Anomalous phase behavior of liquid–vapor phase transition in binary mixtures of DNA-coated particles

Martínez-Veracoechea, Francisco J.; Bozorgui, Behnaz; Frenkel, Daan

doi:10.1039/c0sm00567c

Cited by 29 publications

(47 citation statements)

References 68 publications

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“…Unexpectedly, for wider patches the diamond crystal disappears from the phase diagram and a region in which the liquid is stable down to vanishing T opens up at intermediate ρ, in agreement with a numerical study of DNA-functionalized colloids 12,20 . In this range of densities, the liquid is the thermodynamically stable phase, despite its intrinsic disorder.…”

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confidence: 86%

Liquids more stable than crystals in particles with limited valence and flexible bonds

2013

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All liquids (except helium owing to quantum effects) crystallize at low temperatures, forming ordered structures. The competition between disorder, which stabilizes the liquid phase, and energy, which leads to a preference for the crystalline structure, inevitably favours the crystal when the temperature is lowered and entropy becomes progressively less relevant. The liquid state survives at low temperatures only as a glass, an out-of-equilibrium arrested state of matter. This textbook description holds inevitably for atomic and molecular systems, where particle interactions are set by quantum-mechanical laws. The question remains whether it holds for colloidal particles, where interparticle interactions are usually short-ranged and tunable. Here we show that for patchy colloids with limited valence 1 , conditions can be found for which the liquid phase is stable even in the zero-temperature limit. Our results offer fresh cues for understanding the stability of gels 2 and the glass-forming ability of molecular network glasses 3,4 .The ability to control the selectivity and angular flexibility of interparticle interactions 5 makes it possible to provide valence to colloids. This can be done by means of chemical [6][7][8] or physical 9 patterning of the colloid surface, that is, locally changing either its chemical properties (for example, hydrophobicity), or the physical properties (for example, roughness). Exploiting valence offers enormous possibilities, some of which have been addressed in recent years, theoretically 10 , numerically 4,11,12 and experimentally 2,7,13,14 . As colloidal interactions are typically shortranged, valence provides an implicit quantization of the particle energy, which becomes essentially proportional to the (limited) number of formed bonds. In an optimal arrangement, all particles bind with their maximum number of neighbours and the system is in its lowest possible (ground) energy state. Typically, such an optimal arrangement is spatially ordered, defining the most stable crystal phase(s).In principle, when the density is not too high, it is possible to imagine disordered arrangements in which all particles are fully bonded, with exactly the same energy as the crystal. Such a state, which was recently shown to be stable in a model system for DNA-functionalized colloids 12 , is a liquid: a fluid, disordered phase at temperatures below the critical temperature. Under this unconventional condition, the stability of the system becomes controlled by its entropy, a case reminiscent of (purely entropydriven) hard-sphere particles. In this study we demonstrate that the flexibility of the bonds (encoded in the angular patch width)-a tunable quantity in the design of patchy colloidal particles-is the key element in controlling the entropy of the liquid as compared with that of the crystal. Large binding angles combined with limited valence give rise to a thermodynamically stable, fully bonded liquid phase.Department of Physics, Sapienza, Universitá di Roma, Piazzale Aldo Moro 2, I-00185, Roma,...

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confidence: 86%

Liquids more stable than crystals in particles with limited valence and flexible bonds

2013

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“…Here we present the main features of the model: further details about the model and the simulations can be found in the SI Text (see also refs. 22,23). The guest nano-particles are represented as hard spheres of diameter σ. Simulations were performed in a cubic box of linear dimension L ¼ 10σ and the bulk concentration of nano-particles was fixed at ρ ¼ 0.0038σ −3 .…”

Section: Resultsmentioning

confidence: 99%

Designing super selectivity in multivalent nano-particle binding

Martínez-Veracoechea

Frenkel

2011

Proc. Natl. Acad. Sci. U.S.A.

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A key challenge in nano-science is to design ligand-coated nanoparticles that can bind selectively to surfaces that display the cognate receptors above a threshold (surface) concentration. Nanoparticles that bind monovalently to a target surface do not discriminate sharply between surfaces with high and low receptor coverage. In contrast, "multivalent" nano-particles that can bind to a larger number of ligands simultaneously, display regimes of "super selectivity" where the fraction of bound particles varies sharply with the receptor concentration. We present numerical simulations that show that multivalent nano-particles can be designed such that they approach the "on-off" binding behavior ideal for receptor-concentration selective targeting. We propose a simple analytical model that accounts for the super selective behavior of multivalent nano-particles. The model shows that the super selectivity is due to the fact that the number of distinct ligand-receptor binding arrangements increases in a highly nonlinear way with receptor coverage. Somewhat counterintuitively, our study shows that selectivity can be improved by making the individual ligand-receptor bonds weaker. We propose a simple rule of thumb to predict the conditions under which super selectivity can be achieved. We validate our model predictions against the Monte Carlo simulations.ne of the key challenges in nano-medicine is to acquire the ability to design supramolecular constructs that can target surfaces that display a motif or receptor above a threshold concentration while leaving surfaces with lower coverage of such receptors unaffected (1-4). Experiments indicate that such selective behavior can be obtained using multivalency (5-8). During multivalent interactions a type of particle (henceforth referred to as the "guest") uses multiple ligands to bind simultaneously to several of the receptors displayed by another type of particle or surface (the "host") (9, 10). Mammen et al. (9) recognized the importance of this type of system more than ten years ago. Since then, the concept of multivalency has found numerous applications in cell biology (7, 11), supramolecular chemistry (10), nano-medicine (4, 6), immunology (12, 13), and cancer treatment (2,3,5,14), to name but a few examples. The work of Davis et al. There is a substantial body of theoretical work that aims to explain the pronounced enhancement in binding strength that certain multivalent systems can present in comparison with their monovalent counterparts (15-17). In particular, Kitov and Bundle (18) have pointed out that the strength of multivalent binding can be enhanced if there are many possible permutations in the binding pattern of receptors and ligands. The role of steric repulsion and conformational entropy in multivalent systems have been studied using molecular theories (19) and Monte Carlo (MC) simulations (20, 21). However, a unified picture that explains why high selectivity is observed in some experimental realizations of multivalent systems but not in others is still lacki...

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“…This model can predict the phase separation between a dilute vapor-like phase and a dense phase where NPs are a part of a liquid-like network based on DNA links. In this case, there is a non-monotonous dependence of the coexistence pressure on the temperature, namely the reduced hybridization free energy [169]. This behavior may be attributed to the crossover between two distinct regimes.…”

Section: Coarse-grained Modelsmentioning

confidence: 93%

“…MC simulations combined with histogram re-weighting techniques have been applied in order to construct the phase diagram of DNA-functionalized NPs based on a coarse-grained model [169]. This model can predict the phase separation between a dilute vapor-like phase and a dense phase where NPs are a part of a liquid-like network based on DNA links.…”

Section: Coarse-grained Modelsmentioning

confidence: 99%

Self-assembly of DNA-functionalized colloids

Theodorakis¹,

Fytas²,

Kahl³

et al. 2015

Condens. Matter Phys.

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Colloidal particles grafted with single-stranded DNA (ssDNA) chains can self-assemble into a number of different crystalline structures, where hybridization of the ssDNA chains creates links between colloids stabilizing their structure. Depending on the geometry and the size of the particles, the grafting density of the ssDNA chains, and the length and choice of DNA sequences, a number of different crystalline structures can be fabricated. However, understanding how these factors contribute synergistically to the self-assembly process of DNA-functionalized nano-or micro-sized particles remains an intensive field of research. Moreover, the fabrication of long-range structures due to kinetic bottlenecks in the self-assembly are additional challenges. Here, we discuss the most recent advances from theory and experiment with particular focus put on recent simulation studies.

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Anomalous phase behavior of liquid–vapor phase transition in binary mixtures of DNA-coated particles

Cited by 29 publications

References 68 publications

Liquids more stable than crystals in particles with limited valence and flexible bonds

Liquids more stable than crystals in particles with limited valence and flexible bonds

Designing super selectivity in multivalent nano-particle binding

Self-assembly of DNA-functionalized colloids

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