Meenakshi Dutt, Rutgers, The State University of New Jersey
Hendrik Heinz, University of Colorado-Boulder
Tiffany Walsh, Deakin University
Yaroslava Yingling, North Carolina State University
Symposium Support Air Force Office of Scientific Research
Army Research Office
National Science Foundation
WW2: Colloidal Systems
Monday PM, November 30, 2015
Sheraton, 2nd Floor, Back Bay C
2:30 AM - *WW2.01
Digital Alchemy for Materials Design
Sharon C. Glotzer 1
1Univ of Michigan Ann Arbor United StatesShow Abstract
We present a new approach to the design and optimization of colloidal and nanoparticle assemblies that is generalizable to many types of materials problems. We present a rigorous statistical thermodynamic framework underlying "digital alchemy," in which material features are optimized computationally for target structures and function in an automated fashion. We demonstrate the usefulness of this approach for the self assembly of hard polyhedra, as well as colloidal spheres interacting via oscillating pair potentials, into complex crystals. We discuss extensions of digital alchemy to other materials design problems.
*in collaboration with G. van Anders, D. Klotsa and P. Dodd
3:00 AM - WW2.02
Role of Ligand Dynamics in Structural Stability and Pressure Behavior of Supercrystals Self-Assembled from Crystalline Nanoparticles
Badri Narayanan 1 Sanket A Deshmukh 1 Ganesh Kamath 2 Elena Shevchenko 1 Subramanian Sankaranarayanan 1
1Argonne National Laboratory Lemont United States2University of Missouri Columbia United StatesShow Abstract
Crystalline nanoparticles (CNPs) covered by ligands can self-organize into highly periodic supercrystals (SCs), which possess a range of crystal symmetries (e.g., face-centered cubic FCC, body centered cubic BCC, simple hexagonal SH etc.). These SCs exhibit a variety of exotic properties (e.g, reversible metal-to-insulator transitions, enhanced conductivity), which make them suitable for various energy, technology and device applications. Despite the widespread efforts in synthesis of SCs, a fundamental understanding of the physical forces underlying the self-assembly process is still in its infancy. In particular, the key role played by ligands in driving the self-organization of CNPs into SCs with a particular crystal symmetry, and the influence of their nano-scale dynamics on the physical properties of SCs are still unclear. Here, using coarse grained molecular dynamics (CGMD) based on the well-known MARTINI force field, we demonstrate that the self-assembly of CNPs is critically controlled by the decorating ligands via their (a) self-interaction, (b) mobility on the CNP surface, (c) re-organization/inter-digitation, and associated dynamics. Our quasi-hydrostatic high-pressure small-angle X-ray scattering (SAXS) and X-ray diffraction (XRD) studies showed that the size of CNP building blocks control the symmetry of self assembled SC. Smaller (~4.7) nm PbS particles decorated by oleic acid ligands organize into BCC SC, while at larger sizes (~7 nm) they assemble into FCC SC. Furthermore, the BCC SCs show near-perfect elastic behavior under applied pressures ~55 GPa, while FCC SC show some hysteresis during the loading-unloading cycles without losing its structural integrity. Our CGMD simulations predict pressure behavior during the loading-unloading cycles consistent with our experiments. In addition, these simulations indicate the ligands strongly govern the pressure behavior of SCs via (a) re-arranging on the CNP surface, and (b) inter-digitating with neighboring CNPs without being locked in permanently. These enable the SCs to retain their structural organization even at extremely high pressures by merely reducing the distance between neighboring CNPs. We will discuss these results in the context of engineering novel ordered CNP architectures with prescribed mechanical, electronic, and physical properties.
3:15 AM - WW2.03
Structure of Nanocluster Au24(SCys-CysS)8 Identified by Theoretical and Experimental Studies
Lina Zhao 1
1Chinese Academic Sciences Beijing ChinaShow Abstract
The thiolate group (SR) protected gold nanoclusters (AuNCs) have attracted intense concerns due to the potential applications in catalysis, sensor and biomedicine. A series of Aun(SR)m nanoclusters were synthesized in experiment with size-dependent physical and chemical properties. The chemical formula of Aun(SR)m can be identified by mass spectrum analysis into matched n and m. For example, n = 18 is corresponding to m = 14 as Au18(SR)14. However, determination of the atomic structure of Aun(SR)m is still a challenge in experiments largely because most single crystals of which are difficult to be obtained. To identify the exact structure of Aun(SR)m, the theoretical scientists want to make contributions from the numerical study together with the experimental characterization. Till now, there are some independent predicted or theoretical and experimental consistent structure of Aun(SR)m have been achieved, including Au18(SR)14, Au20(SR)16, Au24(SR)20, [Au25(SR)18]-, and Au38(SR)24. In the theoretical prediction of Aun(SR)m, the density functional theory (DFT) calculations are important tools to give a deep insight into the molecular structure of Aun(SR)m. The general structure of these nanoclusters includes a high-symmetric Au-core and a series of semiring staple motifs. The super atom model is utilized to identify the high stable structure of Aun(SR)m by calculating the total number of free valence electron.
Recently, we successfully synthesize the stable Au24Peptide8 complex (Peptide = CysCys-6peptides). As a biomedical probe, Au24Peptide8 is utilized to achieve the quantitation of membrane protein integrin for cancer early diagnosis. However, the atomic structure of Au24Peptide8 is unknown. Especially, it is critical to identify the dominant coupling structure Au24(SCys-CysS)8 for the probe characteristics. Although there are 24 Au atoms in both Au24(SCys-CysS)8 and Au24(SR)20, the ratio of Au:S in amino acid coated Au24(SCys-CysS)8 is unmatched to that in SR coated Au24(SR)20 with the known molecular structure. In this work, we focus on identifying the atomic structure of Au24(SCys-CysS)8. According to the super atom model, the total number of Au24(SCys-CysS)8 is 8e, which satisfies the number of electrons to fill closed electron shell within the framework of spherical jellium model. The atomic structure of Au24(SCys-CysS)8 is resolved by the numerical calculations into Au13 cubocatahedral core and protected -Au-SCys- motifs. For the lowest-energy isomer, we both theoretically compute and experimentally measure its UV-vis absorption spectrum, which is in the good agreement to each other. It is the new knowledge for the atomic structure of amino acid coated AuNCs. Meanwhile, the atomic details of amino acid coated AuNCs support us to applicate the biocompatibility more effectively in biomedicine.
3:30 AM - *WW2.04
Interactions, Aggregation and Self-Assembly of Distributions of Colloids
George Opletal 1 Lin Lai 1 Amanda Susan Barnard 1
1CSIRO Parkville VIC AustraliaShow Abstract
Although the advent of modern theoretical techniques and high performance computing have provided us with a range of sophisticated tools for simulating nanoscale materials, modeling realistic systems to reproduce real experiments remains challenging. Each of the applications for nanoparticles, such as energy conversion and storage, communications, electronics or medicine, all have different material needs; but share one thing in common. All involve large collections of small particles, the properties and stability of which will depend on how and where they are used. Consider for example the case of a non-toxic nanoparticle, such as nanodiamond, being used in nanomedicine the treatment of cancer. Individual particles using for this purpose need to be mechanically stable, able to adsorb and desorb drugs in a controlled fashion, capable of forming porous meso-structures to moderate doses and dose rates, and able operate reliably under relevant thermochemical conditions (not “clean”, and in a vacuum). This means that simulating this application transcends length scales, from molecular, to nanoscale and even micron scale; must capture the complexity of the individual particles and their interactions; and must include the influence of the relevant environments and the proximity of large numbers of particles. In this presentation we will see how quantum mechanical simulations can be used to underpin higher level models that enable the direct simulation of distributions and mixtures of hundreds of thousands of faceted colloidal particles.
4:30 AM - *WW2.05
Entropic Control over Nanoscale Colloidal Crystals
Nathan A. Mahynski 1 Sanat Kumar 2 Athanassios Panagiotopoulos 1
1Princeton University Princeton United States2Columbia University New York United StatesShow Abstract
Globally ordered colloidal lattices have broad utility in a wide range of novel optical and catalytic devices, for example, as photonic bandgap materials. However, the self-assembly of stereospecific structures is often confounded by defects. Small free energy differences different crystal polymorphs, making it difficult to produce a single morphology at will. Current techniques to handle this problem usually rely on energy minimization; many colloids have been computationally engineered with anisotropic pairwise interactions to achieve morphological control. However, the complexity of these designs often makes experimental realization difficult. In this presentation, recent computer simulation and theoretical work [1-3] on the effects of polymeric co-solutes on crystallizing colloidal suspensions is summarized. These can be used to direct colloidal structures by relying upon the polymer's entropic interactions resulting from the interplay between the polymer's internal degrees of freedom and the void structure of a material. This represents a novel design paradigm that has the potential to significantly simplify control over colloidal polymorphism. I will elaborate on how to rationally design the co-solute structure to thermodynamically stabilize a single desired polymorph in a binary mixture, and the consequences that thermal perturbations have on this effect . I will then offer insights into how to design temperature-dependent co-solute “switches” that allow the stability of a polymorph to be controlled via experimentally accessible parameters .
 N. A. Mahynski, A. Z. Panagiotopoulos, D. Meng, and S. K. Kumar; Nature Comm., 5: 4472, 8 pp (2014).
 N. A. Mahynski, S. K. Kumar, and A. Z. Panagiotopoulos; Soft Matter, 11: 280-9(2015).
 N. A. Mahynski, S. K. Kumar, and A. Z. Panagiotopoulos; Soft Matter, DOI: 10.1039/c5sm00631g(2015).
5:00 AM - WW2.06
Pressure Measurement in Large Simulations of Hard Colloids
Michael Eric Irrgang 1 Michael Engel 1 Joshua A Anderson 1 Sharon Glotzer 1
1University of Michigan Ann Arbor Ann Arbor United StatesShow Abstract
In the active field of colloidally self assembled materials, simulation of large systems can be necessary to understand phase coexistence and nucleation, or to observe certain novel behaviors such as hexatic phases. One of the basic tools to understanding the thermodynamics of any system is to measure the state functions, but there are computational challenges for the non-differentiable potentials of the simplest (hard) particle models, particularly as system size is increased.
Computing the pressure -- volume state function is historically expensive in hard particle Monte Carlo simulations and traditional methods are inadequate for studying large systems. NpT simulations are far more computationally expensive than simulations in the NVT ensemble and become impossible for large system sizes. Pressure measurement in NVT simulations is analytic for few particle shapes. Perturbative numerical techniques, historically underutilized, are unclear or insufficient as previously published for general application to large systems of arbitrary particle shapes.
We combine and extend previous methods of pressure calculation from a perturbative thermodynamics approach and present an efficient and highly scalable implementation. This has allowed us to extract previously elusive thermodynamic data with the same computational efficiency as the rest of our highly parallel hard particle Monte Carlo code in studies of unprecedentedly large systems.
5:15 AM - WW2.07
Fundamental Thermodynamic Models for Self and Directed Assembly of Small Ensembles of Colloidal Particles
Raghuram Thyagarajan 1 Dimitrios Maroudas 1 David Ford 1
1Univ of Massachusetts-Amherst Amherst United StatesShow Abstract
The self-assembly of finite clusters of colloidal particles into crystalline objects is a topic of technological interest, as a route to produce photonic crystals and other meta-materials. Quantitatively accurate models of the thermodynamics and dynamics of these systems are essential to producing defect-free crystals. Robust methods for controlling the assembly of these crystals would require reduced dimension process-models that link the particle-level dynamics of the colloids to the actuator states. In this paper, we describe the building of such models for two systems comprising 10-100 micron sized silica particles in aqueous solution that employ either a temperature-tunable depletion interaction potential or externally applied electric field as a mechanism to promote the assembly process. We model the assembly process using coarse-grained representations, based on the Fokker-Planck equation, which can capture both the dynamics and the equilibrium properties of these small clusters. We use diffusion maps (DMaps), a machine learning technique to identify the slow, low-dimensional manifolds in these systems. The DMap coordinates are correlated against a set of candidate order parameters (OPs) to identify a suitable choice of observables. The DMap technique is sensitive to the nature of defects observed in these two systems and this is manifest in the correlations with OPs. We construct free energy and diffusivity landscapes in the chosen OPs that serve as reduced order models for process control policy maps providing an optimal route to defect-free crystals.
To quantify the phase behavior, we have also conducted Monte Carlo simulations of these small colloidal clusters and generated potential energy histograms for various levels of the osmotic pressure (for the depletion potential system) that controls the strength of the interactions. We have used potential energy as the histogram variable to identify the fluid-like and solid-like phases. By carefully tuning the osmotic pressure, we observed bimodal distributions in the potential energy space that is indicative of coexistence between fluid-like and solid-like configurations. We report comparisons of phase behavior for these colloidal clusters obtained from the thermodynamic approach outlined here with results from above mentioned Fokker-Planck order parameter approach.
5:30 AM - WW2.08
Tunable Long Range Forces Mediated by Self-Propelled Colloidal Hard Spheres
Ran Ni 1 Martien Cohen Stuart 2 Peter Bolhuis 1
1University of Amsterdam Amsterdam Netherlands2Wageningen University Wageningen NetherlandsShow Abstract
Most colloidal interactions can be tuned by changing properties of the medium. Here we show that activating the colloidal particles with random self-propulsion can induce giant effective interactions between large objects immersed in such a suspension. By performing Brownian dynamics simulations, we systematically study the effective force between two hard walls in a 2D suspension of self-propelled (active)colloidal hard spheres . We find that at relatively high densities, the active colloidal hard spheres can form a dynamic crystalline bridge, which induces a strong oscillating long range dynamic wetting repulsion between the walls. With decreasing the density of active colloids, the dynamic bridge gradually breaks, and an intriguing long range dynamic depletion attraction starts dominating the effective interaction between the two walls. The two long range forces oppose each other, and the effective interaction can be tuned from a long range repulsion into a long range attraction by reducing the density of active particles. Our results open up new possibilities to manipulate the motion and assembly of microscopic objects by using active matter.
 R. Ni et al, Phys. Rev. Lett., 114, 018302 (2015)
5:45 AM - WW2.09
Shape Allophiles Improve Entropic Assembly
Eric Harper 1 Ryan L. Marson 1 Joshua A Anderson 1 Greg van Anders 1 Sharon Glotzer 1
1University of Michigan Ann Arbor United StatesShow Abstract
We investigate a class of “shape allophiles” that fit together like puzzle pieces as a method to access and stabilize desired structures by controlling directional entropic forces. Squares are cut into rectangular halves, which are shaped in an allophilic manner with the goal of re-assembling the squares while self-assembling the square lattice. We examine the assembly characteristics of this system via the potential of mean force and torque, and the fraction of particles that entropically bind. We generalize our findings and apply them to self-assemble triangles into a square lattice via allophilic shaping. Through these studies we show how shape allophiles can be useful in assembling and stabilizing desired phases with appropriate allophilic design.
*This work currently in press in Soft Matter
WW1: Bioinspired Materials
Monday AM, November 30, 2015
Sheraton, 2nd Floor, Back Bay C
9:30 AM - *WW1.01
Revealing Molecular Features that Modulate Mesoscale Biomolecular Phenomena
Gregory Voth 1
1University of Chicago Chicago United StatesShow Abstract
Many biomolecular systems such as cell membranes and actin filaments are organized as complex and dynamic mesoscopic structures. However, underlying this fascinating degree of organization are molecular-scale features such as protein structural elements and/or local chemistry (e.g., protonation equilibria and nucleotide hydrolysis) that can greatly affect the mesoscopic behavior. Multiscale simulation can help to reveal these molecular features along with their coupling to the mesoscale behavior. Such results for the membrane remodeling by proteins and ATP hydrolysis in actin filaments will be presented in this talk. The lessons learned from these multiscale simulations can also help to guide in the development of novel soft materials and to predict their mesoscopic behavior via systematic coarse-graining of the molecular-scale interactions.
10:00 AM - WW1.02
Modeling of Morphological Versatility in Self-Assembly of Val-Ala and Ala-Val Dipeptides
Elif Candas 1 Gizem Gokce 1 Busra Demir 3 Gokhan Demirel 2 Ersin Emre Oren 1
1TOBB University of Economics and Technology Ankara Turkey2Gazi University Ankara Turkey3TOBB University of Economics and Technology Ankara TurkeyShow Abstract
In molecular self-assembly process, molecules spontaneously and reversibly form ordered aggregates through a number of attractive and repulsive forces. It has been shown that some dipeptide systems have the ability to self-assemble into various structures. We found that valine-alanine (Val-Ala) dipeptide molecules produce various self-assembled micro-/nano-structures, including square- and rectangular-plates, wires, and rods, depending on the solvents used, whereas alanine-valine (Ala-Val) dipeptides did not self-assemble into any distinct ordered structure under the same experimental conditions. Experimental as well as modeling studies towards the understanding of peptide self-assembly are still in their infancy. Thus, the fabrication of new peptide structures with desired properties mainly depends on our ability to understand/control peptide-peptide interactions in various solvents. In this work, we investigated the self-assembly of Val-Ala and Ala-Val dipeptides by using molecular modeling in aqueous environment. Molecular modeling studies revealed the decisive role of dipeptide/dipeptide and dipeptide/solvent H-bonding interactions on the final structures formed. Simulations also revealed that each one of the 2- and 4-mers of Val-Ala dipeptides have equally distributed intra- and inter-molecular H-bonds; however, this is not the case for Ala-Val peptides. This structural difference may be the reason for the formation of long-range ordered structures, which observed experimentally for Val-Ala dipeptides contrary to Ala-Val dipeptides. Supported by TUBA GEBIP awards to Demirel G. and Oren EE.
10:15 AM - WW1.03
Computational Design of Soft Materials via Coupling of Particle Dynamics and Continuum Approaches
Xiang Yu 1 Fikret Aydin 1 Leebyn Chong 1 Meenakshi Dutt 1
1Rutgers University Piscataway United StatesShow Abstract
We develop a computational model by coupling implicit solvent coarse-grained dry martini model with a lattice-Boltzmann fluid in order to design and characterize nanostructured soft materials. The long range hydrodynamic effects are included in the system through the implementation of the Lattice-Boltzmann fluid. This removes the necessity of using explicit solvent molecules. The particle dynamics is resolved via the Molecular Dynamics simulation method. Our objective is to generate a stable vesicle composed of single (DPPC) and multiple (DPPC and DOPC) phospholipid species through the use of implicit solvent coarse grained model with long range hydrodynamics in order to investigate physiological processes occurring on the mesoscopic spatio-temporal scales. By using a four to one mapping scale of Martini model, the DPPC molecule is represented by four head beads and eight tail beads. The twelve beads are further divided into four types, each with different interaction energies and length scales. Analogous models are developed for the other phospholipids. The vesicle is initially equilibrated using the Dry Martini force field without Lattice-Boltzmann fluid. In order to couple Dry Martini model with Lattice-Boltzmann fluid, 36 nodes are built on the surface of the hydrophilic head beads of the phospholipid molecules. These nodes and the surrounding head beads are treated as a rigid particle so that hydrodynamic forces can be transferred from fluid to lipid molecules. We investigate the dynamical, structural and morphological properties of the resulting hybrid aggregates. The results of our investigations can be used for the design and prediction of novel hybrid soft and bio-materials at the mesoscale for various applications in medicine, sensing and energy.
10:30 AM - WW1.04
Secondary Structure Transition and Critical Stress during the Assembly of Spider Silk Fibers
Tristan Giesa 1 Carole Celia Perry 2 Markus Buehler 1
1MIT Cambridge United States2Nottingham Trent University Nottingham United KingdomShow Abstract
Spiders spin their silk from an aqueous solution to a solid fiber in ambient conditions. However, to date the assembly mechanism in the spider gland has not been satisfactorily explained. By means of molecular dynamics simulations, we investigated structural transitions during the assembly of N. Clavipes MaSP1 dragline silk. These shear induced transitions in the core sequence ((AAAAAAGGAGQGGYGGLGSQGAGRGGLGGQGAG)n; n=2-6) are important for the formation of aligned β-sheet nanostructures in the fiber. We found that a critical shear stress of 300 - 800 MPa induces an α-β-transition in the core poly-alanine region of the MaSP1 structure that is maintained after relaxation in aqueous media. While the transition stress is independent of the number of MaSP1 repeats, the β-crystal is stable only in larger configurations. The minimum size for a stable structure was shown to be six poly-alanine regions for a single chain and four poly-alanine regions for simulations performed on assemblages of multiple chains. This marks the smallest molecule size that gives rise to a ‘silk-like&’ structure. In addition, the presence of water was found to stimulate the formation of additional β-sheet secondary structure components not present after the shear induced transition.
Using a probability analysis of the secondary structure allowed us to identify specific amino acids that transition from α-helix to β-sheet. In addition to portions of the poly-alanine section these amino acids include glycine, leucine and glutamine. The stability of the β-sheet structure appears to arise from a close proximity in space of helices in the initial spidroin state. Our results are in agreement with the forces exerted by spiders in the silking process and the experimentally determined global secondary structure of spidroin and pulled MaSp1 silk. This is the first time that the shear stress has been quantified in connection with a secondary structure transition. Our study emphasizes the role of shear in the assembly process of silk and can guide the design of microfluidic devices that attempt to mimic the natural spinning process.
10:45 AM - WW1.05
Chain and Fibrous Network Formation in Magnetorheological Suspensions
Colin Reynolds 1 David Robinson 1 Valeriy Titarenko 2 Michael Juniper 1 Mark Wilson 1 Dirk Aarts 1 William Sampson 2 Roel Dullens 1
1University of Oxford Oxford United Kingdom2University of Manchester Manchester United KingdomShow Abstract
Many applications of fibrous materials, such as scaffolds for tissue engineering or applications in fuel cells, rely on the control of network properties such as void size distributions. Fibrous networks formed in magnetorheological fluids offer the possibility of tuning such fibrous structures. A deep understanding of the mechanisms that lead to network formation is a prerequisite for controlling network architecture, potentially giving rise to novel devices.
Here, we use super-paramagnetic polystyrene particles and optical video microscopy to investigate field-induced structure formation at the mesoscale and single particle level. First we address the chain formation at low packing fractions and use simple statistical considerations to fully predict the distribution of coordination numbers for individual particles. The validity of our approach is confirmed using computer simulations in which the starting configuration of the chain forming system is systematically varied from random to deterministic. We show that chain growth proceeds via a compound Poisson process, such that at all times the coordination number distribution fully characterises the chain length distribution and vice versa.
We then investigate the formation of fibrous networks at higher packing fractions. We use statistical geometry and statistical modelling to quantify and rationalise the observed structures. We also apply our approach of analysing self-assembly through coordination number statistics to these network forming systems.
Finally, we explore the possibilities of network formation in mixtures of super-paramagnetic and non-magnetic particles suspended in a ferrofluid. In the presence of a magnetic field, these magnetic holes and excesses act as dipoles pointing in opposite directions and assemble into structures distinct from those of the single component system.
11:30 AM - *WW1.06
Molecular Simulation Analysis of Nanoparticle-Biomolecule Interactions: Challenges and Developments
Qiang Cui 1
1UW-Madison Madison United StatesShow Abstract
In this talk I'll discuss the use of molecular simulation techniques to probe the interaction between nanoparticle and biomolecules. This is motivated by the increasing interest in the environmental and health impact of nano materials. Molecular simulations are able to provide a molecular level understanding of physical factors that dictate the strength and specificity of such interactions. I'll discuss the challenges associated with such simulations and the relevant developments made in our group, which touch upon both sampling methodologies and model potentials at different resolutions. Applications to nano-particle interactions with peptides and lipids will be presented as examples.
12:00 PM - WW1.07
Exploring Conformational Changes of Nucleic Acids upon Binding to Histone-Mimic Nanoparticles Using All-Atom Simulation
Jessica Nash 1 Abhishek Singh 1 Nan K. Li 1 Yaroslava Yingling 1
1North Carolina State University Chapel Hill United StatesShow Abstract
Nucleic acid based nanotechnology and gene theraphy approaches depend on the compaction, or packaging, of the nucleic acids DNA and RNA. Though there has been much experimental work on the interactions of DNA with proteins, the atomic details of DNA- nanoparticle binding remain to be comprehensively elucidated. Even less is known about the binding of double stranded RNA with cationic molecules. Here, we report the results of a comprehensive large scale all-atom simulation investigation of the binding ligand-functionalized gold nanoparticles (NPs) binding to the nucleic acids double stranded DNA and RNA as a function of NP charge and solution salt con- centration. Our simulations show that low charge NPs bind to DNA and cause little distortion of the DNA helix, however, nanoparticles with charges of +30 or higher cause DNA to bend and wrap in a way similar to nucleosome. Moreover, shape of the NP ligand corona plays an essential role in quality of DNA wrapping. The nanoparticles cause different behavior with short segments of RNA in that they are not able to induce bending for even the most highly charged nanoparticles in 0.1M NaCl. To compact RNA, a combination of highly charged nanoparticles with low salt concentration is required.
12:15 PM - WW1.08
Atomistic Modeling of Biologically Active Nanoparticles and Nanomedicines
Petr Kral 1
1University of Illinois at Chicago Chicago United StatesShow Abstract
First, we discuss our collaborative studies of colloidal nanoparticles with bio-active ligands. In our modeling of protein corona, we examine how different types of ligands control the adsorption, configuration and activity of proteins on nanoparticle surfaces . Next, we investigate how nanoparticles couple to and affect the functions of larger cellular and biological units . In our collaborative modeling of nanomedicines, we discuss the stability of micelles, their ability to carry drugs, and their interaction with membranes and receptors . Many different types of monomeric units are considered and compared in these nanomedicines.
 W. Lyn et al., submitted.
 S. Sen, in preparation.
 L. Vukovicacute; et al., JACS 133, 13481 (2011); Langmuir 29, 15747 (2013); H.-J. Hsu et al., Macromol., 47, 6911 (2014); C. R. James et al., JACS 136, 11316 (2014); A. Lote et al., Macro Lett. 3, 829 (2014) & submitted.
12:30 PM - WW1.09
Pathway for Insertion of Amphiphilic Nanoparticles into Lipid Bilayers from Atomistic Molecular Dynamics Simulations
Reid Van Lehn 1 Alfredo Alexander-Katz 2
1California Institute of Technology Pasadena United States2Massachusetts Institute of Technology Cambridge United StatesShow Abstract
Gold nanoparticles (NPs) are versatile materials with surface properties that can be chemically modified to mimic typical biological macromolecules. Recently, NPs protected by a binary monolayer of purely hydrophobic and anionic, end