Fabrication of Ag@Fe2O3 hybrid materials as ultrasensitive SERS substrates for the detection of organic dyes and bilirubin in human blood

Noble metal nanoparticle aggregates are attracting increasing interest as SERS active substrates for the ultrasensitive detection of environmental and biological samples. Deposition of noble metal nanoparticles on magnetic metal oxide is an effective way to not only realize the assembly of noble metal particles, but also enrich analytes in highly diluted solution. Herein, Ag@Fe 2 O 3 hybrid was prepared by a simple method and applied for sensitive and recyclable SERS detection. The low detection limit of R6G (LOD = 9.3 × 10 −10  M) and CV (LOD = 1.7 × 10 −9  M) demonstrated the excellent sensitivity for SERS application. The high stability during long-term detection illustrated the super detection capability of the Ag@Fe 2 O 3 hybrid substrate. The synergistic effect of the electromagnetic enhancement originated from nanogaps between densely and closely distributed Ag nanoparticles, the chemical enhancement from semiconductor material of Fe 2 O 3 and the magnetic enrichment of the analyte molecules was account for the excellent SERS performance of the Ag@Fe 2 O 3 substrate. As a result, the Ag@Fe 2 O 3 hybrid substrate was successfully applied to detect bilirubin in human blood and showed excellent detection ability (LOD = 2.3 × 10 −8  M).