Growth of Carbon, Boron Nitride and ZnO Nanotubes for Biosensors Jason P. Moscatello, Jiesheng Wang, Benjamin Ulmen, Vijaya K. Kayastha, Ming Xie, Samuel L. Mensah, Shun Wu, Archana Pandey, Chee Huei Lee, Abhishek Prasad, Yoke Khin Yap * Department of Physics, Michigan Technological University, Houghton, Michigan 49931, USA * Corresponding author: ykyap@mtu.edu Nanotubes have significant portions of their atoms located at the surfaces and represent the future of biological devices. With such small dimensions, sensitivities and applications previously impossible are being made real. Not all nanomaterials are currently at the same level of proficiency, however. Carbon nanotubes are a mature, easily grown and controlled nanostructure, but boron nitride and zinc oxide are still coming into their own. Yet progress in all three species of nanotubes is making applications easier than before. Introduction Nanotubular structures are highly interdisciplinary in their use. Here we review the properties and applications of three particularly noteworthy nanotubes for biological applications: carbon, boron nitride and zinc oxide nanotubes. The ability to effectively create and test applications depends ultimately on the ease and control of synthesis; therefore the current state of growth for each of these nanotubes developed in our group will be discussed, focusing on ease and control of growth parameters such as size, diameter, number of walls, etc. Carbon Nanotubes Since the discovery of their structural properties (1), carbon nanotubes (CNTs) have attracted great attention due to their high aspect ratio, superior mechanical and electronic properties and high chemical stability, while additional properties make them suitable particularly for biological application. For example, the ability to elastically buckle can protect delicate samples during probing (2), single-walled carbon nanotubes (SWCNTs) have been shown to be able to move into living cells (3) and every atom is on their surface (4). Together, these characteristics make CNTs versatile components for biological applications, as the following review will show. Wong et al. used an oxidizing process to open the tips of multi-walled carbon nanotubes (MWCNTs) for use as a functionalized probe. The oxidation also formed carboxyl groups at the open ends which were then coupled to amide groups via carbodiimide chemistry to form selective bonds. The now-functionalized MWCNT was used as a probe in tapping mode atomic force microscope (AFM) experiments on a patterned self-assembled monolayer (SAM) substrate. The AFM phase image clearly show differences in phase between the two distinct SAM regions due to varying adhesion forces between each substrate SAM and the functionalized MWCNT AFM probe tip (2). ECS Transactions, 3 (26) 1-13 (2007) 10.1149/1.2753275, copyright The Electrochemical Society 1