Conductance-Based Biophysical Distinction and Microfluidic Enrichment of Nanovesicles Derived from Pancreatic Tumor Cells of Varying Invasiveness

Abstract

Diagnostics based on exosomes and other extracellular vesicles (EVs) are emerging as strategies for informing cancer progression and therapies, since the lipid content and macromolecular cargo of EVs can provide key phenotypic and genotypic information on the parent tumor cell and its microenvironment. We show that EVs derived from more invasive pancreatic tumor cells that express high levels of tumorspecific surface proteins and are composed of highly unsaturated lipids that increase membrane fluidity, exhibit significantly higher conductance versus those derived from less invasive tumor cells, based on dielectrophoresis measurements. Furthermore, through specific binding of the EVs to gold nanoparticle-conjugated antibodies, we show that these conductance differences can be modulated in proportion to the type as well as level of expressed tumor-specific antigens, thereby presenting methods for selective microfluidic enrichment and cytometry-based quantification of EVs based on invasiveness of their parent cell.

Brownian Motion and Large Electric Polarizabilities Facilitate Dielectrophoretic Capture of Sub‐200 nm Gold Nanoparticles in Water

“…In addition to artificial sub‐micron nanoparticles, DEP has recently been applied to smaller biological nano‐objects: proteins, nucleic acids, and extracellular vesicles . In the case of proteins and nucleic acids, the required very high electric field gradients are achieved using sub‐micron and nanometer‐scale electrode gaps, that concentrate the electric field gradients in extremely small volumes.…”

“…[27,29] In addition to artificial sub-micron nanoparticles, DEP has recently been applied to smaller biological nano-objects: proteins, [30][31][32][33][34] nucleic acids, [35,36] and extracellular vesicles. [37,38] In the case of proteins and nucleic acids, the required very high electric field gradients are achieved using sub-micron and nanometer-scale electrode gaps, that concentrate the electric field gradients in extremely small volumes. One particularly suitable method for obtaining such high electric field strengths consists of applying the electric field externally and focussing it through insulating dielectric nanostructures.…”

Toward low‐voltage dielectrophoresis‐based microfluidic systems: A review

“…Furthermore, when studying the effect of nanopipette geometry on particle entrapment, the greatest number of particles trapped was obtained with a 2 μm pore size (compared to lower pore sizes) when polystyrene beads were suspended in 10 mM KCl medium. The next year, a device was able to manipulate the response of nanostructures such as exosomes and extracellular vesicles from pancreatic tumor cells using a 70 V rms AC signal at frequencies ranging from 0.01 to 1.5 MHz [93]. The nanostructures were treated as dielectric spheres with a conductive shell due to the electric double layer.…”

High-Sensitivity in Dielectrophoresis Separations

“…Throughout it development, researchers have chosen media conductivity to allow for larger DEP force magnitudes and potential separations. Swami and co-workers have demonstrated a number of sensitive separations, isolating cells with mitochondrial structure variations [9], extracellular vesicles from pancreatic tumor cells based on invasiveness [57], and bacterial (Clostridium difficile) cells with altered envelope structure [58]. While the approach does not eliminate size dependence, as we show in Section 2, it can be leveraged to increase the relative contribution of particle electrical properties to variations in the resultant DEP force.…”