Proteins field-effect transistors

Yau ST, Qian G (2005) A prototype protein field-effect transistor. Appl Phys Lett 86 103508-103511... 

Maraccio G, Biasco A, Visconti P, Bramanti A, Pompa PP, Calabi F, Cingolani R, Rinaldi R, Comi S, Di Felice R, Molinari E, Verbeet MP, Canters GW (2005) Towards protein field-effect transistors report and model of a prototype. Adv Mater 17 816-822... 

This volume of the series focuses on the photochemistry and photophysics of metal-containing polymers. Metals imbedded within macromolecular protein matrices form the basis for the photosynthesis of plants. Metal-polymer complexes form the basis for many revolutionary advances occurring now. The contributors to many of these advances are authors of chapters in this volume. Application areas covered in this volume include nonlinear optical materials, solar cells, light-emitting diodes, photovoltaic cells, field-effect transistors, chemosensing devices, and biosensing devices. At the heart of each of these applications are metal atoms that allow the assembly to function as required. The use of boron-containing polymers in various electronic applications was described in Volume 8 of this series. 

The acid-base behavior of proteins can reveal some important properties with respect to both their composition (selectivity) and their concentration (sensitivity). The most direct way to exploit these acid-base properties is to make use of acid-base titration, Titrant should be added somehow and the resulting change in pH should be measured. Since the ion-sensitive field-effect transistor (ISFET) is suitable for fast (and local) pH detection, an ISFET can be used for protein titration if the protein to be detected can be immobilized in a membrane, deposited on top of the device. Advantages are the small amount of protein necessary for the characterization owing to the small membrane volume, and the relatively short time needed to perform a full titration. 

Siwy et al. demonstrated the utility of a single conically shaped gold nanotube that was embedded in a mechanically and chemically robust polymeric membrane [142]. They reported biofunctionalized conical Au nanotubes, which are potentially useful for obtaining highly sensitive and selective protein biosensors. So et al. introduced a single walled carbon nanotube field effect transistor (SWNT-FET) combined with aptamers as an alternative to the corresponding antibody [143]. 

Principle of setup of a biosensor. B = bioactive layer, containing recognition molcules (enzymes, antibodies, receptor proteins) T = transducer, a probe sensitive to the primary signal produced by the recognition process (potentiometric or amperometric electrode, FET (Field-effect transistor), piezoelectric crystal) A amplifier, R = recorder. 

Maehashi, K., Katsura, T., Kerman, K., Takamura, Y., Matsumoto, K., Tamiya, E. (2007). Label-free protein biosensor based on aptamer-modified carbon nanotube field-effect transistors. Anal Chem 79, 782-787. 

T. Goda,Y. Miyahara, Detection ofmicroenvironmental changes induced by protein adsorption onto self-assembled monolayers using an extended gate-field effect transistor, Anal. Chem. 82 (2010) 1803-1810. 

Other sensor platforms have also been explored, such as surface plasmon resonance, field-effect transistors, other optical/spectrophotometric methods, for example, Raman spectroscopy and chemiluminescence, and electrochemical techniques. Very recently, Cai et al. have demonstrated that arrays of carbon-nanotube tips with an imprinted nonconducting polymer coating can recognize proteins below the picograms per liter level, using electrochemical impedance spectroscopy. Devices for the specific recognition of human ferritin and human papillomavirus-derived E7 protein were described (Figure 34). 

---