Microfluidic Platform for Profiling of Extracellular Vesicles from Single Breast Cancer Cells.

Extracellular vesicles (EVs) are considered as valuable biomarkers to discriminate healthy from diseased cells such as cancer. Passing cytosolic and plasma membranes before their release, EVs inherit the biochemical properties of the cell. Here, we determine protein profiles of single EVs to understand how much they represent their cell of origin.

Continuous Electroformation of Gold Nanoparticles in Nanoliter Droplet Reactors.

Gold nanoparticles (AuNPs) are employed in numerous applications, including optics, biosensing and catalysis. Here, we demonstrate the stabilizer-free electrochemical synthesis of AuNPs inside nanoliter-sized reactors. Droplets encapsulating a gold precursor are formed on a microfluidic device and exposed to an electrical current by guiding them through a pair of electrodes.

Identifying extracellular vesicle populations from single cells.

Extracellular vesicles (EVs) are constantly secreted from both eukaryotic and prokaryotic cells. EVs, including those referred to as exosomes, may have an impact on cell signaling and an incidence in diseased cells. In this manuscript, a platform to capture, quantify, and phenotypically classify the EVs secreted from single cells is introduced.

In-Droplet Electrophoretic Separation and Enrichment of Biomolecules.

We demonstrate the in-droplet separation and enrichment of molecules from small organic molecules to long nucleic acids (lambda DNA). Electric potentials are applied via two parallel three-dimensional electrodes, which interface the nanodroplets through polydimethylsiloxane (PDMS)-carbon composite membranes. These membranes enable the generation of uniform electric fields inside the droplets, while simultaneously preventing the formation of electrolytic byproducts.

Exploiting Particle Mutual Interactions To Enable Challenging Dielectrophoretic Processes.

Dielectrophoresis (DEP) is the motion of particles under the influence of a nonuniform electric field. In insulator-based dielectrophoresis (iDEP), the required nonuniform electric fields are generated with insulating structures embedded in a microchannel. These structures distort the electric field distribution when an electric potential is applied.

Repayment policy for multiple loans.

The Repayment Policy for Multiple Loans is about a given set of loans and a monthly incoming cash flow: what is the best way to allocate the monthly income to repay such loans? In this article, we close the almost 20-year-old open question about how to model the repayment policy for multiple loans problem together with its computational complexity. Thus, we propose a mixed integer linear programming model that establishes an optimal repayment schedule by minimizing the total amount of cash required to repay the loans. We prove that the most employed repayment strategies, such as the highest interest debt and the debt snowball methods, are not optimal.

Refinement of current monitoring methodology for electroosmotic flow assessment under low ionic strength conditions.

Current monitoring is a well-established technique for the characterization of electroosmotic (EO) flow in microfluidic devices. This method relies on monitoring the time response of the electric current when a test buffer solution is displaced by an auxiliary solution using EO flow. In this scheme, each solution has a different ionic concentration (and electric conductivity).

Isolation and enrichment of low abundant particles with insulator-based dielectrophoresis.

Isolation and enrichment of low-abundant particles are essential steps in many bio-analytical and clinical applications. In this work, the capability of an insulator-based dielectrophoresis (iDEP) device for the detection and stable capture of low abundant polystyrene particles and yeast cells was evaluated. Binary and tertiary mixtures of particles and cells were tested, where the low-abundant particles had concentration ratios on the order of 1:10 000 000 compared to the other particles present in the mixture.

Polarization behavior of polystyrene particles under direct current and low-frequency (<1 kHz) electric fields in dielectrophoretic systems.

The relative polarization behavior of micron and submicron polystyrene particles was investigated under direct current and very low frequency (<1 kHz) alternating current electric fields. Relative polarization of particles with respect to the suspending medium is expressed in terms of the Clausius-Mossotti factor, a parameter of crucial importance in dielectrophoretic-based operations. Particle relative polarization was studied by employing insulator-based dielectrophoretic (iDEP) devices.

Dielectrophoretic manipulation of particle mixtures employing asymmetric insulating posts.

A novel scheme for particle separation with insulator-based dielectrophoresis (iDEP) was developed. This technique offers the capability for an inverted order in particle elution, where larger particles leave the system before smaller particles. Asymmetrically shaped insulating posts, coupled with direct current (DC) biased low-frequency alternating current (AC) electric potentials, were used to successfully separate a mixture of 500 nm and 1 μm polystyrene particles (size difference of 0.

Experimental and theoretical study of dielectrophoretic particle trapping in arrays of insulating structures: Effect of particle size and shape.

Insulator-based dielectrophoresis (iDEP) employs insulating structures embedded in a microchannel to produce electric field gradients. This contribution presents a detailed analysis of the regions within an iDEP system where particles are likely to be retained due to dielectrophoretic trapping in a microchannel with an array of cylindrical insulating structures. The effects of particle size and shape on dielectrophoretic trapping were analyzed by employing 1 and 2 μm polystyrene particles and Escherichia coli cells.