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Surface Potentials: The Unexplored Way to Develop Sensors for Small Organic Ions and Large Biomolecules

Luc J. Nagels 

University of Antwerp, Department of Chemistry, Groenenborgerlaan 171, Antwerp 2020, Belgium


Many surfaces develop potentials when they contact solutions containing ionized substances. Very often, intermolecular attractions between the surface materials and the ionized substances are the basis of these "non-Faradaic" potentiometric phenomena. Until now, potentiometric sensing has made little use of the phenomenon to determine small organic ions and large biomolecules. Some reasons for this slow evolution are the lack of good theoretical models, and the lack of synthetic receptor molecules to attract small organics and large biomolecules to the specific surfaces used in potentiometry. Our group developed equipment to screen potentiometric electrode coatings for the determination of ionizable organics, using HPLC and CE. This equipment speeds up coating testing and allows one to perform measurements on less available but important (bio-)organics. Organic acids, oligonucleotides, amines, aminoalcohols, farmaceutical drugs, analgesic drugs, and proteins have been dealt with sofar. The electrode coatings that are most successful are the so-called "liquid membrane" types, based on PVC. When macrocyclic or podant host molecules are incorporated, the best recognized organic substances can be determined with extremely low detection limits. These host molecules are very efficient for the determination of a very important class of hydrophilic compounds. This approach is shown to work also for large biomolecules such as oligonucleotides. Another way of decreasing detection limits for the hydrophilic compounds is to increase the hydrophilicity of the electrode coating surface. For proteins, we used antibodies linked to the surface of conductive polymers as a recognition strategy. Applications of the electrode coatings will be shown in application for detection in HPLC and CE, as well as links will be given to DNA- and proteome chip technology.


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Related papers

Presentation: Keynote lecture at SMCBS 2003 Workshop, by Luc J. Nagels
See On-line Journal of SMCBS 2003 Workshop

Submitted: 2003-10-06 20:14
Revised:   2009-06-08 12:55