Multiple and sensitive SERS detection of cancer-related exosomes based on gold-silver bimetallic nanotrepangs
Exosomes are endogenous vesicles of cells, which can be used as important biomarkers for cancers. In this work, we developed a sensitive and reliable SERS sensor for simultaneous detection of multiple cancer-related exosomes. The SERS detection probes were made of bimetallic SERS-active nanotags, gold-silver-silver core-shell-shell nanotrepangs (GSSNTs), which were composed of bumpy surface nanorod (gold nanotrepang, GNT) cores and bilayer silver shells, and decorated with linker DNAs, which were complementary to the aptamer targeting exosomes. Three kinds of SERS detection probes were designed via adopting different Raman reporter molecules and linker probes. The capture probes were prepared by modifying specific aptamers of the target exosomes on magnetic beads (MBs). In the absence of target exosomes, SERS detection probes were coupled with MBs via specific DNA hybridization as an aptamer-based SERS sensor. In the presence of the target exosomes, the aptamer specifically recognized and captured the exosomes, and GSSNTs were subsequently released into the supernatant. Therefore, attenuated SERS signals were detected on the MBs, indicating the presence of target exosomes. The proposed aptamer-based SERS sensor is expected to be a facile and sensitive method for multiplex detection of cancer biomarkers and offers the opportunity for future applications in clinical diagnosis.