Rapid manipulation of extracellular vesicles using dielectrophoretic mechanism

Extracellular vesicles (EVs) are small entities that are released by most cell types. EVs are important form of intercellular communication and a rich source of biomarkers for a wide variety of diseases. Many methods for EVs isolation have been utilized, however, most of them have significant drawbacks including lengthy processing time, high cost, shortfalls in selectivity and surface marker dependency. In consideration of these issues, this paper discussed on the dielectrophoresis (DEP) microelectrode method designed to rapidly isolate EVs from its medium. The advantage of this DEP microelectrode is the capability of isolating EVs using a droplet of 1 µL placed onto the microelectrode within 30 s and 20 V peak-to-peak (Vp-p) of alternating current (AC). The method used in the characterization of sample are dynamic light scattering (DLS) and transmission electron microscopy (TEM); both prove the heterogeneity of EVs’ population and the EVs appear to be spherical with size ranging from 40 to 200 nm. The experimental results from this preliminary experiment show that the DEP microelectrode was able to manipulate EVs as evidenced by the negative dielectrophoresis (NDEP) fluorescent images. Further investigation of grid analysis conducted shows the consistency of the theory and the results presented. Corrected Total Cell Fluorescence (CTCF) values from the grid analysis concluded that the EVs were manipulated to the center of region of interest, (ROI). Therefore, this DEP technique suggests a rapid strategy for EVs isolation from its medium in small quantity while maintaining accuracy and cost-effectivity

Rapid ESKAPE pathogens detection method using tapered dielectrophoresis electrodes via crossover frequency analysis

This paper introduces the versatile of an electrokinetic technique by using the non-uniform electric field for dielectrophoresis (DEP) application. This technique is defined as electromicrofluidics. The potential application for portable and real time detection method of Enterococcus faecium (EF), Staphylococcus aureus (SA), Klebsiella pneumoniae (KP), Acinetobacter baumannii (AB), Pseudomonas aeruginosa (PA) and Enterobacter aerogenes (EA), which are the (ESKAPE) bacteria. The MATLAB analytical modelling was used in simulating the polarisation factor and velocities of bacteria based on Clausius-Mossotti factor (CMF). The validation of CMF simulation through the DEP experimental can be quantified based on the response of alternating current (AC) voltage applied using 6 voltage peak to peak (Vp-p) to their input frequencies from 100 to 15000 kHz. The droplet method was deployed to place properly 0.2 μL of sample onto DEP microelectrode. The velocities and crossover frequency (fxo) ranges of bacteria were determined through bacteria trajectory in specific time interval monitored by microscope attached with eyepiece camera. The applied range of input frequencies from 100 to 15000 kHz at 6 Vp-p for each bacteria were successfully identified the unique ranges of frequencies response for detection application. The advantages of this works are selective with rapid capability for multidrug resistant (MDR) bacteria detection application

Protein Albumin Manipulation and Electrical Quantification of Molecular Dielectrophoresis Responses for Biomedical Applications

Research relating to dielectrophoresis (DEP) has been progressing rapidly through time as it is a strong and controllable technique for manipulation, separation, preconcentration, and partitioning of protein. Extensive studies have been carried out on protein DEP, especially on Bovine Serum Albumin (BSA). However, these studies involve the usage of dye and fluorescent probes to observe DEP responses as the physical properties of protein albumin molecular structure are translucent. The use of dye and the fluorescent probe could later affect the protein’s physiology. In this article, we review three methods of electrical quantification of DEP responses: electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and capacitance measurement for protein BSA DEP manipulation. The correlation of these methods with DEP responses is further discussed. Based on the observations on capacitance measurement, it can be deduced that the electrical quantifying method is reliable for identifying DEP responses. Further, the possibility of manipulating the protein and electrically quantifying DEP responses while retaining the original physiology of the protein and without the usage of dye or fluorescent probe is discussed