195. NOVEL DIELECTROPHORETIC DEVICE FOR CANCER CELL, STEM CELL AND DNA BIOMARKER ISOLATION AND DETECTION

Department: NanoEngineering
Faculty Advisor(s): Michael Heller | Sadik Esener

Primary Student
Name: Rajaram Krishnan
Email: rkrishna@ucsd.edu
Phone: 858-822-5699
Grad Year: 2010

Abstract
The overall goal for our NCI NanoTumor Center project is the development of new dielectrophoretic (DEP) technology that allows cancer cells, high molecular weight (hmw) DNA nanoparticulates and other cancer biomarkers, as well as drug delivery nanoparticles to be isolated and detected directly in whole blood or plasma. Achieving this goal required overcoming the basic limitation of DEP to low conductance (ionic strength) samples. Last year, we achieved this key milestone in demonstrating the separation and detection of DNA nanoparticles in high-conductance solutions (Electrophoresis #29, pp.1765-74, 2008). Having overcome this limitation of DEP, we have now been able to demonstrate for the first time that DEP could be used for the separation of nanoparticles and hmw DNA biomarkers directly from whole blood. Both fluorescent nanoparticles and fluorescent-stained hmw DNA in undiluted whole blood samples were separated and held in DEP high field regions and then detected after the blood cells were removed by a fluidic wash. In buffy coat blood, with reduced cell numbers, 40nm nanoparticles concentrated into the DEP high field regions while the blood cells concentrated into the DEP low field regions. A fluidic wash then selectively removed the cells while the nanoparticles remained trapped. We further showed that unlabeled hmw DNA could first be separated by DEP, and then stained with a fluorescent dye for subsequent detection. This was an important result that demonstrated both the intrinsic advantage of DEP for separating unlabeled analytes and the potential for using the technology in a seamless sample to answer process. In the area of stem cells, we have been able to use DEP to carry out the separation of cardiomyocytes from fibroblasts and endotherial cells. Efforts are now being carried out to demonstrate in-situ fluorescent antibody assays for cellular antigens and PCR detection of hmw DNA separated from whole blood. The overall goal for our research efforts are to continue development of a new generation of “seamless” sample to answer diagnostic systems; where a complex sample is run through the device, and the specific analytes are rapidly concentrated onto microscopic locations and subsequently detected. Such DEP systems will allow complex clinical and other biological samples such as blood, plasma and serum to be rapidly and directly analyzed for a variety of important disease related biomarkers.

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