1. Biosensor Development Aptasensor for a small organic molecule, TCA Peter Pfeiffer Bioengineering and Bioelectrochemistry Group University Rovira i Virgili Tarragona, 02.03.2005 Supervisor: Dr. Ioanis Katakis

2. Facing the Problem Low odour threshold (8-20 ppt) Abundance of other compounds Arising from the nature of the problem the sensor has to be sensitive easy to use cheap!

3. Components of Biosensors Biosensors are devices that use biological reactions for detecting target analytes. They couple a biological recognition element (interacting with the target analyte) with a physical transducer that translates the biorecognition event into a useful electrical signal.

4. Antibodies-Aptamers Avoiding animal systems Can be functionalised No batch to batch differences Higher stability Higher affinity/selectivity Antibodies and aptamers can bind the relative target with high affinity and specificity. However, aptamers offer advantages that make them very promising in analytical and diagnostic applications.

5. My work Detection methods Fluorescent intensity, quenching, anisotropy Colorimetric Quartz Crystal Microbalance Atomic Force Microscope- cantilever Surface Plasmon Resonance Molecular beacons Enzyme Linked Immunoassay Need of added agents Detection limit in the μM-nM range New, simple electrochemical detection method: Impedance Spectroscopy

6. R C R CT Warburg element Potential Double layer Bulk Diff.

7. What problems I shall face Sensitivity – Detection limit Odour threshold: 8-20 ppt –pM range My system will be capable to deal with this (?) Amplification Good knowledge of my electrical circuit model of my system to target usefully signal transduction.

8. Future Interests Recognition – Affinity Signal generation Signal transduction 100% electron-photon photon-electron conversion Photon semiconductors –photonic crystals Illumination techniques, LED Sensor development Photonics - optoelectronics Energy conservation Quantum theory Ultraviolet catastrophe