Nanostructured Substrates Research Articles

Clarifying the Relationship between the Lithium Deposition Coverage and Microstructure in Lithium Metal Batteries.

Improving the reversibility of lithium metal batteries is one of the challenges in current battery research. This requires better fundamental understanding of the evolution of the lithium deposition morphology, which is very complex due to the various parameters involved in different systems. Here, we clarify the fundamental origins of lithium deposition coverage in achieving highly reversible and compact lithium deposits, providing a comprehensive picture in the relationship between the lithium microstructure and solid electrolyte interphase (SEI) for lithium metal batteries. Systematic variation of the salt concentration offers a framework that brings forward the different aspects that play a role in cycling reversibility. Higher nucleation densities are formed in lower concentration electrolytes, which have the advantage of higher lithium deposition coverage; however, it goes along with the formation of an organic-rich instable SEI which is unfavorable for the reversibility during (dis)charging. On the other hand, the growth of large deposits benefiting from the formation of an inorganic-rich stable SEI is observed in higher concentration electrolytes, but the initial small nucleation density prevents full coverage of the current collector, thus compromising the plated lithium metal density. Taking advantages of the paradox, a nanostructured substrate is rationally applied, which increases the nucleation density realizing a higher deposition coverage and thus more compact plating at intermediate concentration (∼1.0 M) electrolytes, leading to extended reversible cycling of batteries.

Design of Ag/TiO2/Ag Composite Nano-Array Structure with Adjustable SERS-Activity.

How to fabricate large area controllable surface-enhanced Raman scattering (SERS) active nanostructure substrates has always been one of the important issues in the development of nanostructure devices. In this paper, nano-etching technology and magnetron sputtering technology are combined to prepare nanostructure substrate with evolvable structure, and Ag/TiO2/Ag composites are introduced into the evolvable composite structure. The activity of SERS is further enhanced by the combination of TiO2 and Ag and the electron transfer characteristics of TiO2 itself. Deposition, plasma etching, and transfer are carried out on self-assembled 200 nm polystyrene (PS) colloidal sphere arrays. Due to the shadow effect between colloidal spheres and the size of metal particles introduced by deposition, a series of Ag/TiO2/Ag nanostructure arrays with adjustable nanostructure substrates such as nano-cap (NC), nano cap-star (NCS), and nano particle-disk (NPD) can be obtained. These nanoarrays with rough surfaces and different evolutionary structures can uninterruptedly regulate optical plasmon resonance and reconstruct SERS hotspots over a large range, which has potential application value in surface science, chemical detection, nanometer photonics, and so on.

Application of SERS in the Detection of Fungi, Bacteria and Viruses.

In this review, we report the recent advances of SERS in fungi, bacteria, and viruses. Firstly, we briefly introduce the advantage of SERS over fluorescence on virus identification and detection. Secondly, we review the feasibility analysis of Raman/SERS spectrum analysis, identification, and fungal detection on SERS substrates of various nanostructures with a signal amplification mechanism. Thirdly, we focus on SERS spectra for nucleic acid, pathogens for the detection of viruses and bacteria, and furthermore introduce SERS-based microdevices, including SERS-based microfluidic devices, and three-dimensional nanostructured plasmonic substrates.

Reflective FT-NIR and SERS studies of HER-II breast cancer biomarker using plasmonic-active nanostructured thin film immobilized oriented antibody.

We describe the fabrication of plasmonic-active nanostructured thin film substrate as a label-free surface-enhanced Raman scattering (SERS)-based biosensor immobilized covalently with monoclonal HER-II antibody (mAb) to detect overexpressed HER-II as a biomarker in breast cancer serum (BCS). Oriented conjugation of mAb via hydrazone linkage to provide higher mAb accessibility was characterized by UV-vis and reflective Fourier transform near-infrared (FT-NIR) spectroscopic techniques. The interaction of BCS with mAb was studied by FT-NIR and nonresonant SERS at 637 nm. The results showed detection of glycoprotein content at different laser powers including a rise in amino acid and glycan content with varying results at higher power. With nonresonant SERS we observed nonlinear behavior of peak intensity. Analysis of variance was implemented to determine the effect of laser power which was found not to be a contributing factor. However, at the nanoscale, factors including the heating effect and aggregation of molecules can contribute to the nonlinearity of peak intensity.

Electro Fluid Dynamics: A Route to Design Polymers and Composites for Biomedical and Bio-Sustainable Applications.

In the last two decades, several processes have been explored for the development of micro and/or nanostructured substrates by sagely physically and/or chemically manipulating polymer materials. These processes have to be designed to overcome some of the limitations of the traditional ones in terms of feasibility, reproducibility, and sustainability. Herein, the primary aim of this work is to focus on the enormous potential of using a high voltage electric field to manipulate polymers from synthetic and/or natural sources for the fabrication of different devices based on elementary units, i.e., fibers or particles, with different characteristic sizes—from micro to nanoscale. Firstly, basic principles and working mechanisms will be introduced in order to correlate the effect of selected process parameters (i.e., an applied voltage) on the dimensional features of the structures. Secondly, a comprehensive overview of the recent trends and potential uses of these processes will be proposed for different biomedical and bio-sustainable application areas.

Gene Electrotransfer into Mammalian Cells Using Commercial Cell Culture Inserts with Porous Substrate.

Gene electrotransfer is one of the main non-viral methods for intracellular delivery of plasmid DNA, wherein pulsed electric fields are used to transiently permeabilize the cell membrane, allowing enhanced transmembrane transport. By localizing the electric field over small portions of the cell membrane using nanostructured substrates, it is possible to increase considerably the gene electrotransfer efficiency while preserving cell viability. In this study, we expand the frontier of localized electroporation by designing an electrotransfer approach based on commercially available cell culture inserts with polyethylene-terephthalate (PET) porous substrate. We first use multiscale numerical modeling to determine the pulse parameters, substrate pore size, and other factors that are expected to result in successful gene electrotransfer. Based on the numerical results, we design a simple device combining an insert with substrate containing pores with 0.4 µm or 1.0 µm diameter, a multiwell plate, and a pair of wire electrodes. We test the device in three mammalian cell lines and obtain transfection efficiencies similar to those achieved with conventional bulk electroporation, but at better cell viability and with low-voltage pulses that do not require the use of expensive electroporators. Our combined theoretical and experimental analysis calls for further systematic studies that will investigate the influence of substrate pore size and porosity on gene electrotransfer efficiency and cell viability.

Silica-nanoparticle reinforced lubricant-infused copper substrates with enhanced lubricant retention for maintenance-free heat exchangers

Copper substrates are widely used in heat exchangers due to their low cost and high thermal conductivity. While copper substrates have been modified to exhibit non-wetting property via lubricant infusion to enhance condensation heat transfer efficiency, these engineered surfaces often lack chemical robustness and lubricant retention, limiting their long-term use without maintenance. In this work, we present a new strategy in which omniphobic and chemically inert fluorocarbon oil is infused into a nanostructured copper substrate reinforced with silica nanoparticles (SiNP) to achieve enhanced durability and acid-resistive properties. We demonstrate that the assembly of SiNP layer prior to lubricant infusion serves as a physical barrier and provides additional anchoring points for the lubricant to retain via capillary force. Moreover, we show that SiNP-reinforced liquid-infused surface (LIS) exhibits excellent non-wetting and self-cleaning properties, leading to enhanced stability against acid exposure as well as dust, oil, and microbial contamination. Based on the excellent long-term stability in heat transfer performance even under harsh environmental challenges, we envision that the SiNP-reinforced LIS presented in this work will provide new insight in the design of robust and maintenance-free lubricant-infused surfaces for energy and environmental applications.

Two-dimensional metamaterials as meta-foams for optimized surface-enhanced solar steam generation

We report on a new class of metamaterials, which consists of meta-foams, optimized for high performance in enhanced solar steam generation. The design of these meta-foams involves precise dimensional control of a periodic two-dimensional micro-pore array. Proof-of-concept of meta-foams efficiency is demonstrated using two fabrication technologies. The first one involves microscale plasma etching onto a nanostructured black silicon substrate. As an alternative low-cost technique, we also use 3D printing of a graphene-containing polymer material. The experimental validation shows that the best evaporation rate reaches 1.34 kg/(h·m2) under 1 sun illumination, in open-air conditions under normal temperature and relative humidity conditions of 20 °C and 58%, an unmatched value so far under similar conditions, while the theoretical limit is estimated at 1.5 kg/(h·m2). This corresponding to a 89% conversion efficiency. Experimental data concur well with the predicted performance obtained by numerical simulations. The proposed model simultaneously accounts for both heat and mass transfer, including photothermal conversion and water phase change, to guide the optimization towards the maximization of the evaporation rate, an important figure of merit in many applications, including solar heat harvesting and solar water purification.

Advanced microplastic monitoring using Raman spectroscopy with a combination of nanostructure-based substrates.

Micro(nano)plastic (MNP) pollutants have not only impacted human health directly, but are also associated with numerous chemical contaminants that increase toxicity in the natural environment. Most recent research about increasing plastic pollutants in natural environments have focused on the toxic effects of MNPs in water, the atmosphere, and soil. The methodologies of MNP identification have been extensively developed for actual applications, but they still require further study, including on-site detection. This review article provides a comprehensive update on the facile detection of MNPs by Raman spectroscopy, which aims at early diagnosis of potential risks and human health impacts. In particular, Raman imaging and nanostructure-enhanced Raman scattering have emerged as effective analytical technologies for identifying MNPs in an environment. Here, the authors give an update on the latest advances in plasmonic nanostructured materials-assisted SERS substrates utilized for the detection of MNP particles present in environmental samples. Moreover, this work describes different plasmonic materials—including pure noble metal nanostructured materials and hybrid nanomaterials—that have been used to fabricate and develop SERS platforms to obtain the identifying MNP particles at low concentrations. Plasmonic nanostructure-enhanced materials consisting of pure noble metals and hybrid nanomaterials can significantly enhance the surface-enhanced Raman scattering (SERS) spectra signals of pollutant analytes due to their localized hot spots. This concise topical review also provides updates on recent developments and trends in MNP detection by means of SERS using a variety of unique materials, along with three-dimensional (3D) SERS substrates, nanopipettes, and microfluidic chips. A novel material-assisted spectral Raman technique and its effective application are also introduced for selective monitoring and trace detection of MNPs in indoor and outdoor environments.Graphical abstract

Molecular Immobilization and Resonant Raman Amplification by Complex-Loaded Enhancers (MIRRACLE) on copper (II)-chitosan-modified SERS-active metallic nanostructured substrates for multiplex determination of dopamine, norepinephrine, and epinephrine.

Aunique approach based on Molecular Immobilization and Resonant Raman Amplification by Complex-Loaded Enhancers (MIRRACLE) on copper (II)-chitosan-modified SERS-active metallic nanostructured substrates is proposed for sensitive and rapid determination of the catecholamines (CA)dopamine, norepinephrine, and epinephrine. The ternary (CA)2Cu(4AAP)2 complexes were characterized by the appearance of new absorbance bands at 555, 600, and 500nm for dopamine, norepinephrine, and epinephrine, respectively. The new absorbance band matched with a broad surface plasmon resonance band of utilized silver nanoparticles: 450-600nm, and 633excitation wavelength. We observed enhancement factors up to 3.6·106 due to the additional resonant enhancement. The multiplexing capabilities of quantitative spectral unmixing for Raman spectra of a group of CAs, which differ by only either hydroxy or methyl group, at the fingerprint region were successfully demonstrated with the direct classic least squares model. The achieved nM limits of detection with only 1.5 mW laser power and analysis of spiked human blood plasma samples proved the possibility of the multiplex determination of the catecholamines at the level of reference concentrations in the blood of healthy people as well as promise for the future facilitation in the precision diagnosis of neuroendocrine tumors and neurodegenerative diseases.

Broadband Low Reflection Surfaces With Silicon Nano-tube Square Arrays And Quantum Dot Layers

In this study, we take as a starting nanostructure which is already optimized in terms of the silicon nanopillar arrays’ structure pillar height, pillar diameter, and filling ratio such that the optical reflection from its surface is very low (weighted average reflection 3.75 percent). Full-field Finite Difference Time Domain method is used to simulate electric and magnetic fields and calculate the reflection from the modified nanostructured substrate surfaces in 400nm-1100nm spectral range. In this paper, we present the optimization of the structure in terms of the silicon nanotube structure cavity diameter, step coverage of the dielectric thin film. As a result, the weighted reflection is decreased to 3.35 percent. We also want to simulate the quantum dot solution layer deposited over the nanostructure. We modeled the quantum dots as Lorentz dielectric and decreased the optical reflection even lower level of 3.1 percent. Optimization recipe is clearly presented, and the developed method is not only useful for square arrays but also for regular arrays of nanopillars in general for photovoltaic devices.

Strongly enhanced propagation and non-reciprocal properties of CdSe nanowire based on hybrid nanostructures at communication wavelength of 1550 nm

We theoretically investigate the propagation and non-reciprocal properties of cadmium selenide (CdSe) nanowire (NW), and achieve strongly field enhancement at communication wavelength of 1550 nm when combined with the hybrid nanostructure. By varying the parameters of the nanostructure, i.e., MgF2 and Ag substrates, together with grooves, relations between these properties and the parameters are illustrated in details. Particularly, with an optimal design, the propagation performance of the NW is highly improved. Moreover, by breaking the symmetry of the system, the non-reciprocal property without time modulations is obtained with high contrast employing the further optimal design. These novel results are significant to related applications such as photonic integrated circuit and optical communications.

Comparative investigation of neuronal development on nano- and micro-topographic continuous silicon substrates

Neuronal responses at the cell-material interface are very crucial in many fields such as tissue engineering, stem cell differentiation, and tissue implants. Here we fabricated silicon substrates with nano- and micro- topographies, and observed responses of neurons on each substrate. It’s found that the outgrowth of neurites could be promoted on nano- and micro-featured silicon substrates compared with the flat control substrate. Surprisingly, filopodia protrusions of neurites exhibited fewer and shorter on nano-structured substrate than that on flat and micro-structured substrates. The intrinsic cytoskeleton re-arrangement was also induced by the nano-/micro-featured topography, which exhibited great potential in tuning the neuronal subcellular behaviors and the correlated neuronal functions.

SALDI-MS and SERS Multimodal Imaging: One Nanostructured Substrate to Rule Them Both.

Imaging techniques based on mass spectrometry or spectroscopy methods inform in situ about the chemical composition of biological tissues or organisms, but they are sometimes limited by their specificity, sensitivity, or spatial resolution. Multimodal imaging addresses these limitations by combining several imaging modalities; however, measuring the same sample with the same preparation using multiple imaging techniques is still uncommon due to the incompatibility between substrates, sample preparation protocols, and data formats. We present a multimodal imaging approach that employs a gold-coated nanostructured silicon substrate to couple surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) and surface-enhanced Raman spectroscopy (SERS). Our approach integrates both imaging modalities by using the same substrate, sample preparation, and data analysis software on the same sample, allowing the coregistration of both images. We transferred molecules from clean fingertips and fingertips covered with plasticine modeling clay onto our nanostructure and analyzed their chemical composition and distribution by SALDI-MS and SERS. Multimodal analysis located the traces of plasticine on fingermarks and provided chemical information on the composition of the clay. Our multimodal approach effectively combines the advantages of mass spectrometry and vibrational spectroscopy with the signal enhancing abilities of our nanostructured substrate.

Broadband Low Reflection Surfaces with Silicon Nano-pillar Square Arrays for Energy Harvesting

In this work, optimization of the nanopillar arrays and thin films coated on silicon substrate has been investigated in order to minimize the optical reflection loss from the silicon substrate surface. Nano-pillars's height, incline angle, array properties are systematically optimized. Full field Finite Difference Time Domain method is used to simulate EM fields and calculate the reflection from the modified nanostructured substrate surfaces in 400nm-1100nm spectral range. Optimization recipe is clearly presented and it is not only useful for square arrays but for regular arrays of nano-pillars in general.

Bioinspired three-dimensional hierarchical micro/nano-structured microdevice for enhanced capture and effective release of circulating tumor cells

The efficient capture and release of the circulating tumor cells (CTCs) are promising for the CTC related cancer diagnosis and subsequent analysis. However, it is a great challenge to isolate and enrich the rare CTCs from the complex peripheral blood sample, which inhibits its broad translating to the clinical applications. Although various papers reported that the nanostructure substrates can improve the capture efficiency of CTCs, few of researches constructed 3D hierarchical micro/nano-structured microdevice to enhance the efficiency of CTC capture and release with a simple manner. Herein, a bio-inspirited 3D epithelial cell adhesion molecule (EpCAM) aptamer modified rose petal derived ZnO microchip (EpCAM-RPD-ZnO-Chip) was designed to realize efficient capture and release of the CTCs. The 3D rough spherical concave surfaces on the EpCAM-RPD-ZnO-Chip guaranteed the maximum contact with the CTCs, thus improving the capture efficiency. Moreover, simple release of CTCs by dissolving ZnO under moderate acidic condition was achieved. The topographical and target molecular recognition cooperatively contributed to highly efficient capture of CTCs. The scanning electron microscope (SEM) image clearly showed that the filopodias and lamellipodias of CTCs stretched and attached to the ZnO nanomaterials. In sum, the proposed 3D EpCAM-RPD-ZnO-Chip is expected to be a promising tool for capture and release of CTCs in clinical trials, which might lay a foundation for downstream analysis and precise drug susceptibility test for the cancer treatment.

Nanoscale engineering of ring-mounted nanostructure around AAO nanopores for highly sensitive and reliable SERS substrates

Surface-enhanced Raman scattering (SERS) is recognized as one of the most favored techniques for enhancing Raman signals. The morphology of the SERS substrate profoundly affects molecular Raman spectra. This study aimed to construct a ring-mounted nanostructured substrate via liquid–liquid two-phase self-assembly incorporated with anodic aluminum oxide (AAO) membrane transfer techniques. High-density nanoparticles (NPs) assembled on AAO membranes were ascribed to reduce the diameters of the nanopores, with Au–Ag alloy NPs to regulate the dielectric constant so as to reveal the local surface plasmon resonance tunability. SERS engineered in this way allowed for the fabrication of a ring-mounted nanostructured substrate where the distribution density of NPs and dielectric constant could be independently fine-tuned. High SERS activity of the substrate was revealed by detecting the enhanced factor of crystal violet and rhodamine 6G molecules, which was up to 1.56 × 106. Moreover, SERS of thiram target molecules confirmed the supersensitivity and repeatability of the substrate as a practical application. The results of this study manifested a low-cost but high-efficiency ring-mounted nanostructured SERS substrate that might be suitable in many fields, including biosensing, medical research, environmental monitoring, and optoelectronics.

Nanoporous Substrates with Molecular-Level Perfluoroalkyl/Alkylamide Surface for Laser Desorption/Ionization Mass Spectrometry of Small Proteins.

The rapid detection of biomolecules greatly contributes to health management, clinical diagnosis, and prevention of diseases. Mass spectrometry (MS) is effective for detecting and analyzing various molecules at high throughput. However, there are problems with the MS analysis of biological samples, including complicated separation operations and essential pretreatments. In this study, a nanostructured organosilica substrate for laser desorption/ionization mass spectrometry (LDI-MS) is designed and synthesized to detect peptides and small proteins efficiently and rapidly. The surface functionality of the substrate is tuned by perfluoroalkyl/alkylamide groups mixed at a molecular level. This contributes to both lowering the surface free energy and introducing weak anchoring sites for peptides and proteins. Analyte molecules applied onto the substrate are homogeneously distributed and readily desorbed by the laser irradiation. The organosilica substrate enables the efficient LDI of various compounds, including peptides, small proteins, phospholipids, and drugs. An amyloid β protein fragment, which is known as a biomarker for Alzheimer's disease, is detectable at 0.05 fmol μL-1. The detection of the amyloid β at 0.2 fmol μL-1 is also confirmed in the presence of blood components. Nanostructured organosilica substrates incorporating a molecular-level surface design have the potential to enable easy detection of a wide range of biomolecules.

Морфология поверхности полуполярных GaN-слоев при эпитаксии на наноструктурированной подложке Si

It has been studied the morphology of the surface of the semipolar gallium nitride layers synthesized on nano-structured Si(100) or Si(113) substrates with a V-shaped or U–shaped surface profile, respectively. The morphology of the surface of the semipolar layers indicates that the different height-to-width ratio of the GaN(11-22) and GaN(10-11) blocks is associated with a higher growth rate of the GAN(11-22) face than GaN(10-11) and with different growth rates of the semipolar and polar crystal faces during the nucleation of the layer on a nano-structured substrate.

Nanoporous anodic alumina with ohmic contact between substrate and infill: Application to perovskite solar cells

AbstractThe use of a nanostructured aluminum substrate as the cathode for a perovskite photovoltaic device is described. This cathode consists of an aluminum substrate onto which a highly ordered array of aluminum oxide tubular pores was grown via anodization. The 1‐μm thick pores – arranged in a closed‐packed hexagonal pattern – were subsequently selectively etched at the bottom to remove the so‐called aluminum oxide barrier layer. The subsequent infiltration of the pores with the components of a methylammonium lead iodide perovskite solar cells, and the completion with a semi‐transparent anode, have shown to allow the establishment of an ohmic contact between the substrate itself and the components infiltrated into the Al2O3 pores. Indeed, a clear rectifying behavior was observed on the full devices, as well as modest photovoltaic conversion efficiencies. This paper demonstrates that an ohmic contact can be established between the aluminum substrate from which nanoporous anodic alumina was grown, and that the pores can be used to compartmentalize the infill material down to the nanoscopic level.