A potentiometric biosensor for rapid on-site disease diagnostics.

Quantitative point-of-care (POC) devices are the next generation for serological disease diagnosis. Whilst pathogen serology is typically performed by centralized laboratories using Enzyme-Linked ImmunoSorbent Assay (ELISA), faster on-site diagnosis would infer improved disease management and treatment decisions. Using the model pathogen Bovine Herpes Virus-1 (BHV-1) this study employs an extended-gate field-effect transistor (FET) for direct potentiometric serological diagnosis. BHV-1 is a major viral pathogen of Bovine Respiratory Disease (BRD), the leading cause of economic loss ($2 billion annually in the US only) to the cattle and dairy industry. To demonstrate the sensor capabilities as a diagnostic tool, BHV-1 viral protein gE was expressed and immobilized on the sensor surface to serve as a capture antigen for a BHV-1-specific antibody (anti-gE), produced in cattle in response to viral infection. The gE-coated immunosensor was shown to be highly sensitive and selective to anti-gE present in commercially available anti-BHV-1 antiserum and in real serum samples from cattle with results being in excellent agreement with Surface Plasmon Resonance (SPR) and ELISA. The FET sensor is significantly faster than ELISA (<10 min), a crucial factor for successful disease intervention. This sensor technology is versatile, amenable to multiplexing, easily integrated to POC devices, and has the potential to impact a wide range of human and animal diseases.

Impedimetric immunosensor for the detection of circulating pro-inflammatory monocytes as infection markers.

Circulating blood monocytes belong to the first line of defense against pathogens and inflammation. Monocytes can be divided into three populations defined by the expression of the cell surface molecules, CD 14 and CD 16. The CD 14(++) CD 16(-) cells, called "classical" monocytes, represent 85% to 95% of the total monocytes in a healthy person whereas CD 14(-) CD 16(+), called "proinflammatory" monocytes, are found in greater numbers in the blood of patients with acute inflammation and infectious diseases. This increase in the concentration of proinflammatory monocytes can be a good indicator of an infectious state. This study presents an immunosensor based on impedance detection for specific cell trapping of classical and proinflammatory monocytes. The grafting of specific antibodies (CD 14 or CD 16) was based on the use of mixed SAM associated with protein G. Each step of the functionalization was characterized by electrochemical methods, quartz crystal microbalance and atomic force microscopy. Faradaic electrochemical impedance spectroscopy and voltametric analysis confirmed the success of the modification process with a surface coverage reaching 92% for the antibody layer. The increase in the deposited mass at each step of the modification process confirmed this results revealing that one protein G in two was bound to an antibody. The cell trapping capacity, evaluated by the variation in the film resistance using non-faradaic impedance spectroscopy revealed that the cell trapping is selective, depending on the specific antibody grafted and quantitative with the range of detection being 1000 to 30,000 infected cells. This range of detection is consistent with the application targeted.

Electrochemical behavior of indolone-N-oxides: relationship to structure and antiplasmodial activity.

Indolone-N-oxides exert high parasiticidal activity at the nanomolar level in vitro against Plasmodium falciparum, the parasite responsible for malaria. The bioreductive character of these molecules was investigated using cyclic voltammetry and EPR spectroelectrochemistry to examine the relationship between electrochemical behavior and antimalarial activity and to understand their mechanisms of action. For all the compounds (37 compounds) studied, the voltammograms recorded in acetonitrile showed a well-defined and reversible redox couple followed by a second complicated electron transfer. The first reduction (-0.88V