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Photonic Crystal Enhanced SERS Detection of Analytes Separated by Ultrathin Layer Chromatography Using a Diatom Frustule Monolayer
摘要： Diatoms are single-celled algae that biologically fabricate nanostructured silica shells with ordered pore arrays called frustules that resemble a 2D photonic crystal. A monolayer of Pinnularia frustules isolated from cell culture is deposited on a glass substrate and then conformally coated with silver nanoparticles (AgNPs) to serve as a nanostructured thin film for ultrathin layer chromatography (UTLC). Malachite green and Nile red are resolved in toluene mobile phase and the separated analytes are profiled micro-Raman spectroscopy, where plasmonic AgNPs provide surface-enhanced Raman scattering (SERS). The AgNP-diatom frustule monolayer improves SERS detection of malachite green by an average factor of 1.8 ± 0.1 over the plasmonic AgNP layer on glass. Analysis of hot spots on the AgNP-diatom frustule monolayer reveals that nearly 20% of the SERS active area intensifies the SERS signal at least tenfold over the SERS signal for AgNP on glass. Diatom-SERS enhancement is attributed to guided-mode resonances of the Raman laser source, which in turn further enhances the localized surface plasmonic resonance from AgNPs. Overall, the AgNP-diatom frustule monolayer thin film is a new functional material that uniquely enables separation of analytes by UTLC, quantitative SERS detection of separated analytes, and photonic enhancement of the SERS signals.
关键词： ultrathin layer chromatography,Raman,diatoms,surface-enhanced Raman scattering (SERS),photonic crystals
更新于2025-09-23 15:21:01
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Self-assembled monolayer film of concave star-shaped Au nanocrystals as highly efficient SERS substrates
摘要： In this work, various geometries of Au nanocrystals with sharp tips including decahedra, concave star, and spindle were synthesized through Ag underpotential deposition-dominated growth approach based on utilizing a novel type of Au nanoseed (i.e., pentatwinned Au nanospheres). These as-prepared Au nanocrystals exhibited a broad localized surface plasmon resonance (LSPR) tunability from visible to near-infrared region. Furthermore, we fabricated the monolayer film based on Au nanocrystals with different morphologies through liquid/liquid interface self-assembly technique, which displayed strong shape-dependent surface enhanced Raman scatting (SERS) performance. More significantly, concave star-shaped Au nanocrystals with ten sharp tips endowed them with 12-fold higher SERS enhancements than Au nanospheres, which was in line with the simulation results by finite difference time domain (FDTD) method. Our study provides a novel route for fabrication of Au nanocrystals with diversified structures, and the efficient SERS substrates have great prospect for the applications in ultrasensitive chemical and biological sensing.
关键词： Au nanocrystals,SERS,Self-assembly,LSPR,Underpotential deposition
更新于2025-09-23 15:21:01
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A new SERS substrate of self-assembled monolayer film of gold nanoparticles on silicon wafer for the rapid detection of polycyclic aromatic hydrocarbons
摘要： A facile and rapid method for the SERS detection of polycyclic aromatic hydrocarbons (PAHs) was reported. The Au colloids assemble to form gold nanoparticles (Au NPs) monolayer film at the air/water interface through the modification of n-dodecanethiol (DT), and then the film was directly transferred by tilt-lifting onto the silicon wafer to fabricate uniformed SERS substrate. PAHs could be preconcentrated into DT layer on the surface of the SERS substrate through the hydrophobic interaction, and detected by SERS. The linear range of detection for Benzo[a]-pyrene (B[a]P) is from 10-8 to 10-5 mol/L with a linearity (R2) of 0.92 to 0.99. The recovery rates range from 89.5% to 103.7%. The detection limit can reach the ng/L level. Pyrene (Pyr) and Chrysene (Chr) were also detected by SERS. The substrate had good stability, uniformity, reproducibility and reusability, which demonstrated that the DT-functionalized Au NPs film prepared by the self-assembly method at the air/water interface could be used as a reliable SERS candidate for the rapid analysis of PAHs.
关键词： self-assembled monolayer (SAM),air/water interface,SERS,polycyclic aromatic hydrocarbons (PAHs),gold nanoparticles (Au NPs)
更新于2025-09-23 15:21:01
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Graphene Boosted Silver Nanoparticles as Surface Enhanced Raman Spectroscopic Sensors and Photocatalysts for Removal of Standard and Industrial Dye Contaminants
摘要： Uncontrolled volumes of textile effluents (TE) discharged into water-bodies significantly escalate the possibility of health hazards and environmental deterioration owing to the presence of hazardous dye contaminants. In this work, the toxic components in real TE were sensed on a graphene boosted silver nanoparticles (Ag-rGO) platform through surface enhanced Raman scattering (SERS) technique. Transmission electron microscopic images of Ag-rGO showed spherical Ag nanoparticles of ~8 nm dispersed on wrinkled graphene oxide sheets. The efficiency of the substrate as a SERS sensor and photocatalytic substrate was first analyzed on commercial dyes such as rhodamine6G, Congo red and malachite green. In TE, carcinogenic azo dye contaminants were effectively identified from the presence of N=N and C-N bands present in the SERS spectra. Further, removal of these dye contaminants in TE through visible light assisted photocatalysis by Ag-rGO was also evaluated. High degradation rate constant of ~9 x 10-3/min was observed in TE after visible light assisted photocatalysis by Ag-rGO. Synergistically, the dual utility of Ag-rGO can be attributed to the enhanced electromagnetic field originating from the plasmonic nature of Ag nanoparticles and the strengthened charge transfer due to the adsorptive nature of rGO. Furthermore, the reduced particle size and suppressed fluorescence also aids the sensing and removal. These results suggest feasible development of sensitive, scalable, stable intermediate dye sensing and removal/ water recycling structures based on Ag-rGO to be incorporated at the discharge stage of textile dyeing industries.
关键词： Dye contaminants,Textile effluent,SERS,Ag/rGO,Photocatalysis
更新于2025-09-23 15:21:01
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Design and preparation of centrifugal microfluidic chip integrated with SERS detection for rapid diagnostics
摘要： A microfluidic SERS chip integrated with blood separation and in-situ detection was designed and fabricated for the rapid detection of clinical blood samples. Each functional unit in the microfluidic SERS chip consist of separation-decantation cavity based on centrifugal separation principle, mixing channels and SERS detection chamber built with integrated nano-Au on Ag film microstructure. The serum creatinine was selected as a typical sample to demonstrate the capability of microfluidic SERS chip. It was found that the creatinine SERS characteristic peaks at 678 cm-1 can be effectively identified and the detection limit could be as low as 4.42 × 10-3 μmol mL-1 in water. The blood samples were also tested in microfluidic SERS chip. The whole separation and test process could be completed within 2 min, which is a significant improvement in the field of creatinine detection. The whole blood of six cases clinical blood samples were also tested, and the results were consistent with the enzymatic results. The developed microfluidic SERS chip has advantages including reduction of the required quantity of blood sample, reusable and easy to operate. It is expected to provide a new method for rapid diagnostics.
关键词： Surface enhanced Raman spectroscopy (SERS),blood separation,centrifugal microfluidic chip,Ag film@nano-Au substrate,rapid diagnostics
更新于2025-09-23 15:21:01
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Light trapping induced flexible wrinkled nanocone SERS substrate for highly sensitive explosive detection
摘要： We reported an ultrasensitive TNT detection method via a novel light trapping induced wrinkled nanocone flexible SERS substrate, which was fabricated by colloidal lithography and oxygen plasma etching on transparent PET film. Especially, a set of nanowrinkles with 50-60nm was found on the sidewall of nanocone after etching. By coating 30nm gold film, this flexible SERS substrate provided uniform hot spots, which demonstrated high reproducibility and sensitivity. 4-ATP molecules based Meisenheimer complex, which is a well-known charge-transfer interaction between electron-poor TNT and electron-rich amino group, was taken to detect ultra-low concentration of TNT explosive. The Raman signal of TNT was significantly enhanced by charge-transfer, light trapping effect and coupled electromagnetic field. The detection sensitivity of TNT molecules was as low as 10-13mol/L, and show a good linear response in the range from 10-8 to 10-13mol/L. Consequently, by brushing this flexible SERS substrate onto a cloth bag, trace amount of TNT residues with concentration as low as 10-10mol/L can be easily analyzed. It is believed that the proposed highly sensitive and uniform flexible substrate provides a significant solution for trace analysis of TNT residue in criminal forensic, military and security check.
关键词： Nanowrinkle,Nanocone,Flexible materials,Light trapping,SERS
更新于2025-09-23 15:21:01
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ON THE COOPERATIVITY EFFECT IN WATSON&CRICK AND WOBBLE PAIRS FOR A HALOURACIL SERIES AND ITS POTENTIAL QUANTITATIVE APPLICATION STUDIED THROUGH SERS
摘要： The nature of the cooperativity effect of hydrogen bonds in Watson & Crick and wobble base pairs formed with thymine, uracil and its 5-halogenated derivatives (5-fluoro, -chloro and -bromouracil) have been studied through SERS, and using chemometric tools to process data and extract relevant information. Remarkable differences between the two kinds of pairs were clearly observed and the behavior correlated to the withdrawing character of different substituents at the 5- position of uracil was verified. Multivariate analyses have also unveiled information about pair’s stability and a stronger cooperativity effect seems to rule the Watson & Crick pairs when compared to wobble pairs. Defined patterns in the behavior of Watson & Crick pairs allowed the design of an indirect methodology for quantifying 5-bromouracil using a PLS method with variable selection. LOD values of 0.037 and 0.112 mmol L-1 in absence and presence of structurally similar interferences were reached, while its direct SERS quantification is only possible at around 45 mmol L-1.
关键词： SERS,5-halogenated derivatives,Watson & Crick pairs,wobble pairs,multivariate analyses,quantitative application,chemometric tools,cooperativity effect,hydrogen bonds
更新于2025-09-23 15:21:01
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Rapid Tartrazine Determination in Large Yellow Croaker with Ag Nanowires Using Surface-Enhanced Raman Spectroscopy
摘要： In this work, surface-enhanced Raman spectroscopy (SERS) technology coupled with Ag nanowires was shown to be a promising tool in the detection of tartrazine in large yellow croaker for the first time. Ag nanowires with a uniform diameter were fabricated by an efficient and manageable polyol method. The partial least square model was established for the quantitative analysis of tartrazine, which showed a relatively high linear correlation between actual and predicted concentrations of standard tartrazine solutions. An optimal sample preparation method was also selected and used to extract tartrazine from large yellow croaker within 20 min. The lowest concentration detected was 20.38 ng/cm2, which fully meets the requirements of tartrazine testing in aquatic products. This study indicated that SERS technology combined with the as-prepared Ag nanowires could detect tartrazine sensitively and provide an easily operable and time-saving way to monitor tartrazine in large yellow croaker.
关键词： SERS,tartrazine,large yellow croaker,Ag nanowires
更新于2025-09-23 15:21:01
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In situ imaging of live-cell extracellular pH during cell apoptosis with SERS
摘要： Extracellular pH (pHe) is an important regulating factor that determines many cellular processes, including proliferation, differentiation, and apoptosis. In our previous work, we developed 4-MPy (4-mercaptopyridine) modified Au nanoparticles as intracellular pH sensors based on surface-enhanced Raman spectroscopy (SERS). We herein modified Au nanoparticles-assembled solid SERS substrate with 4-MPy molecules for in situ pHe sensing during apoptosis. We found a more acidic extracellular environment of cancer cells than that of normal cells from the pH imaging. We then in situ investigated the temporal and spatial evolution of pHe of cancer cells after addition of transforming growth factor-β (TGF-β). The pHe showed a fast decrease at the beginning, followed by a slow decrease until the complete loss of cellular functions and the pH values in and out of the cells became similar. This work shows that our SERS substrate combined with in situ cell culture system is well suitable for in situ pHe sensing during cell processes and will be a promising technique for understanding more pHe-related biological and pathological issues.
关键词： apoptosis,live-cell imaging,TGF-β,extracellular pH,SERS
更新于2025-09-23 15:21:01
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Blue laser-induced photochemical synthesis of CuAg nanoalloys on h-BN supports with enhanced SERS activity for trace-detection of residual pesticides on tomatoes
摘要： The copper (Cu)-based nanoalloys loaded on graphene-like nanoplates have a great promise for boosting surface-enhanced Raman scattering spectroscopy (SERS), due to low-cost Cu species in comparison with noble metals and unique additional Raman enhancement originated from two-dimensional (2D) supports. Herein, we report an ingenious strategy to load highly dense and monodisperse CuAg nanoalloys (NAs) on hexagonal boron nitride (h-BN) by blue laser (405 nm) -induced photochemical reaction. Without the aid of any complex auxiliary reagents, the co-reduction of Cu and Ag ions is driven by photon-excited electron on semiconductor h-BN, resulting in the coalescence and overgrowth of “clean” CuAg NAs. As expected, the proposed h-BN/CuAg NAs provide ultrahigh SERS activity with the limit of detections (LODs) of crystal violet (CV) at femtomole level (~10?16 M), thiram and tricyclazole at pico-molar (10?12 M) and nanomolar levels (10?9 M), respectively. Most importantly, the as-prepared h-BN/CuAg NAs were also directly combined with polyethylene terephthalate (PET) by simple dripping and drying processes to form uniform flexible substrates. The low-cost Cu-based flexible substrates can be used to realize the ultrasensitive SERS detection of residual tricyclazole on tomato surfaces, thus facilitating the widespread precise assessment of pesticide residues in various practical applications.
关键词： CuAg nanoalloys,Pesticide detection,SERS analyses,Flexible SERS substrate,Photochemical reaction
更新于2025-09-23 15:19:57