mathematical modeling of the sensor response. There is a lack of models for
impedimetric aptasensors, which is probably one reason for the low transfer to
commercial products.
In general, impedimetric biosensors are favored due to the possibility of label-free
measurements. But only non-faradaic measurement techniques are truly label-free,
and recent applications of non-faradaic impedimetric aptasensors show significant
lower sensitivities than faradaic impedimetric aptasensors. Thus, more research in
non-faradaic impedance sensors is needed.
Despite the doubt that aptamers are not suitable for the application in real
samples, their excellent performance in human serum and blood samples down
to the pM range has been shown by several researchers. However, the majority
of publications lack validation with real samples. As the work with real samples
might often not be possible, we recommend that calibration curves are taken
in spiked artificial matrices instead of buffer solution. Furthermore, we recommend
that instead of absolute signal values, relative values are plotted and normalized
to the electrode area or the number of aptamers to enable comparison of sensor
performance.
The full potential of impedimetric aptasensors has not yet been exploited.
However, the success of impedimetric aptasensors depends equally on the advances
in aptamer selection and synthesis, in impedimetric measurement techniques, and
in surface modifications and assay design. Besides other transducer types,
the potential of electrochemical biosensors is outstanding for the application
in miniaturized point-of-care devices.
Acknowledgments We thank SciGraphics (contact@scigraphics.de) for contributing the
illustrations for this chapter.
References
1. Rodriguez MC, Kawde AN, Wang J (2005) Aptamer biosensor for label-free impedance
spectroscopy detection of proteins based on recognition-induced switching of the surface
charge. Chem Commun 34:4267–4269. https://doi.org/10.1039/b506571b
2. Xu D, Xu D, Yu X, Liu Z, He W, Ma Z (2005) Label-free electrochemical detection for
aptamer-based array electrodes. Anal Chem 77(16):5107–5113. https://doi.org/10.1021/
ac050192m
3. de-los-Santos-Álvarez N, Lobo-Castañón MAJ, Miranda-Ordieres AJ, Tuñón-Blanco P (2008)
Aptamers as recognition elements for label-free analytical devices. TrAC Trends Anal Chem
27(5):437–446. https://doi.org/10.1016/j.trac.2008.03.003
4. Mascini M (2009) Aptamers in bioanalysis. Wiley, Hoboken
5. Hianik T, Wang J (2009) Electrochemical aptasensors - recent achievements and perspectives.
Electroanalysis 21(11):1223–1235. https://doi.org/10.1002/elan.200904566
6. Sassolas A, Blum LJ, Leca-Bouvier BD (2009) Electrochemical aptasensors. Electroanalysis
21(11):1237–1250. https://doi.org/10.1002/elan.200804554
7. Ferapontova EE, Gothelf KV (2011) Recent advances in electrochemical aptamer-based
sensors. Curr Org Chem 15(4):498–505
Impedimetric Aptamer-Based Biosensors: Principles and Techniques
37
impedimetric aptasensors, which is probably one reason for the low transfer to
commercial products.
In general, impedimetric biosensors are favored due to the possibility of label-free
measurements. But only non-faradaic measurement techniques are truly label-free,
and recent applications of non-faradaic impedimetric aptasensors show significant
lower sensitivities than faradaic impedimetric aptasensors. Thus, more research in
non-faradaic impedance sensors is needed.
Despite the doubt that aptamers are not suitable for the application in real
samples, their excellent performance in human serum and blood samples down
to the pM range has been shown by several researchers. However, the majority
of publications lack validation with real samples. As the work with real samples
might often not be possible, we recommend that calibration curves are taken
in spiked artificial matrices instead of buffer solution. Furthermore, we recommend
that instead of absolute signal values, relative values are plotted and normalized
to the electrode area or the number of aptamers to enable comparison of sensor
performance.
The full potential of impedimetric aptasensors has not yet been exploited.
However, the success of impedimetric aptasensors depends equally on the advances
in aptamer selection and synthesis, in impedimetric measurement techniques, and
in surface modifications and assay design. Besides other transducer types,
the potential of electrochemical biosensors is outstanding for the application
in miniaturized point-of-care devices.
Acknowledgments We thank SciGraphics (contact@scigraphics.de) for contributing the
illustrations for this chapter.
References
1. Rodriguez MC, Kawde AN, Wang J (2005) Aptamer biosensor for label-free impedance
spectroscopy detection of proteins based on recognition-induced switching of the surface
charge. Chem Commun 34:4267–4269. https://doi.org/10.1039/b506571b
2. Xu D, Xu D, Yu X, Liu Z, He W, Ma Z (2005) Label-free electrochemical detection for
aptamer-based array electrodes. Anal Chem 77(16):5107–5113. https://doi.org/10.1021/
ac050192m
3. de-los-Santos-Álvarez N, Lobo-Castañón MAJ, Miranda-Ordieres AJ, Tuñón-Blanco P (2008)
Aptamers as recognition elements for label-free analytical devices. TrAC Trends Anal Chem
27(5):437–446. https://doi.org/10.1016/j.trac.2008.03.003
4. Mascini M (2009) Aptamers in bioanalysis. Wiley, Hoboken
5. Hianik T, Wang J (2009) Electrochemical aptasensors - recent achievements and perspectives.
Electroanalysis 21(11):1223–1235. https://doi.org/10.1002/elan.200904566
6. Sassolas A, Blum LJ, Leca-Bouvier BD (2009) Electrochemical aptasensors. Electroanalysis
21(11):1237–1250. https://doi.org/10.1002/elan.200804554
7. Ferapontova EE, Gothelf KV (2011) Recent advances in electrochemical aptamer-based
sensors. Curr Org Chem 15(4):498–505
Impedimetric Aptamer-Based Biosensors: Principles and Techniques
37