A multifunctional magnetic graphene surface-enhanced Raman scattering (SERS) substrate was fabricated successfully by the layer-by-layer assembly of silver and graphene oxide (GO) nanoparticles (NPs) on the magnetic ferroferric oxide particles (Fe3O4@GO@Ag). This ternary particle possesses magnetic properties, SERS activity, and adsorption ability simultaneously. Owing to the multifunction of this Fe3O4@GO@Ag ternary complex, we put forward a new method called a surface magnetic solid-phase extraction (SMSPE) technique, for the SERS detections of pesticide residues on the fruit peels. SMSPE integrates many sample pretreatment procedures, such as surface extraction, separation sample, and detection, all-in-one. So this method shows great superiority in simplicity, rapidity, and high efficiency above other standard methods. The whole detection process can be finished within 20 min including the sample pretreatment and SERS detection. Owing to the high density of Ag NPs, the detection sensitivity is high enough that the lowest detectable concentrations are 0.48 and 40 ng/cm(2) for thiram and thiabendazole, which are much lower than the maximal residue limits in fruit prescribed by the U.S. Environmental Protection Agency. This multifunctional ternary particle and its corresponding analytical method have been proven to be applicable for practical samples and also valuable for other surface analysis.

Tb 3+ -and Eu 3+ -doped lanthanum oxysulfide nanocrystals (NCs) with homogeneous grain size have been prepared by a gel-network coprecipitation method using gelatin as the template and ammonium sulfate as the sulfurizing agent and a following reduction process at relatively low temperatures (750 °C) in a H 2 atmosphere. The products were characterized using thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffractometry (XRD), and transmission electron microscopy (TEM). The gelatin template can act as a "nanoreactor", which is beneficial to the dispersion and size control of the coprecipitation product. The high decomposition temperature (about 482 °C) of the gelatin network is advantageous to prevent aggregation of the newly formed (LaO) 2 SO 4 NCs during calcination of the coprecipitation product. Single hexagonal phase La 2 O 2 S NCs were obtained by reduction of the (LaO) 2 SO 4 powder, and the NCs are equiaxial in shape with particle sizes ranging from 40 to 50 nm. The photoluminescence spectra and time-resolved spectra of the La 2 O 2 S:Tb(Eu) in phosphate buffer were investigated. The results show that the La 2 O 2 S:Tb NCs have a strong luminescence at 544 nm, whose intensity decreases along with decreasing particle size. Concentration quenching occurs when the Tb concentration reaches 8 mol %. The fluorescence color of the La 2 O 2 S:Eu NCs depends on the concentration of Eu 3+ ions. The red emission (at 625 nm) from 5 D 0 transition has a much longer decay time than the green emission from 5 D 1 transition of the La 2 O 2 S:Eu NCs. The Tb 3+ -and the Eu 3+ -doped La 2 O 2 S NCs have respective fluorescence lifetimes of 1.10 and 0.41 ms in phosphate buffer, allowing their potential applications in biological labeling.

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Molecularly imprinted polymers (MIPs) have the ability of predesigned specific recognition that can be selected to construct reliable functional materials. Combining the MIPs with magnetic nanoparticles results in magnetic MIPs (MMIPs) which possess both facile manipulation and high selectivity. In this report, MMIP microspheres are fabricated by coating a layer of MIPs on Fe3O4@Ag for SERS-based sensing of molecular species. The obtained Fe3O4@Ag@MIPs are further applied for simple, rapid, ultrasensitive, and label-free SERS detection of sibutramine (SIB, illegal additive), with a low LOD of 1.0 × 10–9 M. Moreover, the MMIP microspheres exhibit ultrahigh adsorption efficiency, selectivity, reusability, and good structural stability, which demonstrates the potential application for SERS. Particularly, the proposed approach of MMIPs-SERS can be successfully applied to quick screening of SIB in slimming supplements such as capsules, tea powder, and tablets, and the content for those is 6.18, 13.61, and 3.09 mg g–1, respectively. These properties make MMIP microspheres a promising SERS substrate to detect illegal additives in health-related products and chemical pollutants in the environment.