Forensic Applications of Nanotechnology

Background and Aims The classification of renal diseases is dependent on the evaluation of kidney biopsies using light microscopy techniques. Ultrastructural details (e.g. podocyte foot processes, amyloid fibrils, Fabri's intracellular inclusions) need transmission electron microscopy (TEM) which has high costs, requires specialized personnel and is time consuming. Therefore, alternative techniques are highly desirable. Here we report our experience with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Method Paraffin-embedded kidney sections (3μm thick) were examined after dewaxing and Jones-methenamine methane staining for type IV collagen fibers. Dried urine sediments were prepared using standard methods for urine cytological analysis. Analysis was then performed using atomic force microscopy (nGauge system) on dried specimens and with Scanning Electron Microscopy (Zeiss) after gold-spattering of the surface. Reference images were obtained by standard microscopy. Results The combination of SEM and thin paraffin sections allows the observation of ultrastructural details in kidney biopsies with a very simple and fast preparation. AFM is even faster than SEM, as it does not require any preparation of the surface of the sample. An important advantage of SEM is the possibility to view the sample at low magnification, which makes it easier to identify the location of the glomeruli. It is thus possible to switch from small magnifications (100x) to very extreme magnifications (10000x). Notably, the interpretation of the images requires knowledge of the artifacts induced by paraffin inclusion. Specifically, structures and cells containing lipids (for example foamy cells) appear empty. Chromatin is also condensed in the nuclei around the periphery of the nucleus and in spike structures whit large empty areas. The recognition of nuclei in SEM and AFM is important for the subsequent interpretation of the images. Podocyte pedicles fusion can be identified relatively easily in SEM and in AFM. Both techniques add relevant ultrastructural details of urine sediment cells, from epithelial cells to isolated tubular cells. Also, casts show many ultrastructural features which are not evident in classical optical microscopy. It is also possible to measure the thickness of the basement membrane with great precision both in SEM and with AFM. The major limitation of this approach is the limited experience of pathologists with these methods and the absence of an atlas of normal and pathological kidney. Conclusion Considering the affordable costs of SEM and AFM instruments and the simple preparation of samples for their analysis, these should be considered a valid alternative to TEM. SEM and AFM are alternative methods, simple and relatively cheap and very fast to obtain ultrastructural details of renal biopsies. We thank ANED and AST for the great support given to research.

Replica Microscopy and Scanning Electron Microscopy of Laser Impacts on the Skin

Self‐organization of metallic nanoparticles (NPs) has recently been reported upon visible continuous‐wave (cw) laser exposure [1]. The self‐organized structures are Ag NP gratings embedded in a thin TiO 2 film deposited on glass. Such composite structures exhibit singular visual effects that can find applications in secured traceability. The related optical properties directly depend on the NP size distribution, the average grating period, the organization rate and the TiO 2 thickness and refractive index. These sample features appear to be largely controlled by the temperature rise that occurs during the laser‐induced self‐organization process. The aim of the present contribution is to estimate the plasmon‐induced temperature rise which appears to be strongly influenced by the laser scanning speed. To do so, Raman microspectroscopy and various modes of transmission electron microscopy (TEM) are used. The latter allow accurate information to be acquired on the NP size distributions resulting from different temperature rises, on their localization in the film and on the phase and chemical changes that occur in the film and the substrate surrounding NPs. Finally, we show how such thermal effects can be considerably decreased when using femtosecond (fs) laser pulses to initiate the NP self‐organization. The TiO 2 thin layer used in this work is initially mesoporous and amorphous and contains small silver NP of 1‐3 nm as described in a previously published article [1]. The self‐organized growth of silver NPs is implemented by scanning a laser beam focused on the sample surface at a constant speed. Post mortem Raman microspectroscopy shows that TiO 2 remains amorphous or adopt successively anatase, both anatase and rutile or only rutile crystalline forms for increasing laser scanning speeds, which was confirmed by high resolution TEM micrographs. Further in situ Raman microspectrocopy characterizations also attest an increase in temperature from 200°C to 750°C from low speed to higher speed in a range where anatase is formed; This increase of the temperature when the scanning speed increases was totally unexpected. In addition to TEM crystallographic characterization, scanning electron microscopy (SEM) appeared to be useful to identify different morphologies for anatase and rutile nanocrystals and to study changes in the nanocrystal density as a function of speed. Scanning TEM (STEM) micrographs and electron energy loss spectroscopy (EELS) analysis of sample cross‐sections prepared by focused ion beam (FIB) give further interesting information about the in‐depth structure of samples. Ag nanoparticles are located below the TiO 2 film (Fig. 1a) made of TiO 2 nanocrystals immersed in a Si‐based amorphous phase, in a new interfacial thin amorphous layer mixing both Ti from the initial film and Si from the glass substrate (Fig. 1b). A three‐dimensional reconstruction of the film sample from a series of FIB‐SEM experiments confirms that all Ag NPs are rather spherical and located in a single plane just below the nanocrystalized TiO 2 layer. High angle annular dark field scanning TEM (HAADF STEM) imaging was used to study systematically non‐monotonous changes in the NP size distribution with the temperature rise for many samples. All studies that we have performed so far point out that the temperature rise can be considered as a drawback since it affects the integrity of the supporting material; we present here few results obtained with fs laser pulses in order to investigate a way to self‐organize metallic NPs without high temperature rise in order to preserve the substrate and give the ability to work on softer substrates like plastic ones. Self‐organization can successfully be obtained without altering the substrate top surface (Fig. 1 c‐d). Ag NPs remain localized in the TiO 2 films, which is only locally crystallized around the grown NPs, as attested by STEM‐diffraction maps recorded in TEM. To conclude, this paper demonstrates the interest of a multimodal application of TEM techniques in order to provide a thorough study of the 3D nanostructure and chemical composition of complex samples made of Ag NP gratings embedded in a nanocrystallized TiO 2 film, which result from laser‐induced self‐organization processes. It provides crucial information on thermal effects that drive the laser‐induced self‐organization process.

SiC thin films (undoped and doped with SnO 2 at 1 at.%, 5 at.% and 10 at.% concentrations) are prepared using pulsed laser deposition on quartz substrates kept at room temperature. The XRD patterns show a crystalline cubic phase for the undoped and 10 at.% SnO 2 doped SiC thin films while 1 at.% and 5 at.% SnO 2 doped SiC thin films exhibit an amorphous nature. The formation of nanorods with a non-uniform distribution of nanoparticles are studied using various microscopic techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Non-uniform distribution of particles with an average diameter 50 nm is seen in SEM micrographs of undoped SiC. On doping with 10 at.% SnO 2 , nanorods of average length of 1 micron are formed which is evidenced from the SEM image. TEM images also supports the formation of nanorods of average diameter of 20 nm in the 10 at.% SnO 2 doped SiC thin films. TEM images also suggest the formation of nano particles of size ∼ 5 nm in 10 at.% SnO 2 doped SiC thin films. A low surface roughness of 3.6 and 1.69 nm is obtained for the undoped SiC and 10 at.% SnO 2 doped SiC thin films from the AFM analysis. The presence of Raman bands in the region 500– 600 cm−1 for all the samples indicates the disorder prevailing in the films. It is seen that with higher dopant concentrations, this band becomes more well-defined and appear with more intensities at higher wave numbers which suggests that SnO 2 doping increases disorder in the crystallites in the films. Optical band gaps of the films are estimated from the UV-Vis absorption spectra. Variation in band gap observed with doping concentration may be due to broadening of the absorption edge occurred by the impurity levels. A near interface trap induced blue photoluminescence is observed in the undoped, 5 at.% and 10 at.% SnO 2 doped SiC thin films. The open aperture Z-scan measurements revealed strong absorptive nonlinearities. The Z scan curves suggest that the films are good saturable absorbers with saturation intensity I s being 6 × 1012 and 5.9 × 1012 W/m2, respectively for the 1 at.% and 10 at.% SnO 2 doped SiC films.

The objective of this study is to produce chitin nanowhiskers (CNW) from bacterial fermentation of tiger prawn waste. For this purpose, chitin was first extracted from tiger prawn waste using bacterial fermentation process followed by isolation of CNW using acid hydrolysis process. The isolated CNW from fermented tiger prawn waste (FCNW) were investigated using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), x-ray diffractometer (X-RD) and thermogravimetric analysis (TGA). FTIR spectra analysis indicates that the acid hydrolysis of chitin did not altered the chemical structure of isolated FCNW. TEM analysis revealed that the produced FCNW displayed a nanoscale structure with an average length and width of 100 and 10 nm. AFM images of FCNW indicate the presence of spindle-like features. The X-RD analysis revealed that the acid hydrolysis process enhanced the crystallinity of FCNW from 20 to 46 % compared to chitin due to the removal of the amorphous region. The TGA results revealed that the FCNW is more thermally stable than fermented chitin (FC) and CNW from commercial chitin. The relatively good thermal stability of FCNW shows its suitability in a range of applications such as reinforcing fillers in green nanocomposites.

In this thesis, geometry is used as a basis for conducting experiments aimed at growing and arranging inorganic minerals on curved interfaces. Mineralisation is directed using crystalline and liquid-crystalline metallic soaps and surfactant/water systems as templates.¶ A review of the history, syntheses, structure and liquid crystallinity of metallic soaps and other amphiphiles is presented as a foundation to understanding the interfacial architectures in mesostructured template systems in general. ...

The aqueous leaf extract of Jatropha curcas was used for the synthesis of silver nanoparticles (Jc-AgNps) which were further evaluated for its antibacterial potential against food borne pathogens. J. curcas leaf extract could synthesize stable silver nanoparticles (Zeta potential: -23.4 mV) with absorption band at 430 nm. Fourier transform infrared spectroscopy indicated various biological compounds responsible for capping and stabilizing Jc-AgNps in suspension, while the presence of silver was authenticated by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray. Jc-AgNps were confirmed to be uniform in shape, size and behavior through dynamic light scattering, transmission electron microscopy (TEM), X-ray diffraction, SEM, and atomic force microscopy (AFM) analysis. To investigate the antibacterial activity, disk diffusion and microplate dilution assays were performed and zone of inhibition (ZOI) as well as minimum inhibitory/bactericidal concentrations (MIC/MBCs) were evaluated against selected bacterial strains. Overall results showed that Escherichia coli (ZOI: 23 mm, MBC: 0.010 mg/ml) was the most sensitive organism, whereas Staphylococcus aureus (ZOI: 14.66 mm, MBC: 0.041 mg/ml) and Salmonella enterica (ZOI: 16.66 mm, MBC: 0.041 mg/ml) were the least sensitive against Jc-AgNps. The detailed microscopic investigations using SEM, TEM, and AFM were performed to understand the antibacterial impacts of Jc-AgNps against Listeria monocytogenes. SEM and TEM analysis showed the clear deformation and disintegration of treated L. monocytogenes cells, whereas AFM established a decrease in the height and cell surface roughness (root mean square value) in the treated L. monocytogenes.

Titanium dioxide (TiO2) thin films were deposited on Si wafer and glass substrates by direct current (dc) magnetron sputtering, by which the photocatalytic phase, anatase, was obtained under the optimum deposition conditions of O2/(O2+Ar) flow ratios and substrate biases. TiO2 thin films doped with Sn or Nb were prepared on glass substrates by dc/rf (radio frequency) magnetron co-sputtering, in which dc and rf were utilized for Ti and Sn or Nb targets, respectively, and the samples were post-annealed at temperatures ranging from 473 to 773 K for 1 h in ambient air. Microstructure, surface morphology, chemistry, and optical properties of the un-doped, Sn-doped, and Nb-doped TiO2 films were characterized in details by glancing incidence X-ray diffraction (GIXD), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) combined with energy dispersive spectroscopy (EDS), differential thermal analysis/thermogravimetry (DTA/TG), atomic force microscopy (AFM), UV/visable spectrophotometry, ellipsometry, and X-ray photoelectron spectroscopy (XPS). In addition, the photocatalytic activity was evaluated by measurement of the degeneration of methylene blue under UV/visible irradiation. The analytical results of GIXD show that the anatase phase is the dominant phase at an O2/(O2+Ar) flow ratio of over 40 %, whereas the films exhibit the rutile phase dispersed in amorphous matrix at an O2/(O2+Ar) flow ratio of 20 %. Microstructure and optical properties of the TiO2 films are dependent closely upon the rf power applied to the substrates as a bias. The anatase phase with columnar structure was obtained for the films prepared at rf powers of 0 and 5 W; whereas the films exhibit a rutile phase with equi-axial crystals at rf powers of 15 and 25 W. The rf-bias-assisted TiO2 films have a smoother surface than that without rf bias, and the absorbance edges shift to long wavelengths. The TiO2 films with a rutile phase have a higher refractive index, whereas better photocatalytical properties were observed for the films having anatase phase. TiO2 films with various Sn or Nb doping contents were investigated on the microstructure, optical properties, and photocatalytic activities. All the as-deposited TiO2 films on glass substrate were amorphous. The concentration of Sn in rf powers of 100 and 200 W and Nb in rf powers of 200, 300, and 400 W were 6.65 and 16.4 at.% for Sn and 1.98, 3.56, and 4.9 at.% for Nb, respectively, by X-ray photoelectron spectroscopy. GIXD revealed a polycrystalline phase for the Nb-doped films post-annealed at temperature 523 K, in contrast to the un-doped one that has to be annealed at temperature 723 K, indicating that Nb dopant can enhance the crystallization of amorphous TiO2. Furthermore, the Nb-doped film post-annealed at 673 K was found to have an anatase-dominanted phase with a fine grain microstructure, while the Sn-doped film post-annealed at 673 K was found to have a coexistence of anatase/rutile duplex and amorphous structure, as observed by using TEM. Heat treatment also induces a change in the surface morphology of the TiO2 films examined by FE-SEM. The optical properties of the TiO2 films were characterized by UV/visible spectrophotometry. The average transmittance of the Sn-doped and Nb-doped films is higher than 85%. Absorption zone in visible regime and optical band gap of the Sn-doped or Nb-doped TiO2 films increase with the doping contents. Under visible light irradiation, all the Nb-doped TiO2 films exhibit better photocatalytic activity than that of un-doped and Sn-doped ones. Among them, the Nb-doped TiO2 film with rf power of 400 W post-annealed at temperature 673 K shows the best photocatalytic performance.

We studied nanoparticles by several high resolution microscopic methods as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and scanning probe techniques especially atomic force microscopy (AFM) in contact and non-contact mode. While AFM in non-contact mode gives reliable information for 100 nm range nanoparticles it fails for smaller particles, showing lack of reproducibility. TEM and SEM prove to be reliable. By SEM imaging the agglomeration behavior and the structure of agglomerates are discussed in detail.

Erythrocytes infected by certain species of malarial parasites show two types of alterations of erythrocyte membranes such as electron-dense protrusions called knobs and caveola-vesicle complexes (Aikawa et al., 1975, Am. J. Path. 79: 285; Aikawa, 1977, Bull. WHO 55:2). The knobs are found on the membrane of erythrocytes infected with falciparum-type malaria parasites. These knobs form focal junctions with the endothelial cell membranes or with the knobs of other erythrocytes, resulting in the sequestration of these infected erythrocytes along the vascular endothelium (Trager et al., 1966, Bull. WHO 35: 883; Luse and Miller, 1971, Am. J. Trop. Med. Hyg. 20: 655; Aikawa et al., 1972, Z. Zellforsch. 124: 72; Udeinya et al., 1981, Science 213: 555). The erythrocyte membrane covering the knobs is immunologically different from the rest of the erythrocyte membrane (Kilejian et al., 1977, Exp. Parasitol. 42: 157; Langreth et al., 1979, J. Exp. Med. 150:1241; Chulay et al., 1981, Am. J. Trop. Med. Hyg. 30: 12). The erythrocytes infected with small trophozoites show few knobs, but they increase in number as the parasite grows within the erythrocyte. Because the morphology of these knobs is still not fully understood, we have attempted to characterize them by transmission and scanning electron microscopy together with freeze-fracture and etch techniques. Plasmodiumfalciparum (Camp strain) in Aotus erythrocytes and P. falciparum (Thailand and Liberian strains) in human erythrocytes were obtained from culture (Udeinya et al., 1981, Science 213: 555). The infected erythrocytes were fixed in 2% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) containing 4% sucrose, washed in 0.1 M cacodylate buffer and postfixed for 1 hr in 1% osmium tetroxide. After fixation, the samples were centrifuged and then processed for thin section transmission and scanning electron microscopy. Freeze-fracturing and etching were performed on P. falciparum in human RBC's. Fracturing was carried out at -120 C under a vacuum of 2 X 10-7 Torr. Etching was performed at -100 C, under a vacuum of 2 X 10-7 Torr for 2 min. The surfaces obtained were replicated with platinum and carbon. Replicas were cleaned as described previously (Aikawa et al., 1981, J. Cell Biol. 91: 55). Transmission electron microscopy was performed with a JEOL 100CX electron microscope. Scanning electron microscopy was performed with a JEOL 100CX electron microscope with a scanning unit at 20 kV. Thin-section electron microscopy showed many knobs on the erythrocytes infected with P. falciparum (Fig. 1). Each knob is a cone-shaped, electron-dense structure measuring 30 to 40 nm in height and 9 to 100 nm in width and is covered by the erythrocyte membrane. The base is not sharply demarcated, but gradually merges into the erythrocyte cytoplasm. Scanning electron microscopy showed numerous cone-shaped knobs evenly distributed over the entire erythrocyte surface (Fig. 2). The distribution pattern of the knobs was more easily detectable by scanning electron microscopy than by thin-section transmission electron microscopy. Therefore, scanning electron microscopy appears to be a useful and easy method for the study of knob distribution. Freeze-fracture and etching demonstrated that the knobs were protruded structures and were evenly distributed over the erythrocyte membrane. The P face of the infected, human RBC membrane showed evenly distributed intramembrane particles (IMP) and no aggregation or depletion of IMP could be observed over the erythrocyte membrane covering the knobs (Fig.

Thermoelectrics are an important class of materials with great potential in alternative energy applications. In this study, two-dimensional (2D) nanoplates of the layered chalcogenides, Sb2Te3 and Bi2Te3, are synthesized and composites of the two are investigated for their thermoelectric properties. The two materials, Sb2Te3 and Bi2Te3, were synthesized as hexagonal, 2D nanoplates via a colloidal polyol route. The as-synthesized Sb2Te3 and Bi2Te3 vary drastically from one another in their lateral and vertical dimensions as revealed by scanning electron microscopy and atomic force microscopy. The single crystalline nanoplate nature is deduced by high-resolution transmission electron microscopy and selected area electron diffraction. Nanoplates have well-defined hexagonal facets as seen in the scanning and transmission electron microscopy images. The nanoplates were consolidated as an anisotropic nanostructured pellet via spark plasma sintering. Preferred orientation observed in the powder X-ray diffraction pattern and scanning electron microscopy images of the fractured pellets confirm the anisotropic structure of the nanoplates. Thermoelectric properties in the parallel and perpendicular directions were measured, revealing strong anisotropy with a significant reduction to thermal conductivity in the perpendicular direction due to increased phonon scattering at nanoplate interfaces. All compositions, except that of the 25% Bi2Te3 nanoplate composite, behave as degenerate semiconductors with increasing electrical resistivity as the temperature increases. The Seebeck coefficient is also increased dramatically in the nanocomposites, the highest reaching 210 μV/K for 15% Bi2Te3. The increase in Seebeck is attributed to energy carrier filtering at the nanoplate interfaces. Overall, these enhanced thermoelectric properties lead to a drastic increase in the thermoelectric performance in the perpendicular direction, with zT ∼ 1.26, for the 15% Bi2Te3 nanoplate composite at 450 K.

The fine structure of the cuticle of adult female Onchocerca volvulus, a tissue-dwelling nematode parasite of man, was studied. Although the cuticle is composed of the 3 layers characteristic of nematodes (cortex, matrix, and fiber), there were also unusual features. The most notable modification is in the trilaminate membrane, which covers the external surface of the cuticle. Scanning (SEM) and transmission (TEM) electron microscopy disclose that this membrane is projected into numerous folds, substantially increasing the surface area. Many authors have described the fine structural morphology of the cuticle of various species of nematodes (Watson, 1965a, b; Lee, 1966a, b, 1970; Bonner and Weinstein, 1972). Most nematode surfaces are smooth except for annulations (Weise, 1973), but microvilli have been observed on the surface of Bradynema sp. (Riding, 1970), which inhabits the hemocoel of insects. A light microscopy study of Onchocerca volvulus (Neafie, 1972) shows little more than a deeply striated cuticle. Since this nematode resides within a subcutaneous fibrotic nodule of host origin for long periods of time, the possibility of cuticular structural specialization exists. Therefore a study of the fine structure of the cuticle of adult female 0. volvulus in situ was undertaken. MATERIALS AND METHODS Transmission electron microscopy (TEM) Nodules containing 0. volvulus adults were excised from the subcutaneous tissue of persons living in the endemic area of San Pedro Yepocapa, Guatemala. These nodules were placed immediately into either ice-cold glutaraldehyde buffered with 0.1 M cacodylate (pH 7.2) or into 10% formalin. The nodules were then cut into small pieces and placed into fresh fixative overnight, rinsed in 0.25 M cacodylate buffer, and postfixed Received for publication 4 February 1974. * Supported, in part, by Research Grant AI-02347 from the NIH. in ice-cold 1% OO04 in 0.25 M cacodylate-HCl (pH 7.2) for 3 hr. Adult female worms were teased free from formalin-fixed tissue, rinsed in 0.25 M cacodylate-HCl (pH 7.2), and postfixed in 1% OO,4 in 0.25 M cacodylate-HCl (pH 7.2). Dehydration in all cases was in ethanol and propylene oxide with embedment in Araldite 502. Thin sections were cut with diamond knives on a Reichert OmU2 ultratome, mounted on naked 200/300 mesh copper girds, and stained with uranyl acetate (Watson, 1958) followed by lead citrate (Reynolds, 1963). A Hitachi HU-11A electron microscope, operating at 50 kv, was used for viewing and recording at initial magnifications up to 60,000X. Scanning electron microscopy (SEM) Adult female worms were teased from nodules fixed in 10% formalin, followed by postfixation in 1% Os04 in 0.25 M cacodylate-HCl (pH 7.2). Anterior, middle, and posterior portions were selected. These were then dehydrated through ethanol to amyl acetate, critical point dried and coated with gold-paladium. Viewing was on an AMR Model 1000 scanning electron microscope, operating at 10 kv, with original magnifications of 1,000 and 5,000X.

The objective of this work has been to identify the root cause of the reduced etch rate of fixed abrasive sawing (FAS) cut wafers during damage etching. The etch rate in alkaline solutions was measured as a function of time, temperature and different pre-cleaning processes, both for FAS and standard slurry wafers. The results showed a maximum etch rate for KOH concentrations around 20-30 wt%. The etch rate of FAS wafers was lower compared to slurry wafers during the initial 5-10 minutes of etching, dependent upon KOH concentration and temperature. In order to characterize the wafer surface, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), as well as reflectance measurements were used. By comparing the cross sections of the surface structure of as cut slurry and as cut FAS wafers, both an amorphous silicon layer and a defect layer were observed, but is concluded to not limiting initial higher etch rate. Furthermore during the initial stage of damage etching inverted square pillars were always formed. The walls of the pillars were constructed by the fast etching {110} planes. The depth of the pillars is found to be shallower for FAS cut wafers due to initially lower surface roughness. Therefore, the surface area exposed for the damage etch solution is larger for the slurry cut wafers, which explains the larger etching rate for the slurry cut wafers during the initial stage of the etching.

ADVERTISEMENT RETURN TO ISSUEPREVReviewNEXTFundamental Studies of Nanofluidics: Nanopores, Nanochannels, and NanopipetsDaniel G. Haywood, Anumita Saha-Shah, Lane A. Baker*, and Stephen C. Jacobson*View Author Information Department of Chemistry, Indiana University, Bloomington, Indiana 47405-7102, United States*E-mail: [email protected]*E-mail: [email protected]Cite this: Anal. Chem. 2015, 87, 1, 172–187Publication Date (Web):November 18, 2014Publication History Published online3 December 2014Published inissue 6 January 2015https://doi.org/10.1021/ac504180hCopyright © 2014 American Chemical SocietyRIGHTS & PERMISSIONSACS AuthorChoiceArticle Views10349Altmetric-Citations193LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (6 MB) Get e-AlertsSUBJECTS:Ions,Nanochannels,Nanofluidics,Nanoparticles,Nanopores Get e-Alerts

In nanotechnology, it is the unique properties arising from nanometre-scale structures that lead not only to their technological importance but also to a better understanding of the underlying science. Over the last twenty years, material properties at the nanoscale have been dominated by the properties of carbon in the form of the C60 molecule, single- and multi-wall carbon nanotubes, nanodiamonds, and recently graphene. During this period, research published in the journal Nanotechnology has revealed the amazing mechanical properties of such materials as well as their remarkable electronic properties with the promise of new devices. Furthermore, nanoparticles, nanotubes, nanorods, and nanowires from metals and dielectrics have been characterized for their electronic, mechanical, optical, chemical and catalytic properties.Scanning probe microscopy (SPM) has become the main characterization technique and atomic force microscopy (AFM) the most frequently used SPM. Over the past twenty years, SPM techniques that were previously experimental in nature have become routine. At the same time, investigations using AFM continue to yield impressive results that demonstrate the great potential of this powerful imaging tool, particularly in close to physiological conditions. In this special issue a collaboration of researchers in Europe report the use of AFM to provide high-resolution topographical images of individual carbon nanotubes immobilized on various biological membranes, including a nuclear membrane for the first time (Lamprecht C et al 2009 Nanotechnology 20 434001).Other SPM developments such as high-speed AFM appear to be making a transition from specialist laboratories to the mainstream, and perhaps the same may be said for non-contact AFM. Looking to the future, characterisation techniques involving SPM and spectroscopy, such as tip-enhanced Raman spectroscopy, could emerge as everyday methods. In all these advanced techniques, routinely available probes will be needed to make them mainstream methods, as was indeed the case for establishing AFM. At the same time, both transmission electron microscopy and scanning electron microscopy have undergone major developments in resolution, spectroscopic techniques, and new techniques such as tomography.It is exciting to speculate in which areas new properties of materials at the nanoscale will be discovered over the next twenty years, and how characterization methods will evolve, but it is the unimaginable and unpredictable that will bring the most dramatic changes to nanotechnology.