Abstract：Surface-enhanced Raman spectroscopy (SERS) has been developed as a powerful tool in surface science due to its ultrahigh surface sensitivity up to the single molecular detection. The enhancement mechanisms include electromagnetic enhancement mechanism (EM) andchemical enhancement mechanism (CM). In general, the dominant contributor to most SERS processes is the EM, and the local electromagnetic field in the EM greatly enhance the surface Raman signal intensity of the adsorbed molecules. In addition, the medium has traditionally played a vital role in SERS measurements, as the medium also exhibits a certain influence on the local electromagnetic field as well as the EM enhancements. Shell-isolated nanoparticles (SHINs) can avoid direct contact between the medium and SERS enhancement source through the inert shell on the surface of the particles. However, up to now, few studies have been conducted on the effect of dielectrics on the shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS), which is often due to the poor homogeneity of SERS substrates. Herein, two core-shell nanostructures embedded with probe molecules were fabricated successfully, i. e. (55 nm Au-PNTP)@SiO2 and (110 nm Au-pMBA)@SiO2 with the shell thickness of about 3.5 and 4.0 nm, respectively. The continuous shell layer covered the Au core nanoparticles compactly without pinhole effect. The core-shell nanoparticles monolayer layer was assembled at the liquid-liquid interface, and it was transferred to flat solid surface as SERS substrate. The monolayer film of (55 nm Au-PNTP)@SiO2 exhibited the uniform SERS effect with the relative standard deviation (RSD) of about 5.38%, while RSD of 5.97% for (110 nm Au-pMBA)@SiO2. Therefore, the reasonable performance of the monolayer film allowed serving as qualified SERS substrate. The medium effect was explored on the monolayer film in the water and air system. It demonstrated that the pinhole free continuous shell and the probe embedded into the shell brought isolation of the EM source and the probes with the medium condition. Although the outside medium (condition) was changed from air to water, the real medium of the probes and the Au core was still surrounded by the SiO2 shell. Consequently, the SERS signal intensity was independent of the outside medium. The probe molecules of PNTP and pMBA was embedded into the SiO2 shell, and the SPR catalysis reaction was absent due to the isolation of oxygen and solvent. Thus the spectral feature of probes was quite stable. It indicated that no influence on the SERS effect was observed by different medium for the probes embedded nanostructures. It was expected to develop the probes embedded nanostructures as SERS substrate for the sensitive detection in a different medium, and as an internal standard for calibration of SERS effect.
刘 恪，张晨杰，徐敏敏，姚建林. (Au-Probe)@SiO2单层纳米粒子膜制备及表面增强拉曼光谱研究[J]. 光谱学与光谱分析, 2020, 40(09): 2764-2769.
LIU Ke, ZHANG Chen-jie, XU Min-min, YAO Jian-lin. Fabrication on Monolayer Film of (Au-Probe)@SiO2 Nanoparticles and Its Surface Enhanced Raman Spectroscopic Investigation. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2020, 40(09): 2764-2769.
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