Nanoscale Physical Properties Research Articles

Depth dependence of hardness and reaction in metakaolin‐based geopolymers cured at low humidity

AbstractCompared to metakaolin‐based sodium and potassium geopolymers cured at 20°C/100% relative humidity, geopolymers, which were cured at 20°C/40% relative humidity, were found to have considerable changes in the nanoscale structure and physical properties near the surface due to dehydration that occurred before completely hardening. For low‐humidity samples, the density in a thin near‐surface region was higher than the bulk, while porosity and BET specific surface area were greatly diminished. The microhardness at the exposed surface was low but increased sharply within a small depth before decreasing with depth to a constant value, which depended on the initial water content and charge‐balancing cation. 29Si NMR spectroscopy showed that the extent of reaction also varied with distance from the exposed surface. Both the elevated microhardness and incomplete reaction were detected at distances of up to 1.5 cm from the exposed surface, indicating that premature dehydration can cause microstructural changes over length scales that may be significant in large, ambiently cured 3D‐printed geopolymers. These effects are reduced by the use of sodium rather than potassium as the charge‐balancing cation and by raising the initial water content of the geopolymer, although higher water content caused greater surface deformation during drying.

Emerging multi-frequency surface strain force microscopy

During the past decade, Scanning Probe Microscopy (SPM) based surface strain detection techniques have been extensively used in the characterization of functional materials, structures, and devices. Here, we refer these techniques as Surface Strain Force Microscopy (SSFM), which mainly includes the Piezoresponse Force Microscopy, Atomic Force Acoustic Microscopy, Atomic Force Microscopy-Infrared spectroscopy (or photothermal induced resonance), Piezomagnetic Force Microscopy, and Scanning Joule Expansion Microscopy. The inception of SSFM opens up a pathway to study the nanoscale physical properties by using a sharp tip to detect the local field-induced surface strain. Through measuring the signals of the surface strain, multiple physical properties, such as the electromechanical, mechanical, photothermal, magnetic, thermoelastic properties, can be characterized with an unprecedented spatial resolution. In order to further develop and overcome the fundamental issues and limitations of the SSFM, the multi-frequency SPM technology has been introduced to the SSFM-based techniques, leading to the emerging of multi-frequency SSFM (MF-SSFM). As a technical breakthrough of the SSFM, MF-SSFM has demonstrated substantial improvements in both performance and capability, resulting in increased attentions and numerous developments in recent years. This Perspective is, therefore, aimed at providing a preliminary summary and systematic understanding for the emerging MF-SSFM technology. We will first introduce the basic principles of conventional SSFM and multi-frequency SPM techniques, followed by a detailed discussion about the existing MF-SSFM techniques. MF-SSFM will play an increasingly important role in future nanoscale characterization of the physical properties. As a result, many more advanced and complex MF-SSFM systems are expected in the coming years.

Nanoscale physical and chemical properties of individual airborne magnetic particles from vehicle emissions

Diesel and petrol powered vehicles are contributors to the magnetic fraction of atmospheric particles in the urban atmosphere. For an assessment of the health effects of vehicle-emitted magnetic particles, the mineralogical characters of particles present in engine exhaust vs. those produced by braking need to be understood. We collected magnetically separated individual particles directly from both brake wear and engine exhaust, from the air inside a car cabin while driving on a motorway, and from the ambient urban atmosphere. The morphologies, sizes, chemical compositions and spatial associations of magnetic particles with other constituents of vehicle emissions were characterized using scanning and transmission electron microscopy techniques. Magnetic separates typically contained particles that were aggregates of a large number of nanocrystals. Particles from engine exhaust, car cabin and urban air were similar, with diameters ∼1–4 μm, consisting predominantly of ∼10 nm-sized, randomly oriented crystals of magnetite and minor hematite. In contrast, brake debris particles were larger (∼1–10 μm in diameter) and contained mostly ∼7 nm-sized hematite, in addition to metallic iron and minor goethite. Particles in all samples comprised carbonaceous constituents besides iron oxides. In the exhaust and ambient particles carbon was present in both amorphous and semi-ordered forms, encompassing the nanocrystals, suggesting a high-temperature formation. In contrast, only amorphous carbon was found in brake wear. Besides the main components (Fe, O, C) several additional elements, including Mg, Al, Si, P, S, Cl, Sn, Ca, Mn, Zn, Cu, Pb and Zr occurred in the particles, with some minor differences between the distinct types of samples. Whereas the overall characteristics of magnetic particles in exhaust emissions were similar to those of ambient particles, the brake emissions produced slightly different particle types, particularly in terms of size and mineralogy. Thus, based on the qualitative assessment of particle properties in direct emissions and ambient air, a significant portion of magnetic particles in urban air appears to originate from vehicle emissions. Although the aggregate particles have sizes in the μm range, they still may represent a potential health risk on inhalation. Synopsis: This article discusses the nanoscale properties of magnetic particles from vehicle emissions, for a better understanding of their sources and health effects. • The magnetic fraction of vehicle-derived airborne particulate matter can be collected using a simple device. • Exhaust emissions may constitute a substantial source of magnetic particles in urban environments. • Magnetic fraction of brake wear predominantly originates from the corrosion of the brake disc. • The primary magnetic agglomerates are small enough to reach the lungs upon inhalation.

Three-Dimensional Atomically Resolved Analytical Imaging with a Field Ion Microscope

Abstract Atom probe tomography (APT) helps elucidate the link between the nanoscale chemical variations and physical properties, but it has a limited structural resolution. Field ion microscopy (FIM), a predecessor technique to APT, is capable of attaining atomic resolution along certain sets of crystallographic planes albeit at the expense of elemental identification. We demonstrate how two commercially available atom probe instruments, one with a straight flight path and one fitted with a reflectron lens, can be used to acquire time-of-flight mass spectrometry data concomitant with a FIM experiment. We outline various experimental protocols making the use of temporal and spatial correlations to best discriminate field-evaporated signals from the large field-ionized background signal, demonstrating an unsophisticated yet efficient data mining strategy to provide this discrimination. We discuss the remaining experimental challenges that need to be addressed, notably concerned with accurate detection and identification of individual field-evaporated ions contained within the high field-ionized flux that contributes to a FIM image. Our hybrid experimental approach can, in principle, exhibit true atomic resolution with elemental discrimination capabilities, neither of which atom probe nor FIM can individually fully deliver—thereby making this new approach, here broadly termed analytical field ion microscopy (aFIM), unique.

Nanoscale physical parameters of source rocks identified by atomic force microscopy: A review

The refinement of nanoscale physical parameters of source rocks has benefitted from continuous innovations in technology and methods. Traditional methods for detecting reservoir physical properties are limited by the properties of the instruments. Atomic force microscopy (AFM) provides new methods and approaches for furthering our understanding and exploring the nanoscale world. Its wide range of applications and gradually developed multiscenario application modes make it an ideal tool for the characterization of nanoscale physical properties of source rocks (coal, shale, mudstone, sandstone, etc.). We highlight the advantages of AFM in regard to performing nondestructive 3D imaging and mechanical property measurements with nanoscale resolution in any desired environment (air, vacuum, liquid). The limitations of AFM applied to source rocks are also summarized. The process has great potential in micro/nanopore characterization, surface morphology characterization, in situ micromechanical property acquisition, wettability research, and so on. The gradual development and improvement of this new model will expand new methods, bring enlightenment to basic research on unconventional oil and gas resources, and provide a scientific basis for the exploration and development of unconventional oil and gas resources.

Nano-scale physical properties characteristic to metastatic intestinal cancer cells identified by high-speed scanning ion conductance microscope

Recent genetic studies have indicated relationships between gene mutations and colon cancer phenotypes. However, how physical properties of tumor cells are changed by genetic alterations has not been elucidated. We examined genotype-defined mouse intestinal tumor-derived cells using a high-speed scanning ion conductance microscope (HS-SICM) that can obtain high-resolution live images of nano-scale topography and stiffness. The tumor cells used in this study carried mutations in Apc (A), Kras (K), Tgfbr2 (T), Trp53 (P), and Fbxw7 (F) in various combinations. Notably, high-metastatic cancer-derived cells carrying AKT mutations (AKT, AKTP, and AKTPF) showed specific ridge-like morphology with active membrane volume change, which was not found in low-metastatic and adenoma-derived cells. Furthermore, the membrane was significantly softer in the metastatic AKT-type cancer cells than other genotype cells. Importantly, a principal component analysis using RNAseq data showed similar distributions of expression profiles and physical properties, indicating a link between genetic alterations and physical properties. Finally, the malignant cell-specific physical properties were confirmed by an HS-SICM using human colon cancer-derived cells. These results indicate that the HS-SICM analysis is useful as a novel diagnostic strategy for predicting the metastatic ability of cancer cells.

Biomarkers of exposure to metal nanoparticles in workplaces: methodology and preliminary results

BACKGROUND AND AIM: When the particle size is decreased to the nanoscale range, physical and chemical properties appear to change offering various new opportunities but bringing new risks and uncertainties also. The growing use of metal nanoparticles (MNPs) in industry may potentially lead to an increased human exposure to these substances. In this study, urine and blood as biomarkers of exposure were used to assess the exposure of workers to MNPs in two nanomaterial manufacturing companies. METHODS: When the particle size is decreased to the nanoscale range, physical and chemical properties appear to change offering various new opportunities but bringing new risks and uncertainties also. The growing use of metal nanoparticles (MNPs) in industry may potentially lead to an increased human exposure to these substances. In this study, urine and blood as biomarkers of exposure were used to assess the exposure of workers to MNPs in two nanomaterial manufacturing companies. RESULTS:The preliminary results showed NPs of Ag (29±0.5 nm) in urine and NPs of Au (15±0.2 nm), In (38±0.2 nm) and Ti (90±3.2 nm) in blood of workers from the company A. Nanoparticles of Ir, Pd and Pt were not detected neither in urine nor in blood of workers from company B. In addition, Ag NPs in urine, and Au and Ti NPs in blood were also detected in control subjects indicating the importance of daily-life exposure sources. CONCLUSIONS:The methodology can be recommended because fast and reliable for the measurement of MNPs in humans to contribute to safe workplace environments and health protection. KEYWORDS: Occupational exposures, heavy metals, biomarkers of exposure

Phase Field Simulation on the Surface Morphology of Cu/Ti Nano Thin Film

Cu/Ti binary thin film system has many applications for micro-/nano- electro mechanical systems (MEMS/NEMS), micro-electronics and optoelectronics. In nanoscale, the quality and many physical properties of nano thin films are strongly depended on its surface morphology. In the present paper the development of surface morphology of double layered Cu/Ti thin film heterostructure with different composition and thickness has been studied by using the phase field method. The developed method is based on solving Cahn-Hilliard equations of multi-order parameters with considering the interfacial energy and elastic energy. The simulation results show that the thickness of Ti layer and Cu layer in the double-layer thin film structure can affect the surface roughness. For the heterostructures with the Cu layer thickness was fixed at 20 nm, the surface roughness was found to vary from 0.608 nm to 0.712 nm, when the Ti layer thickness increased from 10 nm to 30 nm. The calculated surface morphology and roughness was similar to the experimentally measured values. It is believed that this simulation method is useful in designing multi-layered thin film structure for practical applications.

Nanocomposite scaffolds composed of Apacite (apatite-calcite) nanostructures, poly (ε-caprolactone) and poly (2-hydroxyethylmethacrylate): The effect of nanostructures on physico-mechanical properties and osteogenic differentiation of human bone marrow mesenchymal stem cells in vitro.

Nanocomposite scaffolds were fabricated from poly (ε-caprolactone) (PCL), Poly (2-hydroxyethylmethacrylate) (PHEMA), and Apacite (Apatite-calcite) nanostructures (15 and 25wt%). The nanoscale structure, physical and chemical properties, mechanical properties, hydrophilic behavior, degradability and osteogenic properties of the fabricated scaffolds were evaluated. The results showed that the mechanical strength, degradation, wetting ability, and mechanical strength of PCL-PHEMA scaffolds significantly increases upon inclusion of Apacite nanoparticles up to 25wt%. Accordingly, the best mechanical values (E~7.109MPa and σ~0.414MPa) and highest degradability (32% within 96h) were recorded for PCL-PHEMA scaffolds containing 25wt% of Apacite. Furthermore, highest porosity and roughness were observed in the PCL-PHEMA/25% Apacite as a result of the Apacite nanoparticles inclusion. There was no cytotoxicity recorded for the fabricated scaffolds based on the results obtained from MTT assay and acridine orange staining. Alkaline phosphatase activity, calcium content quantification, Van Kossa staining, FESEM and real time PCR tests confirmed the biomineralization, and the differentiation potential of the nanocomposite scaffolds. Overall, the 3D structure, optimum porosity and balanced dissolution rate of PCL-PHEMA/25% Apacite providing a balanced microenvironment resulted in improved cell adhesion, cell behavior, and replication, as well as osteogenic induction of human bone-marrow-derived mesenchymal stem cells (hBM-MSCs).

2D black phosphorus dotted with silver nanoparticles: An excellent lubricant additive for tribological applications

Black phosphorus (BP) is a new two-dimensional (2D) material with attractive nanoscale chemical and physical properties. Herein, black phosphorus dotted with silver nanoparticles (Ag/BP) was synthesized via a facile and in-suit chemical reduction approach without reductant. The tribological properties of as-prepared Ag/BP nanocomposite as lubricant additive in poly-alpha-olefin (PAO6) based oil were investigated by a ball-on-disc tribometer. The results demonstrate that the oil dispersed with trace amount of Ag/BP nanoadditives shows excellent lubricating performance for the steel/steel contact. The friction coefficient and wear rate of the oil dispersed with 0.075 wt% Ag/BP nanoadditives are reduced by 73.4% and 92.0% respectively, as compared to the based PAO6 oil. The possible friction-reducing and anti-wear mechanisms of Ag/BP nanoadditives in oil are illustrated by analyzing the wear scar surfaces. During scratching, the Ag/BP nanomaterials serves not only as a friction-reducing and anti-wear additive, but also as a catalyst to decompose the based PAO oil for forming a carbon-based tribofilm under ambient condition that further reduces the friction and wear. The findings here provide a novel insight into the design of lubricant additive incorporated in base oil and suggests a new potential application of black phosphorus in lubrication and tribology.

Multiscale model of integrin adhesion assembly

The ability of adherent cells to form adhesions is critical to numerous phases of their physiology. The assembly of adhesions is mediated by several types of integrins. These integrins differ in physical properties, including rate of diffusion on the plasma membrane, rapidity of changing conformation from bent to extended, affinity for extracellular matrix ligands, and lifetimes of their ligand-bound states. However, the way in which nanoscale physical properties of integrins ensure proper adhesion assembly remains elusive. We observe experimentally that both β-1 and β-3 integrins localize in nascent adhesions at the cell leading edge. In order to understand how different nanoscale parameters of β-1 and β-3 integrins mediate proper adhesion assembly, we therefore develop a coarse-grained computational model. Results from the model demonstrate that morphology and distribution of nascent adhesions depend on ligand binding affinity and strength of pairwise interactions. Organization of nascent adhesions depends on the relative amounts of integrins with different bond kinetics. Moreover, the model shows that the architecture of an actin filament network does not perturb the total amount of integrin clustering and ligand binding; however, only bundled actin architectures favor adhesion stability and ultimately maturation. Together, our results support the view that cells can finely tune the expression of different integrin types to determine both structural and dynamic properties of adhesions.

Strained 2D Layered Materials and Heterojunctions

Abstract2D layered materials and heterojunctions with excellent ductility and controllable atomic‐layer thicknesses have shown promise for use in advanced electronics and optical functional devices. Tailoring of nanoscale configurations and physical properties is essential and required for bespoke fabrication of advanced devices based on 2D materials. Due to the high strain tolerance of 2D layered materials, strain engineering is an effective method to tune their behaviors of electrons and phonons. A wide variety of 2D materials are available with tunable bandgaps from interface coupling effects, making 2D layered heterojunctions a versatile platform for understanding fundamental physical issues. Most physical properties and functional applications can be tailored by applying strain to 2D layered materials and heterostructures to realize a scheduled target in carrier concentration, mobility, and barrier height. Herein, the latest research on the roles of strain in modulating the physical properties of 2D layered materials and heterojunctions is introduced, focusing on the physical properties behind strain modulation in 2D materials. Understanding and manipulating strain in 2D layered materials and heterojunctions is important and beneficial for creating tunable electronic and optoelectronic constructions with advanced components, including functional flexible and wearable devices.

Insights into Nano-Scale Physical and Mechanical Properties of Epoxy/Boehmite Nanocomposite Using Different AFM Modes.

Understanding the interaction between nanoparticles and the matrix and the properties of interphase is crucial to predict the macroscopic properties of a nanocomposite system. Here, we investigate the interaction between boehmite nanoparticles (BNPs) and epoxy using different atomic force microscopy (AFM) approaches. We demonstrate benefits of using multifrequency intermodulation AFM (ImAFM) to obtain information about conservative, dissipative and van der Waals tip-surface forces and probing local properties of nanoparticles, matrix and the interphase. We utilize scanning kelvin probe microscopy (SKPM) to probe surface potential as a tool to visualize material contrast with a physical parameter, which is independent from the mechanics of the surface. Combining the information from ImAFM stiffness and SKPM surface potential results in a precise characterization of interfacial region, demonstrating that the interphase is softer than epoxy and boehmite nanoparticles. Further, we investigated the effect of boehmite nanoparticles on the bulk properties of epoxy matrix. ImAFM stiffness maps revealed the significant stiffening effect of boehmite nanoparticles on anhydride-cured epoxy matrix. The energy dissipation of epoxy matrix locally measured by ImAFM shows a considerable increase compared to that of neat epoxy. These measurements suggest a substantial alteration of epoxy structure induced by the presence of boehmite.

Dynamic AFM on Viscoelastic Polymer Samples with Surface Forces

Dynamic atomic force microscopy (dAFM) is widely used to characterize polymer viscoelastic surfaces in the air/vacuum environments; however, the link between the instrument observables (such as energy dissipation or phase contrast) and the nanoscale physical properties of the polymer surfaces (such as local viscoelasticity, relaxation, and adhesion) remains poorly understood. To shed light on this topic, we present a computational method that enables the prediction and interpretation of dAFM observables on samples with arbitrary surface forces and linear viscoelastic constitutive properties with a first-principles approach. The approach both accelerates the computational method introduced by Attard and embeds it within the tapping mode amplitude reduction formula (or, equivalently, frequency modulation frequency shift/damping formula) to recover the force history and instrument observables as a function of the set point amplitude or Z distance. The method is validated against other reliable computational ...

Necessity of two-dimensional visualization of validity in the nanomechanical mapping of atomic force microscopy for sulphur cross-linked rubber.

The importance of the two-dimensional (2D) visualization of validity for nanomechanical mapping in atomic force microscopy (AFM) for sulphur cross-linked rubber is emphasized for accurately interpreting the nanoscale physical properties on the surface of the soft material. The “R-factor,” evaluated to be the difference between the experimental and theoretical force–deformation curves, was considered to be the reliability index of the AFM analysis for all data points on the sample surface. A small R-factor corresponds to high accuracy. The advantage of the R-factor mapping method is demonstrated using nanomechanical mapping data of the inhomogeneous isoprene rubber network by the Johnson–Kendall–Roberts and the Derjaguin, Muller, and Toporov contact mechanics models. The 2D R-factor mapping clearly and correctly supported the roles of sulphur cross-linking reagents to control the network morphology of vulcanizates. Additionally, the blanket effect, which is induced by the rubber layer on the hard part and influences experimental force–deformation curves, is firstly proposed in this study. Nanomechanical mapping with 2D reliability indexes is expected to contribute to an advance in AFM studies on soft matter such as rubber materials, leading to a more accurate understanding of the structural characteristics of the rubber networks. Thus, this validity confirmation method is necessary for developing rubber science and technology.

Changes in lipid membranes may trigger amyloid toxicity in Alzheimer's disease.

Amyloid-beta peptides (Aβ), implicated in Alzheimer’s disease (AD), interact with the cellular membrane and induce amyloid toxicity. The composition of cellular membranes changes in aging and AD. We designed multi-component lipid models to mimic healthy and diseased states of the neuronal membrane. Using atomic force microscopy (AFM), Kelvin probe force microscopy (KPFM) and black lipid membrane (BLM) techniques, we demonstrated that these model membranes differ in their nanoscale structure and physical properties, and interact differently with Aβ1–42. Based on our data, we propose a new hypothesis that changes in lipid membrane due to aging and AD may trigger amyloid toxicity through electrostatic mechanisms, similar to the accepted mechanism of antimicrobial peptide action. Understanding the role of the membrane changes as a key activating amyloid toxicity may aid in the development of a new avenue for the prevention and treatment of AD.

Computational integration of nanoscale physical biomarkers and cognitive assessments for Alzheimer's disease diagnosis and prognosis.

With the increasing prevalence of Alzheimer's disease (AD), significant efforts have been directed toward developing novel diagnostics and biomarkers that can enhance AD detection and management. AD affects the cognition, behavior, function, and physiology of patients through mechanisms that are still being elucidated. Current AD diagnosis is contingent on evaluating which symptoms and signs a patient does or does not display. Concerns have been raised that AD diagnosis may be affected by how those measurements are analyzed. Unbiased means of diagnosing AD using computational algorithms that integrate multidisciplinary inputs, ranging from nanoscale biomarkers to cognitive assessments, and integrating both biochemical and physical changes may provide solutions to these limitations due to lack of understanding for the dynamic progress of the disease coupled with multiple symptoms in multiscale. We show that nanoscale physical properties of protein aggregates from the cerebral spinal fluid and blood of patients are altered during AD pathogenesis and that these properties can be used as a new class of "physical biomarkers." Using a computational algorithm, developed to integrate these biomarkers and cognitive assessments, we demonstrate an approach to impartially diagnose AD and predict its progression. Real-time diagnostic updates of progression could be made on the basis of the changes in the physical biomarkers and the cognitive assessment scores of patients over time. Additionally, the Nyquist-Shannon sampling theorem was used to determine the minimum number of necessary patient checkups to effectively predict disease progression. This integrated computational approach can generate patient-specific, personalized signatures for AD diagnosis and prognosis.

Charge transport in organic nanocrystal diodes based on rolled-up robust nanomembrane contacts.

The investigation of charge transport in organic nanocrystals is essential to understand nanoscale physical properties of organic systems and the development of novel organic nanodevices. In this work, we fabricate organic nanocrystal diodes contacted by rolled-up robust nanomembranes. The organic nanocrystals consist of vanadyl phthalocyanine and copper hexadecafluorophthalocyanine heterojunctions. The temperature dependent charge transport through organic nanocrystals was investigated to reveal the transport properties of ohmic and space-charge-limited current under different conditions, for instance, temperature and bias.

Nanoscale effects on the thermal and mechanical properties of AlGaAs/GaAs quantum well laser diodes: influence on the catastrophic optical damage

In this work we study the catastrophic optical damage (COD) of graded-index separate confinement heterostructure quantum well (QW) laser diodes based on AlGaAs/GaAs. The emphasis is placed on the impact that the nanoscale physical properties have on the operation and degradation of the active layers of these devices. When these laser diodes run in continuous-wave mode with high internal optical power densities, the QW and guide layers can experiment very intense local heating phenomena that lead to device failure. A thermo-mechanical model has been set up to study the mechanism of degradation. This model has been solved by applying finite element methods. A variety of physical factors related to the materials properties, which play a paramount role in the laser degradation process, have been considered. Among these, the reduced thicknesses of the QW and the guides lead to thermal conductivities smaller than the bulk figures, which are further reduced as extended defects develop in these layers. This results in a progressively deteriorating thermal management in the device. To the best of our knowledge, this model for laser diodes is the first one to have taken into account low scale mechanical effects that result in enhanced strengths in the structural layers. Moreover, the consequences of these conflicting size-dependent properties on the thermo-mechanical behaviour on the route to COD are examined. Subsequently, this approach opens the possibility of taking advantage of these properties in order to design robust diode lasers (or other types of power devices) in a controlled manner.

Recent highlights in electro-driven separations- selected applications of alkylthiol gold nanoparticles in capillary electrophoresis and capillary electro-chromatography.

To date, alkylthiol gold nanoparticles (AuNPs) have been widely used in electro-chromatographic separation techniques as a viable alternative to traditional stationary phases. This is mainly due to their stability, chemical inertness, ease of functionality, increased phase ratio, ability to form self-assembled monolayers. They also yield versatile stationary phases with highly specific targeted functionalities. At the nanoscale region, the chemical and physical properties of a molecule display different attributes to that of the parent molecules or material, hence these features can be harnessed in electro-driven chromatographic separations. Application areas illustrating the use of AuNPs in separation science continue to grow and expand to cover many different kinds of analysis. The last decade has witnessed a successful trend in miniaturisation of chemical separation systems toward the micro and nanoscale ranges. Nanoparticle-based stationary phases fit well with performing chemical separations on microfluidic and capillary platforms. In this review the theory of the use of alkylthiol gold nanoparticles in electro-chromatographic driven separation methods will be discussed. This will be followed by details of recent and selected applications showing alkylthiol gold nanoparticles in capillary electrophoretic and open-tubular electro-chromatographic separations. This review will focus solely on alkylthiol based gold nanoparticles, therefore other kinds of chemical moieties bonded to gold nanoparticles are outside the scope of this review. Finally the future outlook of this exciting technology will be outlined in some detail in the final section.