| Carbon nanotubes have attracted much attention and molded a new area ofnanotechnology and material science because of their fascinating and extraordinarystructure, electronic and mechanical properties since discovered in 1991. Differentmethods of synthesizing, isolating, and purifying carbon nanotubes have beendeveloped in the last few years. Also, potential applications of functionalized carbonnanotubes are envisaged. Pioneering studies have reported on the use of carbonnanotubes as separation carrier in capillary electrophoresis (CE). It also appears thatcarbon nanotubes are a very promising carrier system for future applications in drugdelivery and targeting therapy. Based on the research background, we are currentlyexploring the use of functionalized carbon nanotubes as chiral stationary phase formicrochip electrophoresis (MCE) which is regarded as a further miniaturized versionof classic CE, while offers great advantages compared with CE. Further, with toxin asthe cargo protein, we present an exploration of the biological functions of theinternalized toxin protein. This dissertation has great original and frontier innovationand includes five chapters, which are introduced separately as the following:In chapter one, three aspects of the literature about the investigation weresummarized. Firstly, the unique structure properties of carbon nanotubes wereconcisely introduced. Secondly, the methods of functionalization of carbon nanotubeswith biomolecules were summarized. Finally, the application of carbon nanotubesserving as biosensors, separation materials and living systems were summarized. Theoutline and innovation of this dissertation were also proposed.In chapter two, the voltammetric behavior of tryptophan was studied at a glassycarbon electrode modified with single-walled carbon nanotubes (SWNT). In 0.1 MC6H4CO2HCO2K-HCl buffer solution (pH=2.5), the SWNT-modified electrode showshigh electrocatalytic activity toward oxidation of tryptophan. The peak currentincreases linearly with the concentration of tryptophan in the range of 1.2×10-6 to 3.0×10-4. The detection limit is 2.5×10-7 M (signal-to-noise ratio of 3). The resultsindicate two-electron and two-proton transfer was involved in the electrode reactionprocess.In chapter three, a novel method of chiral separation based on protein-stationaryphase immobilized in poly(methyl methacrylate) (PMMA) microfluidic chip wasdeveloped. Bovine serum albumin (BSA), which was conjugated with the shortenedcarboxylic SWNT, was employed as the chiral selector. Successful separation oftryptophan enantiomers was achieved in less than 70 s with a resolution factor of 1.35utilizing a separation length of 32 mm. This is the first example of chiral separationbased on SWNT-BSA conjugates as stationary phase immobilized in microchipchannel. The stability of the stationary phase in the channel was examined by MCEwith laser-induced fluorescence (LIF) detection. Factors that influence the chiralseparation resolution were examined. Under the optimized conditions, the proposedmodified chip revealed adequate repeatability concerning run-to-run. These resultsshow that the use of SWNT-BSA conjugates within microfluidic channels holds greatpromise for a variety of analytical schemes.In chapter four, the recombined ricin A chain protein (RTA) was transported intoliving L-929 mouse fibroblasts by multiwalled carbon nanotubes (MWNT) and thetoxin protein was found to perform biological functions evidenced by cancer celldeath induction. The protein-nanotube conjugates were prepared by spontaneouslyadsorbing of RTA on the side of the highly water-soluble acid-oxidized MWNT.Using immunofluorescence analysis, the transported RTA via nanotube carriers insidethe cell was visualized by confocal microscopy. The effects of the incubation time andconcentrations of the conjugates on cell death were also evaluated. General effectswere observed on several mammalian cell lines. This is the first example of the toxinprotein killing cancer cells by carbon nanotube molecular transporters. We thenpresent that selective cancer destruction can be achieved by functionalization ofMWNT with anti-HER-2 antibody. The transporting capabilities of carbon nanotubes combined with suitable functionalization chemistry can open exciting new venues fordrug delivery and cancer therapy.In chapter five, the conclusion of the above work has been obtained firstly, andthen some research directions that can be further achieved have been proposed. |
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