Gold Nanoislands Research Articles

Near-field probing of surface plasmon polariton formation in imprinted gold nanoisland arrays

Large-area imprinting stamps with nanometer-scale features are a rapidly developing area of research in plasmonics. In integrated photonic structures, surface plasmon (SPs) and surface plasmon polaritons (SPPs) are tuned by selecting both the appropriate wavelength and the angle of incidence of the excitation light. The resulting exponential fields can be studied by an optical technique such as scanning near-field optical microscopy (SNOM). Here, we report on the application of the aperture-type SNOM technique to characterize, at nanoscopic and microscopic scales, the formation of the SPPs and the beat pattern formed with the superposition of SPs and the effective component of the probing light formed in discrete metallic nanostructures of Au fabricated on imprinting stamps. We discuss a model to describe the beat pattern in terms of this superposition and demonstrate that the dominant SPs have a transverse nature. Our experiments are supported by modeling the optical response and near-field in gold nanostructures using the simulation tool Tidy3D. Our results provide a straightforward way to investigate and characterize SPPs at the nanostructure level.

Label-free detection of formaldehyde in water by titanium doped MoS2 gold nanoislands LSPR sensor

Formaldehyde is a known human carcinogen widely present in various industrial processes. Dissolved formaldehyde in water poses a significant threat to human health, not solely gases. Here, a novel label-free detection scheme of formaldehyde in aqueous environment via Ti-doped MoS2 as the functionalized layer on a localized surface plasmon resonance (LSPR) sensor is reported. It has been found that the strong adsorption of formaldehyde on Ti-doped MoS2 attached on gold nanoislands induces a strong local refractive index change and enables sensitive detection. Besides, the characterization and LSPR experimental results also highlight the contribution of the nanoislands morphology to facilitate improved surface attachment of Ti-doped MoS2, and in turn improves the sensing performance. Along with experimental work, density functional theory (DFT) calculation has shown the strong formaldehyde adsorption on Ti-doped MoS2 with water molecules included, therefore confirming its feasibility and effectiveness for sensing. The sensor has successfully achieved an excellent detection limit of 0.104 ppb with its selectivity studied and confirmed using DFT calculations and experiment. The practical value of this research lies in its potential development of this light-based sensor for water quality monitoring with the major advantages of facile synthesis, fast detection, and label-free sensing offered by LSPR.

Persistence of Structural Lubricity on Contaminated Graphite: Rejuvenation, Aging, and Friction Switches.

Using atomic force microscopy experiments and molecular dynamics simulations of gold nanoislands on graphite, we investigate why ultralow friction commonly associated with structural lubricity can be observed even under ambient conditions. Measurements conducted within a few days after sample synthesis reveal previously undiscovered phenomena in structurally lubric systems: rejuvenation, a drop in kinetic friction of an order of magnitude shortly after the onset of sliding; aging, a significant increase in kinetic friction forces after a rest period of 30 min or more; and switches, spontaneous jumps between distinct friction branches. These three effects are drastically suppressed a few weeks later. Imaging of a contamination layer and simulations provide a consistent picture of how single- and double-layer contamination underneath the gold nanoislands as well as contamination surrounding the nanoislands affect structural lubricity without leading to its breakdown.

Sponge-shaped Au nanoparticles: a stand-alone metallic photocatalyst for driving the light-induced CO2 reduction reaction

Coinage metal nanoparticles (NPs) enable plasmonic catalysis by generating hot carriers that drive chemical reactions. Making NPs porous enhances the adsorption of reactant molecules. We present a dewetting and dealloying strategy to fabricate porous gold nanoparticles (Au-Sponge) and compare their CO2 photoreduction activity with respect to the conventional gold nanoisland (Au-Island) morphology. Porous gold nanoparticles exhibit an unusually broad and red-shifted plasmon resonance which is in agreement with the results of finite difference time domain (FDTD) simulations. The key insight of this work is that the multi-step reduction of CO2 driven by short-lived hot carriers generated by the d → s interband transition proceeds extremely quickly as evidenced by the generation of methane. A 3.8-fold enhancement in the photocatalytic performance is observed for the Au-Sponge in comparison to the Au-Island. Electrochemical cyclic voltammetry measurements confirm the 2.5-fold increase in the surface area and roughness factor of the Au-Sponge sample due to its porous nature. Our results indicate that the product yield is limited by the amount of surface adsorbates i.e. reactant-limited. Isotope-labeled mass spectrometry using 13CO2 was used to confirm that the reaction product (13CH4) originated from CO2 photoreduction. We present the plasmon-mediated photocatalytic transformation of 4-aminothiophenol (PATP) into p,p'-dimercaptoazobenzene (DMAB) using Au-Sponge and Au-Island samples.

Analyte-dependent Rabi splitting in solid-state plexcitonic sensors based on plasmonic nanoislands strongly coupled to J-aggregates

A key challenge in the field of plexcitonic quantum devices is the fabrication of solid-state, device-friendly plexcitonic nanostructures using inexpensive and scalable techniques. Lithography-free, bottom-up nanofabrication methods have remained relatively unexplored within the context of plexcitonic coupling. In this work, a plexcitonic system consisting of thermally dewetted plasmonic gold nanoislands (AuNI) coated with a thin film of J-aggregates was investigated. Control over nanoisland size and morphology allowed for a range of plasmon resonances with variable detuning from the exciton. The extinction spectra of the hybrid AuNI/J-aggregate films display clear splitting into upper and lower hybrid resonances, while the dispersion curve shows anti-crossing behavior with an estimated Rabi splitting of 180 eV at zero detuning. As a proof of concept for quantum sensing, the AuNI/J-aggregate hybrid was demonstrated to behave as a plexcitonic sensor for hydrochloric acid vapor analyte. This work highlights the possibility of using thermally dewetted nanoparticles as a platform for high-quality, tunable, cost-effective, and scalable plexcitonic nanostructures for sensing devices and beyond.

(Digital Presentation) A Microfluidic Approach for Direct Immobilization of Extracellular Vesicles on Gold Nanoislands for Efficient Detection Using Localized Surface Plasmon Resonance

Extracellular vesicles (EVs) are crucial for intercellular communication and are potential biomarkers for cancer diagnosis. To improve the detection of EVs, we have developed a platform that uses an ultra-thin film of gold to form gold nanoislands. This platform allows for the direct immobilization of EVs onto the gold nanoislands, using a simple microfluidic device. Detection of the EVs is based on the Localized Surface Plasmon Resonance (LSPR) method. With this innovative approach, we aim to enhance the accuracy and efficiency of EV detection, which could ultimately lead to faster detection and therefore the possibility of an early-stage diagnosis of cancer.Gold nanoparticles are deposited on glass substrates using physical vapor deposition to create an ultra-thin layer of gold. Annealing the nanoparticle film forms gold nano-islands, which are drops with varying shapes and sizes from solid dewetting. A PDMS microfluidic device with a tapered channel of 200-micron depth and a 4mm diameter collection chamber bonded to gold-coated substrates is used to detect EVs from MCF7. The EVs flow through the channel at a rate of 10 µL/min, and the LSPR spectrum of the gold nanoislands is measured before and after EV immobilization. Changes in the refractive index of the surrounding medium due to the presence of EVs cause a shift in the Au LSPR band, which can be used to detect EVs.In this study, we will utilize extracellular vesicles (EVs) obtained from a breast cancer cell line (MCF7) that had been grown in a small bioreactor. A simple microfluidic device will be designed and fabricated to evaluate the Localized Surface Plasmon Resonance (LSPR) shift of the gold plasmon band for different EV concentrations. The microfluidic device was chosen due to its high reproducibility, sensitivity, and ability to work with small amounts of EVs. To understand the sensitivity of this platform, a calibration curve will be plotted and compared with the results of other platforms that we have previously studied. To validate the LSPR detection using the microfluidic device, the eluted exosomes from the device will be characterized using TRPS and FESEM techniques.Overall, our findings will demonstrate the potential of utilizing EVs and LSPR-based microfluidic devices as a promising tool for the detection of EVs and further clinical analysis for cancer diagnosis.

Efficient colorimetric point-of-care detection and imaging of multiple biomolecules utilizing photonic liquid crystal composite on gold nanoisland thin films for label-free sensing

Efficient colorimetric point-of-care detection and imaging of multiple biomolecules utilizing photonic liquid crystal composite on gold nanoisland thin films for label-free sensing

Laser pulse shape transformation in hybrid LC cells containing gold nano-island films

A nano-structured surface containing an Au nano-island film is used to fabricate hybrid liquid crystal (HLC) cells. HLCs are characterized by faster response times. The dynamic holographic technique is applied to make the conversion of the laser pulse shape by using HLCs. From a comparative analysis of experimental results with theoretical modeling of a dynamic process, the time constants of the dynamic grating recording and relaxation have been determined.

H-Glass Supported Hybrid Gold Nano-Islands for Visible-Light-Driven Hydrogen Evolution.

Flat panel reactors, coated with photocatalytic materials, offer a sustainable approach for the commercial production of hydrogen (H2) with zero carbon footprint. Despite this, achieving high solar-to-hydrogen (STH) conversion efficiency with these reactors is still a significant challenge due to the low utilization efficiency of solar light and rapid charge recombination. Herein, hybrid gold nano-islands (HGNIs) are developed on transparent glass support to improve the STH efficiency. Plasmonic HGNIs are grown on an in-house developed active glass sheet composed of sodium aluminum phosphosilicate oxide glass (H-glass) using the thermal dewetting method at 550°C under an ambient atmosphere. HGNIs with various oxidation states (Au0, Au+, and Au-) and multiple interfaces are obtained due to the diffusion of the elements from the glass structure, which also facilitates the lifetime of the hot electron to be ≈2.94ps. H-glass-supported HGNIs demonstrate significant STH conversion efficiency of 0.6%, without any sacrificial agents, via water dissociation. This study unveils the specific role of H-glass-supported HGNIs in facilitating light-driven chemical conversions, offering new avenues for the development of high-performance photocatalysts in various chemical conversion reactions for large-scale commercial applications.

Optical Observations of Sputtered Au-nanostructures and Characterizations

o develop novel optoelectronic devices, controlling and predetermined absorption is necessary. In the current work, the gold nano-islands were sputtered onto quartz surface substrates using a DC sputtering unit with an optimized chamber. The effects of the sputtering time (10, 15, and 20 seconds) on the characteristics of the golden layers deposited on quartz substrates were studied. Au nanofilms were investigated by XRD (X-ray diffraction), UV-Vis (ultraviolet-visible light) diffractometer, and AFM (atomic force microscopy) techniques. The thicknesses of the three films prepared at different sputtering times (10, 15, and 20 seconds) were calculated using the theoretical deposition formula method. The average layer thickness, and hence the size of the golden crystallites, rose from 6.8 to 13.6 nm when the sputtering period was increased. The X-ray spectra revealed a very distinguish peak at (111), pointing that the gold single crystal has fully oriented along [111] and the gold film has a pure crystalline Fcc structure. When deposition times are lengthened, the color of the resulting films changes from blue to green. Nano-films have seen important changes in their surface shape and roughness. The structural layer of Au's surface is remarkably semi-spherical, giving it the appearance of spherolytic and hummock-like. Analyzing the UV-VIS spectra of the precipitated structures using Tauc's paradigm revealed the optical energy gap (non-zero Eg in the range of 2.36 to 2.38 eV) that is associated with the nanostructure's semiconducting properties. In addition, as the sputtering duration increases from 10 to 20 seconds, the wavelengths at which peak values of the surface plasmon resonance occur shift from 610 to 650 nm, and the widths of the peaks rise. The AFM images of the ultra-thin Au layers showed smooth surfaces whose roughness decreases from 1.82 to 0.673 nm with increasing sputtering time from 10 to 20 nm. Solar cells can take advantage of the higher absorption in the blue spectrum region by using a set of depositing parameters and prescribed thicknesses. In addition, the formation of nano-islands can also be used as nucleation sites (seed layer) to promote the growth of various nanostructures to obtain a good aspect ratio and improve the performance of various optoelectronic devices and gas sensors.

Comparing silver and gold nanoislands’ surface plasmon resonance for bisacodyl and its metabolite quantification in human plasma

Gold and silver nanoparticles have witnessed increased scientific interest due to their colourful colloidal solutions and exceptional applications. Comparing the localized surface plasmon resonance (LSPR) of gold and silver nanoparticles is crucial for understanding and optimizing their optical properties. This comparison informs the design of highly sensitive plasmonic sensors, aids in selecting the most suitable nanoparticles for applications like surface-enhanced infrared spectroscopy (SEIRA) and biomedical imaging, and guides the choice between gold and silver nanoparticles based on their catalytic and photothermal properties. Ultimately, the study of LSPR facilitates the tailored use of these nanoparticles in diverse scientific and technological applications. Two SEIRA methods combined with partial least squares regression (PLSR) chemometric tools were developed. This development is based on the synthesis of homogeneous, high-dense deposited metal nanoparticle islands over the surface of glass substrates to be used as lab-on-chip SEIRA sensors for the determination of bisacodyl (BIS) and its active metabolite in plasma. SEM micrographs revealed the formation of metallic islands of colloidal citrate-capped gold and silver nanoparticles of average sizes of 29.7 and 15 nm, respectively. BIS and its active metabolite were placed on the nanoparticles’ coated substrates to be directly measured, then PLSR chemometric modelling was used for the quantitative determinations. Plasmonic citrate-capped gold nanoparticle substrates showed better performance than those prepared using citrate-capped silver nanoparticles in terms of preparation time, enhancement factor, PLSR model prediction, and quantitative results. This study offers a way to determine BIS and its active metabolite in the concentration range 15–240 ng/mL in human plasma using inexpensive disposable glass-coated substrates that can be prepared in 1 h to get results in seconds with good recovery between 98.77 and 100.64%. The sensors provided fast, simple, selective, molecular-specific and inexpensive procedures to determine molecules in their pure form and biological fluid.

Gold-Deposited Graphene Nanosheets for Self-Cleaning Graphene Surface-Enhanced Raman Spectroscopy with Superior Charge-Transfer Contribution.

The interaction of graphene with metals initiates charge-transfer interaction-induced chemical enhancements, which critically depend on the doping effect from deposited metallic configurations. In this paper, we have explored the gold nanoparticle-decorated monolayer graphene nanosheets for the large graphene-induced Raman enhancement of adsorbed analytes, indicating the surface-enhanced Raman spectroscopy (SERS) capabilities of metal-doped graphene (G-SERS). Here, the systematically sputtered Au thickness optimization procedure revealed noticeable modifications in the graphene Raman spectra and photoluminescence (PL) background quenching, which indicated favorable charge transfer through n-type doping of chemical vapor deposition-grown graphene nanosheets. The highly consistent, individually distributed morphology of the gold nanoislands over graphene nanosheets depicted a reproducibly uniform G-SERS signal with excellent relative standard deviation values (<5%), resulting in the strongest Raman intensity enhancement factors of ∼108 (MB) (methylene blue) and 107 (DPA) (2,6-pyridinedicarboxylic acid) composed of the weakest PL background. The combined charge-transfer-induced chemical enhancement and electromagnetic enhancement from individual Au nanoislands result in a lowering of detectability down to 10-16 M (MB) and 10-11 M (DPA) concentrations with efficient time-dependent signal stability. Additionally, the GAu demonstrated its effective (∼94.4%) photocatalytic degradation capabilities by decomposing MB dye molecules from a concentration of 1 μM to 2.52 fM within 60 min. Therefore, the prominent charge-transfer contribution through controlled Au decoration over graphene nanosheets provides a potential strategy for fabricating superior SERS sensors and photocatalysts exhibiting adequate signal consistency, stability, and photodegradation efficiency through overcoming the limitations of the traditional sensing platforms.

α-MoO3 Microflakes Decorated with Gold Nanoislands as SERS-Active Substrates

α-MoO₃ Microflakes Decorated with Gold Nanoislands as SERS-Active Substrates

Simultaneous detection of SARS-CoV-2 S1 protein by using flexible electrochemical and Raman enhancing biochip

Flexible laser-scribed graphene (LSG) substrates with gold nanoislands have been developed as biochips for in situ electrochemical (EC) and surface-enhanced Raman scattering (SERS) biodetection (biomolecules and viral proteins). A flexible biochip was fabricated using CO2 laser engraving polyimide (PI) films to form a 3D porous graphene-like nanostructure. Gold nanoislands were deposited on the LSG substrates to enhance the intensity of the Raman signals. Moreover, the addition of auxiliary and reference electrodes induced a dual-function EC-SERS biochip with significantly enhanced detection sensitivity. The biochip could selectively and easily capture SARS-CoV-2 S1 protein through the SARS-CoV-2 S1 antibody immobilized on EC-SERS substrates using 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The grafted antibody specifically bound to SARS-CoV-2, resulting in a significant increase in the SERS signal of the target analyte. The limit of detection (LOD) of the SARS-CoV-2 S1 protein was 5 and 100 ng/mL by using EC and SERS detection, respectively. Although the LOD of the SARS-CoV-2 S1 protein detected using SERS is only 100 ng/mL, it can provide fingerprint information for identification. To improve the LOD, EC detection was integrated with SERS detection. The three-electrode detection chip enables the simultaneous detection of SERS and EC signals, which provides complementary information for target identification. The dual-functional detection technology demonstrated in this study has great potential for biomedical applications, such as the rapid and sensitive detection of SARS-CoV-2.

A distinction of gliomas at cellular and tissue level by surface-enhanced Raman scattering spectroscopy

Glioblastoma multiforme (GBM) is the most common malignant primary brain tumor in adults. The precise identification and distinction of GBM heterogeneity from surrounding brain parenchyma at the cellular level and even at the tissue level are important for GBM therapy. In this study, GBM cells are distinguished from normal astrocytes and non-central nervous system (CNS) tumor cells by surface-enhanced Raman scattering (SERS) based on gold nanoshell (SiO2@Au) particles and support vector machine (SVM) algorithm. In addition, the gold nanoisland (AuNI) SERS substrates are further developed and explored for accurate detection of GBM at the tissue level. The distinction between glioma and trauma tissues, identification of different tumor grades, and IDH mutation are realized with the assistance of orthogonal partial least squares discriminant analysis (OPLS-DA) in a rapid, non-invasive, and convenient method. The results show that the developed SERS-based analytical method has the potential for practical application for the detection of GBM at the single-cell and tissue levels and even for real-time intraoperative diagnosis.

Lung Cancer Cell-Derived Exosome Detection Using Electrochemical Approach towards Early Cancer Screening.

Lung cancer is one of the deadliest cancers worldwide due to the inability of existing methods for early diagnosis. Tumor-derived exosomes are nano-scale vesicles released from tumor cells to the extracellular environment, and their investigation can be very useful in both biomarkers for early cancer screening and treatment assessment. This research detected the exosomes via an ultrasensitive electrochemical biosensor containing gold nano-islands (Au-NIs) structures. This way, a high surface-area-to-volume ratio of nanostructures was embellished on the FTO electrodes to increase the chance of immobilizing the CD-151 antibody. In this way, a layer of gold was first deposited on the electrode by physical vapor deposition (PVD), followed by thermal annealing to construct primary gold seeds on the surface of the electrode. Then, gold seeds were grown by electrochemical deposition through gold salt. The cell-derived exosomes were successfully immobilized on the FTO electrode through the CD-151 antibody, and cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were used in this research. In the CV method, the change in the current passing through the working electrode is measured so that the connection of exosomes causes the current to decrease. In the EIS method, surface resistance changes were investigated so that the binding of exosomes increased the surface resistance. Various concentrations of exosomes in both cell culture and blood serum samples were measured to test the sensitivity of the biosensor, which makes our biosensor capable of detecting 20 exosomes per milliliter.

Simultaneous electrochemical detection of glycated and human serum albumin for diabetes management

Developing highly selective and sensitive biosensors for diabetes management blood glucose monitoring is essential to reduce the health risks associated with diabetes. Assessing the glycation (GA) of human serum albumin (HSA) serves as an indicator for medium-term glycemic control, making it suitable for assessing the efficacy of blood glucose management protocols. However, most biosensors are not capable of simultaneous detection of the relative fraction of GA to HSA in a clinically relevant range. Here, we report an effective miniaturised biosensor architecture for simultaneous electrochemical detection of HSA and GA across relevant concentration ranges. We immobilise DNA aptamers specific for the detection of HSA and GA on gold nanoislands (Au NIs) decorated screen-printed carbon electrodes (SPCEs), and effectively passivate the residual surface sites. We achieve a dynamic detection range between 20 and 60 mg/mL for HSA and 1–40 mg/mL for GA in buffer solutions. The analytical utility of our HSA and GA biosensor architectures are validated in mice serum indicating immediate potential for clinical applications. Since HSA and GA have similar structures, we extensively assess our sensor specificity, observing high selectivity of the HSA and GA sensors against each other and other commonly present interfering molecules in blood such as glucose, glycine, ampicillin, and insulin. Additionally, we determine the glycation ratio, which is a crucial metric for assessing blood glucose management efficacy, in an extensive range representing healthy and poor blood glucose management profiles. These findings provide strong evidence for the clinical potential of our biosensor architecture for point-of-care and self-assessment of diabetes management protocols.

Multi-Functional Applications of H-Glass Embedded with Stable Plasmonic Gold Nanoislands.

Metal nanoparticles (MNPs) are synthesized using various techniques on diverse substrates that significantly impact their properties. However, among the substrate materials investigated, the major challenge is the stability of MNPs due to their poor adhesion to the substrate. Herein,it isdemonstrated how a newly developed H-glass can concurrently stabilize plasmonic gold nanoislands (GNIs) and offer multifunctional applications. The GNIs on the H-glassaresynthesized using a simple yet, robust thermal dewetting process. The H-glass embedded with GNIs demonstrates versatility in its applications, such as i) acting as a room temperature chemiresistive gas sensor (70% response for NO2 gas); ii) serving as substrates for surface-enhanced Raman spectroscopy for the identifications of Nile blue (dye) and picric acid (explosive) analytes down to nanomolar concentrations with enhancement factors of 4.8 × 106 and 6.1 × 105 , respectively; and iii) functioning as a nonlinear optical saturable absorber with a saturation intensity of 18.36 × 1015 Wm-2 at 600nm, and the performance characteristics are on par with those of materials reported in the existing literature. This work establishes a facile strategy to develop advanced materials by depositing metal nanoislands on glass for various functional applications.

A near-infrared fluorescence-enhancing plasmonic biosensing microarray identifies soluble PD-L1 and ICAM-1 as predictive checkpoint biomarkers for cancer immunotherapy

Sensitive and accurate biomarker-driven assay guidance has been widely adopted to identify responsive patients for immune checkpoint blockade (ICB) therapy to impede disease progression and extend survival. However, most current assays are invasive, requiring surgical pathology specimens and only informing monochronic information. Here, we report a multiplexed enhanced fluorescence microarray immunoassay (eFMIA) based on a nanostructured gold nanoisland substrate (AuNIS), which macroscopically amplifies near-infrared fluorescence (NIRF) of a structurally symmetric IRDye78 fluorophore by over two orders of magnitude of 202.6-fold. Aided by non-contact piezo-driven micro-dispensing (PDMD), eFMIA simultaneously and semi-quantitatively detected intracellular and secreted programmed death-ligand 1 (PD-L1) and intercellular adhesion molecule-1 (ICAM-1) in human nasopharyngeal carcinoma (NPC) cells. The assay performance was superior to fluorescence immunoassays (FIA) and enzyme-linked immunosorbent assays (ELISA), with lower detection limits. Using eFMIA, we found significantly differential levels of soluble PD-L1 (sPD-L1) and sICAM-1 in the sera of 28 cancer patients, with different clinical outcomes following anti-PD-1 ICB therapy. With a well-characterized mechanism, the high-performance plasmonic multiplexed assay with the composite biomarkers may be a valuable tool to assist clinicians with decision-making and patient stratification to afford predictive ICB therapy responses.

Growth of highly oriented crystalline gold nanoislands on MgO(001) substrates for surface-enhanced Raman scattering chips by pulsed laser deposition

Highly oriented crystalline gold nanoislands (NIs) are self-assembled on MgO(001) substrates by pulsed laser deposition. Morphologies of the gold NIs are significantly dependent on the substrate temperature during gold deposition. Symmetrical-shaped NIs with Au(111) orientation are existence parallel to the MgO(001) substrate at low temperatures deposition (350 and 550 °C), while square-shaped and hexagonal-shaped gold NIs are co-existence whose crystallinity was Au(001) and Au(111), respectively. Extinction spectra of the gold NIs on MgO(001) substrates show that wide-range of photo-energy is disappeared. For a simple and useful plasmonic device, the produced gold NIs on MgO(001) substrates are applied to the surface-enhanced Raman scattering (SERS) chips. The SERS properties of the chips are evaluated using 4-MBA as a model analyte. From the SERS signal of a 4-MBA ring breathing mode, we obtain a significant enhancement factor over 107, which is approximately 10 times higher than that of a conventional SERS chip.