Dielectrophoretic isolation of DNA and nanoparticles from blood

Abstract

The ability to effectively detect disease‐related DNA biomarkers and drug delivery nanoparticles directly in blood is a major challenge for viable diagnostics and therapy monitoring. A DEP method has been developed which allows the rapid isolation, concentration and detection of DNA and nanoparticles directly from human and rat whole blood. Using a microarray device operating at 20 V peak‐to‐peak and 10 kHz, a wide range of high molecular weight (HMW)‐DNA and nanoparticles were concentrated into high‐field regions by positive DEP, while the blood cells were concentrated into the low‐field regions by negative DEP. A simple fluidic wash removes the blood cells while the DNA and nanoparticles remain concentrated in the DEP high‐field regions where they can be detected by fluorescence. HMW‐DNA could be detected at 260 ng/mL, which is a detection level suitable for analysis of disease‐related cell‐free circulating DNA biomarkers. Fluorescent 40 nm nanoparticles could be detected at 9.5 × 109 particles/mL, which is a level suitable for monitoring drug delivery nanoparticles. The ability to rapidly isolate and detect DNA biomarkers and nanoparticles from undiluted whole blood will benefit many diagnostic applications by significantly reducing sample preparation time and complexity.

Low level epifluorescent detection of nanoparticles and DNA on dielectrophoretic microarrays

“…This reduces, but does not remove, the probability that individual strands of DNA will be bound to and carried away with cells and other nanoparticulates. The pDEP collection of HMW DNA (1 kbp and higher) from low and high conductance buffers has been previously demonstrated [33][34][35]. In addition, blood cells will experience nDEP in high conductance solutions, causing them to be pushed away from the positive trapping zones [23].…”

“…The use of DEP under high conductance conditions has now been clearly demonstrated for separations of nanoparticles and high molecular weight (HMW) DNA [35] and cancer-related cell free circulating (cfc) DNA and virus [36] directly from un-diluted whole blood. The design of new DEP systems that complement the common epifluorescent microscope will result in improved assays and diagnostics for detecting very low levels of DNA biomarkers, nanoparticles and virus in both clinical and environmental samples.…”

“…The separation of polystyrene nanoparticles in high conductance buffers and blood has been demonstrated through prior work [33][34][35][36], but cannot be reliably repeated in blood for lower levels. The nanoparticles used in this research are coated with carboxylate groups, which increase the surface potential and provide a net negative charge.…”

Detecting cancer biomarkers in blood: challenges for new molecular diagnostic and point-of-care tests using cell-free nucleic acids

“…In earlier DEP work, sample dilution to low-conductance conditions (<1 mS/cm) was required before effective DEP separations could be carried out [95,96,98,121,122]. New AC electrokinetic (DEP) techniques and microarray devices have been developed that allowed nanoscale entities, including high-molecular-weight (hmw) DNA and nanoparticles, to be isolated from highconductance (>10 mS/cm) buffer solutions [123][124][125][126].…”

Integrated microfluidic systems for molecular diagnostics: A universal electrode platform for rapid diagnosis of urinary tract infections

“…among these techniques, electrokinetics is one of the most promising microfluidic platforms for point-of-care diagnostics because of its low power consumption, cost-effectiveness, simplicity in microelectrode fabrication, and advancement in a portable electronic interface [5], [6]. recent efforts in electrokinetics have enabled various fundamental microfluidic operations, such as mixing, concentration, and separation, to be performed in highconductivity physiological fluids [7]- [11]. furthermore, electrokinetics can be implemented conveniently in electrochemical sensing platforms [9].…”