RESUMO
Recently it has been proposed to use sensors based on genetically engineered reporter cells to perform continuous online water monitoring. Here we describe the design, assembly and performance of a novel flow-through device with immobilized genetically modified yeast cells that produce a fluorescent protein upon stimulation with diclofenac whose intensity is then detected by fluorescence microscopy. Although other devices employing immobilized cells for the detection of various analytes have already been described before, as novelty our system allows safe enclosure of the sensor cells, and thus, to obtain fluorescent signals that are not falsified by a loss of cells. Furthermore, the yeast cells are prevented from being released into the environment. Despite the safe containment, the immobilized reporter cells are accessible to nutrients and analytes. They thus have both the ability to grow and respond to the analyte. Both in cell culture medium and standardized synthetic wastewater, we are able to differentiate between diclofenac concentrations in a range from 10 to 100 µM. As particularly interesting feature, we show that only the biologically active fraction of diclofenac is detected. Nowadays, contamination of wastewater with diclofenac and other pharmaceutical residues is becoming a severe problem. Our investigations may pave the way for an easy-to-use and cost-efficient wastewater monitoring method.
Assuntos
Anti-Inflamatórios não Esteroides/análise , Técnicas Biossensoriais , Diclofenaco/análise , Proteínas de Fluorescência Verde/metabolismo , Saccharomyces cerevisiae/metabolismo , Águas Residuárias/análise , Poluentes Químicos da Água/análise , Células Imobilizadas/metabolismo , Proteínas de Fluorescência Verde/genética , Dispositivos Lab-On-A-Chip , Saccharomyces cerevisiae/genéticaRESUMO
An efficient algorithm for modeling dispersive media in finite-difference time-domain methods is presented. It is based on the auxiliary differential equation method for treatment of Lorentz media with an arbitrary number of relaxations. The algorithm shows excellent accuracy of second order in time and space and is efficient in both memory requirements and computational effort.