We have developed a sensitive method for the detection of specific genes simultaneously. First, DNA was amplified by a novel asymmetric multiplex PCR with universal primer(s). Second, the 6-carboxytetramethylrhodamine (TAMRA)-labeled PCR products were hybridized specifically with oligonucleotide microarrays. Finally, matched duplexes were detected by using a laser induced fluorescence scanner. The usefulness of this method was illustrated by analyzing severe acute respiratory syndrome (SARS) coronavirus RNA. The detection limit was 100 copies/μL. The results of the asymmetric multiplex nested reverse transcription-PCR were in agreement with the results of the microarray hybridization, while no hybridization signal was lost like what has happened with applicons from the symmetric amplifications. This reliable method can be applied to the identification of other microorganisms, screening of the genetic diseases, and other fields.

Developing new methods and technologies in order to pattern neurons into regular networks is of utmost scientific interest in the field of neurological research. An efficient method here is developed for trapping neurons and constructing ordered neuronal networks on bioelectronic chips by using arrayed negative dielectrophoretic (DEP) forces. A special bioelectronic chip with well defined positioning electrode arrays was designed and fabricated on silicon substrate. When a high frequency AC signal was applied, the cell positioning bioelectronic chip (CPBC) is able to provide a well-defined non-uniform electric field, and thus generate negative DEP forces. The parameters, such as size of positioning electrode, conductivity of working solution, amplitude and frequency of power signal and cell concentration, were investigated to optimize the performance of the CPBC. When the neuron suspension was added onto the energized bioelectronic chip, the neurons were immediately trapped and quickly formed the predetermined pattern. Neurons may adhere and then be cultured directly on the CPBC, and show good neuron viability and neurite development. The formation of the ordered neuronal networks after two-week culture demonstrates that negative dielectrophoretic force assisted construction of ordered neuronal networks is effective, and it could be used to assist in monitoring functional activities of neuronal networks.

and three genes related to cell wall biogenesis were induced, indicating that the cell membrane and cell wall were also affected by the presence of polyene antibiotics. It was observed that the pleiotropic drug resistance network in yeast cells was activated after exposure to amphotericin B, possibly contributing to the acquisition of amphotericin B resistance. Part of the gene expression alteration measured by microarray was confirmed by quantitative RT–PCR.

Nanocrystal up-conversion phosphors (UCP), ytterbium- and erbium-codoped lanthanum molybdate (La2(MoO4)3:Yb,Er), were prepared for the first time for potential uses in bioassays especially in biochip-based analysis. The La2(MoO4)3:Yb,Er nanocrystals, with an average diameter of 50nm, were prepared via a hydrothermal method. After being annealed at 800℃ for 5h, strong emission of these nanocrystals was observed when excited with a 980nm infrared (IR) laser. Fluorescent intensity of these nanocrystals is much stronger than that of bulk materials. Down-conversion spectrum of the nanocrystal phosphors was also examined. Two-photon excitation mechanism was proposed for the up-conversion process. Factors affecting the up-conversion fluorescent intensity were also studied. The particlesizedependent phenomenon was first observed for nanocrystal UCP, and the mechanism was discussed.

Dielectrophoretic separation of E. coli bacteria from a mixture containing blood cells followed by electronic lysis was performed on a microfabricated bioelectronic chip by applying a series of high voltage pulses. Bacteria were isolated from human blood cells using dielectrophoresis to direct the prokaryotic cells to 25 microlocations directly above individually-addressable platinum microelectrodes on a chip. The surface of the chip, including the platinum electrodes and the rest of the non-metallized area, was coated with an agarose permeation layer to prevent the direct contact of cells with the electrode and also to minimize the non-specific adhesion of cells and lysate to the chip surface. The platinum electrodes were 80μm in diameter and had a center-to-center spacing of 200μm. Analysis of the electronically-lysed bacterial mixture showed that it contained a spectrum of nucleic acids including RNA, plasmid DNA and genomic DNA. The lysate was then further analysed by electronically-enhanced nucleic acid hybridization on different bioelectronic chips made for specific DNA and RNA hybridization analyses. Dielectrophoretic cell separation followed by electronic lysis has significant potential as a sample preparation process for chip-based electronic-hybridization assays in an integrated DNA/RNA analysis system.