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Sensing Reversible Protein-Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors.

Münzer AM, Seo W, Morgan GJ, Michael ZP, Zhao Y, Melzer K, Scarpa G, Star A - J Phys Chem C Nanomater Interfaces (2014)

Bottom Line: We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker.Binding affinities at different pH values were quantified, and the sensor's response at various ionic strengths was analyzed.Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS).

View Article: PubMed Central - PubMed

Affiliation: Institute for Nanoelectronics, Technische Universität München , Arcisstraße 21, 80333, Munich, Germany.

ABSTRACT
We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor's response at various ionic strengths was analyzed. Furthermore, protein "fingerprints" of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS).

No MeSH data available.


Transistor characteristics of a biotinylated SWNT FET before (black)and after (red) NeutrAvidin adsorption, measured at pH 3.4 (a) andat pH 6.3 (b). (c) Transfer characteristics of an unfunctionalizeddevice before (black) and after (red) NeutrAvidin adsorption measuredat pH 6.5. (d) Normalized sensor response (I0 – IP)/gm of pyrene-biotin-functionalized SWNT FET toward NeutrAvidin(blue) and streptavidin (gray) under different buffer concentrationsas a function of buffer pH. The protein response was measured in 1.6–2mM buffer (triangles) and 0.8–0.9 mM buffer (circles) concentrations.Error bars result from averaging responses of several devices. Thesolid lines represent sigmoidal Boltzmann fits.
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fig2: Transistor characteristics of a biotinylated SWNT FET before (black)and after (red) NeutrAvidin adsorption, measured at pH 3.4 (a) andat pH 6.3 (b). (c) Transfer characteristics of an unfunctionalizeddevice before (black) and after (red) NeutrAvidin adsorption measuredat pH 6.5. (d) Normalized sensor response (I0 – IP)/gm of pyrene-biotin-functionalized SWNT FET toward NeutrAvidin(blue) and streptavidin (gray) under different buffer concentrationsas a function of buffer pH. The protein response was measured in 1.6–2mM buffer (triangles) and 0.8–0.9 mM buffer (circles) concentrations.Error bars result from averaging responses of several devices. Thesolid lines represent sigmoidal Boltzmann fits.

Mentions: Additionally, pH-dependent measurementswith two other biotin-bindingproteins, NeutrAvidin and streptavidin, were performed. For each pHvalue, transfer curves were recorded before and after protein incubation.All protein incubations were conducted in 10 mM PBS buffer (pH 7)for 15 min. In contrast to measurements with CaptAvidin, however,sensors cannot be regenerated after binding to biotin; thus, eachmeasurement requires a new transistor. Typical transfer curves areshown in Figure 2. The curves in panels a andb were collected for biotinylated devices at buffer pH’s of3.4 and 6.3, respectively. We observed that the threshold voltageshift after NeutrAvidin incubation depends on the buffer pH (experimentswith streptavidin reveal the same trend, thus transfer characteristicsare not shown). For the experiment conducted at pH 3.4, the thresholdvoltage shifts toward more negative gate voltages and for pH 6.3 thethreshold voltage shifts in the opposite direction. This phenomenondoes not occur for experiments with unfunctionalized SWNT FETs asshown in Figure 2c. The ID–VG measurements in Figure 2c show an overall decrease in device conductanceand a slight tilt of the curve after protein adsorption, indicatingthat the mobility of the device is affected upon protein adsorption,a phenomenon which does not appear if a spacer provided by the functionalizationprevents unspecific protein adsorption onto the sidewalls of the carbonnanotubes.


Sensing Reversible Protein-Ligand Interactions with Single-Walled Carbon Nanotube Field-Effect Transistors.

Münzer AM, Seo W, Morgan GJ, Michael ZP, Zhao Y, Melzer K, Scarpa G, Star A - J Phys Chem C Nanomater Interfaces (2014)

Transistor characteristics of a biotinylated SWNT FET before (black)and after (red) NeutrAvidin adsorption, measured at pH 3.4 (a) andat pH 6.3 (b). (c) Transfer characteristics of an unfunctionalizeddevice before (black) and after (red) NeutrAvidin adsorption measuredat pH 6.5. (d) Normalized sensor response (I0 – IP)/gm of pyrene-biotin-functionalized SWNT FET toward NeutrAvidin(blue) and streptavidin (gray) under different buffer concentrationsas a function of buffer pH. The protein response was measured in 1.6–2mM buffer (triangles) and 0.8–0.9 mM buffer (circles) concentrations.Error bars result from averaging responses of several devices. Thesolid lines represent sigmoidal Boltzmann fits.
© Copyright Policy
Related In: Results  -  Collection

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fig2: Transistor characteristics of a biotinylated SWNT FET before (black)and after (red) NeutrAvidin adsorption, measured at pH 3.4 (a) andat pH 6.3 (b). (c) Transfer characteristics of an unfunctionalizeddevice before (black) and after (red) NeutrAvidin adsorption measuredat pH 6.5. (d) Normalized sensor response (I0 – IP)/gm of pyrene-biotin-functionalized SWNT FET toward NeutrAvidin(blue) and streptavidin (gray) under different buffer concentrationsas a function of buffer pH. The protein response was measured in 1.6–2mM buffer (triangles) and 0.8–0.9 mM buffer (circles) concentrations.Error bars result from averaging responses of several devices. Thesolid lines represent sigmoidal Boltzmann fits.
Mentions: Additionally, pH-dependent measurementswith two other biotin-bindingproteins, NeutrAvidin and streptavidin, were performed. For each pHvalue, transfer curves were recorded before and after protein incubation.All protein incubations were conducted in 10 mM PBS buffer (pH 7)for 15 min. In contrast to measurements with CaptAvidin, however,sensors cannot be regenerated after binding to biotin; thus, eachmeasurement requires a new transistor. Typical transfer curves areshown in Figure 2. The curves in panels a andb were collected for biotinylated devices at buffer pH’s of3.4 and 6.3, respectively. We observed that the threshold voltageshift after NeutrAvidin incubation depends on the buffer pH (experimentswith streptavidin reveal the same trend, thus transfer characteristicsare not shown). For the experiment conducted at pH 3.4, the thresholdvoltage shifts toward more negative gate voltages and for pH 6.3 thethreshold voltage shifts in the opposite direction. This phenomenondoes not occur for experiments with unfunctionalized SWNT FETs asshown in Figure 2c. The ID–VG measurements in Figure 2c show an overall decrease in device conductanceand a slight tilt of the curve after protein adsorption, indicatingthat the mobility of the device is affected upon protein adsorption,a phenomenon which does not appear if a spacer provided by the functionalizationprevents unspecific protein adsorption onto the sidewalls of the carbonnanotubes.

Bottom Line: We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker.Binding affinities at different pH values were quantified, and the sensor's response at various ionic strengths was analyzed.Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS).

View Article: PubMed Central - PubMed

Affiliation: Institute for Nanoelectronics, Technische Universität München , Arcisstraße 21, 80333, Munich, Germany.

ABSTRACT
We report on the reversible detection of CaptAvidin, a tyrosine modified avidin, with single-walled carbon nanotube (SWNT) field-effect transistors (FETs) noncovalently functionalized with biotin moieties using 1-pyrenebutyric acid as a linker. Binding affinities at different pH values were quantified, and the sensor's response at various ionic strengths was analyzed. Furthermore, protein "fingerprints" of NeutrAvidin and streptavidin were obtained by monitoring their adsorption at several pH values. Moreover, gold nanoparticle decorated SWNT FETs were functionalized with biotin using 1-pyrenebutyric acid as a linker for the CNT surface and (±)-α-lipoic acid linkers for the gold surface, and reversible CaptAvidin binding is shown, paving the way for potential dual mode measurements with the addition of surface enhanced Raman spectroscopy (SERS).

No MeSH data available.