Penicillin biosensor based on a capacitive field-effect structure functionalized with a dendrimer/carbon nanotube multilayer

• Published in: Biosensors & bioelectronics 2009-10, Vol.25 (2), p.497-501
• Main Authors: Siqueira, José R., Abouzar, Maryam H., Poghossian, Arshak, Zucolotto, Valtencir, Oliveira, Osvaldo N., Schöning, Michael J.
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensors; Biotechnology; Capacitive electrolyte-insulator-semiconductor sensor; Carbon nanotubes; Dendrimers; Dendrimers - chemistry; Electric Capacitance; Electrochemistry - instrumentation; Electrodes; Equipment Design; Equipment Failure Analysis; Field-effect devices; Fundamental and applied biological sciences. Psychology; Layer-by-layer; Methods. Procedures. Technologies; Nanotechnology - instrumentation; Nanotubes, Carbon - chemistry; Nanotubes, Carbon - ultrastructure; Penicillin biosensor; Penicillins - analysis; Transducers; Various methods and equipments
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2009.07.007

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. 55mV/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 5.0μM to 25mM, was evaluated for an EIS-NT with the penicillinase enzyme immobilized onto the surfaces, via constant–capacitance (ConCap) measurements, achieving a sensitivity of ca. 116mV/decade. The presence of the nanostructured PAMAM/SWNT LbL film led to sensors with higher sensitivity and better performance.