Amorphous Carbon Monolayer: A van der Waals Interface for High-Performance Metal Oxide Semiconductor Devices.

Ultrasmall-scale semiconductor devices (≤5 nm) are advancing technologies, such as artificial intelligence and the Internet of Things. However, the further scaling of these devices poses critical challenges, such as interface properties and oxide quality, particularly at the high-/semiconductor interface in metal-oxide-semiconductor (MOS) devices. Existing interlayer (IL) methods, typically exceeding 1 nm thickness, are unsuitable for ultrasmall-scale devices.

Preparation of fragmented polyethylene nanoplastics using a focused ultrasonic system and assessment of their cytotoxic effects on human cells.

With the growing prevalence of plastic use, the environmental release of plastic waste is escalating, and fragmented nanoscale plastic particles are emerging as significant environmental threats. This study aimed to evaluate the cytotoxic effects of fragmented polyethylene nanoplastics (PE NPs) manufactured using a focused ultrasonic system. The ultrasonic irradiation process generated fragmented PE NPs with a geometric mean diameter of 85.

Visualization Materials Using Silicon-Based Optical Nanodisks (ViSiON) for Enhanced NIR Imaging in Ophthalmology.

ViSiON (visualization materials composed of silicon-based optical nanodisks) is presented, which offers a unique optical combination of near-infrared (NIR) optical properties and biodegradability. Initially, numerical simulations are conducted to calculate the total extinction and scattering effects of ViSiON by the diameter-to-thickness ratio, predicting precise control over its scattering properties in the NIR region. A top-down patterning technique is employed to synthesize ViSiON with accurate diameter and thickness control.

Dual-Function Janus Nanozymes for Performance Evaluation and Application in a Surrogate Virus Neutralization Test with Vaccinated Samples.

The need exists for biosensing technologies capable of sensitively and accurately detecting various biomarkers. In response, the development of nanozymes is actively underway; they have advantages in stability, cost, performance, and functionalization over natural enzymes commonly used for signal amplification in sensing technologies. However, the performance of nanozymes is interdependent with factors such as shape, size, and surface functional moiety, making it challenging to perform quantitative performance comparisons based on the nanozyme material.

Theoretical and experimental comparison of the performance of gold, titanium, and platinum nanodiscs as contrast agents for photoacoustic imaging.

Exogenous contrast agents in photoacoustic imaging help improve spatial resolution and penetration depth and enable targeted molecular imaging. To screen efficient photoacoustic signaling materials as contrast agents, we propose a light absorption-weighted figure of merit (FOM) that can be calculated using material data from the literature and numerically simulated light absorption cross-sections. The calculated light absorption-weighted FOM shows that a Ti nanodisc has a photoacoustic conversion performance similar to that of an Au nanodisc and better than that of a Pt nanodisc.

Enhanced detection sensitivity through enzyme-induced precipitate accumulation in LSPR-active nano-valleys.

Biomolecule detection based on the localized surface plasmon resonance (LSPR) phenomenon has advantages in label-free detection, good sensitivity, and measurement simplicity and reproducibility. However, in order to ultimately be used for actual diagnosis, the ability to detect trace amounts of biomarkers is necessary, which requires the development of signal enhancement strategies that enable ultrasensitive detection. In this paper, we provide a straightforward and efficient route to boost LSPR sensitivity based on multiple sample washings.

Analyte-Induced Desert Rose-like Ag Nanostructures for Surface-Enhanced Raman Scattering-Based Biomolecule Detection and Imaging.

Biomolecule detection based on surface-enhanced Raman scattering (SERS) for application to biosensors and bio-imaging requires the fabrication of SERS nanoprobes that can generate strong Raman signals as well as surface modifications for analyte-specific recognition and binding. Such requirements lead to disadvantages in terms of reproducibility and practicality, and thus, it has been difficult to apply biomolecule detection utilizing the advantages of the SERS phenomenon to actual clinically relevant analysis. To achieve reproducible and practical SERS signal generation in a biomolecule-specific manner without requiring the synthesis of nanostructures and their related surface modification to introduce molecules for specific recognition, we developed a new type of SERS probe formed by enzyme reactions in the presence of Raman reporters.

Gold Nanoparticle-Enhanced and Roll-to-Roll Nanoimprinted LSPR Platform for Detecting Interleukin-10.

Localized surface plasmon resonance (LSPR) is a powerful platform for detecting biomolecules including proteins, nucleotides, and vesicles. Here, we report a colloidal gold (Au) nanoparticle-based assay that enhances the LSPR signal of nanoimprinted Au strips. The binding of the colloidal Au nanoparticle on the Au strip causes a red-shift of the LSPR extinction peak, enabling the detection of interleukin-10 (IL-10) cytokine.

Active Accumulation of Spherical Analytes on Plasmonic Hot Spots of Double-Bent Au Strip Arrays by Multiple Dip-Coating.

To achieve sensitive plasmonic biosensors, it is essential to develop an efficient method for concentrating analytes in hot spots, as well as to develop plasmonic nanostructures for concentrating light. In this study, target analytes were delivered to the surface of double-bent Au strip arrays by a multiple dip-coating method; they were self-aligned in the valleys between neighboring Au strips by capillary forces. As the valleys not only accommodate target analytes but also host strong electromagnetic fields due to the interaction between adjacent strips, sensitive measurement of target analytes was possible by monitoring changes in the wavelength of a localized surface plasmon resonance.

Tailoring cubic and dodecagonal quasicrystalline mesophases of mesoporous organosilica nanoparticles and core/shell structure.

Herein, the synthesis of mesoporous organosilica nanoparticles with cubic and dodecagonal quasicrystalline mesophases is reported. Mesoporous nanoparticles are synthesized by base-catalyzed hydrolysis and condensation reactions of silane-based monomers in the presence of hexadecyltrimethylammonium bromide (CTAB), which is used as a structure-directing agent to form the mesostructures. Cubic orders in the mesophases are formed using tetraethoxysilane monomers, and the mesophase is tuned to the dodecagonal quasicrystalline order by using binary monomers including tetraethoxysilane and dimethyldiethoxysilane.

Discrimination of single nucleotide mismatches using a scalable, flexible, and transparent three-dimensional nanostructure-based plasmonic miRNA sensor with high sensitivity.

Localized surface plasmon resonance (LSPR) biosensors have attracted much interest due to their capacity for multiplexing, miniaturization, and high performance, which offers the potential for their integration into lab-on-a-chip platforms for point-of-care (POC) diagnostics. The need for microRNA (miRNA)-sensing platforms is particularly urgent because miRNAs are key regulators and biomarkers in numerous pathological processes and diseases. Unfortunately, however, development of such miRNA-sensing platforms has not yet been achieved.

Highly robust, uniform and ultra-sensitive surface-enhanced Raman scattering substrates for microRNA detection fabricated by using silver nanostructures grown in gold nanobowls.

Highly sensitive and reproducible surface enhanced Raman spectroscopy (SERS) requires not only a nanometer-level structural control, but also superb uniformity across the SERS substrate for practical imaging and sensing applications. However, in the past, increased reproducibility of the SERS signal was incompatible with increased SERS sensitivity. This work presents multiple silver nanocrystals inside periodically arrayed gold nanobowls (SGBs) via an electrochemical reaction at an overpotential of -3.

Characterization and application of porous gold nanoparticles as 2-photon luminescence imaging agents: 20-fold brighter than gold nanorods.

Two-photon nonlinear microscopy with the aid of plasmonic contrast agents is an attractive bioimaging technique capable of generating high-resolution images in 3 dimensions and facilitating targeted imaging with deep tissue penetration. In this work, physically synthesized gold nanoparticles containing multiple nanopores are used as 2-photon contrast agents and are reported to emit a 20-fold brighter 2-photon luminescence as compared to typical contrast agents, that is, gold nanorods. A successful application of our porous gold nanoparticles is experimentally demonstrated by in vitro nonlinear optical imaging of adipocytes at subcellular level.

Stacked Gold Nanodisks for Bimodal Photoacoustic and Optical Coherence Imaging.

Herein, we report on biological imaging nanoprobes: physically synthesized gold nanodisks that have inherent optical advantages-a wide range of resonant wavelengths, tunable ratio of light absorption-to-scattering, and responsiveness to random incident light-due to their two-dimensional circular nanostructure. Based on our proposed physical synthesis where gold is vacuum deposited onto a prepatterned polymer template and released from the substrate in the form of a nanodisk, monodisperse two-dimensional gold nanodisks were prepared with independent control of their diameter and thickness. The optical benefits of the Au nanodisk were successfully demonstrated by the measurement of light absorbance of the nanodisks and the application of stacked nanodisks, where a smaller sized Au nanodisk was laid atop a larger nanodisk, as bimodal contrast agents for photoacoustic microscopy and optical coherence tomography.

Intraocular application of gold nanodisks optically tuned for optical coherence tomography: inhibitory effect on retinal neovascularization without unbearable toxicity.

Bare gold nanospheres have been shown to have anti-angiogenic effects but are optically unfavorable because their resonant wavelength lies in the visible spectrum. Here, we design gold nanodisks with a higher scattering capability than gold nanorods and with a resonant wavelength at near-infrared region - the area where the source of light utilized by optical coherence tomography (OCT) lies. With a physical synthesis system, we then fabricate 160-nm-sized gold nanodisks exhibiting resonant wavelength at 830 nm.

Facile three-dimensional nanoarchitecturing of double-bent gold strips on roll-to-roll nanoimprinted transparent nanogratings for flexible and scalable plasmonic sensors.

We develop scalable 3D plasmonic nanoarchitectures comprising a double-bent nanoscale Au strip array integrated within the transparent nanograting framework, which can be continuously fabricated on a large-area flexible substrate via roll-to-roll nanoimprint lithography and angled Au deposition, realizing localized surface plasmon resonance with higher sensitivity in a smaller footprint.

Physically-synthesized gold nanoparticles containing multiple nanopores for enhanced photothermal conversion and photoacoustic imaging.

Physically-synthesized gold nanoparticles having a narrow size distribution and containing multiple nanopores have been utilized as photothermal converters and imaging contrast agents. Nanopores within the gold nanoparticles make it possible to increase the light-absorption cross-section and consequently exhibit distinct improvements in photothermal conversion and photoacoustic imaging efficiencies.

A Semitransparent and Flexible Single Crystal Si Thin Film: Silicon on Nothing (SON) Revisited.

Ultrathin single crystal Si films offer a versatile vehicle for high performance flexible and semitransparent electric devices due to their outstanding optoelectric and mechanical properties. Here, we demonstrate the formation of an ultrathin (100) single crystal Si film based on morphological evolution of nanoporous Si during high temperature annealing. Square arrays of cylindrical Si pores are formed by nanoimprint lithography and deep reactive etching and then subjected to annealing in hydrogen ambient.

Guided formation of sub-5 nm interstitial gaps between plasmonic nanodisks.

To achieve a reliable formation of a surface-enhanced Raman scattering (SERS) sensor with evenly distributed hot spots on a wafer scale substrate, we propose a hybrid approach combining physical nanolithography for preparing Au nanodisks and chemical Au reduction for growing them. During the chemical growth, the interstitial distance between the nanodisks decreased from 60 nm to sub-5 nm. The resulting patterns of the nanogap-rich Au nanodisks successfully enhance the SERS signal, and its intensity map shows only a 5% or less signal variation on the entire sample.

Facile fabrication of silver nanoclusters as promising surface-enhanced Raman scattering substrates.

We present a simple wet chemical method to make thin film of silver nanoclusters on glass or silicon substrate. The method includes immersion of glass or silicon substrate into a saturated solution of silver nitrate in n-octanol. After 24 h, thin film of silver nanoclusters, which are micrometer-scale aggregates of silver nanoparticles with average size in the range of 80-100 nm, are formed on the substrate.

Strongly enhanced THz emission caused by localized surface charges in semiconducting Germanium nanowires.

A principal cause of THz emission in semiconductor nanostructures is deeply involved with geometry, which stimulates the utilization of indirect bandgap semiconductors for THz applications. To date, applications for optoelectronic devices, such as emitters and detectors, using THz radiation have focused only on direct bandgap materials. This paper reports the first observation of strongly enhanced THz emission from Germanium nanowires (Ge NWs).

Porous gold nanodisks with multiple internal hot spots.

For increasing the number of internal hot spots in the individual plasmonic nanoparticles, porous Au nanostructures were synthesized by a hybrid approach combining a physical process, which defined the overall shapes and dimensions of the nanostructures, and a chemical process, which incorporated nanopores inside the patterned nanostructures. This approach allows us to synthesize lithographically designed Au nanodisks containing numerous internal Raman hot spots in the form of nanopores. The increased number of hot spots successfully improved SERS intensity, and this experimental result was further elucidated by numerical electromagnetic simulations.

Three-tiered Au nano-disk array for broadband interaction with light.

We demonstrate a straightforward method to enlarge the spectral window for broadband interaction with light, by creating a plasmonic nanostructure composed of closely spaced multiple Au nano-disks. The vertically stacked, Au nano-disks of three different sizes make it possible to merge the individual spectral windows of the internal nano-disks into one broadband window, and can be simply generated by a single-step electron-beam lithography step with subsequent sputter deposition.

Raman-active two-tiered Ag nanoparticles with a concentric cavity.

A two-tiered Ag nanoparticle containing a cavity at the center of each nanoparticle is generated by two simple steps of nano-imprinting and metal vacuum deposition. It enables sub-zeptomole detection of organic molecules and five orders of the dynamic sensing range.