RESUMO
A low-cost method for carbon nanotubes (CNTs) network production from solutions on flexible polyethylene naphthalate substrates has been adopted to prepare high quality and well characterized SWCNT bundle layers to be used as the active layer in chemiresistor gas sensors. Two types of SWCNTs have been tested: pristine SWCNTs, deposited from a surfactant solution, and covalently functionalized SWCNTs, deposited from a dimethyl-acetamide solution. The humidity effects on the sensitivity of the SWCNTs network to NH3 have been investigated. The results show that relative humidity favors the response to NH3, confirming recent theoretical predictions. The COOH-functionalized sample displays the largest response owing to both its hydrophilic nature, favoring the interaction with H2O molecules, and its largest surface area. Compared to data available in the literature, the present sensors display a remarkable sensitivity well below the ppm range, which makes them quite promising for environmental and medical applications, where NH3 concentrations (mostly of the order of tens of ppb) have to be detected.
RESUMO
In this research we investigated the response of DNA-modified carbon nanotubes in the presence of thrombin and albumin. We analyzed aptamer-carbon nanotube interactions by Raman spectroscopy and by analyzing resistance after each step of biosensor assembly. We have shown that intensity of G-band decreases due to interconnection of aptamer and carbon nanotube and this also evaluates in decrease of sensor structure resistance. The response of the sensor exposed to thrombin and albumin differs essentially from each other. This fact serves as the prerequisite for the development of a highly selective biosensor. Results of this investigation can be used in creation of new generation of personal health monitoring systems.
