Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Fast parallel algorithms for short-range molecular dynamics

Gold nanoparticles have been used in biomedical applications since their first colloidal syntheses more than three centuries ago. However, over the past two decades, their beautiful colors and unique electronic properties have also attracted tremendous attention due to their historical applications in art and ancient medicine and current applications in enhanced optoelectronics and photovoltaics. In spite of their modest alchemical beginnings, gold nanoparticles exhibit physical properties that are truly different from both small molecules and bulk materials, as well as from other nanoscale particles. Their unique combination of properties is just beginning to be fully realized in range of medical diagnostic and therapeutic applications. This critical review will provide insights into the design, synthesis, functionalization, and applications of these artificial molecules in biomedicine and discuss their tailored interactions with biological systems to achieve improved patient health. Further, we provide a survey of the rapidly expanding body of literature on this topic and argue that gold nanotechnology-enabled biomedicine is not simply an act of ‘gilding the (nanomedicinal) lily’, but that a new ‘Golden Age’ of biomedical nanotechnology is truly upon us. Moving forward, the most challenging nanoscience ahead of us will be to find new chemical and physical methods of functionalizing gold nanoparticles with compounds that can promote efficient binding, clearance, and biocompatibility and to assess their safety to other biological systems and their long-term term effects on human health and reproduction (472 references).

The golden age: gold nanoparticles for biomedicine

Molecular self-assembly is the spontaneous association of molecules under equilibrium conditions into stable, structurally well-defined aggregates joined by noncovalent bonds. Molecular self-assembly is ubiquitous in biological systems and underlies the formation of a wide variety of complex biological structures. Understanding self-assembly and the associated noncovalent interactions that connect complementary interacting molecular surfaces in biological aggregates is a central concern in structural biochemistry. Self-assembly is also emerging as a new strategy in chemical synthesis, with the potential of generating nonbiological structures with dimensions of 1 to 10(2) nanometers (with molecular weights of 10(4) to 10(10) daltons). Structures in the upper part of this range of sizes are presently inaccessible through chemical synthesis, and the ability to prepare them would open a route to structures comparable in size (and perhaps complementary in function) to those that can be prepared by microlithography and other techniques of microfabrication.

Molecular self-assembly and nanochemistry: A chemical strategy for the synthesis of nanostructures

In the past decade, mesoporous silica nanoparticles (MSNs) have attracted more and more attention for their potential biomedical applications. With their tailored mesoporous structure and high surface area, MSNs as drug delivery systems (DDSs) show significant advantages over traditional drug nanocarriers. In this review, we overview the recent progress in the synthesis of MSNs for drug delivery applications. First, we provide an overview of synthesis strategies for fabricating ordered MSNs and hollow/rattle-type MSNs. Then, the in vitro and in vivo biocompatibility and biotranslocation of MSNs are discussed in relation to their chemophysical properties including particle size, surface properties, shape, and structure. The review also highlights the significant achievements in drug delivery using mesoporous silica nanoparticles and their multifunctional counterparts as drug carriers. In particular, the biological barriers for nano-based targeted cancer therapy and MSN-based targeting strategies are discussed. We conclude with our personal perspectives on the directions in which future work in this field might be focused.

Mesoporous Silica Nanoparticles: Synthesis, Biocompatibility and Drug Delivery

Within the field of nanotechnology, nanoparticles are one of the most prominent and promising candidates for technological applications. Self-assembly of nanoparticles has been identified as an important process where the building blocks spontaneously organize into ordered structures by thermodynamic and other constraints. However, in order to successfully exploit nanoparticle self-assembly in technological applications and to ensure efficient scale-up, a high level of direction and control is required. The present review critically investigates to what extent self-assembly can be directed, enhanced, or controlled by either changing the energy or entropy landscapes, using templates or applying external fields.

Directed Self-Assembly of Nanoparticles

This chapter provides a brief overview of recent progress in the synthesis of silica-coated nanomaterials and their significant impact in different areas such as spectroscopy, magnetism, catalysis, and biology. The need to increase the topological complexity of colloid-based structures for the creation of designer materials with specific functionalities demands a better understanding of the relationships between material topology and material function. A number of reports have been devoted to silica coating of colloidal nanoparticles by aqueous classical methods such as Stober synthesis, use of silane coupling agents, and the sodium silicate water-glass methodology. Microemulsions are macroscopically homogeneous mixtures of water, organic solvent (oil), and surfactant, which on the microscopic level consist of heterogeneous domains of water and organic solvent separated by a surfactant monolayer. Various general approaches toward silica coating of inorganic nanoparticles within W/O microemulsions have been considered so far.

Recent Progress on Silica Coating of Nanoparticles and Related Nanomaterials

Research on metal nanoparticles has been boosted by a wide variety of applications that often require a precise definition of the morphological features at the nanometer scale. Although the preparation (often based on colloid chemistry) of metal nanoparticles with many different shapes and sizes has been developed and optimized for spheres, rods, cubes, platelets and other shapes, the last few years have seen a rising interest in branched morphologies. This review article describes the main synthetic processes for the fabrication of such branched nanoparticles, often termed as nanostars, as well as some of the principal applications that have been found. A special emphasis is given to optical properties related to localized surface plasmon resonances and surface enhanced spectroscopies, for which nanostars have been predicted and demonstrated to shine brighter than any other shapes, thus opening new avenues for highly sensitive detection or biolabelling, among other applications.

Nanostars shine bright for you Colloidal synthesis, properties and applications of branched metallic nanoparticles

Twisting nanoparticles: Plasmonic circular dichroism was experimentally obtained in chiral 3D organizations of gold nanorods obtained by self-assembly of the nanoantennas onto a fiber template with a twisted morphology. Numerical simulations based on coupled dipoles confirm the crucial role of gold nanorods in this intense circular dichroism

Andrés Guerrero-Martínez

Papers

Recent Progress on Silica Coating of Nanoparticles and Related Nanomaterials

Nanostars shine bright for you Colloidal synthesis, properties and applications of branched metallic nanoparticles

Intense Optical Activity from Three‐Dimensional Chiral Ordering of Plasmonic Nanoantennas

From Individual to Collective Chirality in Metal Nanoparticles

ナノスターはあなたのために光を放つ:コロイド合成,特性および枝分れした金属ナノ粒子の応用