Nanomanipulation Technique Research Articles

Tapered fiber coupling of single photons emitted by a deterministically positioned single nitrogen vacancy center

A diamond nano-crystal hosting a single nitrogen vacancy (NV) center is optically selected with a confocal scanning microscope and positioned deterministically onto the subwavelength-diameter waist of a tapered optical fiber (TOF) with the help of an atomic force microscope. Based on this nano-manipulation technique, we experimentally demonstrate the evanescent coupling of single fluorescence photons emitted by a single NV-center to the guided mode of the TOF. By comparing photon count rates of the fiber-guided and the free-space modes and with the help of numerical finite-difference time domain simulations, we determine a lower and upper bound for the coupling efficiency of (9.5 ± 0.6)% and (10.4 ± 0.7)%, respectively. Our results are a promising starting point for future integration of single photon sources into photonic quantum networks and applications in quantum information science.

Development of nanomanipulator using a high-speed atomic force microscope coupled with a haptic device

The atomic force microscope (AFM) has been widely used for surface fabrication and manipulation. However, nanomanipulation using a conventional AFM is inefficient because of the sequential nature of the scan-manipulation scan cycle, which makes it difficult for the operator to observe the region of interest and perform the manipulation simultaneously. In this paper, a nanomanipulation technique using a high-speed atomic force microscope (HS-AFM) is described. During manipulation using the AFM probe, the operation is periodically interrupted for a fraction of a second for high-speed imaging that allows the topographical image of the manipulated surface to be periodically updated. With the use of high-speed imaging, the interrupting time for imaging can be greatly reduced, and as a result, the operator almost does not notice the blink time of the interruption for imaging during the manipulation. This creates a more intuitive interface with greater feedback and finesse to the operator. Nanofabrication under real-time monitoring was performed to demonstrate the utility of this arrangement for real-time nanomanipulation of sample surfaces under ambient conditions. Furthermore, the HS-AFM is coupled with a haptic device for the human interface, enabling the operator to move the HS-AFM probe to any position on the surface while feeling the response from the surface during the manipulation.

Transfer printing and nanomanipulating luminescent photonic crystal membrane nanocavities

The release of photoluminescent InGaAsP photonic crystal nanocavity chiplets from the host chip for creating autonomous functional microparticles is demonstrated. A transfer printing method using a soft polymeric material as a stamp is used to transfer cavity arrays to other substrates. Alternatively, cavities are transferred individually by a nanomanipulation technique. The chiplets can be fully deterministically positioned on both the host chip and another substrate (glass) with the nanomanipulator. The chiplets have the striking property of spontaneously orienting themselves with their plane perpendicular to the receiving surface. At each stage of the process, the condition of the cavities as dependent on their immediate surroundings is monitored from their photoluminescence spectrum.

Nanomanipulation of Single RNA Molecules

An RNA sequence can fold into many thermodynamically stable structures on a drawing board. However, experimentalists focus on RNAs dominated by a single most stable structure because it is difficult to distinguish polymorphic structures, and because it is impossible to have many molecules to uniformly adopt a suboptimal structure. Many experiments are done on folding trajectories directly leading to the most stable conformations. Such a narrow folding energy landscape excludes potential interesting observations, including alternative conformations, intermediates, and routes. Many of these alternative folding are employed in gene regulations, such as transcription attenuation and riboswitch. A solution to survey manifold folding energy landscape is single-molecule nanomanipulation technique using optical tweezers. Examining one molecule at a time eliminates necessity to deconvolute structure polymorphism adopted by many molecules, a major challenge in ensemble studies. Structure manipulation with nanometer precision allows access and identification of suboptimal or even rare structures and folding pathways. Specifically, an RNA molecule is stretched and relaxed from its 5’- and 3’-ends like a rubber band. Applied force destabilizes structures to various degrees depending on folding energy and size of each structure. Therefore, modulation of force changes structure populations of an RNA. We will illustrate this idea by two examples. An RNA kissing complex is manipulated into multiple stable conformations, each with a distinctive end-to-end distance. This method makes it possible to access folding intermediates and measure substep kinetics. In another example, a single-strand is manipulated into various stable and metastable structures, and a subsequent force protocol lead these structure to the most stable conformation.

Far-Field Optical Imaging of a Linear Array of Coupled Gold Nanocubes: Direct Visualization of Dark Plasmon Propagating Modes

Plasmonic nanoantenna arrays hold great promise for diffraction-unlimited light localization, confinement, and transport. Here, we report on linear plasmonic nanoantenna arrays composed of colloidal gold nanocubes precisely assembled using a nanomanipulation technique. In particular, we show the direct evidence of dark propagating modes in the plasmon coupling regime, allowing for transport of guided plasmon waves without far-field radiation losses. Additionally, we demonstrate the possibility of plasmon dispersion engineering in coupled gold nanocube chains. By assembling a nanocube chain with two sections of coupled nanocubes of different intercube separations, we are able to produce the effect of a band-pass nanofilter.

Real-time measurements of sliding friction and elastic properties of ZnO nanowires inside a scanning electron microscope

A real-time nanomanipulation technique inside a scanning electron microscope (SEM) has been used to investigate the elastic and frictional (tribological) properties of zinc oxide nanowires (NWs). A NW was translated over a surface of an oxidised silicon wafer using a nanomanipulator with a glued atomic-force microscopic tip. The shape of the NW elastically deformed during the translation was used to determine the distributed kinetic friction force. The same NW was then positioned half-suspended on edges of trenches cut by a focused ion beam through a silicon wafer. In order to measure Young’s modulus, the NW was bent by pushing it at the free end with the tip, and the interaction force corresponding to the visually observed bending angle was measured with a quartz tuning fork force sensor.

High‐resolution imaging and nano‐manipulation of biological structures on surface

In this mini-review we discuss our recent findings on imaging and manipulation of biological macromolecular structures by atomic force microscopy (AFM). In the first part of this review, we focus on high-resolution imaging of selected biological samples. AFM images of membrane proteins have revealed detailed conformational features related to identifiable biological functions. Different self-assembling behaviors of short peptides into supramolecular structures on various substrates under controlled environmental conditions have been systematically studied with AFM imaging. In the second part, we present a novel nano-manipulation technique for manipulating, isolating, amplifying, and sequencing of individual DNA molecules, which may find unique applications in the analysis of difficult sequence structures. Finally, we discuss how to characterize the elasticity of individual biomolecules and live cells. These results demonstrate that not only the high resolution capacity of the AFM is suited to resolve certain biological questions, but can also be applied to single molecule isolation and biomechanical analysis with its unique advantages.

Enhancement of the zero phonon line emission from a single nitrogen vacancy center in a nanodiamond via coupling to a photonic crystal cavity

Using a nanomanipulation technique a nanodiamond with a single nitrogen vacancy center is placed directly on the surface of a gallium phosphide photonic crystal cavity. A Purcell-enhancement of the fluorescence emission at the zero phonon line (ZPL) by a factor of 12.1 is observed. The ZPL coupling is a first crucial step towards future diamond-based integrated quantum optical devices.

Plasmon Hybridization in Individual Gold Nanocrystal Dimers: Direct Observation of Bright and Dark Modes

We apply a nanomanipulation technique to assemble pairs of monodispersed octahedral gold nanocrystals (side length, 150 nm) along their major axes with a varying tip-to-tip separation (25-125 nm). These pairs are immobilized onto indium tin oxide coated silica substrates and studied as plasmonic dimers by polarization-selective total internal reflection (TIR) microscopy and spectroscopy. We confirm that the plasmon coupling modes with the scattering polarization along the incident light direction result from the transverse-magnetic-polarized incident light, which induces two near-field-coupled dipole moments oriented normal to the air-substrate interface. In such cases, both in-phase (antibonding) and antiphase (bonding) plasmon coupling modes can be directly observed with the incident light wave vector perpendicular and parallel to the dimer axis, respectively. The observation of antiphase plasmon coupling modes ("dark" plasmons) is made possible by the unique polarization nature of the TIR-generated evanescent field. Furthermore, with decreasing nanocrystal separation, the plasmon coupling modes shift to shorter wavelengths for the incident light perpendicular to the dimer axis, whereas relatively large red shifts of the plasmonic coupling modes are found for the parallel incident light.

Thermal tweezers for manipulation of adatoms and nanoparticles on surfaces heated by interfering laser pulses

We conduct the detailed numerical investigation of a nanomanipulation and nanofabrication technique—thermal tweezers with dynamic evolution of surface temperature, caused by absorption of interfering laser pulses in a thin metal film or any other absorbing surface. This technique uses random Brownian forces in the presence of strong temperature modulation (surface thermophoresis) for effective manipulation of particles/adatoms with nanoscale resolution. Substantial redistribution of particles on the surface is shown to occur with the typical size of the obtained pattern elements of ∼100 nm, which is significantly smaller than the wavelength of the incident pulses used (532 nm). It is also demonstrated that thermal tweezers based on surface thermophoresis of particles/adatoms are much more effective in achieving permanent high maximum-to-minimum concentration ratios than bulk thermophoresis, which is explained by the interaction of diffusing particles with the periodic lattice potential on the surface. Typically required pulse regimes including pulse lengths and energies are also determined. The approach is applicable for reproducing any holographically achievable surface patterns, and can thus be used for engineering properties of surfaces including nanopatterning and design of surface metamaterials.

Investigation of the morphology, viability and mechanical properties of yeast cells in environmental SEM

The mechanical properties of biological cells at nanoscale may be characterized using an environmental scanning electron microscopy (ESEM) combined with a force measurement device. However, the electron beam radiation in an ESEM may damage a specimen. So far, little is known about the radiation damage to biological cells. In this work, single yeast cells were imaged using an ESEM under both high and low vacuum modes. The changes in their morphology and viability were monitored as a function of radiation time for a given beam current of 538 pA corresponding to 10 kV accelerating voltage and spot size 4. Under the two modes, the radiation damage to the morphology of yeast cells became evident after an exposure time of 3 min, but under the low vacuum mode, the damage to their morphology was more severe. However, all cells lost their viability after 5 min under the high vacuum mode with the electron beam off from an initial viability of 95+/-1%. In contrast, the viability of cells under the low vacuum mode was found to be approximately 20% after 20 min. In addition, a newly developed ESEM-based nanomanipulation technique was applied to measure the force imposed on single yeast cells and their deformation, including contact diameter and central lateral diameter for the compression of single yeast cells to a given displacement within a time frame of 1 min, and the data obtained may be used to validate mathematical modeling of the stress-strain relationship for the compression of cells in order to determine their intrinsic mechanical property parameters.

Investigation of radiation damage to microcapsules in environmental SEM

The radiation damage to a specimen in the chamber of electron microscopes has been studied extensively in the past few years. However, for the specific case of specimens with a core/shell structure, such as microcapsules and biological cells, there has been little experimentation devoted to understanding how the radiation may affect their mechanical properties. In the present work, single melamine formaldehyde (MF) microcapsules were imaged using an environmental electron microscope (ESEM) under both dry and wet modes under conditions of different accelerating voltages. The changes in the morphology (shape) were monitored as a function of radiation time. In addition, a newly developed ESEM based nanomanipulation technique was used to measure how the force imposed on single MF microcapsules for a given deformation changed with radiation time, in order to identify a time window within which the radiation damage to the microcapsules may be negligible in order to be able to study the mechanical properties of the particles. Based on the findings, the nanomanipulation technique was applied to measure the force versus displacement for compressing single microcapsules to rupture, including determination of their rupture mode.

Novel manipulation in environmental scanning electron microscope for measuring mechanical properties of single nanoparticles

A novel nanomanipulation technique has been developed to measure the mechanical properties of single nanoparticles. The principle of this technique is to compress single nanoparticles between two flat surfaces comprising a glass slide and the tip of a calibrated glass cantilever inside the chamber of an environmental scanning electron microscope (ESEM), so that the force being imposed on them and their deformation can be determined by a series of images of the particles and the position of the cantilever. The cantilever is held by a nanomanipulator that has a resolution of 0·5 nm. The novel nanomanipulation technique, and a previously developed micromanipulation technique, were first used to measure the force required to compress single microparticles (ranging from 1 to 3 μm in diameter) of methacrylic acid copolymer Eudragit E100 to different deformations under dry mode conditions, to validate results from the former. Results showed that there is no significant difference in the data obtained using these two techniques, which implies that the new nanomanipulation technique is highly reliable. The new technique was then applied to single polymethylmethacrylate (PMMA) particles ranging from 530 to 950 nm in diameter. They were compressed and held, compressed and released, and compressed to different deformations, and the force imposed on the particles was determined simultaneously. This work demonstrates the feasibility of measuring the mechanical properties of single nanoparticles, and the developed technique can find wide application in mechanical characterisation of different nanoparticles.

Single-Molecule DNA Nanomanipulation: Detection of Promoter-Unwinding Events by RNA Polymerase

Publisher Summary This chapter aims to describe a nanomanipulation technique that makes it possible to mechanically and quantitatively stretch and supercoil a single linear DNA molecule. This chapter reviews the technique, which is an extension to the study of protein DNA interactions that leads to DNA untwisting, particularly to the study of promoter unwinding by RNA polymerase during the initiation of transcription. It discusses the response of the DNA to mechanical changes in supercoiling when calibrated, the system can be used to observe in real-time interactions between a single enzyme molecule and its supercoiled DNA substrate. It explains the application of this method in the study of RNA polymerase-induced promoter unwinding, along with bending/compaction of the DNA by RNA polymerase. With this assay, there is a possibility to quantitatively study the role of DNA sequence and supercoiling, temperature, nucleotides, effectors, and activators in formation of the transcription bubble. This technique may be applicable to the real-time study of a variety of protein–DNA interactions that cause deformation of the DNA, such as the unwinding of origins of replication or the binding of transcription factors.