Molecular fingerprinting of biological nanoparticles with a label-free optofluidic platform

Abstract

Label-free detection of multiple analytes in a high-throughput fashion has been one of the long-sought goals in biosensing applications. Yet, for all-optical approaches, interfacing state-of-the-art label-free techniques with microfluidics tools that can process small volumes of sample with high throughput, and with surface chemistry that grants analyte specificity, poses a critical challenge to date. Here, we introduce an optofluidic platform that brings together state-of-the-art digital holography with PDMS microfluidics by using supported lipid bilayers as a surface chemistry building block to integrate both technologies. Specifically, this platform fingerprints heterogeneous biological nanoparticle populations via a multiplexed label-free immunoaffinity assay with single particle sensitivity. First, we characterise the robustness and performance of the platform, and then apply it to profile four distinct ovarian cell-derived extracellular vesicle populations over a panel of surface protein biomarkers, thus developing a unique biomarker fingerprint for each cell line. We foresee that our approach will find many applications where routine and multiplexed characterisation of biological nanoparticles are required.

Label-Free Electrochemical Imaging of Single Extracellular Vesicles

“…[11][12][13] Nanoparticle tracking analysis (NTA) is widely used but lacks sensitivity and the ability to profile EVs. 14 Techniques with high sensitivities, such as interferometric scattering (iSCAT), [15][16][17] surface plasmon resonance (SPR), 18,19 single particle interferometric reflectance imaging sensor (SP-IRIS), 20,21 and dark-field microscopy, 22,23 offer exceptional capabilities for imaging and sizing single EVs. However, they typically do not provide comprehensive profiles of single EVs either, as they measure only the binding of EVs to antibodyfunctionalized surfaces, thus limiting the detection to one type of protein per single EV.…”