Biomedical subjects

Cheng-Wey Wei

Publications and source records attributed to Cheng-Wey Wei.

3 recordsLinked to original sources

PubMed2006

Elucidating in vitro cell-cell interaction using a microfluidic coculture system.

This work presents a novel microfluidic coculture system that improves the accuracy of evaluating the interaction between cocultured cell types. A microfluidic coculture chip, fabricated by CO(2) laser direct-writing on polymethyl methacrylate (PMMA), was designed to separate two cell types using a microchannel, while permitting transfer of cellular media. The system has two up-stream wells and five down-stream wells. As an example, released inflammatory cytokines (e.g., interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha)), activated in up-stream macrophages, flow through a microfluidic mixing system, generating linear concentration gradients in down-stream wells and inducing down-stream osteoblasts to release prostaglandin E2 (PGE2), a well-known bone resorption marker. Osteoblast viability was assessed by 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay. This novel coculture system can be applied to evaluate cell-cell interaction while physically separating interacting cells.

Cell Communication↗

PubMed2005

Using a microfluidic device for 1 microl DNA microarray hybridization in 500 s.

This work describes a novel and simple modification of the current microarray format. It reduces the sample/reagent volume to 1 microl and the hybridization time to 500 s. Both 20mer and 80mer oligonucleotide probes and singly labeled 20mer and 80mer targets, representative of the T-cell acute lymphocytic leukemia 1 (TAL1) gene, have been used to elucidate the performance of this hybridization approach. In this format, called shuttle hybridization, a conventional flat glass DNA microarray is integrated with a PMMA microfluidic chip to reduce the sample and reagent consumption to 1/100 of that associated with the conventional format. A serpentine microtrench is designed and fabricated on a PMMA chip using a widely available CO2 laser scriber. The trench spacing is compatible with the inter-spot distance in standard microarrays. The microtrench chip and microarray chip are easily aligned and assembled manually so that the microarray is integrated with a microfluidic channel. Discrete sample plugs are employed in the microchannel for hybridization. Flowing through the microchannel with alternating depths and widths scrambles continuous sample plug into discrete short plugs. These plugs are shuttled back and forth along the channel, sweeping over microarray probes while re-circulation mixing occurs inside the plugs. Integrating the microarrays into the microfluidic channel reduces the DNA-DNA hybridization time from 18 h to 500 s. Additionally, the enhancement of DNA hybridization reaction by the microfluidic device is investigated by determining the coefficient of variation (CV), the growth rate of the hybridization signal and the ability to discriminate single-base mismatch. Detection limit of 19 amol was obtained for shuttle hybridization. A 1 mul target was used to hybridize with an array that can hold 5000 probes.

Basic Helix-Loop-Helix Proteins↗

PubMed2003

Behavior of MG-63 cells on nylon/chitosan-blended membranes.

In this work, the properties of nylon, chitosan, and their blended membranes were investigated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction analysis. The SEM photographs show that the undulating surface of the nylon membrane became less obvious by blending with chitosan. The DSC and X-ray diffraction analysis show that constitutionally different features in the combination of two polymer chains were revealed, suggesting that nylon and chitosan are immiscible at the microscopic level in the blended membranes. Furthermore, an attempt was made to understand whether the two components contribute independently to the adhesion, growth, and activation of MG-63 osteoblastlike cells. The cell adhesion increased with increasing chitosan content, indicating that the affinity between the cells and the membranes increased with increasing chitosan content. Although the blended membranes with higher nylon content exerted an inhibitory effect on cell adhesion, cells cultured on the nylon membrane proliferated at higher rates and the nylon membrane was the least stimulating of MG-63 cell cytokine production over a 4-day period when compared with all the other membranes. Combined with the result of cell growth and cell activation, the chitosan content in the blended membrane did not proportionally influence the behavior of MG-63 cells. It is proposed that cell's size was larger than the scale of nylon or chitosan domain in the blended membranes because of the incomplete miscibility between them. Therefore, even if the composition of the blended membranes is systematically changed, every cell covers a multiphase surface that is considered a totally new material for cells. Consequently, cell growth and cell activation on a blended membrane are not simply proportional to their composition. In contrast, cell adhesion is a simpler process, like a physical adsorption process, which is related to the bulk property of a blended membrane.

Biocompatible Materials↗