On-chip light sheet illumination enables diagnostic size and concentration measurements of membrane vesicles in biofluids

Abstract

Cell-derived membrane vesicles that are released in biofluids, like blood or saliva, are emerging as potential non-invasive biomarkers for diseases, such as cancer. Techniques capable of measuring the size and concentration of membrane vesicles directly in biofluids are urgently needed. Fluorescence Single Particle Tracking microscopy has the potential of doing exactly that, by labelling the membrane vesicles with a fluorescent label and analysing their Brownian motion in the biofluid. However, unbound dye in the biofluid can cause high background intensity that strongly biases the fluorescence Single Particle Tracking size and concentration measurements. While such background can be avoided with light sheet illumination, current set-ups require specialty sample holders that are not compatible with high-throughput diagnostics. Here, a microfluidic chip with integrated light sheet illumination is reported, and accurate fluorescence Single Particle Tracking size and concentration measurements of membrane vesicles in cell culture medium and in interstitial fluid collected from primary human breast tumours are demonstrated.3

Particle tracking in drug and gene delivery research: State-of-the-art applications and methods

“…Light sheet microscopy can thus achieve optical sectioning, similar to confocal microscopy, but with less photobleaching and faster acquisition rates. A number of recent papers report improved signal-to-noise ratio, and good spatial and temporal resolution, using light sheet microscopy-based particle tracking [148, 152, 153]. …”

Rab27 GTPases Distribute Extracellular Nanomaps for Invasive Growth and Metastasis: Implications for Prognosis and Treatment

“…One promising approach combines on-chip microfiltration and miniaturized nuclear magnetic resonance to enable quantitative detection of exosomes labeled with target-specific magnetic nanoparticles [38]. We developed a low-cost disposable microfluidic chip with integrated light sheet illumination for high-throughput exosome staging in cancer patients [39]. Light sheet illumination enables on-chip detection of exosomes that are fluorescently labeled directly in biofluids without pre-processing steps.…”

Optical transport, lifting and trapping of micro-particles by planar waveguides

“…The diverging light fields between the waveguide gap can also combine waveguide trapping with on-chip fluorescence imaging [21]. Lifting particles away from the surface of the waveguide might improve the signal-to-noise ratio when analyzing biological samples.…”