Dacian Roman

Significant toxic role for single-walled carbon nanotubes during normal embryogenesis.

UNLABELLED In order to investigate the effect of SWCNTs in the embryo, we examined the outcome of SWCNTs in avian embryo at an early stage of development. We found that SWCNTs-treatment inhibits the angiogenesis of the chorioallantoic membrane (CAM) and in the chicken embryo. Moreover, we showed that SWCNTs can harm the normal development of the embryo since all SWCNTs-exposed embryos are smaller in comparison with their matched controls. We also found that the majority of SWCNTs-exposed embryos die before 12days of incubation. Macroscopic examination did not reveal any anomalies in these embryos. However, RT-PCR analysis of eleven genes, which are important regulators of cell proliferation, apoptosis, survival and angiogenesis, shows that these genes are deregulated in brain and liver tissues from SWCNTs-treated embryos in comparison with their matched controls. This study suggests that SWCNTs could have a very toxic effect on the normal development of the embryo. FROM THE CLINICAL EDITOR In this study, a significant toxicity of single-walled carbon nanotubes was observed during normal embryogenesis: the nanotubes inhibited the angiogenesis of the chorioallantoic membrane (CAM) in chicken embryos. All exposed embryos died before 12 days of incubation, suggesting a severe effect.

Analytical solutions and validation of electric field and dielectrophoretic force in a bio-microfluidic channel

In a microbiological device, cell or particle manipulation and characterization require the use of electric field on different electrodes in several configurations and shapes. To efficiently design microelectrodes within a microfluidic channel for dielectrophoresis focusing, manipulation and characterization of cells, the designer will seek the exact distribution of the electric potential, electric field and hence dielectrophoresis force exerted on the cell within the microdevice. In this paper we describe the approach attaining the analytical solution of the dielectrophoretic force expression within a microchannel with parallel facing same size electrodes present on the two faces of channel substrates, with opposite voltages on the pair electrodes. Simple Fourier series mathematical expressions are derived for electric potential, electric field and dielectric force between two distant finite‐size electrodes. Excellent agreement is found by comparing the analytical results calculated using MATLAB™ with numerical ones obtained by Comsol. This analytical result can help the designer to perform simple design parametric analysis. Bio‐microdevices are also designed and fabricated to illustrate the theoretical solution results with the experimental data. Experiments with red blood cells show the dielectrophoretic force contour plots of the analytical data matched to the experimental results.

Real-time continuous dielectrophoretic separation of malignant cells

The present design introduces an optimized version of a microfluidics chip that uses dielectrophoresis phenomenon as a method of separation of the abnormal cells from the blood stream. Negative and positive dielectrophoretic forces (DEP) generated by a non-uniform electric field are engaged to separate the normal blood cells from the malignant ones. By fine tuning the parameters of the electric field different types of abnormal cells are isolated.

Microfluidic device fabrication with serigraphy technique

This article provides the design and fabrication details of a new technique to build a microfluidic device with two parallel substrates and a silicone gasket. The fabrication process uses screen printing technology offering fast and low-cost microdevices without the need for high-cost fabrication equipment and special photoresist processes. Hermetic microfluidic channels of 300 µm width and 50 µm height having parallel facing electrodes on two substrates are made with simple serigraphy technique using silicone rubber. The fabricated devices were experimentally tested for detection and characterization of polystyrene particles and living cells by negative and positive dielectrophoresis. The reported technique enables simple manipulation, centering, detection and characterization of living cells at low and high frequencies.

Droplet evaporation in capillary bridges

The demand for precise and accurate medical instruments that are also cost-effective drove the design towards the concept of Lab-on-a-Chip. These miniature systems are usually built on a single die and are able to perform multiple test through the manipulation of minimum amounts of analytes and markers. Such chips have significantly changed the way the bio-tests are carried out. However, significant challenges associated with such tests are still to be addressed. The phenomena occurring in the capillary bridges drew the attention of the scientific community from the beginning of the nineteenth century and experiments were extensively carried out.© 2008 ASME