596745]},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
Three-dimensional ordered lattices of nanoparticles (NPs) linked by DNA have potential applications in novel devices and materials, but most experimental attempts to form crystals result in amorphous packing. Here we use a coarse-grained computational model to address three factors that impact the stability of bcc and fcc crystals formed by DNA-linked NPs : (i) the number of attached strands to the NP surface, (ii) the size of the NP core, and (iii) the rigidity of the strand attachment. We find that allowing mobility in the attachment of DNA strands to the core NP can very slightly increase or decrease melting temperature T(M). Larger changes to T(M) result from increasing the number of strands, which increases T(M), or by increasing the core NP diameter, which decreases T(M). Both results are consistent with experimental findings. Moreover, we show that the behavior of T(M) can be quantitatively described by the model introduced previously [F. Vargas Lara and F. W. Starr, Soft Matter, 7, 2085 (2011)]. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3596745]
Vargas Lara, Fernando; Starr, Francis W.
Stability of DNA-linked nanoparticle crystals I: Effect of linker sequence and length Journal Article
In: SOFT MATTER, vol. 7, no. 5, pp. 2085-2093, 2011, ISSN: 1744-683X.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{vs11,
title = {Stability of DNA-linked nanoparticle crystals I: Effect of linker sequence and length},
author = {Vargas Lara, Fernando and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/vs11.pdf},
doi = {10.1039/c0sm00989j},
issn = {1744-683X},
year = {2011},
date = {2011-01-01},
journal = {SOFT MATTER},
volume = {7},
number = {5},
pages = {2085-2093},
abstract = {The creation of three-dimensional, crystalline-ordered nanoparticle (NP) structures linked by DNA has proved experimentally challenging. Here we aim to systematically study parameters that influence the relative thermodynamic and kinetic stability of such crystals. To avoid experimental bottlenecks and directly control molecular-scale parameters, we carry out molecular dynamics simulations of a coarse-grained model in which short DNA strands (6 to 12 bp) are tethered to a NP core. We examine the influence of the number of bases per strand L, number of linking bases l and the number of spacer bases s on the stability of crystal states. We also consider the effect of using a single linking NP type versus a binary linking system. We explicitly compute the free energy, entropy, and melting point T(M) for BCC and FCC lattices. We show that binary systems are preferable for generating BCC lattices, while a single NP type generates the most stable FCC crystals. We propose a simple model for short DNA strands that can account for T(M) of all our data. The model also indicates that the heat of fusion between crystal and amorphous phases grows linearly with l, providing a route to maximize the relative crystal stability.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
The creation of three-dimensional, crystalline-ordered nanoparticle (NP) structures linked by DNA has proved experimentally challenging. Here we aim to systematically study parameters that influence the relative thermodynamic and kinetic stability of such crystals. To avoid experimental bottlenecks and directly control molecular-scale parameters, we carry out molecular dynamics simulations of a coarse-grained model in which short DNA strands (6 to 12 bp) are tethered to a NP core. We examine the influence of the number of bases per strand L, number of linking bases l and the number of spacer bases s on the stability of crystal states. We also consider the effect of using a single linking NP type versus a binary linking system. We explicitly compute the free energy, entropy, and melting point T(M) for BCC and FCC lattices. We show that binary systems are preferable for generating BCC lattices, while a single NP type generates the most stable FCC crystals. We propose a simple model for short DNA strands that can account for T(M) of all our data. The model also indicates that the heat of fusion between crystal and amorphous phases grows linearly with l, providing a route to maximize the relative crystal stability.
2010
Rivera, Jose L.; Starr, Francis W.
Rapid Transport of Water via a Carbon Nanotube Syringe Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 114, no. 9, pp. 3737-3742, 2010, ISSN: 1932-7447.
Abstract | BibTeX | Tags: Nanotechnology, Water | Links:
@article{rs10,
title = {Rapid Transport of Water via a Carbon Nanotube Syringe},
author = {Rivera, Jose L. and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/rs10.pdf},
doi = {10.1021/jp906527c},
issn = {1932-7447},
year = {2010},
date = {2010-03-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {114},
number = {9},
pages = {3737-3742},
abstract = {The controlled flow of water molecules at the nanoscale is an initial step to many fluidic processes ill nanotechnology. Here we show how thin films of water call be drawn through a nanosyringe built from a carbon nanotube membrane and a ``plunger''. By increasing the speed of withdrawal of the plunger, we call obtain Molecular transport through the membrane at flux rates exceeding 1()25 molecules cm(-2) s(-1). Above I threshold speed around 0.25 nm/ns (25 cm/s), molecules cannot fill the chamber created by the plunger motion as fast as the chamber expands, and the resulting flux rate drops. By considering hydrophobic or hydrophilic Plungers, we unexpectedly find that the nature of the water-plunger interactions does not affect the flux rate or the threshold plunger speed. While the water structure near the plunger Surface differs significantly For different plunger interactions, the failure of the film away From the plunger surface is responsible for loss of transport. As I result, the surface interactions play a limited role in controlling the flux.},
keywords = {Nanotechnology, Water},
pubstate = {published},
tppubtype = {article}
}
The controlled flow of water molecules at the nanoscale is an initial step to many fluidic processes ill nanotechnology. Here we show how thin films of water call be drawn through a nanosyringe built from a carbon nanotube membrane and a ``plunger''. By increasing the speed of withdrawal of the plunger, we call obtain Molecular transport through the membrane at flux rates exceeding 1()25 molecules cm(-2) s(-1). Above I threshold speed around 0.25 nm/ns (25 cm/s), molecules cannot fill the chamber created by the plunger motion as fast as the chamber expands, and the resulting flux rate drops. By considering hydrophobic or hydrophilic Plungers, we unexpectedly find that the nature of the water-plunger interactions does not affect the flux rate or the threshold plunger speed. While the water structure near the plunger Surface differs significantly For different plunger interactions, the failure of the film away From the plunger surface is responsible for loss of transport. As I result, the surface interactions play a limited role in controlling the flux.
Dai, Wei; Hsu, Chia Wei; Sciortino, Francesco; Starr, Francis W.
Valency Dependence of Polymorphism and Polyamorphism in DNA-Functionalized Nanoparticles Journal Article
In: LANGMUIR, vol. 26, no. 5, pp. 3601-3608, 2010, ISSN: 0743-7463.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Polyamorphism | Links:
@article{dhss10,
title = {Valency Dependence of Polymorphism and Polyamorphism in DNA-Functionalized Nanoparticles},
author = {Dai, Wei and Hsu, Chia Wei and Sciortino, Francesco and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/dhss.pdf},
doi = {10.1021/la903031p},
issn = {0743-7463},
year = {2010},
date = {2010-03-01},
journal = {LANGMUIR},
volume = {26},
number = {5},
pages = {3601-3608},
abstract = {Nanoparticles (NP) functionalized with single-stranded DNA (ssDNA) offer a route to custom-designed, self-assembled nanomaterials with potentially unusual properties, The bonding, selectivity of DNA guarantees one-to-one binding to form double-stranded DNA (dsDNA), and an appropriate base sequence results in head-to-tail binding linking NP into networks. We explore the phase behavior and structure of a model for NP functionalized with between 3 and 6 short ssDNA through simulations of a coarse-grained molecular model, allowing us to examine both the role of the number of attached strands (valency) and their relative orientations. The NP assemble into networks where the number of NP links is controlled by the number of attached strands, The large length scale of the DNA links relative to the core NP size opens the possibility for the formation of interpenetrating networks that give rise 10 multiple thermodynamically distinct states. We find that the 3-functionalized NP have only a single phase transition between a dilute solution of NPs and an assembled network state. 4-Functionalized NP (with tetrahedral symmetry) exhibit four amorphous phases, or polyamorphism, each higher density phase consisting of an additional interpenetrating network. The two investigated geometries of 5-functionalized NP both exhibit two phase transitions and three amorphouos phases. Like the 4-functionalized NP, the highest density phase consists of interpenetrating networks, demonstrating that regular symmetry is not a prerequisite for interpenetration to produce thermodynamically distinct phases. The width of theh coexistence regions for all phase transitions increase with increasing functionality. Finally, for 6-functionalized NP with octahedral symmetry. the possibility of observing disordered phases with significantly bonded particles is preempted by the formation of ordered crystal phases, Interestingly, the extreme softness of the potential combined with the directional interaction allows for the formation of (at least) six distinct crystalline structures (ie., polymorphism) consisting of up to six interpenetrating simple cubic lattices.},
keywords = {Biophysics, DNA, Nanotechnology, Polyamorphism},
pubstate = {published},
tppubtype = {article}
}
Nanoparticles (NP) functionalized with single-stranded DNA (ssDNA) offer a route to custom-designed, self-assembled nanomaterials with potentially unusual properties, The bonding, selectivity of DNA guarantees one-to-one binding to form double-stranded DNA (dsDNA), and an appropriate base sequence results in head-to-tail binding linking NP into networks. We explore the phase behavior and structure of a model for NP functionalized with between 3 and 6 short ssDNA through simulations of a coarse-grained molecular model, allowing us to examine both the role of the number of attached strands (valency) and their relative orientations. The NP assemble into networks where the number of NP links is controlled by the number of attached strands, The large length scale of the DNA links relative to the core NP size opens the possibility for the formation of interpenetrating networks that give rise 10 multiple thermodynamically distinct states. We find that the 3-functionalized NP have only a single phase transition between a dilute solution of NPs and an assembled network state. 4-Functionalized NP (with tetrahedral symmetry) exhibit four amorphous phases, or polyamorphism, each higher density phase consisting of an additional interpenetrating network. The two investigated geometries of 5-functionalized NP both exhibit two phase transitions and three amorphouos phases. Like the 4-functionalized NP, the highest density phase consists of interpenetrating networks, demonstrating that regular symmetry is not a prerequisite for interpenetration to produce thermodynamically distinct phases. The width of theh coexistence regions for all phase transitions increase with increasing functionality. Finally, for 6-functionalized NP with octahedral symmetry. the possibility of observing disordered phases with significantly bonded particles is preempted by the formation of ordered crystal phases, Interestingly, the extreme softness of the potential combined with the directional interaction allows for the formation of (at least) six distinct crystalline structures (ie., polymorphism) consisting of up to six interpenetrating simple cubic lattices.
Dai, Wei; Kumar, Sanat K.; Starr, Francis W.
Universal two-step crystallization of DNA-functionalized nanoparticles Journal Article
In: SOFT MATTER, vol. 6, no. 24, pp. 6130-6135, 2010, ISSN: 1744-683X.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{dks10,
title = {Universal two-step crystallization of DNA-functionalized nanoparticles},
author = {Dai, Wei and Kumar, Sanat K. and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/dks10.pdf},
doi = {10.1039/c0sm00484g},
issn = {1744-683X},
year = {2010},
date = {2010-01-01},
journal = {SOFT MATTER},
volume = {6},
number = {24},
pages = {6130-6135},
abstract = {We examine the crystallization dynamics of nanoparticles reversibly tethered by DNA hybridization. We show that the crystallization happens readily only in a narrow temperature ``slot'', and always proceeds via a two-step process, mediated by a highly-connected amorphous intermediate. For lower temperature quenches, the dynamics of unzipping strands in the amorphous state is sufficiently slow that crystallization is kinetically hindered. This accounts for the well-documented difficulty of forming crystals in these systems. The strong parallel to the crystallization behavior of proteins and colloids suggests that these disparate systems crystallize in an apparently universal manner.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
We examine the crystallization dynamics of nanoparticles reversibly tethered by DNA hybridization. We show that the crystallization happens readily only in a narrow temperature ``slot'', and always proceeds via a two-step process, mediated by a highly-connected amorphous intermediate. For lower temperature quenches, the dynamics of unzipping strands in the amorphous state is sufficiently slow that crystallization is kinetically hindered. This accounts for the well-documented difficulty of forming crystals in these systems. The strong parallel to the crystallization behavior of proteins and colloids suggests that these disparate systems crystallize in an apparently universal manner.
2007
Rivera, Jose L.; Rico, Jose L.; Starr, Francis W.
Interaction of water with cap-ended defective and nondefective small carbon nanotubes Journal Article
In: JOURNAL OF PHYSICAL CHEMISTRY C, vol. 111, no. 51, pp. 18899-18905, 2007, ISSN: 1932-7447.
Abstract | BibTeX | Tags: Nanotechnology, Water | Links:
@article{rrs07,
title = {Interaction of water with cap-ended defective and nondefective small carbon nanotubes},
author = {Rivera, Jose L. and Rico, Jose L. and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/rrs.pdf},
doi = {10.1021/jp075989r},
issn = {1932-7447},
year = {2007},
date = {2007-12-01},
journal = {JOURNAL OF PHYSICAL CHEMISTRY C},
volume = {111},
number = {51},
pages = {18899-18905},
abstract = {We present a theoretical study of the structure, local curvature angles, and reactivity of cap-ended (7,0), defective and nondefective carbon nanotubes. We find that the most reactive sites are the atoms that form part of the caps even when the Stone-Wales defect is present. Each carbon in the carbon nanotube is located at the top of a pyramidal structure with three walls of 5-, 6-, or 7-carbon rings. Among the carbons making up the caps, the most reactive sites are the top pyramidal atoms between two 5-carbon rings and one 6-carbon ring and each 5-carbon ring has attached another 5-carbon ring. The least reactive sites are the top pyramidal atoms between three 6-carbon rings. The. activity of each pyramidal structure is strongly correlated to its local curvature angle. The dissociation of one water molecule on the surface of the carbon nanotubes confirms the location of the most active site. The dissociation of water produces a hydroxyl group and a hydrogen atom united each to two adjacent carbon atoms. The dissociation process of water on carbon nanotubes is energetically favorable starting from the isolated molecules.},
keywords = {Nanotechnology, Water},
pubstate = {published},
tppubtype = {article}
}
We present a theoretical study of the structure, local curvature angles, and reactivity of cap-ended (7,0), defective and nondefective carbon nanotubes. We find that the most reactive sites are the atoms that form part of the caps even when the Stone-Wales defect is present. Each carbon in the carbon nanotube is located at the top of a pyramidal structure with three walls of 5-, 6-, or 7-carbon rings. Among the carbons making up the caps, the most reactive sites are the top pyramidal atoms between two 5-carbon rings and one 6-carbon ring and each 5-carbon ring has attached another 5-carbon ring. The least reactive sites are the top pyramidal atoms between three 6-carbon rings. The. activity of each pyramidal structure is strongly correlated to its local curvature angle. The dissociation of one water molecule on the surface of the carbon nanotubes confirms the location of the most active site. The dissociation of water produces a hydroxyl group and a hydrogen atom united each to two adjacent carbon atoms. The dissociation process of water on carbon nanotubes is energetically favorable starting from the isolated molecules.
Knauert, Scott T.; Douglas, Jack F.; Starr, Francis W.
The effect of nanoparticle shape on polymer-nanocomposite rheology and tensile strength Journal Article
In: JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS, vol. 45, no. 14, pp. 1882-1897, 2007, ISSN: 0887-6266.
Abstract | BibTeX | Tags: Nanocomposites, Nanotechnology, Polymers | Links:
@article{kds07,
title = {The effect of nanoparticle shape on polymer-nanocomposite rheology and tensile strength},
author = {Knauert, Scott T. and Douglas, Jack F. and Starr, Francis W.},
url = {http://fstarr.web.wesleyan.edu/publications/kds.pdf},
doi = {10.1002/polb.21176},
issn = {0887-6266},
year = {2007},
date = {2007-07-01},
journal = {JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS},
volume = {45},
number = {14},
pages = {1882-1897},
abstract = {Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocomposites in mind, we investigate how particle shape influences the melt shear viscosity eta and the tensile strength tau, which we determine via molecular dynamics simulations. Our simulations of compact (icosahedral), tube or rod-like, and sheet-like model nanoparticles, all at a volume fraction phi approximate to 0.05, indicate an order of magnitude increase in the viscosity 17 relative to the pure melt. This finding evidently can not be explained by continuum hydrodynamics and we provide evidence that the eta increase in our model nanocomposites has its origin in chain bridging between the nanoparticles. We find that this increase is the largest for the rod-like nanoparticles and least for the sheet-like nanoparticles. Curiously, the enhancements of 17 and tau exhibit opposite trends with increasing chain length N and with particle shape anisotropy. Evidently, the concept of bridging chains alone cannot account for the increase in tau and we suggest that the deformability or flexibility of the sheet nanoparticles contributes to nanocomposite strength and toughness by reducing the relative value of the Poisson ratio of the composite. The molecular dynamics simulations in the present work focus on the reference case where the modification of the melt structure associated with glass-formation and entanglement interactions should not be an issue. Since many applications require good particle dispersion, we also focus on the case where the polymer-particle interactions favor nanoparticle dispersion. Our simulations point to a substantial contribution of nanoparticle shape to both mechanical and processing properties of polymer nanocomposites. (c) 2007 Wiley Periodicals, Inc.},
keywords = {Nanocomposites, Nanotechnology, Polymers},
pubstate = {published},
tppubtype = {article}
}
Nanoparticles can influence the properties of polymer materials by a variety of mechanisms. With fullerene, carbon nanotube, and clay or graphene sheet nanocomposites in mind, we investigate how particle shape influences the melt shear viscosity eta and the tensile strength tau, which we determine via molecular dynamics simulations. Our simulations of compact (icosahedral), tube or rod-like, and sheet-like model nanoparticles, all at a volume fraction phi approximate to 0.05, indicate an order of magnitude increase in the viscosity 17 relative to the pure melt. This finding evidently can not be explained by continuum hydrodynamics and we provide evidence that the eta increase in our model nanocomposites has its origin in chain bridging between the nanoparticles. We find that this increase is the largest for the rod-like nanoparticles and least for the sheet-like nanoparticles. Curiously, the enhancements of 17 and tau exhibit opposite trends with increasing chain length N and with particle shape anisotropy. Evidently, the concept of bridging chains alone cannot account for the increase in tau and we suggest that the deformability or flexibility of the sheet nanoparticles contributes to nanocomposite strength and toughness by reducing the relative value of the Poisson ratio of the composite. The molecular dynamics simulations in the present work focus on the reference case where the modification of the melt structure associated with glass-formation and entanglement interactions should not be an issue. Since many applications require good particle dispersion, we also focus on the case where the polymer-particle interactions favor nanoparticle dispersion. Our simulations point to a substantial contribution of nanoparticle shape to both mechanical and processing properties of polymer nanocomposites. (c) 2007 Wiley Periodicals, Inc.
Largo, Julio; Starr, Francis W.; Sciortino, Francesco
Self-assembling DNA dendrimers: A numerical study Journal Article
In: LANGMUIR, vol. 23, no. 11, pp. 5896-5905, 2007, ISSN: 0743-7463.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{lss,
title = {Self-assembling DNA dendrimers: A numerical study},
author = {Largo, Julio and Starr, Francis W. and Sciortino, Francesco},
url = {http://fstarr.web.wesleyan.edu/publications/lss.pdf},
doi = {10.1021/la063036z},
issn = {0743-7463},
year = {2007},
date = {2007-05-01},
journal = {LANGMUIR},
volume = {23},
number = {11},
pages = {5896-5905},
abstract = {DNA is increasingly used as a specific linker to template nanostructured materials. We present a molecular dynamics simulation study of a simple DNA-dendrimer model designed to capture the basic characteristics of the biological interactions, where selectivity and strong cooperativity play an important role. Exploring a large set of densities and temperatures, we follow the progressive formation of a percolating large-scale network whose connectivity can be described by random percolation theory. We identify the relative regions of network formation and kinetic arrest versus phase separation and show that the location of the two-phase region can be interpreted in the same framework as reduced valency models. This correspondence provides guidelines for designing stable, equilibrium self-assembled low-density networks. Finally, we demonstrate a relation between bonding and dynamics, by showing that the temperature dependence of the diffusion constant is controlled by the number of fully unbonded dendrimers.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
DNA is increasingly used as a specific linker to template nanostructured materials. We present a molecular dynamics simulation study of a simple DNA-dendrimer model designed to capture the basic characteristics of the biological interactions, where selectivity and strong cooperativity play an important role. Exploring a large set of densities and temperatures, we follow the progressive formation of a percolating large-scale network whose connectivity can be described by random percolation theory. We identify the relative regions of network formation and kinetic arrest versus phase separation and show that the location of the two-phase region can be interpreted in the same framework as reduced valency models. This correspondence provides guidelines for designing stable, equilibrium self-assembled low-density networks. Finally, we demonstrate a relation between bonding and dynamics, by showing that the temperature dependence of the diffusion constant is controlled by the number of fully unbonded dendrimers.
Kumar, Pradeep; Starr, Francis W.; Buldyrev, Sergey V.; Stanley, H. Eugene
Effect of water-wall interaction potential on the properties of nanoconfined water Journal Article
In: PHYSICAL REVIEW E, vol. 75, no. 1, 1, pp. 011202, 2007, ISSN: 1539-3755.
Abstract | BibTeX | Tags: Nanotechnology, Water | Links:
@article{ksbs,
title = {Effect of water-wall interaction potential on the properties of nanoconfined water},
author = {Kumar, Pradeep and Starr, Francis W. and Buldyrev, Sergey V. and Stanley, H. Eugene},
url = {http://fstarr.web.wesleyan.edu/publications/ksbs.pdf},
doi = {10.1103/PhysRevE.75.011202},
issn = {1539-3755},
year = {2007},
date = {2007-01-01},
journal = {PHYSICAL REVIEW E},
volume = {75},
number = {1, 1},
pages = {011202},
abstract = {Much of the understanding of bulk liquids has progressed through study of the limiting case in which molecules interact via purely repulsive forces, such as a hard-core or ``repulsive ramp'' potential. In the same spirit, we report progress on the understanding of confined water by examining the behavior of waterlike molecules interacting with planar walls via purely repulsive forces and compare our results with those obtained for Lennard-Jones (LJ) interactions between the molecules and the walls. Specifically, we perform molecular dynamics simulations of 512 waterlike molecules interacting via the TIP5P potential and confined between two smooth planar walls that are separated by 1.1 nm. At this separation, there are either two or three molecular layers of water, depending on density. We study two different forms of repulsive confinement, when the water-wall interaction potential is either (i) 1/r(9) or (ii) a WCA-like repulsive potential. We find that the thermodynamic, dynamic, and structural properties of the liquid in purely repulsive confinements qualitatively match those for a system with a pure LJ attraction to the wall. In previous studies that include attractions, freezing into monolayer or trilayer ice was seen for this wall separation. Using the same separation as these previous studies, we find that the crystal state is not stable with 1/r(9) repulsive walls but is stable with WCA-like repulsive confinement. However, by carefully adjusting the separation of the plates with 1/r(9) repulsive interactions so that the effective space available to the molecules is the same as that for LJ confinement, we find that the same crystal phases are stable. This result emphasizes the importance of comparing systems only using the same effective confinement, which may differ from the geometric separation of the confining surfaces.},
keywords = {Nanotechnology, Water},
pubstate = {published},
tppubtype = {article}
}
Much of the understanding of bulk liquids has progressed through study of the limiting case in which molecules interact via purely repulsive forces, such as a hard-core or ``repulsive ramp'' potential. In the same spirit, we report progress on the understanding of confined water by examining the behavior of waterlike molecules interacting with planar walls via purely repulsive forces and compare our results with those obtained for Lennard-Jones (LJ) interactions between the molecules and the walls. Specifically, we perform molecular dynamics simulations of 512 waterlike molecules interacting via the TIP5P potential and confined between two smooth planar walls that are separated by 1.1 nm. At this separation, there are either two or three molecular layers of water, depending on density. We study two different forms of repulsive confinement, when the water-wall interaction potential is either (i) 1/r(9) or (ii) a WCA-like repulsive potential. We find that the thermodynamic, dynamic, and structural properties of the liquid in purely repulsive confinements qualitatively match those for a system with a pure LJ attraction to the wall. In previous studies that include attractions, freezing into monolayer or trilayer ice was seen for this wall separation. Using the same separation as these previous studies, we find that the crystal state is not stable with 1/r(9) repulsive walls but is stable with WCA-like repulsive confinement. However, by carefully adjusting the separation of the plates with 1/r(9) repulsive interactions so that the effective space available to the molecules is the same as that for LJ confinement, we find that the same crystal phases are stable. This result emphasizes the importance of comparing systems only using the same effective confinement, which may differ from the geometric separation of the confining surfaces.
2006
Starr, Francis W.; Sciortino, Francesco
Model for assembly and gelation of four-armed DNA dendrimers Journal Article
In: JOURNAL OF PHYSICS-CONDENSED MATTER, vol. 18, no. 26, pp. L347-L353, 2006, ISSN: 0953-8984.
Abstract | BibTeX | Tags: Biophysics, DNA, Nanotechnology, Self Assembly | Links:
@article{ss06,
title = {Model for assembly and gelation of four-armed DNA dendrimers},
author = {Starr, Francis W. and Sciortino, Francesco},
url = {http://fstarr.web.wesleyan.edu/publications/ss.pdf},
doi = {10.1088/0953-8984/18/26/L02},
issn = {0953-8984},
year = {2006},
date = {2006-07-01},
journal = {JOURNAL OF PHYSICS-CONDENSED MATTER},
volume = {18},
number = {26},
pages = {L347-L353},
abstract = {We introduce and numerically study a model designed to mimic the bulk behaviour of a system composed of single-stranded DNA dendrimers. Complementarity of the base sequences of different strands results in the formation of strong cooperative intermolecular links. We find that in an extremely narrow temperature range the system forms a large-scale, low-density disordered network via a thermo-reversible gel transition. By controlling the strand length, the gel transition temperature can be made arbitrarily close to the percolation transition, in contrast with recent model systems of physical gelation. This study helps the understanding of self-assembly in this class of new biomaterials and provides a bridge between physical and chemical gels.},
keywords = {Biophysics, DNA, Nanotechnology, Self Assembly},
pubstate = {published},
tppubtype = {article}
}
We introduce and numerically study a model designed to mimic the bulk behaviour of a system composed of single-stranded DNA dendrimers. Complementarity of the base sequences of different strands results in the formation of strong cooperative intermolecular links. We find that in an extremely narrow temperature range the system forms a large-scale, low-density disordered network via a thermo-reversible gel transition. By controlling the strand length, the gel transition temperature can be made arbitrarily close to the percolation transition, in contrast with recent model systems of physical gelation. This study helps the understanding of self-assembly in this class of new biomaterials and provides a bridge between physical and chemical gels.