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Synthesis of Sphere-Like Silver Nanostructures Composed of Self-Assembled Nanosheets
摘要： Sphere-like silver nanostructures composed of self-assembled nanosheets were rapidly synthesized through adding ferrous sulfate into the mixture of silver nitrate and citric acid aqueous solution by magnetic stirring at room temperature for 20 min. The effects of the concentrations of the ferrous sulfate and citric acid on the morphology of the silver nanostructures were investigated in detail. The characterization of the sphere-like silver nanostructures composed of self-assembled nanosheets have been discussed by scanning electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and differential scanning calorimetry. Furthermore, the possible formation mechanism of sphere-like silver nanostructures composed of self-assembled nanosheets was explored. The experimental results show that the high concentration of citric acid and the low concentration of ferric sulfate are better for obtaining the sphere-like silver nanostructures composed of self-assembled nanosheets due to a low diffusion rate of silver atoms to the silver nucleus and a low growth rate of silver ?akes along the {111} facets. Such sphere-like silver nanostructures exhibit a strong surface-enhanced Raman scattering effect associated with their geometries, which is much stronger than that from nanosheets.
关键词： nanosheet,self-assembled,Sphere-like silver nanostructure,surface-enhanced Raman scattering effect
更新于2025-09-23 15:21:01
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Setting Up Surface-Enhanced Raman Scattering Database for Artificial Intelligence-Based Label-Free Discrimination of Tumor Suppressor Genes
摘要： The quality of input data in deep learning is tightly associated with the ultimate performance of machine learner. Taking advantages of unique merits of surface-enhanced Raman scattering (SERS) methodology in the collection and construction of database (e.g., abundant intrinsic fingerprint information, noninvasive data acquisition process, strong anti-interfering ability, etc.), herein we set up SERS-based database of deoxyribonucleic acid (DNA), suitable for artificial intelligence (AI)-based sensing applications. The database is collected and analyzed by silver nanoparticles (Ag NPs)-decorated silicon wafer (Ag NPs@Si) SERS chip, followed by training with a deep neural network (DNN). As proof-of-concept applications, three kinds of representative tumor suppressor genes, i.e., p16, p21 and p53 fragments, are readily discriminated in label-free manners. Prominent and reproducible SERS spectra of these DNA molecules are collected and employed as input data for DNN learning and training, which enables selective discrimination of DNA target(s). The accuracy rate for the recognition of specific DNA target reaches 90.28%.
关键词： surface-enhanced Raman scattering,label-free discrimination,deep neural network,tumor suppressor genes,artificial intelligence
更新于2025-09-23 15:21:01
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Facilitating Tip-Enhanced Raman Scattering on Dielectric Substrates via Electrical Cutting of Silver Nanowire Probes
摘要： TERS is a powerful tool for nanoscale optical characterization of surfaces. However, even after 20 years of development, the parameters for optimal TERS tips are still up for debate. As a result, routine measurements on bulk or dielectric substrates remain exceptionally challenging. Herein we help to alleviate this by using electrical cutting to strategically modify silver nanowire TERS probes. Following cutting, the tips present a large, spherical apex and are often nanostructured with numerous nanoparticles, which we argue improve light collection and optical coupling. This doubles TERS signals on a highly-enhancing, gap-mode substrate compared to our standard nanowire tips, whilst maintaining a high reproducibility and resolution. More interestingly, on a dielectric substrate (graphene on SiO2) the tips give ~7x higher signals than our standard tips. Further investigations point to the non-local nature of the enhancement using standard, smooth, TERS probes without gap-mode, making such nanostructuring highly beneficial in these cases.
关键词： electrical cutting,silver nanowire,TERS,Tip-Enhanced Raman Scattering,nanoscale optical characterization,dielectric substrates
更新于2025-09-23 15:21:01
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In Situ Raman Investigation of TiO2 Nanotube Array-Based Ultraviolet Photodetectors: Effects of Nanotube Length
摘要： TiO2 nanotube arrays (TNAs) with tube lengths of 4, 6, and 7 μm were prepared via two-step anodization. Thereafter, ultraviolet (UV) photodetectors (PDs) with Au/TiO2/Au structures were prepared using these TNAs with different tube lengths. The effects of TNA length and device area on the performance of the device were investigated using in situ Raman spectroscopy. The maximum laser/dark current ratio was achieved by using a TNA with a size of 1 × 1 cm2 and a length of 7 μm, under a 532 nm laser. In addition, when the device was irradiated with a higher energy laser (325 nm), the UV Raman spectrum was found to be more sensitive than the visible Raman spectrum. At 325 nm, the laser/dark current ratio was nearly 24 times higher than that under a 532 nm laser. Six phonon modes of anatase TNAs were observed, at 144, 199, 395, 514, and 635 cm?1, which were assigned to the Eg(1), Eg(2), B1g(1), A1g/B1g(2), and Eg(3) modes, respectively. The strong low-frequency band at 144 cm?1 was caused by the O-Ti-O bending vibration and is a characteristic band of anatase. The results show that the performance of TNA-based PDs is length-dependent. Surface-enhanced Raman scattering signals of 4-mercaptobenzoic acid (4-MBA) molecules were also observed on the TNA surface. This result indicates that the length-dependent performance may be derived from an increase in the specific surface area of the TNA. In addition, the strong absorption of UV light by the TNAs caused a blueshift of the Eg(1) mode.
关键词： UV photodetector,Surface-enhanced Raman scattering,TiO2 nanotube arrays,SERS,Raman spectroscopy
更新于2025-09-23 15:19:57
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Controlled Fabrication of Flower-Shaped Aua??Cu Nanostructures Using a Deep Eutectic Solvent and Their Performance in Surface-Enhanced Raman Scattering-Based Molecular Sensing
摘要： Controlled synthesis of anisotropic bimetallic nanostructures with tunable morphology is of great current interest in surface-enhanced Raman scattering (SERS), plasmonics, and catalysis. Despite huge effort that has been devoted so far, fabrication of bimetallic nanostructures with controlled morphology and size remained to be a great challenge, especially when their shapes are anisotropic. Here, we report a facile, one-step synthetic approach for the fabrication of anisotropic bimetallic gold?copper nanostructures (Au?Cu NSs) of the 200?300 nm size range, using choline chloride/urea (ChCl/urea)-based deep eutectic solvent (DES) as the soft template. A concentration of the CuCl2 precursor in the reaction mixture was found to impact the reduction kinetics of the metal ions, directly affecting the final morphology of the Au?Cu nanostructures and elemental distributions in them. The fabricated anisotropic Au?Cu NSs revealed a high SERS signal for crystal violet (CV) molecules adsorbed at their surfaces, with the signal enhancement factor as high as 0.21 × 106 and capacity of detecting CV molecules of concentrations as low as 10?10 M in their aqueous solutions. The growth mechanism of the anisotropic bimetallic nanostructures in DES and their SERS performance has been discussed. The simple DES-assisted synthesis strategy presented in this work can be adopted for large-scale nonaqueous fabrication of other bimetallic nanostructures in a quite “greener” way.
关键词： deep eutectic solvent,plasmonics,catalysis,anisotropic bimetallic nanostructures,Au?Cu nanostructures,surface-enhanced Raman scattering
更新于2025-09-23 15:19:57
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Surface-enhanced Raman scattering from buffer layer under graphene on SiC in a wide energy range from visible to near-infrared
摘要： Raman signals from the buffer layer between graphene and a SiC substrate are enhanced through the formation of nano-structured Au deposited directly on graphene grown on SiC. This simple method makes it possible to deconvolute multiple graphene and buffer layer peaks in a wide energy range from 1.58 to 2.33 eV and find new buffer layer peaks that are not resolved in conventional Raman scattering spectroscopy. Furthermore, we clearly show a small linear excitation energy dependence for one of the buffer layer peak positions and an absence of energy dependence for the peaks at most of the other positions.
关键词： buffer layer,Surface-enhanced Raman scattering,graphene,SiC,near-infrared
更新于2025-09-23 15:19:57
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Optically controlled hybrid metamaterial of plasmonic spiky gold inbuilt graphene sheets for bimodal imaging guided multimodal therapy
摘要： The development of multifunctional molecular diagnostic platforms for concordant visualization and treatment of diseases with high sensitivity and resolution has recently become a crucial strategy in cancer management. Thus, engineering functional metamaterials with high therapeutic and imaging capabilities to elucidate diseases from morphological behaviors to physiological mechanisms is an unmet need in the current scenario. Here, we report the design of a unique hybrid plasmonic nanoarchitecture, for targeted multiple photo-therapies of breast cancer by simultaneous real time monitoring through fluorescence and surface enhanced Raman scattering (SERS) techniques. The nanoframework consists of plasmonic gold-graphene hybrids tethered with folic acid ligated chitosan modified photosensitizer (PpIX) to afford target specific localized photothermal and photodynamic therapy. The hybrid vehicle also served as an excellent nanocarrier for efficient loading and stimuli responsive release of the chemotherapeutic drug doxorubicin (DOX) to enhance the therapeutic efficacy, thereby forming a trimodal nanomedicine against cancer. The cytotoxic effects induced by the cumulative action of triplet therapeutic tools were visualized through both fluorescence and SERS imaging channels. Moreover, it also generated synchronized therapeutic effects resulting in the effective regression of tumor volume without propagating any toxic effect to other organs of the animals. Taken together, by virtue of strong light-matter interactions, our nanoprobe showed enhanced photoadsorption which facilitate the amplified light reactive therapeutic and imaging efficacies along with targeted and enhanced chemotherapy, both in vitro and in vivo, which may offer a promising outcome in clinical research.
关键词： surface enhanced Raman scattering (SERS),hybrid plasmonic nanoarchitecture,breast cancer,trimodal nanomedicine,fluorescence,doxorubicin (DOX),photothermal and photodynamic therapy,multifunctional molecular diagnostic platforms
更新于2025-09-23 15:19:57
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Low-cost and high sensitivity glucose sandwich detection using a plasmonic nanodisk metasurface
摘要： Glucose detection using Surface-enhanced Raman scattering (SERS) spectroscopy has aroused considerable attention due to its potential in the prevention and diagnosis of diabetes as a result of its unique molecular fingerprinting capability, ultrahigh sensitivity and minimal interference from water. Despite numerous solutions to improve the sensitivity of glucose detection, the development of a new SERS-based strategy to detect glucose with high sensitivity and low-cost is still required. In this study, we propose a simple and sensitive SERS-based plasmonic metasurface sensing platform for a glucose sandwich assay using self-assembled p-mercapto-phenylboronic acid (PMBA) monolayers on a gold nanodisk (Au-ND) metasurface and synthesized silver nanoparticles (Ag NPs) modified with a mixture of p-aminothiophenol (PATP) and PMBA. The localized near-field of the proposed plasmonic metasurface is markedly enhanced due to the coupling between the Au-ND and Ag NPs, which greatly improves detection sensitivity. The experimental results show that SERS signals of the glucose assay are significantly enhanced by more than 8-fold, in comparison with the SERS substrate of smooth Au film and Ag NPs. Moreover, the plasmonic metasurface-based glucose sandwich assay exhibits high selectivity and sensitivity for glucose over fructose and galactose. The developed plasmonic metasurface sensing platform shows enormous potential for highly sensitive and selective SERS-based glucose detection and opens a new avenue for scalable and cost-effective biosensing applications in the future.
关键词： Surface-enhanced Raman scattering (SERS),glucose detection,gold nanodisk (Au-ND),p-mercapto-phenylboronic acid (PMBA),p-aminothiophenol (PATP),silver nanoparticles (Ag NPs),plasmonic metasurface
更新于2025-09-23 15:19:57
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Design of Magnetica??Plasmonic Nanoparticle Assemblies via Interface Engineering of Plasmonic Shells for Targeted Cancer Cell Imaging and Separation
摘要： Magnetic-plasmonic nanoparticles have received considerable attention for widespread applications. These nanoparticles (NPs) exhibiting surface-enhanced Raman scattering (SERS) activities are developed due to their potential in bio-sensing applicable in non-destructive and sensitive analysis with target-specific separation. However, it is challenging to synthesize these NPs that simultaneously exhibit low remanence, maximized magnetic content, plasmonic coverage with abundant hotspots, and structural uniformity. Here, a method that involves the conjugation of a magnetic template with gold seeds via chemical binding and seed-mediated growth is proposed, with the objective of obtaining plasmonic nanostructures with abundant hotspots on a magnetic template. To obtain a clean surface for directly functionalizing ligands and enhancing the Raman intensity, an additional growth step of gold (Au) and/or silver (Ag) atoms is proposed after modifying the Raman molecules on the as-prepared magnetic-plasmonic nanoparticles. Importantly, one-sided silver growth occurred in an environment where gold facets are blocked by Raman molecules; otherwise, the gold growth is layer-by-layer. Moreover, simultaneous reduction by gold and silver ions allowed for the formation of a uniform bimetallic layer. The enhancement factor of the nanoparticles with a bimetallic layer is approximately 107. The SERS probes functionalized cyclic peptides are employed for targeted cancer-cell imaging and separation.
关键词： cell separation,surface-enhanced Raman scattering,bio-sensing,magnetic-plasmonic nanoparticles,cancer-cell imaging
更新于2025-09-23 15:19:57
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A phenylboronate-based SERS nanoprobe for detection and imaging of intracellular peroxynitrite
摘要： A surface-enhanced Raman scattering (SERS) based nanoprobe was developed for detection and imaging of endogenous peroxynitrite in living cells. The probe was fabricated by assembling 3-mercaptophenylboronic acid pinacol ester onto the surface of gold nanoparticles (AuNPs). The detection of peroxynitrite is accomplished via measurement of the changes in the SERS spectra (at 882 cm?1) that are caused by the reaction between probe and peroxynitrite. The probe has a fast response (<30 s), a 0.4 μM lower detection limit and a wide linearity range from 5.0 × 10?7 to 1.0 × 10?4 M. It is biocompatible and highly stable on storage and under various pH conditions. Both the reaction and the SERS signal are highly specific over other species. The nanoprobe was successfully applied to SERS imaging of peroxynitrite that is produced in macrophages under oxidative stress. Conceivably, the method has a most viable tool for use in studies on peroxynitrite-related physiological and pathological processes.
关键词： Surface-enhanced Raman scattering,Boronate ester,Specific reaction,Reactive oxygen species,Gold nanoparticles,Living cell,Oxidative stress,Biosensor
更新于2025-09-23 15:19:57