Satellite Assembly Research Articles

Oriented Assembly of Gold Nanoparticles with Freezing‐Driven Surface DNA Manipulation and Its Application in SERS‐Based MicroRNA Assay

AbstractExceptional amplification of electronic, magnetic, and optical signals can be achieved by assembling inorganic nanoparticles with well‐defined structures in certain orientations. DNA‐programmed assembly of gold nanoparticles (AuNPs) has been employed to construct highly ordered nanostructures for surface‐enhanced Raman scattering (SERS)‐based biosensing. However, the performance of SERS signal amplification is seriously compromised due to limitations in controlling the number and orientation of the conjugated DNA strand on AuNPs surface and the cross‐linked aggregations. Herein, a high‐throughput approach is developed based on freezing‐driven DNA binding, which is capable of precisely manipulating the DNA conjugation number on the surface of AuNPs. It avoids complex post‐treatments and no additional reagents, e.g., salts, acids, or surfactants, are necessary. Most importantly, the DNA–AuNP conjugates are analogous to atoms and serve as building blocks for precise construction of molecule‐like assemblies. The structures such as dimers, trimers, and core–satellite assemblies are obtained in a short period of time with excellent stability by simply varying the DNA conjugation density on the surface of AuNPs. As a result, robust SERS signals in controllable assemblies are successfully achieved, which facilitate highly sensitive detection of microRNAs with a detection limit of 0.12 × 10−12 m, thereby demonstrating their potential in bioassays.

Circular Polarized Light Activated Chiral Satellite Nanoprobes for the Imaging and Analysis of Multiple Metal Ions in Living Cells.

Here, we construct a handedness-dependent circular polarized light (CPL)-activated chiral satellite assemblies formed from DNAzymes and spiny platinum modified with gold nanorods and upconversion nanoparticles (UCNPs), enabling the simultaneous quantitative analysis of multiple divalent metal ions in living cells. The chiral nanoprobes, in coordination with their corresponding divalent metal ions under 980 nm left circular polarized (LCP) light illumination, served as an in situ confocal bioimaging platform for the quantitation of the given intracellular metal ions. The limit of detection (LOD) of the chiral probes in living cells is 1.1 nmol/106 cells, 1.02 nmol/106 cells and 0.45 nmol/106 cells for Zn2+ , Mg2+ , and Cu2+ , respectively.

Circular Polarized Light Activated Chiral Satellite Nanoprobes for the Imaging and Analysis of Multiple Metal Ions in Living Cells

AbstractHere, we construct a handedness‐dependent circular polarized light (CPL)‐activated chiral satellite assemblies formed from DNAzymes and spiny platinum modified with gold nanorods and upconversion nanoparticles (UCNPs), enabling the simultaneous quantitative analysis of multiple divalent metal ions in living cells. The chiral nanoprobes, in coordination with their corresponding divalent metal ions under 980 nm left circular polarized (LCP) light illumination, served as an in situ confocal bioimaging platform for the quantitation of the given intracellular metal ions. The limit of detection (LOD) of the chiral probes in living cells is 1.1 nmol/106 cells, 1.02 nmol/106 cells and 0.45 nmol/106 cells for Zn2+, Mg2+, and Cu2+, respectively.

The effect of γ-radiation on the mechanical properties of structural adhesive

The modular satellite concept iBOSS (intelligent Building Blocks for On-Orbit Satellite Servicing and Assembly) enables on-orbit servicing and reconfiguration of satellite systems and has the potential to be a game changer in the space industry. Such building blocks have to withstand all environmental loads in space, e.g.: radiation, vacuum and thermal cycling.The present paper investigates the mechanical properties of the two component epoxy adhesive 3M SW9323 under the environmental effect of radiation. This adhesive is part of the building block's primary structure. Furthermore, adhesive bonding is the sole joining technique used in the whole structure. It is therefore critical to know the influence of ionizing radiation on its load-carrying capacity. For this purpose bulk specimens were manufactured and exposed to γ-radiation, generated by a 60Co source. Four different doses were achieved by varying the distance to the source and irradiation time. Afterwards the specimen were tested under tensile loading. Using the digital image correlation technique properties like elastic modulus, shear modulus, tensile strength and elongation at break were determined.The results show that the mechanical properties of the bulk specimen of 3M SW9323 are not influenced by γ-radiation up to a dose of 17.6 kGy. This is explained by the phenomena of crosslinking and chain scission which occur simultaneously and cancel each other out. In addition, Fourier-transform infrared spectroscopy (FTIR) was carried out to investigate if one mechanism is predominant. A slight shift in the spectra indicates the supremacy of chain scission.

A fluorometric assay for staphylococcal enterotoxin B by making use of platinum coated gold nanorods and of upconversion nanoparticles.

An aptamer based fluorometric assay is presented for fast and accurate detection of staphylococcal enterotoxin B (SEB). It is making use of platinum-coated gold nanorods (AuNR@Pt) and upconversion nanoparticles (UCNPs). The aptamer against SEB is immobilized on AuNR@Pt while the complementary DNA fragment of SEB aptamer is immobilized on UCNPs. As the concentration of SEB increases, the fluorescence of the satellite assembly (AuNR@Pt-UCNPs) is gradually restored. Under the optimized conditions, fluorescence (best measured at excitation/emission wavelengths of 980/543nm) linearly increases in the 2.0-400pg·mL-1 SEB concentration range. The limit of detection is as low as 0.9pg·mL-1 (at an S/N of 3), significantly lower than existing methods. The method was applied to the determination of SEB in spiked milk samples. The average recoveries ranged from 91.2% to 104.6%, confirming the practicality of this method. Graphical abstract Schematic illustration of a fluorometric assay based on inner filter effect (IFE) between platinum coated gold nanorods (AuNR@Pt) and upconversion nanoparticles (UCNPs) for the determination of staphylococcal enterotoxin B (SEB).

Test Technology in General Assembly of Large Satellites

The special test technology of the assembly, integration and test (AIT) of large satellites was studied, which accurately determine the leakage, alignment and mass property of large satellites, and ensure the reliable operation of large satellites in orbit. The local and total leakage testing technique was developed which based on quadrupole mass spectrometer and helium mass spectrometer. To meet large satellite quality and high precision, the satellite mass property testing equipment of large load bearing based on three coordinate conversion machine has been set up. A laser tracker uniting theodolite measure system with high positional precision and high angle measurement accuracy has been developed. Several large satellites have been tested in the process of AIT with these testing equipment. The quality of the large satellite has been effectively guaranteed.

Satellite Assembly Process Optimization Based on Digital Simulation Technology

In this paper, digital simulation technology is applied to the key link of satellite assembly process. Considering the operating environment, personnel, process equipment and other constraints, the feasibility analysis of the total assembly process scheme oriented to satellite quality control is carried out with the evaluation indexes of the operation space and assembly sequence. Based on the potential risk recognized from the key components of protection, redundancy control, assembly process visible and etc., the assembly process plan is optimized in order to reduce the probability of occurrence of low level of quality problems. The technology proposed in this paper can improve the quality of satellite AIT and provide a solid foundation for the long service life of the satellite in orbit.

Chirality on Hierarchical Self‐Assembly of Au@AuAg Yolk–Shell Nanorods into Core–Satellite Superstructures for Biosensing in Human Cells

AbstractHere, Au@AgAu yolk–shell nanorods (YSNRs) with tunable plasmonic circular dichroism (PCD) responses are synthesized, for the first time, using chiral d‐ or l‐penicillamine. The concentration of chiral molecules and the nanogap size play key roles in the PCD signal of the YSNRs. Importantly, the PCD response could be regulated by changing the aspect ratio of gold nanorods, and the largest anisotropy factor (g‐factor) is 0.009. Remarkably, the YSNRs are used as new chiroptical building blocks together with Au nanoparticles (NPs) to build YSNR@NP core–satellite (CS) assemblies, which display much stronger PCD intensity and an increased g‐factor of 0.021. The theoretical calculation data demonstrate that the significant PCD activity of nanoassemblies is originated from chiral structures and the intrinsic chirality of the building blocks. Noticeably, the developed CS superstructures with photothermal effects are utilized to quantitatively detect zinc ion in living cell lines. This study reports an emerging class of chiral inorganic nanostructures with important future applications, including enantioselective separation, asymmetric catalysis, and biomedical sensing.

Spiny Nanorod and Upconversion Nanoparticle Satellite Assemblies for Ultrasensitive Detection of Messenger RNA in Living Cells

Quantitation and in situ monitoring of target mRNA (mRNA) in living cells remains a significant challenge for the chemical and biomedical communities. To quantitatively detect mRNA expression levels in living cells, we have developed DNA-driven gold nanorod coated platinum-upconversion nanoparticle satellite assemblies (termed Au NR@Pt-UCNP satellites) for intracellular thymidine kinase 1 (TK1) mRNA analysis. The nanostructures were capable of recognizing target mRNA in a sequence-specific manner as luminescence of UCNPs was effectively quenched by Au NR@Pt within the assemblies. Following recognition, UCNPs detached from Au NR@Pt, resulting in luminescence restoration to achieve effective in situ imaging and quantifiable detection of target mRNA. The upconversional luminescence intensity of confocal images showed a good linear relationship with intracellular TK1 mRNA ranging from 1.17 to 65.21 fmol/10 μg RNA and a limit of detection (LOD) of 0.67 fmol/10 μg RNA. We believe that our present assay can be broadly applied for detection of endogenous biomolecules at the cellular and tissue levels and restoration of tissue homeostasis in vivo.

Research to Assembly Scheme for Satellite Deck Based on Robot Flexibility Control Principle

Deck assembly is critical quality control point in final satellite assembly process, and cable extrusion and structure collision problems in assembly process will affect development quality and progress of satellite directly. Aimed at problems existing in deck assembly process, assembly project scheme for satellite deck based on robot flexibility control principle is proposed in this paper. Scheme is introduced firstly; secondly, key technologies on end force perception and flexible docking control in the scheme are studied; then, implementation process of assembly scheme for satellite deck is described in detail; finally, actual application case of assembly scheme is given. Result shows that compared with traditional assembly scheme, assembly scheme for satellite deck based on robot flexibility control principle has obvious advantages in work efficiency, reliability and universality aspects etc.

Digital twin-based smart production management and control framework for the complex product assembly shop-floor

Digital twin technology is considered as a key technology to realize cyber-physical systems (CPS). However, due to the complexity of building a digital equivalent in virtual space to its physical counterpart, very little progress has been achieved in digital twin application, especially in the complex product assembly shop-floor. In this paper, we propose a framework of digital twin-based smart production management and control approach for complex product assembly shop-floors. Four core techniques embodied in the framework are illustrated in detail as follows: (1) real-time acquisition, organization, and management of the physical assembly shop-floor data, (2) construction of the assembly shop-floor digital twin, (3) digital twin and big data-driven prediction of the assembly shop-floor, and (4) digital twin-based assembly shop-floor production management and control service. To elaborate how to apply the proposed approach to reality, we present detailed implementation process of the proposed digital twin-based smart production management and control approach in a satellite assembly shop-floor scenario. Meanwhile, the future work to completely fulfill digital twin-based smart production management and control concept for complex product assembly shop-floors are discussed.

Tuning the Sensing Performance of Multilayer Plasmonic Core-Satellite Assemblies for Rapid Detection of Targets from Lysed Cells.

Optical sensors based on discrete plasmonic nanostructures are invaluable for probing biomolecular interactions when applied as plasmonic rulers or reconfigurable multinanoparticle assemblies. However, their adaptation as a versatile sensing platform is limited by the research-grade instrumentation required for single-nanostructure imaging and/or spectroscopy and complex data fitting and analysis. Additionally, the dynamic range is often too narrow for the quantitative analysis of targets of interest in biodiagnostics, food safety, or environmental monitoring. Herein we present plasmonic assembly comprising a core nanoparticle surrounded by multiple layers of satellite nanoparticles through aptamer linker. The layer-by-layer assembly of the satellite nanoparticles yields uniform discrete nanoparticle clusters on a substrate with enhanced optical properties. Binding of the model target (adenosine 5'-triphosphate, ATP) induces disassembly and leads to a dramatic decrease in the scattering intensity that can be analyzed readily from darkfield images. We demonstrate that the sensing performance, such as detection limit, dynamic range, and sensitivity, can be tuned by controlling the size of the assembly. The substrate-anchored nanoparticle assemblies are selective to only ATP, and not other adenine-containing compounds. By adapting the methodology to a flexible support, cellular ATP can be directly detected by lysing adherent cells in close contact with the plasmonic assemblies-a process that does not require any sample preparation or purification. Enhancing the optical detection signal via designing and engineering nanoparticle assemblies could enable their use with low-cost portable imaging systems and broaden their applicability beyond the study of biomolecular interaction.

Alignment measurement technique for satellite assembly, integration, and test

Alignment measurement technique for satellite assembly, integration, and test

Modelling and control of Base Plate Loading subsystem for The Motorized Adjustable Vertical Platform

Malaysia National Space Agency, ANGKASA is an organization that intensively undergoes many researches especially on space. On 2011, ANGKASA had built Satellite Assembly, Integration and Test Centre (AITC) for spacecraft development and test. Satellite will undergo numerous tests and one of it is Thermal test in Thermal Vacuum Chamber (TVC). In fact, TVC is located in cleanroom and on a platform. The only available facilities for loading and unloading the satellite is overhead crane. By utilizing the overhead crane can jeopardize the safety of the satellite. Therefore, Motorized vertical platform (MAVeP) for transferring the satellite into the TVC with capability to operate under cleanroom condition and limited space is proposed to facilitate the test. MAVeP is the combination of several mechanisms to produce horizontal and vertical motions with the ability to transfer the satellite from loading bay into TVC. The integration of both motions to elevate and transfer heavy loads with high precision capability will deliver major contributions in various industries such as aerospace and automotive. Base plate subsystem is capable to translate the horizontal motion by converting the angular motion from motor to linear motion by using rack and pinion mechanism. Generally a system can be modelled by performing physical modelling from schematic diagram or through system identification techniques. Both techniques are time consuming and required comprehensive understanding about the system, which may expose to error prone especially for complex mechanism. Therefore, a 3D virtual modelling technique has been implemented to represent the system in real world environment i.e. gravity to simulate control performance. The main purpose of this technique is to provide better model to analyse the system performance and capable to evaluate the dynamic behaviour of the system with visualization of the system performance, where a 3D prototype was designed and assembled in Solidworks. From the Solidwork, the model was translated to Simmechanics with the system coordinate and specification i.e mass and inertia and actuator model was designed by using Simpower for simulating the system. Then, the system was integrated with controller by using conventional Proportional-Derivative (PD) controller with 0% steady state error, (ess) and 22.4% overshoot, (P.O) as the results.

A novel SERS-based magnetic aptasensor for prostate specific antigen assay with high sensitivity

The accurate and highly sensitive detection of prostate specific antigen (PSA) is particularly important, especially for obese men and patients. In this report, we present a novel aptamer-based surface-enhanced Raman scattering (SERS) sensor that employs magnetic nanoparticles (MNPs) core-Au nanoparticles (AuNPs) satellite assemblies to detect PSA. The high specific biorecognition between aptamer and PSA caused the dissolution of the core-satellite assemblies, thus the concentration of functionalized AuNPs (signal probes) existing in the supernatant was on the rise with the continual addition of PSA. The aptamer-modified MNPs were used as supporting materials and separation tools in the present sensor. With the assistance of magnet, the mixture was removed from the supernatant for the concentration effects. It was found that the corresponding SERS signals from the supernatant were in direct correlation to PSA concentrations over a wide range and the limit of detection (LOD) was as low as 5.0pg/mL. Excellent recovery was also obtained to assess the feasibility of this method for human serum samples detection. All of these results show a promising application of this method. And this novel sensor can be used for the accurate and highly sensitive detection of PSA in clinic samples in the future.

High Precision Automatic Measurement System Design for Instrument Posture Testing during Satellite Assembly

High Precision Automatic Measurement System Design for Instrument Posture Testing during Satellite Assembly

Highly sensitive surface-enhanced Raman scattering detection of adenosine triphosphate based on core–satellite assemblies

As an important small molecule, adenosine triphosphate (ATP) plays an important role in the regulation of cell metabolism and supplies energy for various biochemical reactions in organisms.

RNA Detection: Gold‐Quantum Dot Core–Satellite Assemblies for Lighting Up MicroRNA In Vitro and In Vivo (Small 34/2016)

RNA Detection: Gold‐Quantum Dot Core–Satellite Assemblies for Lighting Up MicroRNA In Vitro and In Vivo (Small 34/2016)

Robust Nanoparticle-DNA Conjugates Based on Mussel-Inspired Polydopamine Coating for Cell Imaging and Tailored Self-Assembly.

We have demonstrated that mussel-inspired polydopamine can serve as an intermediate coating layer for covalently attaching oligonucleotides on nanostructures of diverse chemical nature, which are made possible by the universal adhesion and spontaneous reactivity of polydopamine. Our results have shown that polydopamine can strongly bond to representative nanoparticles (i.e., Au nanoparticles and magnetic polymer nanobeads) and form a thin layer of coating that allows for attachment of commercially available DNA with thiol or amine end functionality. The resulting DNA-nanoparticle conjugates not only show excellent chemical and thermal stability and high loading density of DNA, but the linked DNA also maintain their biological functions in directing cancer cell targeting and undergo DNA hybridization to form multifunctional magnetic core-plasmonic satellite assemblies. The generally applicable strategy opens new opportunities for easy adoption of DNA-nanoparticle conjugates for broad applications in biosensors and nanomedicine.

Gold‐Quantum Dot Core–Satellite Assemblies for Lighting Up MicroRNA In Vitro and In Vivo

A high yield DNA-driven gold-quantum dot core-satellite is developed for miRNA detection in vitro and vivo. In the presence of the target miRNA, the DNA hairpin between core and satellite is ruined, resulting in the recovery of fluorescence. The limit of detection for miRNA-21 detection in living cells reaches 296 copies per cell.