A poly(dimethylsiloxane) (PDMS) microfluidic chip surface was modified by multilayer-adsorbed and heat-immobilized poly(vinyl alcohol) (PVA) after oxygen plasma treatment. The reflection absorption infrared spectrum (RAIRS) showed that 88% hydrolyzed PVA adsorbed more strongly than 100% hydrolyzed one on the oxygen plasma-pretreated PDMS surface, and they all had little adsorption on original PDMS surface. Repeating the coating procedure three times was found to produce the most robust and effective coating. PVA coating converted the original PDMS surface from a hydrophobic one into a hydrophilic surface, and suppressed electroosmotic flow (EOF) in the range of pH 3-11. More than 1,000,000 plates/m and baseline resolution were obtained for separation of fluorescently labeled basic proteins (lysozyme, ribonuclease B). Fluorescently labeled acidic proteins (bovine serum albumin, beta-lactoglobulin) and fragments of dsDNA phiX174 RF/HaeIII were also separated satisfactorily in the three-layer 88% PVA-coated PDMS microchip. Good separation of basic proteins was obtained for about 70 consecutive runs.
We have developed a new experimental system based on a microfluidic chip to determine severe acute respiratory syndrome coronavirus (SARS-CoV). The system includes a laser-induced fluorescence microfluidic chip analyzer, a glass microchip for both polymerase chain reaction (PCR) and capillary electrophoresis, a chip thermal cycler based on dual Peltier thermoelectric elements, a reverse transcription-polymerase chain reaction (RT-PCR) SARS diagnostic kit, and a DNA electrophoretic sizing kit. The system allows efficient cDNA amplification of SARS-CoV followed by electrophoretic sizing and detection on the same chip. To enhance the reliability of RT-PCR on SARS-CoV detection, duplex PCR was developed on the microchip. The assay was carried out on a home-made microfluidic chip system. The positive and the negative control were cDNA fragments of SARS-CoV and parainfluenza virus, respectively. The test results showed that 17 positive samples were obtained among 18 samples of nasopharyngeal swabs from clinically diagnosed SARS patients. However, 12 positive results from the same 18 samples were obtained by the conventional RT-PCR with agarose gel electrophoresis detection. The SARS virus species can be analyzed with high positive rate and rapidity on the microfluidic chip system.
Myrica rubra Sieb. et Zucc. leaves are commonly used as an astringent, antidiarrheic, and analgesics in folk medicine in China. In the present study, the analgesic activity of myricetin, a major compound in Myrica rubra Sieb. et Zucc. leaves was evaluated in vivo. The analgesic effect of myricetin was tested by a serial of models, such as acetic acid-induced writhing response, formalin-induced paw licking and hot plate test. The sedative activity was evaluated by pentobarbital-induced sleep time. Platelet aggregation induced by collagen and arachidonic acid was also performed in vitro. Myricetin showed a significant inhibition on chemical nociceptive models such as the acetic acid-induced writhing response and the licking time on the late phase in the formalin test in a dose-dependent manner, but did not manifest a signicant effect in hot plate test. Myricetin was also not able to increase the sleeping time induced by pentobarbital, which further indicated that the analgesic effect of myricetin was unrelated to sedation. In addition, myricetin inhibited the content of PGE2 in the peritoneal fluid and platelet aggregation induced by collagen and arachidonic acid in vitro. These results collectively demonstrated that myricetin possessed potent analgesic activity, which was related with peripheral analgesia, but, not with the opioid system. Myricetin may be a potent COX-1 inhibitor with anti-platelet activity.
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