title: Penicillin biosensor based on a capacitive field-effect structure functionalized with a dendrimer/carbon nanotube multilayer.
abstract: Silicon-based sensors incorporating biomolecules are advantageous for processing and possible biological recognition in a small, reliable and rugged manufactured device. In this study, we report on the functionalization of field-effect (bio-)chemical sensors with layer-by-layer (LbL) films containing single-walled carbon nanotubes (SWNTs) and polyamidoamine (PAMAM) dendrimers. A capacitive electrolyte-insulator-semiconductor (EIS) structure modified with carbon nanotubes (EIS-NT) was built, which could be used as a penicillin biosensor. From atomic force microscopy (AFM) and field-emission scanning electron microscopy (FESEM) images, the LbL films were shown to be highly porous due to interpenetration of SWNTs into the dendrimer layers. Capacitance-voltage (C/V) measurements pointed to a high pH sensitivity of ca. 55 mV/pH for the EIS-NT structures. The biosensing ability towards penicillin of an EIS-NT-penicillinase biosensor was also observed as the flat-band voltage shifted to lower potentials at different penicillin concentrations. A dynamic response of penicillin concentrations, ranging from 5.0 microM to 25 mM, was evaluated for an EIS-NT with the penicillinase enzyme immobilized onto the surfaces, via constant-capacitance (ConCap) measurements, achieving a sensitivity of ca. 116 mV/decade. The presence of the nanostructured PAMAM/SWNT LbL film led to sensors with higher sensitivity and better performance.
authors: Instituto de Física de São Carlos, USP, CP 369, 13560-970 São Carlos, Brazil.
authors: José R
authors: JR
authors: Siqueira
authors: Maryam H
authors: MH
authors: Abouzar
authors: Arshak
authors: A
authors: Poghossian
authors: Valtencir
authors: V
authors: Zucolotto
authors: Osvaldo N
authors: ON
authors: Oliveira
authors: Michael J
authors: MJ
authors: Schöning
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D050091:Dendrimers / Q000737:chemistry*; D025802:Electric Capacitance; D004563:Electrochemistry / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D036103:Nanotechnology / Q000295:instrumentation*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010406:Penicillins / Q000032:analysis*; D014159:Transducers
chemical_list: D050091:Dendrimers; D037742:Nanotubes, Carbon; D010406:Penicillins