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Highly Sensitive and Selective Nanogap-Enhanced SERS Sensing Platform
摘要： This paper reports a highly sensitive and selective surface-enhanced Raman spectroscopy (SERS) sensing platform. We used a simple fabrication method to generate plasmonic hotspots through a direct maskless plasma etching of a polymer surface and the surface tension-driven assembly of high aspect ratio Ag/polymer nanopillars. These collapsed plasmonic nanopillars produced an enhanced near-field interaction via coupled localized surface plasmon resonance. The high density of the small nanogaps yielded a high plasmonic detection performance, with an average SERS enhancement factor of 1.5 × 107. More importantly, we demonstrated that the encapsulation of plasmonic nanostructures within nanofiltration membranes allowed the selective filtration of small molecules based on the degree of membrane swelling in organic solvents and molecular size. Nanofiltration membrane-encapsulated SERS substrates do not require pretreatments. Therefore, they provide a simple and fast detection of toxic molecules using portable Raman spectroscopy.
关键词： hotspots,sensors,molecular filtration,surface-enhanced Raman spectroscopy,localized surface plasmon resonance
更新于2025-11-14 15:30:11
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Near-infrared (NIR) surface-enhanced Raman spectroscopy (SERS) study of novel functional phenothiazines for potential use in dye sensitized solar cells (DSSC)
摘要： Near-infrared (NIR) surface-enhanced Raman spectroscopy (SERS) is used to investigate the interaction between six novel phenothiazine-merocyanine dyes containing the three different functional groups rhodanine, 1,3-indanedione and cyanoacylic acid with plasmonic nanomaterials, to decide if the incorporation of plasmonic nanoparticles could enhance the efficiency of a Gr?tzel-type solar cell. The studies were carried out in the solution state using spherical and rod-shaped gold nanostructures. With KCl induced agglomerated spherical gold nanoparticles, forming SERS hot spots, the results showed low detection limits between 0.1 mmol L?1 for rhodanine containing phenothiazine dyes, because of the formation of Au–S bonds and 3 mmol L?1 for cyanoacrylic acid containing dyes, which formed H-aggregates in the watery dispersion. Results with gold nanorods showed similar trends in the SERS measurements with lower limits of detection, because of a shielding effect from the strongly-bound surfactant. Additional fluorescence studies were carried out to determine if the incorporation of nanostructures leads to fluorescence quenching. Overall we conclude that the addition of gold nanoparticles to rhodanine and 1,3-indanedione containing phenothiazine merocyanine dyes could enhance their performance in Gr?tzel-type solar cells, because of their strong interactions with plasmonic nanoparticles.
关键词： surface-enhanced Raman spectroscopy,plasmonic nanoparticles,dye sensitized solar cells,phenothiazine-merocyanine dyes,Near-infrared
更新于2025-11-14 15:16:37
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Ultrasensitive analysis of kanamycin residue in milk by SERS-based aptasensor
摘要： An ultrasensitive method for the kanamycin (KANA) detection in milk sample using surface-enhanced Raman spectroscopy-based aptasensor was employed in the current study. Double strand DNA binding bimetallic gold@ silver nanoparticles were developed as a sensing platform. Probe DNAs were first embedded on the surface of gold nanoparticles by the end-modified thiol, and after silver shell encapsulating, KANA aptamer DNAs with the Raman reporter Cy3 were then hybridized with probe DNAs by complementary base pairing. Results showed that with increase in the KANA concentration, the Raman intensity of Cy3 decreased. Besides achieving selectivity, an ultralow detection limit of 0.90 pg/mL, a broad linear relationship ranging from 10 μg/mL to 100 ng/mL in aqueous reagent and satisfactory recoveries of 90.4–112% in liquid whole milk were obtained. The result of actual sample proved that this aptasensor was promising in trace determination of KANA residue.
关键词： Milk,Kanamycin,Aptamer,Surface enhanced Raman spectroscopy
更新于2025-09-23 15:23:52
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Probing Lithium Carbonate Formation in Trace-O <sub/>2</sub> -Assisted Aprotic Li-CO <sub/>2</sub> Batteries Using in Situ Surface-Enhanced Raman Spectroscopy
摘要： A trace O2-assisted aprotic Li-CO2 battery represents a promising approach for CO2 recycling. However, cathode passivation and large overpotential are frequently observed for current Li-CO2 batteries because of the insolubility and non-conductivity of the discharge product of lithium carbonate (Li2CO3). Toward maximizing the energy capabilities of the Li-CO2 electrochemistry, it is crucially important to have a fundamental understanding of the Li2CO3 formation mechanism in Li-CO2 batteries. In this report, the discharge reaction of a trace O2-assisted Li-CO2 battery has been interrogated with in-situ surface enhanced Raman spectroscopy (SERS). It was found that in high donor number (DN) solvents Li2CO3 formation proceeds primarily via an 'electrochemical solution route' with peroxodicarbonate (C2O6^2-) as the key intermediate; while in low DN solvents Li2CO3 forms via a chemical reaction of Li2O2 and CO2 on the cathode surface, namely a 'chemical surface route'. It is notable that during discharge the trace O2 acts as a 'pseudo-catalyst' to activate CO2 in high DN solvents, but not in low-DN solvents. The mechanistic study presented here will assist to tailor-design better electrolyte systems and enable more energetic electrochemistry operating far away from the poison of Li2CO3.
关键词： surface enhanced Raman spectroscopy,lithium carbonate,O2-assisted aprotic Li-CO2 battery
更新于2025-09-23 15:23:52
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Detection of metal-molecule-metal junction formation by surface enhanced Raman spectroscopy
摘要： Vibrational modes play a key role in characterizing metal-molecule-metal junctions, but their detection currently either requires single-molecule sensitivity or the generation of defect-free large-scale junctions. Here we demonstrate that surface-enhanced Raman scattering (SERS) on non-ideal surfaces can provide a significant amount of information despite many defects in the layer. We determine the vibrational signature of the molecular electronic junction for palladium ions complexed and reduced on 4-mercaptopyridine adsorbed on rough gold and gold nanoparticles using SERS and density functional theory (DFT). We show that these non-ideal surfaces can be used to probe kinetics of metal ion complexation and establish the success of electrochemical metallization. SERS on non-ideal surfaces is thus revealed as a useful tool to rapidly establish the key process parameters in making molecular electronic junctions before embarking on more detailed studies on single molecules or single crystal surfaces.
关键词： gold,4-mercaptopyridine,Metal-molecule-metal junctions,surface-enhanced Raman spectroscopy
更新于2025-09-23 15:22:29
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A Label-free Platform for Identification of Exosomes from Different Sources
摘要： Exosomes contain cell- and cell-state-specific cargos of proteins, lipids, and nucleic acids and play significant roles in cell signaling and cell–cell communication. Current research into exosome-based biomarkers has relied largely on analyzing candidate biomarkers, i.e., specific proteins or nucleic acids. However, this approach may miss important biomarkers that are yet to be identified. Alternative approaches are to analyze the entire exosome system, either by “omics” methods or by techniques that provide “fingerprints” of the system without identifying each individual biomolecule component. Here, we describe a platform of the latter type, which is based on surface-enhanced Raman spectroscopy (SERS) in combination with multivariate analysis, and demonstrate the utility of this platform for analyzing exosomes derived from different biological sources. First, we examined whether this analysis could use exosomes isolated from fetal bovine serum using a simple, commercially available isolation kit or necessitates the higher purity achieved by the “gold standard” ultracentrifugation/filtration procedure. Our data demonstrate that the latter method is required for this type of analysis. Having established this requirement, we rigorously analyzed the Raman spectral signature of individual exosomes using a unique, hybrid SERS substrate made of a graphene-covered Au surface containing quasi-periodic array of pyramids. To examine the source of the Raman signal, we used Raman mapping of low and high spatial resolution combined with morphological identification of exosomes by scanning electron microscopy. Both approaches suggested that the spectra were collected from single exosomes. Finally, we demonstrate for the first time that our platform can distinguish among exosomes from different biological sources based on their Raman signature, a promising approach for developing exosome-based fingerprinting. Our study serves as a solid technological foundation for future exploration of the roles of exosomes in various biological processes and their use as biomarkers for disease diagnosis and treatment monitoring.
关键词： surface-enhanced Raman spectroscopy,graphene,biomarker,exosome,principal component analysis
更新于2025-09-23 15:22:29
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Probing Electrolyte Solvents at Solid/Liquid Interface Using Gap-Mode Surface-Enhanced Raman Spectroscopy
摘要： Understanding the aprotic solution structures at the immediate vicinity of solid/liquid interface (SLI) is critically important for next generation lithium ion battery development. Yet, it is still challenging to investigate the carbonate chemical profiles close to the diffuse layer (about 10 nm) of the electrical double layer at SLI due to the lack of a ultrahigh surface sensitive tool. In this work, we demonstrate the structures of commonly used carbonate solvents (ethylene carbonate (EC) and diethyl carbonate (DEC)) and a carbonate additive (fluoroethylene carbonate (FEC)) in a commercial Li-ion battery electrolyte can be determined at ～17 nm above the electrode surface. This is only enabled by a nanogap surface-enhanced Raman spectroscopy (SERS) technique based on a monolayer gold nanoparticle (Au NP) ensemble. The SERS enhancement factor (EF) of those carbonates was found to depend on the molecular polarizability, with the maximum EF at ～105 found for EC and FEC. Despite their alike chemical structures, this monolayer Au NP SERS substrate is fully capable of discrimiating the different Raman finger prints of EC and FEC. Compared to EC, several vibration modes in FEC, such as C-C skeletal deformation, ring breathing band and C=O stretching band, shift to higher frequencies because of the displacement of a hydrogen atom by a much heavier fluorine atom in a methylene bridge. This counterintuitive observation against the commonly used “ball and spring” model in vibrational spectroscopy is mostly due to the increased bond strength in the FEC ring versus that of EC. A second order empirical polynomial best describes the correlation between the SERS band integration of EC or DEC molar concentration. Our findings open up new opportunities for in-depth understanding of the electrolyte molecular vibrational behaviors at direct solid/liquid interface and developing advanced electrolytes for next generation lithium-ion batteries.
关键词： carbonate solvents,electrolyte,solid/liquid interface,lithium-ion battery,surface-enhanced Raman spectroscopy
更新于2025-09-23 15:22:29
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Controlling surface morphology and sensitivity of granular and porous silver films for surface-enhanced Raman scattering, SERS
摘要： The design of efficient substrates for surface-enhanced Raman spectroscopy (SERS) for large-scale fabrication at low cost is an important issue in further enhancing the use of SERS for routine chemical analysis. Here, we systematically investigate the effect of different radio frequency (rf) plasmas (argon, hydrogen, nitrogen, air and oxygen plasma) as well as combinations of these plasmas on the surface morphology of thin silver films. It was found that different surface structures and different degrees of surface roughness could be obtained by a systematic variation of the plasma type and condition as well as plasma power and treatment time. The differently roughened silver surfaces act as efficient SERS substrates showing greater enhancement factors compared to as prepared, sputtered, but untreated silver films when using rhodamine B as Raman probe molecule. The obtained roughened silver films were fully characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron (XPS and Auger) and ultraviolet–visible spectroscopy (UV–vis) as well as contact angle measurements. It was found that different morphologies of the roughened Ag films could be obtained under controlled conditions. These silver films show a broad range of tunable SERS enhancement factors ranging from 1.93 × 102 to 2.35 × 105 using rhodamine B as probe molecule. The main factors that control the enhancement are the plasma gas used and the plasma conditions, i.e., pressure, power and treatment time. Altogether this work shows for the first time the effectiveness of a plasma treatment for surface roughening of silver thin films and its profound influence on the interface-controlled SERS enhancement effect. The method can be used for low-cost, large-scale production of SERS substrates.
关键词： plasma treatment,sputtering,surface-enhanced Raman spectroscopy (SERS),silver,surface roughening
更新于2025-09-23 15:21:21
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Raman Spectroscopic Analysis of Signaling Molecules–Dopamine Receptors Interactions in Living Cells
摘要： The selective interaction of signaling compounds including neurotransmitters and drugs with the dopamine receptors (DARs) is extremely important for the treatment of neurodegenerative diseases. Here, we report a method to probe the selective interactions of signaling compounds with D1 and D2 DARs in living cells using the combined approach of theoretical calculation and surface-enhanced Raman spectroscopy (SERS). When signaling compounds such as DA, amphetamine, methamphetamine, and methylenedioxypyrovalerone interact with D1 dopamine receptors (DRD1), the intracellular cyclic adenosine monophosphate (cAMP) level is increased. However, the intracellular level of cAMP is decreased when D2 dopamine receptors (DRD2) interact with the abovementioned signaling compounds. In our experiments, we have internalized the silica-coated silver nanoparticles (AgNP@SiO2) in living cells to adsorb biologically generated cAMP which was probed by using SERS. Besides adsorptions of cAMP, AgNP@SiO2 has a crucial role for the enhancement of Raman cross section of the samples. We observed the characteristic SERS peaks of cAMP when DRD1-overexpressed cells interact with the signaling compounds; these peaks were not observed for other cells including DRD2-overexpressed and DRD1?DRD2-coexpressed cells. Our experimental approach is successful to probe the intracellular cAMP and characterize the selectivity of signaling compounds to different types of DARs. Furthermore, our experimental approach is highly capable for in vivo studies because it can probe intracellular cAMP using a low input power of incident laser without significant cell damage. Our experimental results and density functional theory calculations showed that 780 and 1503 cm?1 are signature Raman peaks of cAMP. The SERS peak at 780 cm?1 is associated with C?O, C?C, and C?N stretching and symmetric and asymmetric bending of two O?H bonds of cAMP, whereas the SERS peak at 1503 cm?1 is contributed by the O9?H3 bending mode.
关键词： cyclic adenosine monophosphate,living cells,signaling compounds,dopamine receptors,surface-enhanced Raman spectroscopy
更新于2025-09-23 15:21:21
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Raman spectroscopy coupled with ambient ionization mass spectrometry: A forensic laboratory investigation into rapid and simple dual instrumental analysis techniques
摘要： We present a laboratory experiment, developed around a pair of instrumental analysis techniques, Raman spectroscopy and ambient ionization mass spectrometry (MS), conducted by senior chemistry undergraduate students for bulk analysis of over-the-counter drugs using benchtop versions of the two instruments, as well as trace analysis of illicit drugs utilizing the corresponding portable instruments. The identification and confirmation of seized drugs is a routine operation in forensic laboratories that can be simplified using these two instrumental techniques in tandem. Bulk samples are readily analyzed using conventional Raman spectroscopy followed by paper cone spray ionization (PCSI) MS, while trace analysis is allowed by a simple single-substrate dual-analyzer method using surface enhanced Raman spectroscopy (SERS) from paper followed by paper spray ionization (PSI) MS. The introduction of these novel strategies to the students exposed them to potential career paths in forensic science by means of a hands-on experience that provided fundamental knowledge about this set of analytical methods, including intercomparisons of their performance, as well as practical issues like costs, regulations and databases. The use of portable instrumentation represents an additional learning experience for the students, considering that it is cutting-edge technology that is just now being transferred from academic to industrial labs and that it allows a valuable discussion of the advantages and disadvantages of bringing the laboratory to the field.
关键词： Mass spectrometry,Hands-on learning,Forensic analysis,Drugs of abuse,Paper cone spray ionization,Paper spray ionization,Paper surface enhanced Raman spectroscopy,Raman spectroscopy,Ambient ionization,Laboratory instruction
更新于2025-09-23 15:21:01