Single-walled carbon nanotube-based biosensors for the detection of volatile organic compounds of lung cancer

Detection of volatile organic compounds (VOCs) in human breath to diagnose lung cancer is becoming an important method for widespread screening due to its convenient, rapid and low cost advantages. In this paper, experimental evidence for the detection of both polar and nonpolar VOCs molecules by organic materials functionalized single-walled carbon nanotubes (SWNTs) was investigated. To develop a high-selectivity SWNTs biosensor, nonpolymeric organic materials, tricosane (C23H48) and pentadecane (C15H32) were coated on the single-walled carbon nanotubes (SWNTs) and the prepared device was exposed to representative VOCs polar molecule 1,2,4-trimethybenzene (TMB) and nonpolar molecule decane separately. The results show that the resistance changes of SWNTs biosensor increased to 2.3% for decane and 7.2% for TMB after being functionalized by C23H48; meanwhile, the variation of 3.3% for decane and 5.1% for TMB was observed by C15H32-functionalized SWNTs. The results present that C23H48-functionalized SWNTs show pronounced sensitivity toward polar VOCs molecules, which can donate electrons to the SWNTs after being absorbed. This research is a further step toward the development of a simple and noninvasive diagnostic tool for the widespread screening of lung cancer via breath analysis. (C) 2011 Elsevier B.V. All rights reserved.