氧化石墨烯/金银纳米粒子复合材料的制备及其SERS效应研究

近年来,氧化石墨烯/金银纳米粒子复合材料由于其优异的表面增强拉曼散射（SERS）性能引起了人们极大的关注,在污染物检测、化学传感和癌症诊断等领域具有重要的应用价值。本文综述了氧化石墨烯片层上修饰金银纳米粒子、氧化石墨烯包覆金银纳米粒子、氧化石墨烯附着在金银纳米粒子层三种氧化石墨烯/金银纳米粒子复合材料的制备方法,对其SERS效应进行了详细介绍。SERS研究表明,结合了金银纳米粒子与氧化石墨烯两种材料各自在SERS研究与应用中的优势,氧化石墨烯/金银纳米粒子复合材料的SERS性能比单纯金银纳米粒子更加优异。氧化石墨烯在其中起到了化学增强、分子富集、钝化保护、荧光猝灭的重要作用。氧化石墨烯/金银纳米粒子复合材料在表面增强拉曼光谱中具有广阔的应用前景。     

Monitoring Phosphorylation and Dephosphorylation Reactions by Surface-Enhanced Raman Scattering (SERS) in Model Compounds

Abstract

Raman and Surface-Enhanced Raman Scattering (SERS) spectra of phosphates, polyphosphates, and various phosphate complexes have been recorded. Bands of the vibrational spectra were assigned. The comparison of SERS spectra obtained by using colloidal silver with the corresponding Raman spectrum reveals enhancement and shifts in some bands, suggesting a possible partial charge-transfer mechanism in the SERS effect. Phosphorylation and dephosphorylation reactions brought about by the reactions of cobalt (III) bis trimethylenediamine phosphate/pyrophosphate complexes with nitrophenol/nitrophenyl phosphates are described.     

Significance of chemical enhancement effects in surface-enhanced Raman scattering (SERS) signals of aniline and aminobiphenyl isomers

Surface-enhanced Raman scattering is a useful technique for detecting low levels of aromatic amines as environmental contaminants because it can be used to detect and distinguish among their isomers based on their distinctive SERS spectra. This paper demonstrates the feasibility of measuring the concentrations of aminobiphenyls (ABPs) including 4-ABP, 3-ABP, and 2-ABP down to the levels of about 5, 50, and 250 μg/mL, respectively. The SERS signal intensities of ABPs are dependent on the pH values of the samples and colloidal media. The optimal sample pH values were found to be 6.86, 7.83, and 7.36, for 2-ABP, 3-ABP, and 4-ABP, respectively, whereas the optimum silver colloidal pH ranges from 5.0 to 6.5. A detailed analysis of the different vibrational modes of aniline and the ABP isomers was carried out using computational modeling based on the density functional theory (DFT). Compared to aniline, the ABPs produced greater SERS enhancement of the intensities for the biphenyl ring-breathing mode. The SERS signal for the NH₂ wagging band shows the order of enhancement as given by 4-ABP > 2-ABP > 3-ABP, which correlates well with the HOMO-LUMO energy gap based on the DFT modeling of the amines adsorbed on the silver cluster.     

An investigation of the surface enhanced Raman scattering (SERS) from a new substrate of silver-modified silver electrode by magnetron sputtering

'Pure' silver nanoparticles on silver electrode were prepared by magnetron sputtering. The silver-modified silver electrode has good stability and the silver nanoparticles on silver electrode have homogeneous size distribution. Compared with the silver colloid modified silver electrode, there were no any extraneous component ions on the electrode, for the modified silver nanoparticles are prepared by magnetron sputtering. Synchronously, we obtained much higher quality SERS spectra of adenine molecules on the silver electrode modified by magnetron sputtering (SEMMS), and the study of the adsorption behavior of adenine on the silver-modified silver electrode by surface enhanced Raman scattering (SERS) indicated that the silver-modified silver electrode was highly efficient substrates for SERS investigation. From the rich information on the SEMMS obtained from high-quality potential-dependent SERS, we may deduce the adsorption behavior of adenine and the probable SERS mechanism in the process. The probable reasons are given.     

Coating of silver nanoparticles (AgNPs) on glass fibers by a chemical method as plasmonic surface-enhanced Raman spectroscopy (SERS) sensors to detect molecular vibrations of Doxorubicin (DOX) drug in blood plasma

In the present study, Doxorubicin (DOX) drug in healthy blood plasma was the focus of the investigation by surface-enhanced Raman scattering (SERS). In recent years, chemotherapy has been the most popular treatment for various types of cancer; however, its adverse side effects on the patient's health have made a negative aspect regarding the use of this technique. DOX is the most common chemotherapy drug and is used for the treatment of an extensive range of human malignancies. The surface-enhanced Raman scattering (SERS) is a precise technique for the detection of chemicals and biomaterials with significantly low concentrations. The glass fiber substrates coated with silver nanoparticles (AgNPs) have been used to detect DOX. First, the Tollens' method was applied to prepare the AgNPs, and the characteristics of fabricated AgNPs were evaluated using ultraviolet–visible spectroscopy (UV–Vis) and X-ray diffraction (XRD). Then, AgNPs were coated on the glass fiber substrate by a chemical method. Finally, the enhancement of the Raman signal resulted from the molecular vibrations of DOX was evaluated using these SERS-active substrates as plasmonic and Raman spectroscopy sensors. Afterward, for making the sensors practical, the DOX in blood plasma were deposited on the fabricated sensors, and the Raman vibrations were evaluated. The SERS-active substrates, AgNPs deposited on glass fiber substrates, were fabricated for the detection of DOX in and out of the blood plasma; the limit of detection (LOD) for both was 10^?10 M, and the mean relative standard deviation at concentrations of 10^?10 M of DOX out of blood plasma, and 10^?10 M of DOX in blood plasma were obtained to be 3.76% and 3.61%, respectively for ten repeated measurements in which the AgNPs were SERS-active substrates of the biosensors for detecting the DOX. In addition, the enhancement factor was calculated both experimentally and via finite-difference time-domain (FDTD) simulation, which was 29.76 × 10³ and 24.95 × 10³, respectively. Therefore, these SERS-active substrates can be used to develop microsensors and show positive results for SERS-based investigations.