Versatile hybrid magnetic core silver-shell (Fe3O4@PEI@Ag) microspheres based SERS substrates for detection of organic dyes pollutant

Abstract

In recent years, the development of highly sensitive and versatile substrates for Surface-Enhanced Raman Scattering (SERS) has become pivotal in environmental monitoring. This study introduces a hybrid SERS substrate designed to enhance the detection and discrimination of organic dyes in aqueous environments. In this report, we present silver shell magnetic core (Fe3O4@PEI@Ag) microspheres as a versatile SERS substrate for the detection and differentiation of organic dyes, specifically malachite green (MG), crystal violet (CV), Rhodamine 6G (R6G), and Safranin O (S.O), which are often overlooked water pollutants. The core-shell structure of Fe3O4@PEI@Ag microspheres have been synthesized via seed-mediated growth method. The microspheres, integrates a magnetic core of iron oxide (Fe3O4) through a polymeric layer of polyethyleneimine (PEI) with silver shell (Ag), are optimized to act as magnetic separator and show SERS activity. The SEM measurements confirm the spherical shape of grown nano-particles whereas magnetization experiments confirm the presence of magnetic cores as well non-magnetic layers coating in the end products. These microspheres with aluminium (Al) base combination demonstrate high SERS sensitivity with enhancement factor of 1 × 105, 5.6 × 106, 6.4 × 106, and 4.2 × 105 for MG, CV, R6G, and S.O respectively. The detection limits have been found in the range between 10–8–10–10 for all four dyes. A linear relationship between Raman intensity and concentrations of dyes make it suitable for quantitative analysis of unknown concentration. Principal component analysis (PCA), a multivariate analysis has been adopted to discrimination of dyes. These dyes have been effectively detected quantitative in tap water to express substrate's suitability in real-world application. Their dual functionality, as SERS-active substrate and as magnetic separator, enhances their utility in real-world applications such as organic contaminants in aquatic environments.