MoS₂-Plasmonic Nanocavities for Raman Spectra of Single Extracellular Vesicles Reveal Molecular Progression in Glioblastoma

Abstract

Extracellular vesicles (EVs) are continually released from cancer cells into biofluids, carrying actionable molecular fingerprints of the underlying disease with considerable diagnostic and therapeutic potential. The scarcity, heterogeneity and intrinsic complexity of tumor EVs present a major technological challenge in real-time monitoring of complex cancers such as glioblastoma (GBM). Surface-enhanced Raman spectroscopy (SERS) outputs a label-free spectroscopic fingerprint for EV molecular profiling. However, it has not been exploited to detect known biomarkers at the single EV level. We developed a multiplex fluidic device with embedded arrayed nanocavity microchips (MoSERS microchip) that achieves 97% confinement of single EVs in a minute amount of fluid (<10 μL) and enables molecular profiling of single EVs with SERS. The nanocavity arrays combine two featuring characteristics: (1) An embedded MoS2 monolayer that enables label-free isolation and nanoconfinement of single EVs due to physical interaction (Coulomb and van der Waals) between the MoS2 edge sites and the lipid bilayer; and (2) A layered plasmonic cavity that enables sufficient electromagnetic field enhancement inside the cavities to obtain a single EV level signal resolution for stratifying the molecular alterations. We used the GBM paradigm to demonstrate the diagnostic potential of the SERS single EV molecular profiling approach. The MoSERS multiplexing fluidic achieves parallel signal acquisition of glioma molecular variants (EGFRvIII oncogenic mutation and MGMT expression) in GBM cells. The detection limit of 1.23% was found for stratifying these key molecular variants in the wild-type population. When interfaced with a convolutional neural network (CNN), MoSERS improved diagnostic accuracy (87%) with which GBM mutations were detected in 12 patient blood samples, on par with clinical pathology tests. Thus, MoSERS demonstrates the potential for molecular stratification of cancer patients using circulating EVs.

Additive manufacturing leveraged microfluidic setup for sample to answer colorimetric detection of pathogens

“…LAMP technique was employed in conjugation with a nanostructured platform that plasmonically enhances the amplification reaction. 60 In brief, the irradiation of ambient light on the plasmonic nanosurface 66,67 causes a collective plasmonic oscillation of the free electrons (Fig. 3a).…”

A Panorama of Extracellular Vesicle Applications: From Biomarker Detection to Therapeutics

“…Lithography and 3D printing are the most frequent methods used to fabricate microfluidic devices that can be coupled with signal amplification and detection strategies to permit rapid and sensitive EV detection, and several distinct designs have been used for this purpose, although SERS detectors are commonly used in these designs. For example, one recent study used a 3D printed polydimethylsiloxane (PDMS) microfluidic chip containing embedded arrays of plasmonic nanocavities size to contain single EVs to achieve single EV resolution when read by a label-free method that detected SERS signals associated with EVs derived from different cell types . A second group used a SERS-based microchip design in which a specific antibody was used to directly capture target serum EVs, which were then hybridized with a set of SERS nanotags to allowed multiplex analysis to detect early melanoma, using sensors that contained asymmetric circle-ring electrodes that also promoted nanoscopic flows to enhance sample mixing .…”

“…For example, one recent study used a 3D printed polydimethylsiloxane (PDMS) microfluidic chip containing embedded arrays of plasmonic nanocavities size to contain single EVs to achieve single EV resolution when read by a label-free method that detected SERS signals associated with EVs derived from different cell types. 19 A second group used a SERS-based microchip design in which a specific antibody was used to directly capture target serum EVs, which were then hybridized with a set of SERS nanotags to allowed multiplex analysis to detect early melanoma, using sensors that contained asymmetric circle-ring electrodes that also promoted nanoscopic flows to enhance sample mixing. 20 A third group used an alternate design where antibody-conjugated nanoparticles were used to magnetically sort EVs into different populations based on their relative expression (negative, low, medium, and high) of selected membrane biomarkers and to allow the subsequent analysis of the distinct EV isolate populations.…”

Surface‐Enhanced Raman Spectroscopy‐Based Optical Biosensor for Liquid Biopsy: Toward Precision Medicine

“…To realize a label-free SERS-based technique with single EV resolution, Jalali et al proposed multiplex fluidic SERSbased microchips with embedded arrayed nanocavity (MoSERS, Figure 5B). [79] As proof-of-principle, MoSERS achieve the classification of different molecular tumor subtypes of GBM in individual patients by combining with CNN, with a diagnostic accuracy of 87%.…”