Coaching ribosome biogenesis from the nuclear periphery.

Severe invagination of the nuclear envelope is a hallmark of cancers, aging, neurodegeneration, and infections. However, the outcomes of nuclear invagination remain unclear. This work identified a new function of nuclear invagination: regulating ribosome biogenesis. With expansion microscopy, we observed frequent physical contact between nuclear invaginations and nucleoli. Surprisingly, the higher the invagination curvature, the more ribosomal RNA and pre-ribosomes are made in the contacted nucleolus. By growing cells on nanopillars that generate nuclear invaginations with desired curvatures, we can increase and decrease ribosome biogenesis. Based on this causation, we repressed the ribosome levels in breast cancer and progeria cells by growing cells on low-curvature nanopillars, indicating that overactivated ribosome biogenesis can be rescued by reshaping nuclei. Mechanistically, high-curvature nuclear invaginations reduce heterochromatin and enrich nuclear pore complexes, which promote ribosome biogenesis. We anticipate that our findings will serve as a foundation for further studies on nuclear deformation.

Bioinspired Hybrid Nanostructured PEEK Implant with Enhanced Antibacterial and Anti-inflammatory Synergy.

Implant-associated infections and excessive immune responses are two major postsurgical issues for successful implantation. However, conventional strategies including antibiotic treatment and inflammatory regulation are always compromised due to the comodification of various biochemical agents and instances of functional interference. It is imperative to provide implant surfaces with satisfactory antibacterial and anti-inflammatory properties. Here, a dual-effect nanostructured polyetheretherketone (PEEK) surface (NP@PDA/Zn) with bionic mechano-bactericidal nanopillars and immobilized immunomodulatory Zn2+ is designed. The constructed hybrid nanopillars display remarkable antibacterial performance against Gram-negative and Gram-positive strains through the synergy of physical and chemical bactericidal effects imposed by nanopillars and Zn2+. Meanwhile, the immunoregulatory property is evaluated through the investigation of macrophage polarization both in vitro and in vivo, and the results reveal that NP@PDA/Zn could downregulate the expression of M1-related cytokines and decrease the M1 macrophage recruitment to lower the inflammatory response. Notably, the surface exhibited exceptional biocompatibility with discerning biocidal activity between bacterial and mammalian cells and antioxidant performance that effectively scavenges ROS, minimizing potential cytotoxicity. Taken together, NP@PDA/Zn presents a convenient and promising strategy of combining synergistic bactericidal activity and inflammatory regulation without any mutual interference, which can support the development of multifunctional implant-associated materials.

UV-Vis-NIR Broadband Self-Powered CuInS2/SnO2 Photodetectors and the Application in Encrypted Optical Communication.

Photodetectors (PDs) with broadband photoresponse can meet the demand for multiband detection in complex environments, overcoming the technological complexity issue of integrated narrow-band PDs. Self-powered heterojunction PDs having ultraviolet-visible-near-infrared broadband photoresponse were constructed by using SnO2 nanopillars and CuInS2 nanoflakes. The dimension, crystalline quality, and energy level structure of the SnO2 nanopillars were regulated by changing the concentration of Sn ions in the precursor solution. The optimized interfacial energy band structure of the heterojunction can increase the transfer ability of the photogenerated carrier. The optimum performance is achieved for the CuInS2/SnO2(0.025M) PD prepared at 0.025 M Sn ion concentration in the precursor solution with the responsivities of 1.15, 6.13, and 1.02 mA/W, and detectivities of 1.19 × 1010, 6.35 × 1010, and 1.02 × 1010 Jones under 254 nm solar-blind ultraviolet light, 475 nm visible light, and 940 nm near-infrared light. Furthermore, a proof-of-concept solar-blind ultraviolet-visible-near-infrared encrypted communication system utilizing a broadband self-powered CuInS2/SnO2 PD as the receiving terminal and solar-blind ultraviolet light, ultraviolet light, visible light, and near-infrared light as the carrier and encryption protocol is proposed. The PD has great potential for applications in the field of encrypted optical communication.

Shaping single crystalline BaTiO3nanostructures by focused neon or helium ion milling.

The realization of perovskite oxide nanostructures with controlled shape and dimensions remains a challenge. Here, we investigate the use of helium and neon focused ion beam (FIB) milling in an ion microscope to fabricate BaTiO3nanopillars of sub-500 nm in diameter starting from BaTiO3(001) single crystals. Irradiation of BaTiO3with He ions induces the formation of nanobubbles inside the material, eventually leading to surface swelling and blistering. Ne-FIB is shown to be suitable for milling without inducing surface swelling. The resulting structures are defect-free single crystal nanopillars, which are enveloped, on the top and lateral sidewalls, by a point defect-rich crystalline region and an outer Ne-rich amorphous layer. The amorphous layer can be selectively etched by dipping in diluted HF. The geometry and beam-induced damage of the milled nanopillars depend strongly on the patterning parameters and can be well controlled. Ne ion milling is shown to be an effective method to rapidly prototype BaTiO3crystalline nanostructures.

Fabrication of Metal Contacts on Silicon Nanopillars: The Role of Surface Termination and Defectivity.

The application of nanotechnology in developing novel thermoelectric materials has yielded remarkable advancements in material efficiency. In many instances, dimensional constraints have resulted in a beneficial decoupling of thermal conductivity and power factor, leading to large increases in the achievable thermoelectric figure of merit (ZT). For instance, the ZT of silicon increases by nearly two orders of magnitude when transitioning from bulk single crystals to nanowires. Metal-assisted chemical etching offers a viable, low-cost route for preparing silicon nanopillars for use in thermoelectric devices. The aim of this paper is to review strategies for obtaining high-density forests of Si nanopillars and achieving high-quality contacts on them. We will discuss how electroplating can be used for this aim. As an alternative, nanopillars can be embedded into appropriate electrical and thermal insulators, with contacts made by metal evaporation on uncapped nanopillar tips. In both cases, it will be shown how achieving control over surface termination and defectivity is of paramount importance, demonstrating how a judicious control of defectivity enhances contact quality.

Formation of Si nanopillars through partial sacrificing in super passivation reactive ion etching.

The vertical gate-all-around (VGAA) metal-oxide-semiconductor field-effect transistor (MOSFET) holds remarkable potential in the three-dimensional (3D) integrated circuits (ICs), primarily owing to its capacity for vertical integration. The Si nanopillar, a crucial channel in the VGAA MOSFET, is conventionally shaped via the reactive ion etching (RIE) system employing SF6/O2. Past studies have indicated that high O2gas conditions in RIE often result in Si grasses irregular nanostructures, such as nanospikes on the bottom surface, due to over-passivation. However, this study revealed that ultrahigh O2proportions (>70%), especially when combined with low chamber pressure, inhibit the development of Si grasses in the RIE system (termed as super passivation). Nevertheless, this scenario leads to the segmentation of the Si nanopillar. To address this issue, a proposed partial sacrificing method, achieved by sacrificing the upper segment of the nanopillar through prolonged processing time and reduced mask size, successfully yielded Si nanopillars without Si grasses. Furthermore, an empirical model was developed to elucidate how experimental parameters influence etching characteristics, encompassing etching rate and Si nanopillar shape, through a systematic examination of the RIE etching process. This research significantly contributes to the production of VGAA MOSFETs and 3D ICs.

Uncooled Broadband Photodetection via Light Trapping in Conformal PtTe2-Silicon Nanopillar Heterostructures.

Dirac semimetals have demonstrated significant attraction in the field of optoelectronics due to their unique bandgap structure and high carrier mobility. Combining them with classical semiconductor materials to form heterojunctions enables broadband optoelectronic conversion at room temperature. However, the low light absorption of layered Dirac semimetals substantially limits the device's responsivity in the infrared band. Herein, a three-dimensional (3D) heterostructure, composed of silicon nanopillars (SiNPs) and a conformal PtTe2 film, is proposed and demonstrated to enhance the photoresponsivity for uncooled broadband detection. The light trapping effect in the 3D heterostructure efficiently promotes the interaction between light and PtTe2, while also enhancing the light absorption efficiency of silicon, which enables the enhancement of the device responsivity across a broadband spectrum. Experimentally, the PtTe2-SiNPs heterojunction device demonstrates excellent photoelectric conversion behavior across the visible, near-infrared, and long-wave infrared (LWIR) bands, with its responsivity demonstrating an order-of-magnitude improvement compared to the counterparts with planar silicon heterojunctions. Under 11 µm laser irradiation, the noise equivalent power (NEP) can reach 1.76 nW·Hz-1/2 (@1 kHz). These findings offer a strategic approach to the design and fabrication of high-performance broadband photodetectors based on Dirac semimetals.

Inverted Transflection Spectroscopy of Live Cells Using Metallic Grating on Elevated Nanopillars.

Water absorption of mid-infrared (MIR) radiation severely limits the options for vibrational spectroscopy of the analytes-including live biological cells-that must be probed in aqueous environments. While internal reflection elements, such as attenuated total reflection prisms and metasurfaces, partially overcome this limitation, such devices have their own limitations: ATR prisms are difficult to integrate with multiwell cell culture workflows, while metasurfaces suffer from a limited spectral range and small penetration depth into analytes. In this work, we introduce an alternative live cell biosensing platform based on metallic nanogratings fabricated on top of elevated dielectric pillars. For the MIR wavelengths that are significantly longer than the grating period, reflection-based spectroscopy enables broadband sensing of the analytes inside the trenches separating the dielectric pillars. Because the depth of the analyte twice-traversed by the MIR light excludes the highly absorbing thick water layer above the grating, we refer to the technique as inverted transflection spectroscopy (ITS). The analytic power of ITS is established by measuring a wide range of protein concentrations in solution, with the limit of detection in the single-digit mg mL-1. The ability of ITS to interrogate live cells that naturally wrap themselves around the grating is used to characterize their adhesion kinetic.

Ultrahigh Photosensitivity Based on Single-Step Lay-on Integration of Freestanding Two-Dimensional Transition-Metal Dichalcogenide.

Two-dimensional transition-metal dichalcogenides have attracted significant attention because of their unique intrinsic properties, such as high transparency, good flexibility, atomically thin structure, and predictable electron transport. However, the current state of device performance in monolayer transition-metal dichalcogenide-based optoelectronics is far from commercialization, because of its substantial strain on the heterogeneous planar substrate and its robust metal deposition, which causes crystalline damage. In this study, we show that strain-relaxed and undamaged monolayer WSe2 can improve a device performance significantly. We propose here an original point-cell-type photodetector. The device consists in a monolayer of an absorbing TMD (i.e., WSe2) simply deposited on a structured electrode, i.e., core-shell silicon-gold nanopillars. The maximum photoresponsivity of the device is found to be 23.16 A/W, which is a significantly high value for monolayer WSe2-based photodetectors. Such point-cell photodetectors can resolve the critical issues of 2D materials, leading to tremendous improvements in device performance.

Single-Cell Electrochemical Aptasensor Array.

Despite several demonstrations of electrochemical devices with limits of detection (LOD) of 1 cell/mL, the implementation of single-cell bioelectrochemical sensor arrays has remained elusive due to the challenges of scaling up. In this study, we show that the recently introduced nanopillar array technology combined with redox-labeled aptamers targeting epithelial cell adhesion molecule (EpCAM) is perfectly suited for such implementation. Combining nanopillar arrays with microwells determined for single cell trapping directly on the sensor surface, single target cells are successfully detected and analyzed. This first implementation of a single-cell electrochemical aptasensor array, based on Brownian-fluctuating redox species, opens new opportunities for large-scale implementation and statistical analysis of early cancer diagnosis and cancer therapy in clinical settings.

Multimode hybrid gold-silicon nanoantennas for tailored nanoscale optical confinement.

High-index dielectric nanoantennas, which provide an interplay between electric and magnetic modes, have been widely used as building blocks for a variety of devices and metasurfaces, both in linear and nonlinear regimes. Here, we investigate hybrid metal-semiconductor nanoantennas, consisting of a multimode silicon nanopillar core coated with a gold layer, that offer an enhanced degree of control over the mode selection and confinement, and emission of light on the nanoscale exploiting high-order electric and magnetic resonances. Cathodoluminescence spectra revealed a multitude of resonant modes supported by the nanoantennas due to hybridization of the Mie resonances of the core and the plasmonic resonances of the shell. Eigenmode analysis revealed the modes that exhibit enhanced field localization at the gold interface, together with high confinement within the nanopillar volume. Consequently, this architecture provides a flexible means of engineering nanoscale components with tailored optical modes and field confinement for a plethora of applications, including sensing, hot-electron photodetection and nanophotonics with cylindrical vector beams.

Self-Assembled Complex Three-Phase Core-Shell Nanostructure of Au-CoFe2-TiN with a Magneto-Optical Coupling Effect.

Nanostructured plasmonic-magnetic metamaterials have gained great research interest due to their enhanced magneto-optical coupling effects. Here, we report a complex three-phase nanocomposite design combining ferromagnetic CoFe2 with plasmonic TiN and Au as a multifunctional hybrid metamaterial using either a cogrowth or a templated method. Via the first method of cogrowing three phases, three different morphologies of Au-CoFe2 core-shell nanopillars were formed in the TiN matrix. Via the second method of sequential deposition of a TiN-Au seed layer and a TiN-CoFe2 layer, highly ordered and uniform single-type core-shell nanopillars (i.e., the CoFe2 shell with a Au core) form in the TiN matrix. Both cogrowth and templated growth TiN-CoFe2-Au hybrid systems exhibit excellent epitaxial quality, hyperbolic dispersion, magnetic anisotropy, and a magneto-optical coupling effect. This study provides an effective approach for achieving highly uniform multiphase vertically aligned nanocomposite structures with well-integrated optical, magnetic, and coupling properties.

Design of silicone interfaces with antibacterial properties.

Silicone implants are widely used for plastic or reconstruction medical applications. However, they can cause severe infections of inner tissues due to bacterial adhesion and biofilm growth on implant surfaces. The development of new antibacterial nanostructured surfaces can be considered as the most promising strategy to deal with this problem. In this article, we studied the influence of nanostructuring parameters on the antibacterial properties of silicone surfaces. Nanostructured silicone substrates with nanopillars of various dimensions were fabricated using a simple soft lithography technique. Upon testing of the obtained substrates, we identified the optimal parameters of silicone nanostructures to achieve the most pronounced antibacterial effect against the bacterial culture of Escherichia coli. It was demonstrated that up to 90% reduction in bacterial population compared to flat silicone substrates can be achieved. We also discussed possible underlying mechanisms behind the observed antibacterial effect, the understanding of which is essential for further progress in this field.

Study of GaN coalescence by dark-field X-ray microscopy at the nanoscale.

This work illustrates the potential of dark-field X-ray microscopy (DFXM), a 3D imaging technique of nanostructures, in characterizing novel epitaxial structures of gallium nitride (GaN) on top of GaN/AlN/Si/SiO2 nano-pillars for optoelectronic applications. The nano-pillars are intended to allow independent GaN nanostructures to coalesce into a highly oriented film due to the SiO2 layer becoming soft at the GaN growth temperature. DFXM is demonstrated on different types of samples at the nanoscale and the results show that extremely well oriented lines of GaN (standard deviation of 0.04°) as well as highly oriented material for zones up to 10 × 10 µm2 in area are achieved with this growth approach. At a macroscale, high-intensity X-ray diffraction is used to show that the coalescence of GaN pyramids causes misorientation of the silicon in the nano-pillars, implying that the growth occurs as intended (i.e. that pillars rotate during coalescence). These two diffraction methods demonstrate the great promise of this growth approach for micro-displays and micro-LEDs, which require small islands of high-quality GaN material, and offer a new way to enrich the fundamental understanding of optoelectronically relevant materials at the highest spatial resolution.

Plasmonic Nanopillars-A Brief Investigation of Fabrication Techniques and Biological Applications.

Nanopillars (NPs) are submicron-sized pillars composed of dielectrics, semiconductors, or metals. They have been employed to develop advanced optical components such as solar cells, light-emitting diodes, and biophotonic devices. To integrate localized surface plasmon resonance (LSPR) with NPs, plasmonic NPs consisting of dielectric nanoscale pillars with metal capping have been developed and used for plasmonic optical sensing and imaging applications. In this study, we studied plasmonic NPs in terms of their fabrication techniques and applications in biophotonics. We briefly described three methods for fabricating NPs, namely etching, nanoimprinting, and growing NPs on a substrate. Furthermore, we explored the role of metal capping in plasmonic enhancement. Then, we presented the biophotonic applications of high-sensitivity LSPR sensors, enhanced Raman spectroscopy, and high-resolution plasmonic optical imaging. After exploring plasmonic NPs, we determined that they had sufficient potential for advanced biophotonic instruments and biomedical applications.

Increasing the Stability of Isolated and Dense High-Aspect-Ratio Nanopillars Fabricated Using UV-Nanoimprint Lithography.

Structural anti-reflective coating and bactericidal surfaces, as well as many other effects, rely on high-aspect-ratio (HAR) micro- and nanostructures, and thus, are of great interest for a wide range of applications. To date, there is no widespread fabrication of dense or isolated HAR nanopillars based on UV nanoimprint lithography (UV-NIL). In addition, little research on fabricating isolated HAR nanopillars via UV-NIL exists. In this work, we investigated the mastering and replication of HAR nanopillars with the smallest possible diameters for dense and isolated arrangements. For this purpose, a UV-based nanoimprint lithography process was developed. Stability investigations with capillary forces were performed and compared with simulations. Finally, strategies were developed in order to increase the stability of imprinted nanopillars or to convert them into nanoelectrodes. We present UV-NIL replication of pillars with aspect ratios reaching up to 15 with tip diameters down to 35 nm for the first time. We show that the stability could be increased by a factor of 58 when coating them with a 20 nm gold layer and by a factor of 164 when adding an additional 20 nm thick layer of SiN. The coating of the imprints significantly improved the stability of the nanopillars, thus making them interesting for a wide range of applications.

Templated Synthesis of Diamond Nanopillar Arrays Using Porous Anodic Aluminium Oxide (AAO) Membranes.

Diamond nanostructures are mostly produced from bulk diamond (single- or polycrystalline) by using time-consuming and/or costly subtractive manufacturing methods. In this study, we report the bottom-up synthesis of ordered diamond nanopillar arrays by using porous anodic aluminium oxide (AAO). Commercial ultrathin AAO membranes were adopted as the growth template in a straightforward, three-step fabrication process involving chemical vapor deposition (CVD) and the transfer and removal of the alumina foils. Two types of AAO membranes with distinct nominal pore size were employed and transferred onto the nucleation side of CVD diamond sheets. Subsequently, diamond nanopillars were grown directly on these sheets. After removal of the AAO template by chemical etching, ordered arrays of submicron and nanoscale diamond pillars with ~325 nm and ~85 nm diameters were successfully released.

Semiconductor Thermal and Electrical Properties Decoupled by Localized Phonon Resonances.

Thermoelectric materials convert heat into electricity through thermally driven charge transport in solids or vice versa for cooling. To compete with conventional energy-conversion technologies, a thermoelectric material must possess the properties of both an electrical conductor and a thermal insulator. However, these properties are normally mutually exclusive because of the interconnection between scattering mechanisms for charge carriers and phonons. Recent theoretical investigations on sub-device scales have revealed that nanopillars attached to a membrane exhibit a multitude of local phonon resonances, spanning the full spectrum, that couple with the heat-carrying phonons in the membrane and cause a reduction in the in-plane thermal conductivity, with no expected change in the electrical properties because the nanopillars are outside the pathway of voltage generation and charge transport. Here this effect is demonstrated experimentally for the first time by investigating device-scale suspended silicon membranes with GaN nanopillars grown on the surface. The nanopillars cause up to 21% reduction in the thermal conductivity while the power factor remains unaffected, thus demonstrating an unprecedented decoupling in the semiconductor's thermoelectric properties. The measured thermal conductivity behavior for coalesced nanopillars and corresponding lattice-dynamics calculations provide evidence that the reductions are mechanistically tied to the phonon resonances. This finding paves the way for high-efficiency solid-state energy recovery and cooling.

Large-Scale, Proteinaceous Nanotube Arrays with Programmable Hydrophobicity, Oleophilicity, and Gas Permeability.

Nanotubular structures possess remarkable advantages in a broad range of areas, such as catalysis, sensing, microencapsulation, selective mass transport, filtration, and drug delivery. While the fields of carbon nanotubes and nanotubes made of several noncarbon materials (e.g., metals, oxides, semiconductors) have been progressing rapidly, proteinaceous nanotubes remained largely underexplored. Here, by retrofitting a template wetting approach with multiple silk-based suspensions, we present a rapidly scalable and robust technology for fabricating large arrays (e.g., 20 × 20 cm2) of well-aligned 1D nanostructures made of silk proteins. Benefiting from the polymorphic nature of silk, precise control over the size, density, aspect ratio, and morphology (tubes versus pillars) of silk nanostructures is achieved, which then allows for programmable modulation of the end materials' functions and properties (e.g., hydrophobicity, oleophilicity, and gas permeability). The silk nanotube arrays fabricated present great utility as antifouling coatings against marine algae and in oil extraction from oil-water mixtures.

Hierarchical Topography with Tunable Micro- and Nanoarchitectonics for Highly Enhanced Cardiomyocyte Maturation via Multi-Scale Mechanotransduction.

Enhancing cardiomyocyte (CM) maturation by topographical cues is a critical issue in cardiac tissue engineering. Thus far, single-scale topographies with a broad range of feature shapes and dimensions have been utilized including grooves, pillars, and fibers. This study reports for the first time a hierarchical structure composed of nano-pillars (nPs) on micro-wrinkles (µWs) for effective maturation of CMs. Through capillary force lithography followed by a wrinkling process, vast size ranges of topographies are fabricated, and the responses of CMs are systematically investigated. Maturation of CMs on the hierarchical structures is highly enhanced compared to a single-scale topography: cardiac differentiation of H9C2s (rat cardiomyocytes) on the hierarchical topography is ≈ 2.8 and ≈ 1.9 times higher than those consisting of single-scale µWs and nPs. Both nPs and µWs have important roles in cardiac maturation, and the aspect ratio (height/diameter) of the nPs and the wavelength of the µWs are important in CM maturation. This enhancement is caused by strong focal adhesion and nucleus mediated mechanotransduction of CMs from the confinement effects of the different wavelengths of µWs and the cellular membrane protrusion on the nPs. This study demonstrates how a large family of hierarchical structures is used for cardiac maturation.