Journal of Nano Research Vol. 89

Abstract: Raman spectroscopy is a powerful tool to analyze materials. The demand for analyzing materials in a smaller analytical region is increasing as technology advances. Tip-enhanced Raman spectroscopy (TERS) is an option. However, measuring the surface of three-dimensional bulk materials is quite challenging, since simultaneously excited micro-Raman signals hide the enhanced nano-Raman signals. In 2024, another approach of using a porous gold membrane was reported to dedicate solid surface analysis. However, this method, for example, sacrifices the lateral analytical spot size because nanopores distribute throughout the membrane. Here, 70-nm thick gold microplates with nano-through-holes in the center are fabricated. The gold microplates provide a smaller analytical spot because nano-through-holes are fabricated only in a spatially limited region. The microplates and the surrounding structures are clearly visible under optical microscopes. We moved gold microplates to another location on a silicon substrate using a manipulator and successfully demonstrated nano-Raman measurements of silicon surface via nano-through-holes. The finite-difference time-domain calculations confirmed that enhanced electric fields are available by the nano-through-holes and revealed that the nano-Raman signals come from the surface of silicon within a depth of 5.4 nm.

Abstract: This study investigates the broadband plasmonic resonance properties of gold-based surface-enhanced Raman spectroscopy (SERS) substrates with stochastically disordered nanostructures. We fabricated a nanotextured template topped with sputtered gold. Field emission scanning electron microscopy (FE-SEM) analysis showed random gold nanoclusters with different densities, sizes, and orientations. Simulation results indicated a large number of electromagnetic (EM) modes, including first- and second-generation hotspots as well as touching point geometries that provide a large enhancement factor. With any given excitation wavelength, such disordered SERS structures can provide some mode configurations that resonance, resulting in broadband response. SERS simulations showed considerable electric field intensification across a wide range of wavelengths (600–1600 nm) and provided a relatively uniform SERS response with an areal-averaged enhancement factor ~10⁵ across a broad visible to near-infrared range.

Abstract: Nanobubbles are gaseous vesicles under 1 micrometer in size, widely used in medical imaging and drug delivery. Their compressibility enhances ultrasound imaging, while their small size allows for extravasation into tumors via the enhanced permeation and retention effect. However, drug delivery remains challenging due to high interstitial pressure within tumors, which limits penetration to the core. To address this, nanobubbles can serve as drug delivery devices, with controlled release triggered by focused ultrasound. Understanding their transport behavior is crucial, particularly in the tumor microenvironment. This study investigates the effect of ultrasound and presence of shear on the permeation of nanobubbles through the tumor interstitium. Rhodamine-loaded nanobubbles, mimicking drug-loaded delivery device, were introduced into a membrane insert system containing an agarose-gel layer simulating the tumor interstitium. Nanobubble concentration in the receiver well was monitored via fluorescence intensity, assessing transport efficiency under different conditions. Comparisons with non-echogenic fluorescent dextrans provided insights into distinct nanoparticle behaviors. Results showed that ultrasound significantly enhanced nanobubble permeation, whereas the presence of shear primarily benefited dextran transport. These findings highlight the unique responsiveness of nanobubbles to ultrasound, offering a promising strategy for improving drug delivery in solid tumors.

Abstract: As an ideal candidate for lightweight applications, aramid nanofibers(ANFs)-based aerogel has outstanding thermal stability, corrosion resistance and great mechanical properties. However, some existing complex application scenarios put forward higher requirements for its performance, and multi-functional integration has become its important development direction. Since the intrinsic properties of fillers in the composite aerogel will greatly affect aerogel’s functionality, the structural configuration should be considered at the same time. Herein, we have proposed a preparation method for multilayer functional ANFs-based aerogel through multiple cycle casting and freezing, weak acid enhanced protonation and freeze-drying processes, in which the specific properties of the single functional layer are enhanced by one functional filler and the multifunction integration is achieved by the stacking of multiple functional layers. The prepared representative sample: SiC-CNT-SiC/ANF aerogel exhibits the characteristics of low density, great mechanical properties, excellent heat insulation and flame retardant effect, and good self-heating function. And the four-layer aerogel (CNT-SiC-SiC-SiC/ANF) can not only meet the rapid self-heating in CNT/ANF layer, but also has the overall efficient thermal insulation function. This efficient and flexible preparation method will provide more possibilities for preparing more types of multifunctional ANFs-based aerogels, making them better suitable for complex application scenarios.

Abstract: The increase in the global energy demand necessitates advanced and innovative techniques to meet up with the energy raising needs. The use of nanofluids offers a promising approach to increase oil production in chemical-enhanced oil recovery, especially for matured reservoirs. In this work, Zinc Oxide (ZnO)/Copper Oxide (CuO) nanocomposite was synthesized and evaluated for its suitability for enhanced oil recovery (EOR). Various characterization techniques were carried out including X-ray diffraction (XRD), Energy Dispersion X-Ray (EDX) Spectrophotometry, and Transmission Electron Microscopy (TEM) to investigate the nanocomposite formed. However, a hybrid nanofluid, and a stability study was conducted for potential application in EOR. The material characterization and stability results revealed that ZnO/CuO hybrid nanofluid is promising and shows good potential when utilized in EOR applications.

Abstract: This work, report a simple synthesis of carbon quantum dots (CQDs) derived from Simmondsia chinensis (Jojoba) seed meal. Simmondsia chinensis seed meal was used because it has rich phytochemical contents. The structural, morphological, functional group and optical properties of the obtained CQDs were studied using X-ray diffraction spectroscopy (XRD), Transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR), Zeta potential, UV-vis and spectrophotometer, respectively. The TEM shows that the obtained CQDs have an average size of 8.48 nm. The photoluminescence spectroscopy revealed that the synthesized CQDs can emit tunable bluish photoluminescence with maximum emission intensity was observed at 400 nm under 340 nm excitation wavelength.

Abstract: The nature of the precursor material used in the synthesis of carbon dots can easily affect their properties. Biomass-derived carbon sources are encouraged because they are ecologically sustainable and provide numerous benefits compared to alternative carbon sources. This work presents the synthesis of carbon dots derived from Moringa oleifera leaves using a hydrothermal synthesis technique. The optical, morphological and structural properties of the obtained carbon dots were characterized using UV-vis absorption spectrophotometer, photoluminscence (PL), transition electron microscopy (TEM) and X-ray diffraction (XRD) spectroscopy, respectively. The TEM revealed nearly spherical-shaped dot particles with an average size of 11.24 nm in diameter. The optical properties showed that the obtained carbon dots have green fluorescence, and the fluorescence spectra were found to red-shift as the excitation wavelength increased.

Abstract: In this paper, we developed a facile approach to produce carbon quantum dots (CQDs) using corn silk, a sustainable and natural resource. Corn silk is often used in health products due to its medicinal qualities. However, it has been understudied in terms of its potential to create materials with optical and biological characteristics. These synthesized CQDs were characterized using several techniques including fourier transform infrared spectroscopy (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), nuclear microscope resonance (NMR), UV−vis absorption spectra, photoluminescence (PL) spectroscopy, zeta potential, transmission electron microscope (TEM). The latter has revealed that the product has mostly spherical shapes with an average size 9 nm in diameter with d-spacing 0.24 nm. The FTIR results reveal that the presence of functional groups (including carbonyl, hydroxyl, and amine groups) endows the CQDs with good solubility in water.

Abstract: This study optimizes 28 nm planar MOSFET technology to reduce device leakage current and enhance switching speed. The specific aims are to decrease subthreshold swing (S.S.) and mitigate drain-induced barrier lowering (DIBL) effect. Silvaco TCAD software is used for process (Athena) and device (Atlas) simulations. For the further development of MOSFET technology, we implemented our device (planar 28 nm n-MOSFET) with high-k metal-gate (HK/MG), lightly doped drain (LDD), multi-spacers, and silicide. Simulation validation shows improvements over other 28 nm devices, with lower static power consumption and notable optimizations in both S.S. (69.8 mV/dec) and DIBL effect (30.5 mV/V).