title: Phase behaviour in complementary DNA-coated gold nanoparticles and fd-viruses mixtures: a numerical study.
abstract: A new gel-forming colloidal system based on a binary mixture of fd-viruses and gold nanoparticles functionalized with complementary DNA single strands has been recently introduced. Upon quenching below the DNA melt temperature, such a system results in a highly porous gel state, that may be developed in a new functional material of tunable porosity. In order to shed light on the gelation mechanism, we introduce a model closely mimicking the experimental one and we explore via Monte Carlo simulations its equilibrium phase diagram. Specifically, we model the system as a binary mixture of hard rods and hard spheres mutually interacting via a short-range square-well attractive potential. In the experimental conditions, we find evidence of a phase separation occurring either via nucleation-and-growth or via spinodal decomposition. The spinodal decomposition leads to the formation of small clusters of bonded rods and spheres whose further diffusion and aggregation leads to the formation of a percolating network in the system. Our results are consistent with the hypothesis that the mixture of DNA-coated fd-viruses and gold nanoparticles undergoes a non-equilibrium gelation via an arrested spinodal decomposition mechanism.
authors.affiliation: Physics Department, University of Rome "La Sapienza", Rome, Italy. massimilianochiappini@gmail.com.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Chiappini
authors.affiliation: Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, CB3 0HE, Cambridge, UK.
authors.forename: Erika
authors.initials: E
authors.lastname: Eiser
authors.affiliation: Physics Department, University of Rome "La Sapienza", Rome, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: Sciortino
mesh_terms: D017104:Bacteriophage M13 / Q000737:chemistry*; D018076:DNA, Complementary / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009010:Monte Carlo Method; D044367:Phase Transition; D013696:Temperature; D013816:Thermodynamics
chemical_list: D018076:DNA, Complementary; D006046:Gold
keywords: Soft Matter: Colloids and Nanoparticles