Genetic Sample Preparation Research Articles

An automated micro-solid phase extraction device involving integrated \high-pressure microvalves for genetic sample preparation

This paper presents an automated micro-SPE device for DNA extraction using monolithically integrated high-pressure microvalves. The automated micro-SPE device was fabricated through glass-to-glass thermal bonding and microfluidic system interface technologies. To increase the DNA extraction efficiency, silica beads were packed in the extraction microchannel involving two weir structures. Experimental results show that the DNA extraction efficiency using the automated micro-SPE device containing bare silica beads was 75.87% in the first 8 microl of solution eluted by automated SPE procedure. In addition, the reproducibility of the DNA extraction was evaluated by ten successive measurements. Genomic DNA extracted from human WBCs had an absorbance ratio of DNA to protein (A(260)/A(280)) of 1.56. The applicability of this automated micro-SPE device to genetic sample preparation was verified by PCR amplification of a beta-globulin gene using the genomic DNA extracted from WBCs. Consequently, we demonstrated that the proposed automatic micro-SPE device can extract nucleic acids from biological samples, thereby facilitating its integration with downstream genetic analyses in a micro format.

An active microfluidic system packaging technology

This paper presents the design, fabrication, and characterization of a microfluidic system interface (MSI) technology for integration of complex microfluidic systems containing multiple functionalities. The microfluidic system interface technology provided a simple method for realizing complex arrangements of on-chip/off-chip microfluidic interconnects, integrated microvalves for fluid control, and optical windows for on-chip optical processes. The microfluidic interconnects were designed to provide one-step plug-in fluid interconnection utilizing a post assembled o-ring to ensure a tight seal. The integrated microvalves were completed when the MSI was assembled atop of the microfluidic system. The microvalves have been designed for zero dead volume with a displaced channel volume of 24 nl in the closed state. The valve was pneumatically actuated up to a valve pressure of 450 kPa. The optical windows were designed to allow for analysis operations such as infrared polymerase chain reaction and conventional fluorescence detection. A microfluidic system for genetic sample preparation was used as the test vehicle to prove the usefulness of the MSI technology with respect to complex microfluidic systems containing multiple functionalities. The miniaturized genetic sample preparation system consisted of several functional compartments including cell purification, cell separation, cell lysis, solid phase DNA extraction, polymerase chain reaction and capillary electrophoresis. Use of the MSI technology to enable integration of this complex lab-on-a-chip system in a hybrid multi-chip format was demonstrated. Additionally, functional operation of the solid phase extraction and PCR thermocycling compartments was demonstrated using the MSI.

Diamagnetic capture mode magnetophoretic microseparator for blood cells

This paper presents the characterization of a continuous diamagnetic capture (DMC) mode magnetophoretic microseparator for separating red and white blood cells from diluted whole blood based on their native magnetic properties. The DMC microseparator separated the blood cells using a high-gradient magnetic separation (HGMS) method without the use of additives such as magnetic beads. The microseparator was fabricated using microfabrication technology, enabling the integration of microscale magnetic flux concentrators in an aqueous microenvironment. Experimental results show that the DMC microseparator can continuously separate out 89.7% of red blood cells (RBCs) from diluted whole blood within 5 min using an external magnetic flux of 0.2 T from a permanent magnet. Monitoring white blood cells (WBCs) probed with a fluorescence dye show that 72.7% of WBCs were separated out within 10 min in the DMC microseparator using a 0.2 T external applied magnetic flux. Consequently, the DMC microseparator may facilitate the separation of WBCs from whole blood in applications such as a genetic sample preparation and blood borne disease detection. [1574].

Development of integrated microfluidic system for genetic analysis

Biotechnology, in conjunction with semiconductor and microelectronics, would have a tremendous impact on new solutions in gene and drug discovery, point-of-care systems, pharmacogenomics, and environmental and food safety applications. A combination of microfabrication techniques and molecular biology procedures have the potential to produce powerful, inexpensive, and miniature analytical devices (e.g., microfluidic lab chips), aiding further development of genetic analysis. Microfluidics for biotechnology applications require development of inexpensive, high-volume fabrication techniques and reduction of biochemical assays to the chip format. We discuss design, fabrication, and testing of plastic microfluidic devices for on-chip genetic sample preparation and DNA microarray detection. Plastic microfabrication methods are being used to produce components of a complete microsystem for genetic analysis. A detailed discussion on the development of micromixers, microvalves, cell capture, micro-polymerase chain reaction (PCR) devices, and biochannel hybridization arrays is given. We also describe a path to further individual component integration.

A Modular Microfluidic System for Cell Pre-concentration and Genetic Sample Preparation

A modular system containing mixers, incubation unit, and cell capture unit has been developed using polymer microfluidic chips. A custom interfacing scheme has been used to assemble individual chips into the functional system. This system has been used to perform cell pre-concentration from a complex sample matrix allowing for carrying out assays on rare cell targets appearing in low concentrations in the analyzed sample. We demonstrate that 2 ml of the sample can be processed in a cell capture modular system with cell capture efficiency of 53 and 37% for PBS- and blood-based samples, respectively. We also show that these capture rates are strongly dependent on the effectiveness of pre-capture mixing between the cell containing sample and bead-antibody complexes.

Development of Plastic Microfluidic Devices for Sample Preparation

Microfluidics technology shows excellent potential for applications in biotechnology, chemical sensing, and drug delivery. The use of microfluidics results in cycle time reduction, reagent cost and labor intensity savings due to the benefits of miniaturization, and functional integration. As a result, miniature DNA sample preparation and analytical devices may potentially become part of a point-of-care systems for rapid medical diagnoses. Similar diagnostic devices will benefit veterinary and food safety applications. In this paper, we discuss design, fabrication, and testing of plastic microfluidic devices for on-chip genetic sample preparation. These fabrication methods are being used to produce components of a complete genetic sample preparation micro-system. The detailed discussion on the development of micro-PCR (polymerase chain reaction) devices and bio-channel hybridization arrays is given. We also describe a path to further individual component integration.