Silver nanoparticle aggregates were synthesized on copper foil, which was used for the surface-enhanced Raman spectroscopy (SERS) detection of polycyclic aromatic hydrocarbons (PAHs) with a portable Raman spectrometer. Silver nanoparticle aggregates were prepared by immersing copper foil in the solution of Sn(2+) and AgNO(3) in a cyclic fashion. A four-cycle process was selected for the following experiments due to its high enhancement and relatively convenient experimental procedure. The substrate has greater temporal stability under continuous laser radiation, good uniformity and reproducibility, which indicated that the substrate could provide reliable measurements. The relationship between SERS intensity and concentrations of PAHs was studied. Quantitative analysis of PAHs in aqueous solution was further performed based on the prepared substrate. The log-log plot of normalized SERS intensity to PAHs concentration exhibited a good linear relationship, with the detection limits in the range of 5-500 μg L(-1). Thus, due to the stability, reproducibility and quantitative results, the prepared substrate could be used as a potential SERS sensor for the analysis of environmental pollutants.

Silver nanoplates were prepared by modified galvanic displacement on commercial copper foil. SEM, TEM, UV-vis and XPS were employed to analyze those closely packed silver nanoplates. This type of surface-enhanced Raman spectroscopy substrates showed strong surface plasmon absorption and reliable surface-enhanced Raman activity.

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Nanoplastics are emerging pollutants that pose potential threats to the environment and organisms. However, in-depth research on nanoplastics has been hindered by the absence of feasible and reliable analytical methods, particularly for trace nanoplastics. Herein, we propose a hyphenated method involving membrane filtration and surface-enhanced Raman spectroscopy (SERS) to analyze trace nanoplastics in water. In this method, a bifunctional Ag nanowire membrane was employed to enrich nanoplastics and enhance their Raman spectra in situ, which omitted sample transfer and avoided losing smaller nanoplastics. Good retention rates (86.7% for 50 nm and approximately 95.0% for 100–1000 nm) and high sensitivity (down to 10–7 g/L for 50–1000 nm and up to 105 SERS enhancement factor) of standard polystyrene (PS) nanoplastics were achieved using the proposed method. PS nanoplastics with concentrations from 10–1 to 10–7 g/L and sizes ranging from 50 to 1000 nm were successfully detected by Raman mapping. Moreover, PS micro- and nanoplastics in environmental water samples collected from the seafood market were also detected at the μg/L level. Consequently, the proposed method provides more possibilities for analyzing low-concentration nanoplastics in aquatic environments with high enrichment efficiency, minimal sample loss, and high sensitivity.

Water-solublel-arginine-capped Fe3O4 nanoparticles were synthesized using a one-pot and green method. Nontoxic, renewable and inexpensive reagents including FeCl3,l-arginine, glycerol and water were chosen as raw materials. Fe3O4 nanoparticles show different dispersive states in acidic and alkaline solutions for the two distinct forms of surface bindingl-arginine. Powder X-ray diffraction and X-ray photoelectron spectroscopy were used to identify the structure of Fe3O4 nanocrystals. The products behave like superparamagnetism at room temperature with saturation magnetization of 49.9 emu g−1 and negligible remanence or coercivity. In the presence of 1-ethyl-3-(dimethylaminopropyl) carbodiimide hydrochloride, the anti-chloramphenicol monoclonal antibodies were connected to thel-arginine-capped magnetite nanoparticles. The as-prepared conjugates could be used in immunomagnetic assay.(See supplementary material 1)