| Chemical sensors have emerged as a dynamic way of identifying and quantifying specific analytes of interests in clinical diagnosis, environmental monitoring, process control and most recently homeland security. The need for reliable, ultra sensitive, and fast responsive sensors continues to grow as the complexity of analytes increases. One major challenge in sensor design can be directly related to the insufficient understanding of the underlying recognition mechanism at the sensor-analyte interface. This limitation, which derives from the process of trial and error that is generally used in conventional sensor designs significantly limits sensor sensitivity and selectivity. The central goal of this research is to test the concept of rational sensor design. The concept relies on correlating the molecular structures of analyte and/or sensing material to sensor signals. We tested the concept of rational design using two classes of sensors: (i) chemical sensors for volatile organic compounds (VOCs) using conducting electroactive polymers and; (ii) biochemical sensors for endocrine disrupting compounds (EDCs).; A significant step in rational sensor design is to generate mathematical relationships between the physicochemical properties of the analytes and the sensor response using quantitative structure-activity relationships (QSAR). QSARs were generated for primary alcohols using physicochemical properties (such as molecular weight and volatility) to model the interactions of the analytes with sensor surfaces, while sensor responses were used to depict analyte activity. Results showed the importance of inter- and/or intra-molecular forces governing the interactions of VOCs in sensor responses. For biochemical sensors, instead of using computer aided rational design, we choose a mechanistic approach. In that case, we employed electrochemical techniques to first understand the role of structure in endocrine disrupting activity and then used the knowledge gained from the mechanistic study to develop novel biosensors for EDCs, specifically alkylphenols. The biosensor, which employs underpotentially deposited silver as the redox probe gave limit of detection as low as 10−2ppb. |
