Simultaneous and multiplex detection of exosomal microRNAs based on the asymmetric Au@Au@Ag probes with enhanced Raman signal

摘要

Simultaneous and quantitative detection of multiple exosomal micro RNAs(miRNAs)was successfully performed by a surface-enhanced Raman scattering(SERS)assay consisting of Raman probes and capture probes.In this design,the asymmetric core-shell structured Au@Au@Ag nanoparticles were first synthesized by layer-by-layer self-assembly method and modified with different Raman molecules and recognition sequences(poly A-DNA)to prepare the surface-enhanced Raman probes.Then,the streptavidinmodified magnetic beads were used to immobilize the biotinylated DNA capture sequences(biotin-DNA)to obtain capture probes.In the presence of target exosomal miRNAs,the Raman probes and capture probes could bind to the target exosomal miRNAs in the partial hybridization manner.Thus,the developed SERS sensor could indicate the target miRNAs levels in the buffer solution.Using breast cancerrelated miRNAs as model targets,the limits of detection of this sensor were determined to be 1.076 fmol/L for synthetic miR-21,0.068 fmol/L for synthetic miR-126,and 4.57 fmol/L for synthetic miR-1246,respectively.Such SERS sensors were further employed to detect the miR-21 in 20%human serum and the extraction solution of exosomes,respectively.Therefore,simultaneous and multiplex detection of cancerrelated exosomal miRNAs by this assay could provide new opportunities for further biomedical applications.