Development of novel bioanalytical assays with two integrated signaling schemes and exploitation of bio-conjugated sensing materials

Part One of the thesis describes the development and implementation of novel sensors that integrate two detection methods into one single chip, enabling two independent measurements of biologically significant analytes such as glucose and bacterial toxins. A major problem associated with conventional sensors is the limitations of the single sensing surface, which proves to be inadequate in many cases to provide sufficient information and minimize false reading for decision making. Dual detection is demonstrated as an effective and new approach for quantitation of specific targets in biological substances. The implementation of integrated detection mechanisms allows for independent measurements of two signals, enhances information gathering in the analyte measurement, and opens new avenues for developing analytical methods to eliminate false signal readings.;The dual sensor developed for glucose employed two distinctive mechanisms for signal generation; one with micropatterned electrocatalytic PB arrays for cathodic measurement, and the other with a redox-activated glucose oxidase layer for anodic measurement. The dual sensor for detection of bacterial protein toxin SEB also employed two integrated detection schemes: electrochemical and fluorescent detection on PDMS microchannels. The compact platform leads to the design of a disposable sensing device. Additionally, dual detection of cholera toxin (CT) was explored based on ligand-receptor interaction and liposome signal amplification. Two types of reporting molecules were encapsulated into GM1 functionalized liposomes, intended for sequential fluorescent and electrochemical detection of CT. Part Two describes exploitation of new sensing materials, an important aspect in sensor research to improve the sensing performance since the availability of functional materials is typically the bottleneck for sensor development. This part explored synthesis and characterization of novel sensing materials using diacetylenic amphiphiles and bolaamphiphiles. The synthetic lipids can self assemble to form microstructures exhibiting unique optical and electrochemical properties. A colorimetric biosensor for CT was developed using amino-acid derivatized diacetylenic amphiphiles. The results from the characterization of a series of redox-functionalized microstructures indicate that the formation of redox functionalized microstructure allowed for facile electrochemical communication between the aggregates and electrodes. The method offered simplicity and structural stability while allowing integration of the desirable functionality with ease.