Functionally Engineered Carbon Nanotubes-Peptide Nucleic Acid Nanocomponents
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J13.7.1
Functionally Engineered Carbon Nanotubes-Peptide Nucleic Acid Nanocomponents Krishna V. Singh1, Xu Wang1, Rajeev R. Pandey2, Roger Lake2, Cengiz S. Ozkan3 and Mihrimah Ozkan2,* 1
Department of Chemical and Environmental Engineering 2 Department of Electrical Engineering 3 Department of Mechanical Engineering University of California Riverside, Riverside, CA 92521 * Corresponding author: [email protected]
ABSTRACT Conjugation of carbon nanotubes (CNTs) with biomolecules having molecular recognition results in highly functionalized CNTs, which serve as the templates for self-assembly of novel nanomaterials. Here, we report the synthesis of novel nanocomponents by conjugating single walled carbon nanotubes (SWNTs) with peptide nucleic acid (PNA), an artificial DNA analogue by using carbodiimide coupling. Scanning electron microscopy (SEM) is used as a primary tool for their characterization. SEM micrographs confirm the formation of desired structures. We also modeled and simulated the SWNT-PNA interface using the PM3 semi-empirical package in Gaussian03 RevB.03 program suite for electron transfer and found that there exists an extended set of orbitals. INTRODUCTION Due to their excellent chemical and electrical properties, carbon nanotubes (CNTs) have been used to realize a number of nanodevices [1, 2], but there is a need for integrating these devices into large structures. Self assembly by molecular recognition provides us a robust yet cost effective alternative for this purpose [3]. Nucleic acids especially DNA, because of their inherent molecular recognition, nanoscale dimensions and easy chemical manipulations are the best candidates for imparting molecular recognition to CNTs [4, 5]. But use of DNA is limited due to its charged backbone, low thermal and chemical stability. To overcome these limitations of DNA, this work aims to utilize the superior chemical and structural properties of its artificial analogue, peptide nucleic acid (PNA). PNA has an uncharged backbone, which is made from repeating N-(2-aminoethyl)-glycine units linked by peptide bonds [6]. The comparison between PNA and DNA structure is shown in Figure 1. Few of the advantages of PNA are shorter probe length, stronger hybridization, higher thermal stability, greater resistance to acidic conditions and enzyme degradation, and higher shelf life [7]. In this work we synthesized and characterized SWNT-PNA nanocomponents.
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Figure 1: Comparison of PNA and DNA structures MATERIALS AND METHODS There is very little work done to realize the potential of PNA outside the scope of conventional biology [8]. This work aims to exploit PNA’s ease of functionalization by conjugation to develop SWNT-PNA bioconjugates. As received SWNTs (Sigma Aldrich) were oxidized by refluxing with 1 M HNO3 for 12 hrs. After sonication in acidic mixture and filtration, the CNT cake was suspended in dimethylformamide (DMF, 99.5%) and incubated for 30 min in 2 mM 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride and 5 mM Nhydroxys
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