Functionalization And Application Of Magnetic Nanoparticles Based On Click Chemistry

Magnetic nanoparticles are well-established nanomaterials with diameter below 20 nm exhibiting interesting size-dependent superparamagnetism. In the past decades, magnetic nanoparticles have become a hot research topic and attracted great interest because of their potentially very useful applications. Because of their low toxicity and ability to be manipulated by an external magnetic force, magnetic nanoparticles have been widely applied in magnetic resonance imaging (MRI), targeted drug delivery, magnetic separation of DNA, proteins, and cells, and cancer treatments by hyperthermia and immunoassays.The main work of this paper focuses on the design, synthesis, characterization, and application study of the magnetic nanocomposites. We try our best to combine nano technology, biochemistry and spectroelectrochemisry. This paper concludes following aspects:Chapter 1:IntroductionIntroduce the scheme, features and current study situation of the magnetic nanoparticles. The systhesis methods, traits, and biosensing in magnetic nanoparticles are summarized, as well as the click chemistry, its application in magnetic nanoparticles.Chapter 2:Synthesis, Characterization and Application of Multiwalled Carbon Nanotubes Tethered with Magnetic Nanoparticles via Click ChemistryIn this work we describe a novel, facile method for the decoration of multiwalled carbon nanotubes (MWNTs) with nearly monodisperse y-Fe2O3 nanoparticles and their potential application in magnetic resonance imaging (MRI) and drug delivery. The tethering of the nanoparticles was achieved by the initial activation of the surface of carboxylic acid-MWNTs with alkyne groups, followed by the attachment ofγ-Fe2O3 nanoparticles functionalized with the azide group via click chemistry. Various characterization methods were used to confirm the formation of well-definedγ-Fe2O3 and show that they were tethered to the walls of the MWNTs. The tethered y-Fe2O3 nanoparticles imparted magnetic characteristics to the MWNTs and guide transportation in the direction of an externally applied magnetic field. Furthermore, we found that the y-Fe2O3/MWNTs nanocomposites could be used as enhanced MRI contrast regents. In view of drug delivery, temperature stimuli-responsive lipid bilayer, didecyldimethylammonium chloride (DDAC), was coated onto the surface of y-Fe2O3/MWNTs and small molecule phenol red was selected as drug model. The experimental results show that the y-Fe2O3/MWNTs/DDAC nanocomposites are suitable for the stable encapsulation of low-molecular-weight compounds, which can be released upon irradiation with temperature stimuli, indicating that can be used as an excellent drug delivery nanosystem.Chapter3:Magnetically Switchable Bioelectrocatalytic System Based on Ferrocene Grafted Iron Oxide NanoparticlesA simple and versatile method for the introduction of redox unites onto the surface of magnetic nanoparticles has been developed based on "click" chemistry. Azide functionalized Fe2O3 magnetic nanoparticles were synthesized and further reacted with ethynylferrocene via Cu (I)-catalyzed azide alkyne 1,3-dipolar cycloaddition (CuAAC) reaction. The functionalized magnetic nanoparticles were characterized using a powder X-ray diffractometer (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscope (FTIR), and vibrating sample magnetometer (VSM). The resulting materials have properties of both magnetism and electrochemistry, and the electrochemical properties of the nanoparticles are dependent on the features of ethynylferrocene, while the magnetic properties remain independent of ethynylferrocene. Because of the magnetism of Fe2O3 nanoparticles and the electrocatalytic activity of ferrocene unites, a recyclable, magneto-switchable bioelectrocatalytic system for glucose oxidation in the presence of glucose oxidase is developed by alternate positioning of an external magnet, and the system has a linear response for glucose biosensing over the range of 1.0-10.0 mM.Chapter 4:Magnetically Switchable and Enzyme Controllable Bioelectrocatalytic System Based on Ferrocene Grafted Iron Oxide Nanoparticles Based on chapter 3, ferrocene grafted iron oxide nanoparticles were prepared by alkyne group functionalized ferrocene reacted with azide functionalized magnetic nanoparticles via the "click" chemistry. Transmission microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and X-Ray Diffraction (XRD) were used to characterize the Fe2O3/ferrocene nanocomposites. The ferrocene groups covalently grafted magnetic nanocomposites turned out to own a relatively high contrast, fast electron transfer rate and showed great catalytic properties. Because of the magnetism of Fe2O3 nanoparticles and the electrocatalytic activity of ferrocene unites, a recyclable, magneto-switchable bioelectrocatalytic system is developed by alternate positioning of an external magnet. Moreover, the system is also can be switched off while the lipase enzyme was added into the system based on the catalyzing the hydrolysis of amide chemical bonds.