In Situ Exosomal MicroRNA Determination by Target-Triggered SERS and Fe₃O₄@TiO₂-Based Exosome Accumulation

Abstract

Exosomal microRNAs (miRNAs) have been proved to be important biomarkers for the early diagnosis of cancers. However, the accurate quantification of exosomal miRNAs is hampered either by laborious exosome isolation and lysis or by RNA extraction and the amplification process. Here, we reported an in situ platform for direct exosomal miRNAs from serum samples. First, locked nucleic acid (LNA)-modified Au@DTNB (DTNB is the Raman reporter molecule 5,5′-dithiobis-(2-nitrobenzoic acid)) was synthesized as surface-enhanced Raman scattering (SERS) tags to enter into exosomes and assemble with target miRNAs to induce hot-spot SERS signals. Second, Fe 3 O 4 @TiO 2 nanoparticles were added to enrich the exosomes through affinity interaction of the TiO 2 shell for further SERS detection. Based on the platform, target miRNAs can be directly qualified in situ with a detection limit of 0.21 fM, which is better or comparable with quantitative reverse transcription polymerase chain reaction (qRT-PCR) and other in situ methods reported before. Moreover, neither capture antibody nor ultracentrifugation pretreatment was needed in the whole detection procedure. Using exosomal miRNA-10b as a proof of concept, pancreatic ductal adenocarcinoma (PDAC) patients can be recognized from normal controls (NCs) with an accuracy of 99.6%. The simple and sensitive in situ exosomal miRNA detection assay can be seen as a noninvasive liquid biopsy assay for clinical cancer diagnostic adaption. KEYWORDS: exosomal microRNA, in situ detection, hot-spot SERS, Fe 3 O 4 @TiO 2 , diagnosis of cancers

Advances in the Application of Exosomes Identification Using Surface-Enhanced Raman Spectroscopy for the Early Detection of Cancers

“…The forms of exosome detection by SERS technology are mainly divided into non-labeled and labeled assays. Non-labeled assays provide overall biochemical information about the exosome itself and are easy, fast and inexpensive to perform ( Russo et al, 2020 ; Jiang et al, 2021b ; Guerrini et al, 2021 ). Marker assays, on the other hand, improve the specificity of exosome identification and can also identify and detect secreted exosomes from multiple cancer cell lines simultaneously ( Blanco-Formoso and Alvarez-Puebla, 2020 ; Chen et al, 2020 ; Hao et al, 2020 ).…”

“…The exosomes were then enriched by the addition of Fe3O4@tio2 nanoparticles for further SERS detection. Using this technique to detect exosomal miRNA-10b can be used to effectively identify patients with PDAC (Jiang et al, 2021b). Melanoma is a highly aggressive malignancy originating from melanocytes, the incidence of which is increasing every year (Han et al, 2021a;Dimitriou et al, 2021;Worrede et al, 2021).…”

“…Early diagnosis of patients can be made by detecting differences in SERS signals in plasma-derived exosomes and residual supernatant plasma from pancreatic ductal adenocarcinoma (PDAC), chronic pancreatitis and normal control blood samples ( Pang et al, 2019 ). Jiang et al (2021b) Designed an in situ platform for direct extraction of exosomal miRNA from serum samples. They synthesized locking nucleic acid-modified Au@DTNB as a SERS tag into exosomes and assembled with target miRNAs to induce hotspot SERS signals.…”

“…The exosomes were then enriched by the addition of Fe3O4@tio2 nanoparticles for further SERS detection. Using this technique to detect exosomal miRNA-10b can be used to effectively identify patients with PDAC ( Jiang et al, 2021b ).…”

Exosomes as a new frontier of cancer liquid biopsy

“…C Lipid mediated-separation. Copyright 2018 by Xu [ 65 ], 2021 by Jiang [ 66 ]. D Acoustic-based isolation / Thermophoretic enrichment.…”