Point-of-Care Microelectronic Diagnostics for Early Phase Rickettsial Infections

摘要

Rickettsial diseases (RD) are widely distributed in the world and account for seasonal outbreaks and epidemics. The greatest challenge to clinicians is diagnosing RD at early phases when antibiotic therapy is most effective. This burgeoning problem is further compounded by the unavailability of rapid point-of-care (POC) diagnostics for RD. The focus of this poster will be development and optimization of dielectrophoresis-enhanced microfluidic impedance biosensing (DEP-e-MIB) assay to detect the pathogenic cells in sera. In DEP-e-MIB assays, pathogens are labeled with a DEP label (polystyrene beads) and then injected into the DEP-e-MIB chip for capture of the labeled pathogens and reading impedance changes at the interdigitated electrodes. We have seen detection down to 10^5 cells. However, minor reduction in nonspecific binding can lead to large increment in signal to noise ratio. Specifically, we show how to reduce in the non-specific binding of immunobeads to the electrodes through the choice of bead surface chemistry (epoxy, carboxylate, and aldehyde), and the co-immobilization of polyethylene glycol with antibodies at the electrodes and the beads. Further we also show how this non-specific binding is affected by the use of DEP.