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Self-Assembled Films of Dendrimers and Metallophthalocyanines as FET-Based Glucose Biosensors
Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, São Carlos, SP 13560-970, Brazil
Instituto de Ciências Exatas, Universidade Federal de Itajubá, CP 50, Itajubá, MG 37500-903, Brazil
* Author to whom correspondence should be addressed.
Received: 31 August 2011; in revised form: 20 September 2011 / Accepted: 20 September 2011 / Published: 3 October 2011
Abstract: Separative extended gate field effect transistor (SEGFET) type devices have been used as an ion sensor or biosensor as an alternative to traditional ion sensitive field effect transistors (ISFETs) due to their robustness, ease of fabrication, low cost and possibility of FET isolation from the chemical environment. The layer-by-layer technique allows the combination of different materials with suitable properties for enzyme immobilization on simple platforms such as the extended gate of SEGFET devices enabling the fabrication of biosensors. Here, glucose biosensors based on dendrimers and metallophthalocyanines (MPcs) in the form of layer-by-layer (LbL) films, assembled on indium tin oxide (ITO) as separative extended gate material, has been produced. NH3+ groups in the dendrimer allow electrostatic interactions or covalent bonds with the enzyme (glucose oxidase). Relevant parameters such as optimum pH, buffer concentration and presence of serum bovine albumin (BSA) in the immobilization process were analyzed. The relationship between the output voltage and glucose concentration shows that upon detection of a specific analyte, the sub-products of the enzymatic reaction change the pH locally, affecting the output signal of the FET transducer. In addition, dendritic layers offer a nanoporous environment, which may be permeable to H+ ions, improving the sensibility as modified electrodes for glucose biosensing.
Keywords: glucose biosensor; layer by layer; field effect transistor; enzyme immobilization
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Vieira, N.C.; Figueiredo, A.; de Queiroz, A.A.; Zucolotto, V.; Guimarães, F.E. Self-Assembled Films of Dendrimers and Metallophthalocyanines as FET-Based Glucose Biosensors. Sensors 2011, 11, 9442-9449.
Vieira NC, Figueiredo A, de Queiroz AA, Zucolotto V, Guimarães FE. Self-Assembled Films of Dendrimers and Metallophthalocyanines as FET-Based Glucose Biosensors. Sensors. 2011; 11(10):9442-9449.
Vieira, Nirton C.S.; Figueiredo, Alessandra; de Queiroz, Alvaro A.A.; Zucolotto, Valtencir; Guimarães, Francisco E.G. 2011. "Self-Assembled Films of Dendrimers and Metallophthalocyanines as FET-Based Glucose Biosensors." Sensors 11, no. 10: 9442-9449.