There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

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

The discovery of the enhancement of Raman scattering by molecules adsorbed on nanostructured metal surfaces is a landmark in the history of spectroscopic and analytical techniques. Significant experimental and theoretical effort has been directed toward understanding the surface-enhanced Raman scattering (SERS) effect and demonstrating its potential in various types of ultrasensitive sensing applications in a wide variety of fields. In the 45 years since its discovery, SERS has blossomed into a rich area of research and technology, but additional efforts are still needed before it can be routinely used analytically and in commercial products. In this Review, prominent authors from around the world joined together to summarize the state of the art in understanding and using SERS and to predict what can be expected in the near future in terms of research, applications, and technological development. This Review is dedicated to SERS pioneer and our coauthor, the late Prof. Richard Van Duyne, whom we lost during the preparation of this article.

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Present and Future of Surface-Enhanced Raman Scattering

A rapid and simple method is developed for the determination of medroxyprogesterone acetate (MPA) by CE immunoassay with chemiluminescence (CL). This method is based on the competitive reactions between horseradish peroxidase (HRP)-labeled MPA (MPA-HRP) and free MPA with anti-MPA antiserum. The influencing factors on the electrophoresis and CL detection were studied completely and the optimal conditions of separation and determination were obtained. The linear range was 2.0-50 nmol/L and the LOD for MPA was 0.9 nmol/L. The present method was applied to the analysis of pork tissues.

Determination of medroxyprogesterone acetate residues by CE immunoassay with chemiluminescence detection

Peptide Mediated Chiral Inorganic Nanomaterials for Combating Gram‐Negative Bacteria

Hexestrol (HES) and Diethylstilbestrol (DES) are synthetic hormones, which have been found abuse use in animal-origin food production. We developed an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and immune-chromatographic strip to detect these compounds based on monoclonal antibody. Under optimized conditions, the half-inhibition concentration (IC50) values of ic-ELISA were 0.15 µgL−1 and 0.23 µgL−1 for HES and DES, respectively. Spiked milk samples were analyzed. The recovery of both synthetic hormones in the milk samples was 60.48–102.19% (HES) and 89.34–100.16% (DES). In immune-chromatographic assay, the visual cutoff values at 0.5 and 1.0 µgL−1 respectively for HES and DES, which allow us to detect milk samples of a concentration low to 10 µgL−1 for HES and 15 µgL−1 for DES.

Development of an immunochromatographic assay for hexestrol and diethylstilbestrol residues in milk

In this study, we developed a sensitive surface-enhanced Raman scattering (SERS) sensor based on a self-assembled Au NR oligomer for the detection of mercury ions (Hg2+) in aqueous solution. Taking advantage of the high sensitivity of Raman spectroscopy and high specificity of the T–Hg2+–T base pair, the method was used in ultratrace analysis of Hg2+ in real water samples. The developed Hg2+ detection method showed an excellent linear range from 5 to 5000 pM and a limit of detection (LOD) of 4.3 pM (0.86 pg mL−1). The recovery experiment presented excellent recovery ranging from 88.98%–105.76%, and demonstrated that the sensor could be used to monitor the concentration of Hg2+ for environmental water.

SERS-active Au NR oligomer sensor for ultrasensitive detection of mercury ions

The extensive use of neonicotinoid pesticides has led to their widespread presence in the environment, resulting in considerable safety risks to the ecosystem and human health. In this study, we investigated the biotransformation behavior of a cocktail of multiple neonicotinoids and piperonyl butoxide (PBO) synergist in vivo and their potential environmental health risk. It was found that neonicotinoids with a cyano group, such as acetamiprid and thiacloprid, tended to accumulate in liver and spleen tissues, while others with nitro groups (imidacloprid, thiamethoxam, clothianidin, dinotefuran, and nitenpyram) were mostly excreted in urine. In the presence of the synergist PBO, the metabolism of neonicotinoids in vivo changed, mainly through the nitro reduction pathway, while a low abundance of related metabolites was observed in the conventional hydroxylation and demethylation metabolic pathways, due to inhibition of CYP450 enzymes by the synergist. Furthermore, DNA methylation damage in vivo was exacerbated by the induction of hydroxylamine metabolites formed in the intermediate process of neonicotinoid metabolism with the synergistic effect of PBO, which resulted in a higher level of the O6-methyldeoxyguanosine (O6-medG) biomarker in the liver. Therefore, during the comprehensive evaluation of pesticide environmental risks, attention should be paid not only to the co-exposure mode under real environmental conditions but also to the potential risks of intermediate metabolism and related intermediate metabolites. This study provides a referential strategy and theoretical support for the health risk assessment of co-exposure of chemicals.

Chuanlai Xu

Papers

Determination of medroxyprogesterone acetate residues by CE immunoassay with chemiluminescence detection

Peptide Mediated Chiral Inorganic Nanomaterials for Combating Gram‐Negative Bacteria

Development of an immunochromatographic assay for hexestrol and diethylstilbestrol residues in milk

SERS-active Au NR oligomer sensor for ultrasensitive detection of mercury ions

Potential Environmental Health Risk Analysis of Neonicotinoids and a Synergist.