Injection by Hydrostatic Pressure in Conjunction with Electrokinetic Force on a Microfluidic Chip

A simple method was developed for injecting a sample on a cross-form microfluidic chip by means of hydrostatic pressure combined with electrokinetic forces. The hydrostatic pressure was generated simply by adjusting the liquid level in different reservoirs without any additional driven equipment such as a pump. Two dispensing strategies using a floating injection and a gated injection, coupled with hydrostatic pressure loading, were tested. The fluorescence observation verified the feasibility of hydrostatic pressure loading in the separation of a mixture of fluorescein sodium salt and fluorescein isothiocyanate. This method was proved to be effective in leading cells to a separation channel for single cell analysis

Microfluidic cell culture systems with integrated sensors for drug screening.

Cell-based testing is a key step in drug screening for cancer treatments. A microfluidic platform can permit more precise control of the cell culture microenvironment, such as gradients in soluble factors. These small-scale devices also permit tracking of low cell numbers. As a new screening paradigm, a microscale system for integrated cell culture and drug screening promises to provide a simple, scalable tool to apply standardized protocols used in cellular response assays. With the ability to dynamically control the microenvironment, we can create temporally varying drug profiles to mimic physiologically measured profiles. In addition, low levels of oxygen in cancerous tumors have been linked with drug resistance and decreased likelihood of successful treatment and patient survival. Our work also integrates a thin-film oxygen sensor with a microfluidic oxygen gradient generator which will in future allow us to create spatial oxygen gradients and study effects of hypoxia on cell response to drug treatment. In future, this technology promises to improve cell-based validation in the drug discovery process, decreasing the cost and increasing the speed in screening large numbers of compounds. Copyright 2012 Society of Photo-Optical Instrumentation Engineers. One print or electronic copy may be made for personal use only. Systematic reproduction and distribution, duplication of any material in this paper for a fee or for commercial purposes, or modification of the content of the paper are prohibited.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofReviewedFacult

Electrophoretic Mobility of Carp Erythrocyte on Microfluidic Chip

The electrophoretic mobility of three groups of common carp erythrocyte on polymethal methacrylate chip has been studied by singe-cell imaging. The values of cell electrophoretic mobility were 1.138 × 10-4, 0.1279 × 10-4, -0.8520 × 10-4 cm2V -1s-1 respectively. It is demonstrated that the variation of the cell migration velocity is originated from the change of water quality and Lambda-cyhalothrin. The cell electrophoretic mobility being used as a parameter for cell classification have also been discussed

Electrophoretic Mobility of carp erythrocyte on Microfluidic Chip

The electrophoretic mobility of three groups of common carp erythrocyte on polymethal methacrylate chip has been studied by singe-cell imaging. The values of cell electrophoretic mobility were 1.138 × 10-4, 0.1279 × 10-4, -0.8520 × 10-4 cm2V -1s-1 respectively. It is demonstrated that the variation of the cell migration velocity is originated from the change of water quality and Lambda-cyhalothrin. The cell electrophoretic mobility being used as a parameter for cell classification have also been discussed

Fabrication of two-weir structure-based packed columns for on-chip solid-phase extraction of DNA

Microchip-based packed column SPE of DNA was performed using the microfabricated two-weir structure within a microchannel. We developed two methods to fabricate the two-weir structured glass chips: a "two-side etching/alignment" method and a simplified "one-side/two-step etching" method. The former rnethod required a straightforward alignment step, while the latter approach comprised a simplified wet etching process using paraffin wax as the temporary protective layer. Both methods were convenient and rapid as compared to the previous approaches. Through a reversibly sealed bead-introduction channel, beads can be fed into or out of the chip columns, thus enabling refreshment of the packing materials. Using the proposed chip columns, highly efficient,lambda-DNA extractions (average recovery > 80%) were performed with good chip-to-chip reproducibility (RSD < 10%). The on-chip SPE procedure was completed within 15 min at the flow rate of 3 mu L/min and the bulk of the loaded DNA was eluted within a small volume of similar to 8 mu L. Application of the microchip-based packed columns was demonstrated by purifying PCR-amplifiable genomic DNA from human hepatocellular carcinoma (HepG2) cells and human whole blood samples

ASC Regulates Subcutaneous Adipose Tissue Lipogenesis and Lipolysis via p53/AMPK&alpha; Axis

Obesity has become an extensive threat to human health due to associated chronic inflammation and metabolic diseases. Apoptosis-associated speck-like protein (ASC) is a critical link between inflammasome and apoptosis-inducing proteins. In this study, we aimed to clarify the role of ASC in lipid metabolism. With high-fat diet (HFD) and knockout leptin gene mice (ob/ob), we found that ASC expression in subcutaneous adipose tissue (SAT) correlated with obesity. It could also positively regulate the reprogramming of cellular energy metabolism. Stromal vascular fractions (SVF) cells derived from the SAT of Asc&minus;/&minus; mice or SVF from wild-type (WT) mice transfected with ASC siRNA were used to further investigate the underlying molecular mechanisms. We found ASC deficiency could lead to lipogenesis and inhibit lipolysis in SAT, aggravating lipid accumulation and impairing metabolic balance. In addition, our results showed that p53 and AMPK&alpha; expression were inhibited in SAT when ASC level was low. p53 and AMP-activated protein kinase &alpha; (AMPK&alpha;) were then assessed to elucidate whether they were downstream of ASC in regulating lipid metabolism. Our results revealed that ASC deficiency could promote lipid accumulation by increasing lipogenesis and decreasing lipolysis through p53/AMPK&alpha; axis. Regulation of ASC on lipid metabolism might be a novel therapeutic target for obesity