(387a) Non-Optical Biomolecular Detection in Human Serum Using Interfacial Electrokinetic Transduction

Development of rapid, sensitive and portable detection systems are important for effective detection of diseases in developing countries, biowarfare/anti-terrorism applications, environmental monitoring, and for basic biological research. Biosensors are analytical devices that detects an analyze of interest by combining biological sensing elements with physiochemical transducers. While current biosensing methods are capable of sensitively detecting a variety of target analytes in a laboratory setting, there are inherent difficulties in developing low-cost portable biosensors for point-of-care diagnostics using traditional optical, mass, or electroanalytical-based signal transducers. It is therefore important to develop new biosensing transducer elements for recognizing binding events at low cost and in portable environments. This approach utilizes a novel electrical method that combines a laminar liquid-liquid interact with alternating current (ac) electrokinetics. A bioreaction occurs at the co-flowing liquid interface while an ac electric field is simultaneously applied, displacing the interface across the flow channel. The magnitude and direction of displacement is directly related to both the applied frequency and interfacial electrical properties. Biosensor detection is based on interfacial electrokinetic transduction; binding changes the interfacial electrical properties, which is electrically traduced and detected by monitoring the frequency response of the liquid interface. In this manner, the liquid interface serves as both the substrate for specific binding, and transducer for biomolecular recognition. Furthermore, by implementing electrical impedance spectroscopy (EIS), the interfacial position can be monitored non-optically. Utilizing EIS, the biosensor becomes label-free and non-optical; the magnitude of impedance, which can be monitored on a computer screen, becomes the readable signal. Here, a non-optical, label-free biosensor, which can detect bimolecular reactions in human serum is created by pairing interfacial electrokinetic transduction and electrical impedance spectroscopy.