New trends in ion-selective electrodes - Electrochemical Sensors, Biosensors and Their Biomedical Applications - page 108

instrumentally imposed. While ion-selective electrodes historically have been passive
sensing devices where such control is not possible, much of current research deals with
non-classical response principles where concentration polarizations take place at the
sample-membrane interface. Galvanostatic and voltammetric control of ion-selective
membranes is now also possible and offers an exciting path to novel approaches in extrac-
tion/complexation-based sensing. The key application discussed above has been the devel-
opment of reversible sensors for the anticoagulant heparin and its antidote protamine, but
many other important sensing principles may be developed since the tools are now in
place to fabricate reversible sensors on the basis of otherwise irreversible reactions.
This fi eld is therefore at an exciting stage. Ion-selective electrodes have a proven
track record in terms of clinical and biomedical analysis, with a well-developed the-
ory and a solid history of fundamental research and practical applications. With novel
directions in achieving extremely low detection limits and instrumental control of the
ion extraction process this fi eld has the opportunity to give rise to many new bioana-
lytical measurement tools that may be truly useful in practical chemical analysis.
4.7 ACKWNOWLEDGMENTS
The authors would like to thank the National Institutes of Health (GM071623 and
EB002189) and the National Science Foundation (BIO8-004-00) for fi nancial support
of their research.
4.8 REFERENCES
1. R.P. Buck and E. Lindner, Tracing the history of selective ion sensors. Anal. Chem. 73 , 88A-97A (2001).
2. E. Bakker, P. Buhlmann, and E. Pretsch, Carrier-based ion-selective electrodes and bulk optodes. 1.
General characteristics. Chem. Rev. 97 , 3083-3132 (1997).
3. P. Buhlmann, E. Pretsch, and E. Bakker, Carrier-based ion-selective electrodes and bulk optodes. 2.
Ionophores for potentiometric and optical sensors. Chem. Rev. 98 , 1593-1687 (1998).
4. E. Bakker, P. Buhlmann, and E. Pretsch, Polymer membrane ion-selective electrodes - what are the lim-
its? Electroanalysis 11 , 915-933 (1999).
5. E. Bakker and M. Telting-Diaz, Electrochemical sensors. Anal. Chem. 74 , 2781-2800 (2002).
6. E. Bakker, P. Buhlmann, and E. Pretsch, The phase-boundary potential model. Talanta 63 , 3-20 (2004).
7. S. Mathison and E. Bakker, Effect of transmembrane electrolyte diffusion on the detection limit of car-
rier-based potentiometric ion sensors. Anal. Chem. 70 , 303-309 (1998).
8. T. Sokalski, A. Ceresa, T. Zwickl, and E. Pretsch, Large improvement of the lower detection limit of
ion-selective polymer membrane electrodes. J. Am. Chem. Soc. 119 , 11 347-11 348 (1997).
9. E. Bakker and E. Pretsch, Potentiometric sensors for trace-level analysis. TrAC, Trends Anal. Chem. 24 ,
199-207 (2005).
10. R.D. Johnson and L.G. Bachas, Ionophore-based ion-selective potentiometric and optical sensors. Anal.
Bioanal. Chem. 376 , 328-341 (2003).
11. J. Bobacka, J., A. Ivaska, and A. Lewenstam, Potentiometric ion sensors based on conducting polymers.
Electroanalysis 15 , 366-374 (2003).
12. E. Lindner and R.P. Buck, Microfabricated potentiometric electrodes and their in vivo applications.
Anal. Chem. 72 , 336A-345A (2000).