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

Chiral nanomaterials in biology play indispensable roles in maintaining numerous physiological processes, such as signaling, site-specific catalysis, transport, protection, and synthesis. Like natural chiral nanomaterials, chiral inorganic nanomaterials can also be established with similar size, charge, surface properties, and morphology. However, chiral inorganic nanomaterials usually exhibit extraordinary properties that are different from those of organic materials, such as high g-factor values, broad distribution range, and symmetrical mirror configurations. Because of these unique characteristics, there is great potential for application in the fields of biosensing, drug delivery, early diagnosis, bio-imaging, and disease therapy. Related research is summarized and discussed in this review to showcase the bio-functions and bio-applications of chiral inorganic nanomaterials, including the construction methods, classification and properties, and biological applications of chiral inorganic nanomaterials. Moreover, the deficiencies in existing studies are noted, and future development is prospected. This review will provide helpful guidance for constructing chiral inorganic nanomaterials with specific bio-functions for problem solving in living systems.

Chiral inorganic nanomaterials for biological applications.

Residues of flumetralin, a dinitroaniline herbicide, in foods pose a health risk to humans. In this study, we produced a sensitive monoclonal antibody (mAb) against flumetralin and developed a gold nanoparticle-based lateral flow immunoassay (LFIA) strip for screening flumetralin in orange. The subtype of mAb 3F5 was IgG1 and had a half-maximal inhibitory concentration of 9.43 ng mL-1. The cross-reactivity assay indicated that mAb had good specificity. The LFIA strip had a visual limit of detection of 200 ng g-1 in orange. We obtained results with the naked eye within 15 min. The calculated LOD of the strip in orange was 33.26 ng g-1, with a linear detection of 80.72-1672.10 ng g-1. The strip had recovery rates ranging from 98.4% to 110.1%. Therefore, our developed method is an effective and reliable tool for the rapid detection of flumetralin in orange.

Gold nanoparticle-based lateral flow immunoassay for the rapid detection of flumetralin in orange.

This chapter introduces the overview of pesticides containing the application, characteristics, mode of action, classification, hazard, and the maximum residue levels. Then, the synthetic procedures of pesticide haptens were depicted at length. The antibodies acquired by the forementioned hapten were the most sensitivity to date. Synthesis formats of antigen with various active groups were summarized. The cross-reactivities of antibody were analyzed via the enzyme-linked immunosorbent assay to provide the basis for hapten design. Additionally, authors also presented the pretreatment methods of different samples. Then, the colloidal gold-based immunochromatographic test strips for the determination of pesticides were described including the detection ranges and cutoff values. Finally, the perspective of immunoassays for pesticide analysis was discussed containing three parts: the introduction of computer-assisted molecular modeling, the development of the genetic engineering antibodies, and the application of nanomaterials in pesticide immunoassays.

Pesticide Immunoassay in Food

The original version of this Article contained an error in the spelling of the author Joong Hwan Bahng, which was incorrectly given as Joong Hwan Banhg. This has been corrected in both the PDF and HTML versions of the Article.

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Author Correction: Intracellular localization of nanoparticle dimers by chirality reversal

Tacrolimus is a macrolide immunosuppressant widely used in organ transplantation. Due to the narrow treatment window, therapeutic drug monitoring of the clinical application of tacrolimus is necessary. In this study, a carboxyl group introduced at the hydroxyl or carbon positions of tacrolimus was used to couple with carrier protein to synthesize complete antigens. After screening different immunogens and coating antigens, a highly-sensitive and specific monoclonal antibody (mAb) 4C5 was obtained, with a half inhibitory concentration (IC50) value of 0.26 ng mL-1 determined by indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). A colloidal gold-based immunochromatographic strip (CG-ICS) was established to monitor tacrolimus in human whole blood based on the mAb 4C5. Through visual observation, it was found that the visual limit of detection (vLOD) and cut-off value of qualitative detection were 1.0 and 20.0 ng mL-1, respectively. The calculated LOD (cLOD) value of quantitative detection was 0.16 ng mL-1, and the linear range was 0.48-7.57 ng mL-1. In addition, the results of the CG-ICS for analyzing real positive samples of human whole blood were basically consistent with those of LC-MS/MS. Therefore, the CG-ICS was suitable for rapid and accurate clinical monitoring of tacrolimus.

Chuanlai Xu

Papers

Chiral inorganic nanomaterials for biological applications.

Gold nanoparticle-based lateral flow immunoassay for the rapid detection of flumetralin in orange.

Pesticide Immunoassay in Food

Author Correction: Intracellular localization of nanoparticle dimers by chirality reversal

A gold-based immunochromatographic strip for the specific detection of tacrolimus in whole blood.