Calcium carbonate microparticles with embedded silver and magnetite nanoparticles as new SERS-active sorbent for solid phase extraction

• Published in: Mikrochimica acta (1966) 2017-10, Vol.184 (10), p.3937-3944
• Main Authors: Markina, Natalia E., Markin, Alexey V., Zakharevich, Andrey M., Goryacheva, Irina Yu
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Antibiotics; Calcium carbonate; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Dyes; Extraction; Fluorescence; Iron oxides; Magnetic separation; Magnetite; Microengineering; Microparticles; Nanochemistry; Nanoparticles; Nanotechnology; Original Paper; Polyelectrolytes; Polyethyleneimine; Raman spectroscopy; Rhodamine 6G; Silver; Sorption
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-017-2426-6

The authors describe a dual-use sorbent for solid phase extraction (SPE) in combination with surface-enhanced Raman spectroscopy (SERS). The sorbent consists of calcium carbonate microparticles with incorporated silver nanoparticles (AgNPs) and magnetic nanoparticles (Fe 3 O 4 ). It can be simply prepared, is cost-effective, disposable, and possesses high sorption capabilities together with a Raman enhancement of 10 9 in the best case. Following magnetic separation of the microsphere from the liquid sample, the sorbent matrix (CaCO 3 ) is dissolved in acid so that the AgNPs and the analyte are released. This provides an optimal interaction between them and warrants a strong SERS signal. A new SPE-SERS protocol was worked out and applied to the following model analytes: Rhodamine 6G (a fluorescent dye; R6G), Photosens (a photodynamic dye), and sulfadimethoxine (an antibiotic). The first two possess a high Raman cross-section, while the last one displays comparatively low intrinsic Raman intensity. It is found that coating the surface of the sorbent with polyethyleneimine (a cationic polyelectrolyte) leads to a 2-fold increase in the sorption of Photosens (from 40% to 90%) and to a 6-fold enhancement of the SERS signal. The limits of detection for R6G, Photosens, and sulfadimethoxine (with 78%, 94%, and 41% sorption values, respectively) are 29 pM, 12 nM, and 69 nM, respectively. Raman enhancements are in the range between 10 6 and 10 9 depending on the analyte. Graphical abstract Calcium carbonate microparticles with embedded silver and magnetite nanoparticles are introduced as new SERS-active sorbent for solid phase extraction. Magnetic-based pre-concentration and subsequent release of both silver nanoparticles and analyte result in a significantly enhanced sensitivity.