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MXenes induce epitaxial growth of size-controlled noble nanometals: a case study for surface enhanced Raman scattering (SERS)
摘要： Noble nanometals are of significance in both scientific interest and technological applications, which are usually obtained by conventional wet-chemical synthesis. Organic surfactants are always used in the synthesis to prevent unexpected overgrowth and aggregation of noble nanometals. However, the surfactants are hard to remove and may interfere with plasmonic and catalytic studies, remaining surfactant-free synthesis of noble nanometals a challenge. Herein, we report an approach to epitaxial growth of size-controlled noble nanometals on MXenes. As piloted by density functional theory calculations, along with work function experimental determination, kinetic and spectroscopic studies, epitaxial growth of noble nanometals is initiated via a mechanism that involves an in situ redox reaction. In the redox, MXenes as two-dimensional solid reductants whose work functions are compatible with the reduction potentials of noble metal cations, enable spontaneous donation of electrons from the MXenes to noble metal cations and reduce the cations into nanoscale metallic metals on the outmost surface of MXenes. Neither surfactants nor external reductants are used during the whole synthesis process, which addresses a long-standing interference issue of surfactant and external reductant in the conventional wet-chemical synthesis. Moreover, noble nanometals are size-controlled. Impressively, noble nanometals firmly anchored on MXenes exhibit excellent performance towards surface enhanced Raman scattering. Our developed strategy will promote the nanostructure-controlled synthesis of noble nanometals, offering new opportunities to further improve advanced functional properties towards practical applications.
关键词： SERS,Two-dimensional materials,MXene,In situ redox,Noble metal
更新于2025-09-12 10:27:22
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Wrinkled metal based quantum sensor for In vitro cancer diagnosis
摘要： This article presents a unique 3D biocompatible Aluminum-based quantum structure (QS) for in vitro cancer detection using Surface Enhanced Raman Scattering (SERS). The Al-based QSs fabricated using ultrashort pulsed laser are of two distinct surface characters, wrinkled and smooth spherical. The limit of detection for chemical sensing of Crystal Violet and Rhodamine 6G by the Al-QS was driven up to single molecule sensing (femtomolar concentration). Biological sensing of cysteine, a disease biomarker and carcinoembryonic antigen (CEA), a cancer biomarker was also tested by the Al-QS. The ability of in vitro cell detection using Al-QS was analyzed with three cell lines, mammalian fibroblast and pancreatic and lung cancer cells. The Al-QS were up taken by the cells through label-free self-internalization and were sensed by SERS. Further assay was performed to differentiate cancerous and non-cancerous cells by measuring lipid and protein peak intensity within the cells. The result of this research indicated that SERS based Al-QS could be a suitable candidate for the early diagnosis of cancer.
关键词： SERS,self-internalization,invitro cancer diagnosis,single molecule sensing,metallic quantum probe
更新于2025-09-12 10:27:22
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SERS-Active Substrates Nanoengineering Based on e-Beam Evaporated Self-Assembled Silver Films
摘要： Surface-enhanced Raman spectroscopy (SERS) has been intensely studied as a possible solution in the fields of analytical chemistry and biosensorics for decades. Substantial research has been devoted to engineering signal enhanced SERS-active substrates based on semi-continuous nanostructured silver and gold films, or agglomerates of micro- and nanoparticles in solution. Herein, we demonstrate the high-amplitude spectra of myoglobin precipitated out of ultra-low concentration solutions (below 10 μg/mL) using e-beam evaporated continuous self-assembled silver films. We observe up to 105 times Raman signal amplification with purposefully designed SERS-active substrates in comparison with the control samples. SERS-active substrates are obtained by electron beam evaporation of silver thin films with well controlled nanostructured surface morphology. The characteristic dimensions of the morphology elements vary in the range from several to tens of nanometers. Using optical confocal microscopy we demonstrate that proteins form a conformation on the surface of the self-assembled silver film, which results in an effective enhancement of giant Raman scattering signal. We investigate the various SERS substrates surface morphologies by means of atomic force microscopy (AFM) in combination with deep data analysis with Gwyddion software and a number of machine learning techniques. Based on these results, we identify the most significant film surface morphology patterns and evaporation recipe parameters to obtain the highest amplitude SERS spectra. Moreover, we demonstrate the possibility of automated selection of suitable morphological parameters to obtain the high-amplitude spectra. The developed AFM data auto-analysis procedures are used for smart optimization of SERS-active substrates nanoengineering processes.
关键词： metal film,neural networks,myoglobin,SERS substrate,e-beam evaporation
更新于2025-09-12 10:27:22
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Dumbbell–Like Silica Coated Gold Nanorods and their Plasmonic Properties
摘要： Silica coated gold nanorods with dumbbell-like morphology allowing dual functionalization in an individual nanostructure have attracted great attention for applications such as sensing and biological imaging. We report a detailed study on the feasibility of controlling the morphology of silica coating on gold nanorods. The morphology of the silica shell can be either cylindrical or dumbbell shaped. The morphology of the silica shell can be either cylindrical or dumbbell shaped. With constant GNR concentration, the ratio of CTAB and TEOS concentration is the key to determine the amount of available TEOS for silica deposition on GNR since the TEOS will diffuse towards the surface of GNRs. The effect of morphologies on surface-enhanced Raman scattering (SERS) performance was also investigated and we found that the dumbbell morphology of silica coated gold nanorods has the most significant SERS enhancement. Our study is significant in terms of the capability to control the dumbbell morphology of silica coated gold nanorods, which can eventually broaden the application of these plasmonic nanomaterials.
关键词： SERS,TEOS,plasmonic properties,dumbbell-like morphology,CTAB,Silica coated gold nanorods
更新于2025-09-12 10:27:22
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Plasmonic Microneedle Arrays for in situ Sensing with Surface-Enhanced Raman Spectroscopy (SERS)
摘要： Surface-enhanced Raman spectroscopy (SERS) is a sensitive, chemically specific, and short-time response probing method with significant potential in biomedical sensing. This paper reports the integration of SERS with microneedle arrays as a minimally invasive platform for chemical sensing, with a particular view towards sensing in interstitial fluid (ISF). Microneedle arrays were fabricated from a commercial polymeric adhesive and coated with plasmonically active gold nanorods that were functionalized with the pH-sensitive molecule 4-mercaptobenzoic acid. This sensor can quantitate pH over a range of 5 to 9 and can detect pH levels in an agar gel skin phantom and in human skin in situ. The sensor array is stable and mechanically robust in that it exhibits no loss in SERS activity after multiple punches through an agar gel skin phantom and human skin or after a month-long incubation in phosphate-buffered saline. This work is the first to integrate SERS-active nanoparticles with polymeric microneedle arrays and to demonstrate in situ sensing with this platform.
关键词： SERS,agar gel skin phantom,pH in situ sensing,human skin,Plasmonic microneedle arrays
更新于2025-09-12 10:27:22
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Sensitive detection of polycyclic aromatic hydrocarbons with gold colloid coupled chloride ion SERS sensor
摘要： A simple surface-enhanced Raman spectroscopy (SERS) sensor based on an undecorated gold-colloid substrate was developed for the rapid and effective detection of polycyclic aromatic hydrocarbons (PAH). The SERS enhancement of the bare Au nanoparticles for PAH was achieved by adjusting chemical reduction conditions and Cl? content. The strongest SERS response of this system was achieved with 2.0 mL of trisodium citrate (1%) and 80 μL of NaCl (1 M). With this simple SERS sensor, qualitative and quantitative determination of trace-level naphthalene (NaP), phenanthrene (PHE) and pyrene (PYR) were achieved using a portable Raman spectrometer at detection limits of 1.38 μg L?1, 0.23 μg L?1, and 0.45 μg L?1, respectively. Plots of SERS intensity vs. PAH concentrations were linear, with correlation coefficients (R2) ranging from 0.8729 to 0.9994. More importantly, the SERS sensor was able to accurately identify each PAH in complex mixtures. This SERS technique shows great promise for the rapid and direct detection of aromatic hydrocarbons organic pollutants in field.
关键词： SERS,gold colloid,rapid detection,chloride ion,PAH
更新于2025-09-12 10:27:22
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3D nanoporous plasmonic chips for extremely sensitive NO <sub/>2</sub> detection
摘要： The detection of toxic gas molecules using the surface-enhanced Raman spectroscopy (SERS) technique is very challenging due to the low affinity of gas molecules. Here, we report extremely sensitive SERS-based NO2 gas sensors based on 3D nanoporous Au nanostructures with a high affinity for NO2 gas molecules and high density of hotspots.
关键词： SERS,toxic gas molecules,3D nanoporous plasmonic chips,surface-enhanced Raman spectroscopy,NO2 detection
更新于2025-09-12 10:27:22
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An octahedral Cu <sub/>2</sub> O@AgNCs substrate in liquid-microextraction coupled chemometric algorithms for SERS sensing of chromium( <scp>iii</scp> & <scp>vi</scp> ) species
摘要： The current study assembles liquid-microextraction, surface enhanced Raman spectroscopy (SERS) and chemometric algorithms in one platform for chromium speciation using octahedral Cu2O@Ag nanocomposites (Cu2O@AgNCs) as a SERS substrate. The reaction between cationic dye rhodamine 6G (RG+) and the chlorochromate anion (CrO3Cl?) at pH < 1.0 has been exploited for chromium determination by the phenomenon of ion association. The conditions of microextraction were carefully recorded for suspension. The SERS intensity was followed by depositing the sediment organic phase on the ethanolic octahedral Cu2O@AgNCs, the complex ion associate (RG+$CrO3Cl?) versus a reagent blank. Chemometric algorithms such as partial least squares (PLS) and variable selection competitive adaptive reweighted sampling (CARS)-PLS were applied for masking redundancy in the SERS spectra of the complex ion associate (RG+$CrO3Cl?) formed in the sediment phase extract. Substrate characterization using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDS), stoichiometry, analytical applications, selectivity and standard method validation was performed. The designed octahedral Cu2O@AgNCs/RG+/HCl probe displayed a detection limit of 0.028 mg L?1 for chromium(VI) under optimized chemometric modeling and microextraction conditions.
关键词： SERS,chemometric algorithms,liquid-microextraction,chromium speciation,octahedral Cu2O@Ag nanocomposites
更新于2025-09-12 10:27:22
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Combined SERS/DFT studies of push–pull chromophore self-assembled monolayers: insights into their surface orientation
摘要： Having clear and deep information on the surface/interface of deposited molecules is of crucial importance for the development of efficient optoelectronic devices. This paper reports on a joint experimental/theoretical hybrid approach based on Raman spectroscopy in order to provide information on the orientation of push–pull chromophores deposited onto a gold surface. In addition, several parameters can strongly control or impede the orientation of such molecules on the surface such as: the molecular structure, the surface itself, the method of deposition and the solvents used. From this approach, additional information has been highlighted such as perpendicularly depositing the molecule on the surface, the bithiophene compounds displaying more solvent effects compared to terthiophene molecules and so on. According to the results, the joint SERS/DFT study proves to be an effective tool for probing the arrangement of push–pull chromophores and selecting the right experimental conditions to tune the surface properties.
关键词： SERS,DFT,push–pull chromophores,surface orientation,self-assembled monolayers
更新于2025-09-12 10:27:22
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Direct and Label-Free Detection of MicroRNA Cancer Biomarkers Using SERS-Based Plasmonic Coupling Interference (PCI) Nanoprobes
摘要： MicroRNAs (miRNAs), small non-coding endogenous RNA molecules, are emerging as promising biomarkers for early detection of various diseases and cancers. Practical screening tools and strategies to detect these small molecules are urgently needed in order to facilitate the translation of miRNA biomarkers into clinical practice. In this study, a label-free biosensing technique based on surface-enhanced Raman scattering (SERS), referred to as “plasmonic coupling interference (PCI)”, was applied for the multiplex detection of miRNA biomarkers. The sensing mechanism of the PCI technique relies on the formation of a nanonetwork consisting of nanoparticles with Raman labels located between adjacent nanoparticles that are interconnected by DNA duplexes. Due to the plasmonic coupling effect of adjacent nanoparticles in the nanonetwork, the Raman labels exhibit intense SERS signals. Such effect can be modulated by the addition of miRNA targets of interest that act as inhibitors to interfere with the formation of this nanonetwork, resulting in a diminished SERS signal. In this study, the PCI technique is theoretically analyzed and the multiplex capability for detection of multiple miRNA cancer biomarkers is demonstrated, establishing the great potential of PCI nanoprobes as a useful diagnostic tool for medical applications.
关键词： SERS,PCI,miRNAs,cancer biomarkers,MicroRNAs,plasmonic coupling interference,multiplex detection
更新于2025-09-12 10:27:22