Construction of optimized Au@Ag core-shell nanorods for ultralow SERS detection of antibiotic levofloxacin molecules

Abstract

The abuse of antibiotics in animal husbandry has been regarded as a daunting public health risk, facilitating the emergence and spread of resistant pathogens to humans. Herein, bimetallic Au@Ag core-shell nanorods (NRs) with precise, controllable Ag shell-thickness (2.1~14.1 nm) were fabricated and developed for ultralow detection of levofloxacin molecules using surface enhanced Raman scattering spectroscopy (SERS). We found that the Au@Ag NRs with 7.3 nm Ag shell-thickness provided maximized SERS activity in comparison with other as-prepared nanosubstrates in this paper. The detection limit of levofloxacin molecules was achieved at a nanomole (nM) level of 0.37 ng/L (10 M), providing ultrasensitive assessment of antibiotics in natural ecosystems.

Preparation of a high‐performance thermally shrinkable polystyrene SERS substrate via Au@Ag nanorods self‐assembled to detect pesticide residues

“…The aspect ratio of the Au@Ag nanorods decreases with increasing thickness of the silver nanoshell, showing obvious blue shift. This is because the overall aspect ratio of silver‐coated gold nanorods decreases with the selective deposition of silver on the {200} orientation, and a contribution of optical behavior of Ag different from Au . Its longitudinal plasma absorption peak gradually moved from 813 to 650 nm, and the 796‐ and 776‐nm absorption peaks corresponding to 71.4 × 18.3 nm and 71.3 × 19.5 nm of nanorods closely matched the SERS excitation light source (785 nm) for better resonance absorption and enhanced Raman signal.…”

An atomistic description of alloys and core shells nanoparticles

“…where P is any property. 41 We are here particularly interested in examining if Vegard's law also holds true for the progression of the position of the SPR with mixing of the constituents as indicated in other studies 35,[42][43][44][45][46][47][48][48][49][50][51] for alloys and to some extent core shells or if this is geometry dependent as experiments on nano discs predict. 52 Since the polarizability or extinction cross section differs for Au and Ag it would also be of interest to see if the strength of the response to an external field also follow Vegard's law since the strength of the response determines strength of the local electric field from the SPR.…”

An accuracy improved ratiometric SERS sensor for rhodamine 6G in chili powder using a metal–organic framework support

“…Secondly, 10 mL 4-MBA ethanol solution (0.1 mM) was added into 1 mL of Au NRs and incubated overnight to prepare Au-MBA NRs, aer centrifuged at 12 000 rpm for 10 min, the products were dispersed into 3 mL CTAC (0.02 M), the internal standard molecule 4-MBA was loaded on the surface of Au NRs by strong Au-S bond. 26,27 Finally, the internal standard SERS nanoprobes were prepared by shell growth method, 28 6 mL AgNO 3 (0.1 M) and 24 mL AA (0.1 M) were added in Au-MBA NRs solution and stirred for 1 min. Then the mixture was placed in a water bath maintained at 65 °C for 2.5 h, centrifuged and dispersed in 1 mL water.…”