In this research supported by the Analytical and Surface Chemistry Program, Professor Huixin He and her group seek an extensive understanding of the fundamental mechanism of performance enhancement in a conducting polymer/carbon nanotube composite network, and exploit the highly enhanced composite networks for biosensor applications, especially for multiplex chemical warfare agent detections. By exploiting the salient chemistry of nucleic acids, the surface chemistry and electronic structures of commercially available single walled carbon nanotubes (SWNTs) will be engineered to facilitate the production of highly conductive and highly crystallized interfacial conducting polymers in the composite. The high quality interfacial conducting polymer, will act as an array of conducting polymer nanojunctions, and in turn, modulate the electronic contact junctions between the SWNTs in the composite network. The fundamental knowledge learned will lead to the development of a new molecular detection platform, which will synergistically combine the merits of conducting polymer nanojunctions and carbon nanotube networks. The fast conductance-switch property of the conducting polymer nanojunctions will allow rapid, sensitive, and importantly, selective molecular detection. The remarkable electronic and mechanic properties of carbon nanotubes will confer the conducting polymer nanojunctions with chemical and mechanical stability. The self-assembling capability of the carbon nanotube networks will make the nanojunction fabrication scalable and low cost.
This project focuses on development of a novel sensitive multiplex chemical warfare agent detection system, which is of national interest. Given the widespread applications of conducting polymers in numerous analytical platforms, the proposed activities will have far reaching scientific and economic impacts on sensor development of trace-level monitoring of pollutants, drugs, and pathogenic bacteria for health care, homeland security, agriculture, and food industries. The educational plan will bring nanoscience tools and concepts to a wide range of students on a campus known as the most diverse in the nation. The inherently interdisciplinary nature of this research will produce students with exceptional training in nanotechnology, surface chemistry, and molecular sensing. Research activities designed for undergraduates, and high school students will promote more gifted minority students into the nanoscience ranks. Extensive outreach to the Newark area, a minority-dominated region, will raise the public awareness of the impact of nanoscience on technology.
, and exploiting the highly enhanced composite networks for chemical/biosensor applications. With this support, we discovered that depending on the electronic structures of the carbon nantoubes and surface chemistry, the polymerization process of conducting polymers can be dramatically speeded up (4,500 times faster). More importantly, the quality of the composite was synergistically improved, as demonstrated by the significantly enhanced electrical performance and stabilization under UV irradiation of the obtained nanocomposite. Such enhanced electrical performance and stabilization effects are of academic interest and practical importance. Short lifetime has been a significant problem in devices consisting of organic (polymer) materials. Incorporation of carbon nanotubes into such devices may help develop organic photonic systems with longer life spans and thus commercial values. Furthermore, we designed and studied in a molecular level to control the orientation of a redox center and their influences on the electron transfer between redox enzymes and electrode supports. Finally, we also systematically investigated the influence of contact resistance existed in CNT/conducting polymer networks and between the composite networks and the electrode surface in electrocatalytic reduction of oxygen and glucose oxidation. These fundamental studies provide deeper understanding and guidance to construct efficient electrode materials for glucose sensors and practical enzyme-based biological fuel cell in the future. The multifunctional nanocomposites with high quality have been explored for developing extremely sensitive and selective molecular detection platforms, including a novel non-oxidative approach to electrochemically detect neurotransmitter dopamine for molecular diagnosis of Parkinson's disease; a miniaturized sensitive and selective neuron toxin detection platform for homeland defense, a sensitive glucose and oxygen detection electrodes, a single cell cancer detection platform for early diagnosis of cancer; and an extremely sensitive and selective iron (Fe (III)) sensor (in preparation), which holds a great potential for the studies of carbon sequestration in remote oceans, therefore ecology and climate change. Inspired by the intrinsic low 1/f noise of graphene compared to carbon nanotubes, we also extend our sensing platform from carbon nanotubes to graphene based sensing. With the help of this support, two simple and efficient approaches were developed to directly exfoliate graphite particles to solution processible graphene sheets. The rapid and scalable approaches produce high quality graphene sheets, enabling a broad spectrum of applications by low-cost solution processing, including molecular detection devices. The remarkable discoveries results in one provisional patent, nine peer-reviewed articles, one book chapter. There are still other eight articles in preparation. Through this project, three Ph. D students, three master students, and nine undergraduate students have been accepting extensively scientific training. One Ph.D student and master student have joined companies performing their independent and team research. Another two Ph. D and two master students will have their defense end of this semester or this summer. All the ACS SEED students, joined universities and colleges for higher education. During the funding period, the PI also provided vivid nanoscience and nanotechnology demonstrations to high school students and teachers, such as Hillel Yeshiva High School (Jersey city, NJ) in 2008, Arts High (Newark city) in 2009, and McNair Academic High School in 2010. This project also provides excellent hands-on research opportunities to eight ACS SEED high school students for during summers of 2008-2011, which dramatically inspired their motivation for higher education in nanosciene and nanotechnology.
