Magnetic Nanoparticles Embedded Silver Nanoshell as Highly Sensitive SERS Probe

Abstract

SERS (Surface-enhanced Raman scattering) is an efficient tool for multiplexed analysis of various targets because it has unique signal patterns with narrow band width and is stable to photo-bleaching. The structure of metal substrate is very important in obtaining strong SERS signals. So far, various approaches have been tried to develop new types of metal substrate for sensitive detection of targets at low concentration. In this thesis, a new type of SERS nanoprobe was synthesized which has hundreds of iron oxide magnetic nanoparticles at the core part, and silver shell at the outer part. (Magnetic silver Nanoshell, M AgNS) The surface of silver shell has bumpy structure, which could lead to the formation of hot spots, affording strong SERS signal. Besides, SERS signal could be further intensified by magnetic-induced aggregation. Through this M AgNS nanoprobe, 4-fluorothiophenol (4-FBT) was detected at low concentration as 1 μM, which corresponds to 16 ppb. Thiram and malathion, which are mainly used pesticides in the farm, were also detected at low concentrations using the aggregated M AgNS. The limit of detection (LOD) for thiram was 10 μM, which corresponds to 3 ppm. M AgNS nanoprobe is expected to be utilized in on-site detection of various analytes at low concentrations using a 785 nm portable Raman system.