Preparation, Properties And Application Of Functional Carbon Nano-particles

Carbon material, a kind of relatively common and special materials in earth, cannot only form the hardest material, diamond, but also can form a flexible graphite. Theresearch and applications of carbon material have been the forefront of technologicalinnovation domain, especially carbon nanotubes （CNTs） and graphene, due to theirexcellent performance in electromagnetism, optical, thermodynamics and mechanics,have shown good prospect of application in chemistry, physics, materials science,biology, and many other fields, having caused a huge response to the scientificcommunity and risen in the research upsurge of carbon materials, and become thefocus of research in the various fields. Carbon nanoparticles also have the similarstructure of graphite, but most of the research is based on the smaller carbonnanoparticles （carbon quantum dot）. However, the properties and application researchof the larger carbon nanoparticles have not been reported.This thesis is devoted to the functionallization of carbon nanoparticles. Combinedwith our research in fluorescence sensing, an important design of the development ofanalytical chemistry is to a specific target analyte and produce a measurable signal.Due to high sensitivity, good selectivity and facility for detection, the fluorescencesensor has made great development in recent years. The part of signal conduction isone of the most important factors to the performance of fluorescent sensor, thereforethe research and development of conductive material with good selectivity, highsensitivity, stability and reversibility is worth exploring and perfecting. Based oncarbon nanotubes and graphene as the sensing platform, here we study the properties ofcarbon nanoparticle and the interaction mechanism between carbon nanoparticles andnucleic acid probe to design carbon nanoparticles as fluorescence sensing platform, atthe same time, we also explore the further development of the carbon nanoparticles incatalytic. The main works are as follows:（1） Using a way of burning candle to get carbon ash of insoluble water, weobtain the carbon nanoparticles dispersion in water by our improved method, then thedetailed characterization analysis are carried on through SEM, AFM, DLS, XPS,Raman, FTIR and pH titration. The results show that the prepared carbon nanoparticleshave a relatively good content of oxygen, basically one of every six carbon is oxidizedthrough the calculation.This method is a simple, effective to prepare oxidized carbonnanoparticles, which may realize industrialized production, and it also lay a solid theoretical foundation for our next application.（2） Combined with single-labeled fluorescent probes, we use prepared carbonnanoparticles to construct fluorescent sensing platform, Moreover, the interactionmechanism between fluorescent probes and carbon nanoparticles is studied. Theunderlying sensing mechanism, in contrast to those of common carbon nanostructuresand metal nanoparticles, is based on competition of electrostatic repulsion and π-πstacking interactions.Thus it can be very well to distinguish single-stranded DNA anddouble-stranded DNA. According to these principles, we design sensing platformwhich can realize high sensitivity, high selectivity detection of DNA, Hg²⁺, adenosinetriphosphate （ATP） and thrombin （Thrombin）. Besides the sensing system need not thedouble mark. Meantime, it also ruled out instability caused by non-markers embeddedagent result in not repetitive and low detection sensitivity. Moreover it is a system offluorescence enhancement, thus the effect of solution and other factors on thefluorescence quenching are eliminated. The sensitivity and accuracy of detection areincreased. At the same time, the interaction mechanism of π-π stacking andelectrostatic repulsion between carbon nanoparticles and DNA, as well as theapproximation spherical structure of carbon nanoparticle, which are beneficial toimprove sensitivity of detection.（3） After binding small molecule, the anisotropic of the aptamer changes a little,thus it is difficult to achieve a high sensitive detection. Here, according to theinteraction mechanism of DNA binding to the carbon nanoparticles on the surface by π-πstacking interactions in the third chapter, we combined carbon nanoparticles andfluorescence anisotropy technique to develop a method of signal amplifyingfluorescence anisotropy on the basis of the theory and experiment. The high sensitivityand selectivity detection for ATP and apyraze is realized. This is the first reported thebinding of carbon nano-materials and fluorescence anisotropy applied in detection. Atthe same time, the approach is extremely versatile in that both signal-off and signal-ondetections can be easily realized. The effectiveness, simplicity and diversity of thecCNPs-FA approach will enable the development of a class of probes for rapid, sensitive,and selective detection of biomolecule.（4） The unburnt carbon nanoparticles modified by some DNA and surfactant （SDS,Tween20, DTAB） can dispersion in water easily. Carbon nanoparticle can catalyticperoxidase to oxidize the3,3’,5,5’-tetramethylbbenzidine （TMB）: thereby producing acolor change, in contrast to other carbon nanomaterial, carbon nanoparticles as catalystis not time-consuming, non-expensive, high catalytic efficiency and so on. On the basisof the catalytic properties of carbon nanoparticles modified by different surfactant, carbon nanoparticles modified SDS with the highest catalytic activity is selected forthe detection of H₂O₂. We also believe that this principle can be used to other analyticsassociated with H₂O₂for detection.