Development of biosensors for detection of heavy metal ions and bacteria in liquids

Contamination of supplied and recreational waters by bacterial phatogens and heavy metal ions results in numerous diseases. In recent years, biosensors have emerged as an attractive alternetive for detection of heavy metal ions and bacteria. A biosensor is a portable analytical device that uses biological molecules to detect selectively just one compound within a mix of many others. In general, a biosensor consists of two functional components; a recognition element to provide selective/specific binding with the measurands and a transducer component for signaling the binding event. In this thesis, we aimed to develop a sensor for the detection of heavy metal ions such as cadmium, zinc, copper and cobalt and Enterococcus Faecalis. Due to the best temperature coefficient, AT-cut quartz crystals vibrating in the thickness sheaar mode with a fundementally resonant frequency of 10 MHz with gold (Au) electrodes were used as transducer. For comparison, phthalocyanine and tris (8-hydroxyquimoline) aluminum (Alq3) were used as sensing layer. The developed biosensor is composed of an antibody functionalized cut quartz crystals. The response and recovery time of biosensor were estimated from the measured dynamic response characteristics. Another important aspect of sensor performance, which is repeatability were also investigated.