A biosensor system to monitor waterborne pathogens; coupling immunomagnetic capture and magnetically stabilized fluid bed technologies to detect Giardia cysts

Previous researchers have successfully demonstrated the effectiveness of Immunomagnetic capture of waterborne pathogens in batch processes. For small mass microbes, such as polio viruses, continuous processing has also been successful. When larger entities, such as Giardia cysts and Cryptosporidium oocysts, were attempted, inconsistent results were obtained. This is primarily due to hydrodynamic effects, resulting in receptor-ligand disruption between the paramagnetic microspheres (beads) and these larger cysts. The authors have demonstrated capture efficiencies for Giardia cysts of 100 percent using a Magnetically Stabilized Fluid Bed (MSFB) contactor at flow rates nearly an order of magnitude higher than previously reported. The collection of the bead/cyst complex is on larger spheres that act as a moving filter in a low shear field. The flow field was independently verified through residence time studies, magnetic field mapping and pressure drop measurements to identify both fluidization and stability regions. Nearly ideal fluid-solid countercurrent contact can be brought about. Bubbling and jetting in the fluid phase can be eliminated and thus one can speak much more confidently of the average lifetime of an element of fluid or of a solid particle moving through the bed