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.

/pdf/present-and-future-of-surface-enhanced-raman-scattering-34aqgcm385.pdf

Present and Future of Surface-Enhanced Raman Scattering

In this study, we demonstrate a new strategy for endonuclease assay based on self-assembled chiral supernanostructures made from different-sized gold nanoparticles (AuNPs) and double-stranded DNAs (dsDNAs).

Chiral supernanostructures for ultrasensitive endonuclease analysis.

Establishing a simple and accurate method for Hg2+ detection is of great importance for the environment and human health. In this work, platinum nanoparticles (Pt NPs) with different capped agents and morphologies were synthesized. It was found that Pt NPs exhibited peroxidase-like activity that can catalyze the chemiluminescence (CL) of the luminol system without H2 O2 . The most intensive CL signals were obtained by using PVP-capped Pt NPs as catalysis. Based on the fact that Hg2+ could further enhance the CL intensity in the Pt NPs-luminol CL system, a Pt NPs-catalyzed CL method based on a flow injection system is developed for the sensitive analysis of Hg2+ . When the concentration of Hg2+ in the system increases, the CL intensity would together increase, thereby achieving sensitive Hg2+ detection. The limit of detection (LOD) was calculated to be 8.6 nM. This developed method provides a simple and rapid approach for the sensitive detection of Hg2+ and shows great promise for applications in other complex systems.

Pt NPs catalyzed chemiluminescence method for Hg2+ detection based on a flow injection system

A simple enzyme-linked immunosorbent assay for the detection of hexoestrol (HES) residue has been developed. The HES derivatives, hexoestrol-mono-ether-butyrate-ethyl (HES-MEBE) and hexoestrol-mono-caroxyl-propyl-ethyl (HES-MCPE) were synthesised to enable the coupling of HES and proteins together. The immunogen HES-MCPE-BSA and enzyme-linked antigen HES-MCPE-HRP were prepared by mixed anhydride methods. After the antibody was obtained by immunisation of New Zealand rabbits, a direct enzyme-linked immunosorbent assay was developed for the determination of HES residue. Several parameters were optimised. Excellent linearity (R 2=0.9905) was demonstrated from 0.01 to 8.1 ng/ml. The 50% inhibition value (IC50) and the limit of detection (LOD) were 0.23 and 0.01 ng/ml, respectively. The specificity of the immunoassay was evaluated by determining cross-reactivity of six hormones (diethylstilbestrol, dienestrol, 19-nortestosterone, medroxyprogesterone, testosterone and estrone), and all cross-reactivity...

A direct enzyme-linked immunosorbent assay for hexoestrol residues

The accurate monitoring of trace cancer biomarkers is crucial for the early diagnosis of cancer. In the present study, we constructed a gold nanorod–quantum dot core–satellite assembly using a PSA-aptamer and its complementary DNA and developed an ultrasensitive fluorescence-aptasensor for the detection of prostate specific antigen (PSA) by monitoring fluorescence intensity. The limit of detection (LOD) for PSA was 0.029 aM, with an excellent linear range from 0.1 aM to 10 aM. This super-sensitive aptasensor was demonstrated to be robust in the analysis of human serum samples, and shows great potential for early cancer diagnosis and therapy.

A fluorescence active gold nanorod–quantum dot core–satellite nanostructure for sub-attomolar tumor marker biosensing

We have developed an ultrasensitive indirect competitive enzyme-linked immunosorbent assay for the determination of tartrazine. Two carboxylated analogues of tartrazine with different spacer lengths, and one derivative from commercial tartrazine after a little chemical modification, were synthesized as haptens in order to produce antibodies specific to tartrazine. The effect of sulfonic acid groups on the hapten structure of tartrazine was also studied carefully for the first time. A most specific monoclonal antibody against tartrazine was created and exhibited an IC50 value of 0.105 ng/mL and a limit of detection of 0.014 ng/mL, with no cross-reactivity to other structurally-related pigments. The established immunoassay was applied to the determination of tartrazine in fortified samples of orange juice and in real positive samples of carbonated beverages.

https://www.mdpi.com/1424-8220/13/7/8155/pdf

Chuanlai Xu

Papers

Chiral supernanostructures for ultrasensitive endonuclease analysis.

Pt NPs catalyzed chemiluminescence method for Hg2+ detection based on a flow injection system

A direct enzyme-linked immunosorbent assay for hexoestrol residues

A fluorescence active gold nanorod–quantum dot core–satellite nanostructure for sub-attomolar tumor marker biosensing

Development of an Ultrasensitive Immunoassay for Detecting Tartrazine