A 5-kg time-resolved luminescence photometer with multiple excitation sources

Sensitive detection of influenza viruses with Europium nanoparticles on an epoxy silica sol-gel functionalized polycarbonate-polydimethylsiloxane hybrid microchip

In an effort to develop new tools for diagnosing influenza in resource-limited settings, we fabricated a polycarbonate (PC)-polydimethylsiloxane (PDMS) hybrid microchip using a simple epoxy silica sol-gel coating/bonding method and employed it in sensitive detection of influenza virus with Europium nanoparticles (EuNPs). The incorporation of sol-gel material in device fabrication provided functionalized channel surfaces ready for covalent immobilization of primary antibodies and a strong bonding between PDMS substrates and PC supports without increasing background fluorescence. In microchip EuNP immunoassay (µENIA) of inactivated influenza viruses, replacing native PDMS microchips with hybrid microchips allowed the achievement of a 6-fold increase in signal-to-background ratio, a 12-fold and a 6-fold decreases in limit-of-detection (LOD) in influenza A and B tests respectively. Using influenza A samples with known titers, the LOD of influenza µENIA on hybrid microchips was determined to be ~10(4) TCID50 titer/mL and 10(3)-10(4) EID50 titer/mL. A comparison test indicated that the sensitivity of influenza µENIA enhanced using the hybrid microchips even surpassed that of a commercial laboratory influenza ELISA test. In addition to the sensitivity improvement, assay variation was clearly reduced when hybrid microchips instead of native PDMS microchips were used in the µENIA tests. Finally, infectious reference viruses and nasopharyngeal swab patient specimens were successfully tested using μENIA on hybrid microchip platforms, demonstrating the potential of this unique microchip nanoparticle assay in clinical diagnosis of influenza. Meanwhile, the tests showed the necessity of using nucleic acid confirmatory tests to clarify ambiguous test results obtained from prototype or developed point-of-care testing devices for influenza diagnosis.

Luminescence screening of enrofloxacin and ciprofloxacin residues in swine liver after dispersive liquid-liquid microextraction cleanup

A luminescence method was developed to screen residues of enrofloxacin (ENRO) and its metabolite, ciprofloxacin (CIPRO), in swine liver. Target analytes were extracted in acetonitrile/1.5% trifluoroacetic acid/NaCl, cleaned up by dispersive liquid-liquid microextraction (DLLME), and finally detected by terbium-sensitized luminescence (TSL) using a time-resolved luminescence photometer. CIPRO yielded slightly lower TSL response than ENRO, so a common threshold was derived from CIPRO and applied to both fluoroquinolones. Among 37 samples randomly spiked with CIPRO or ENRO up to 1 μg/g, all 19 samples spiked above the 500 ng/g tolerance were correctly screened as positive with no false negatives, but 3 of 18 samples spiked below 500 ng/g were classified as positive. This method minimized the use of chlorinated solvents and significantly improved sample throughput.