Preparation, Materialization And Properties Of Fluorescent Carbon Dots

Carbon dots are the most popular nanomaterials in recent years among the nanocarbon family, including fullerene, the carbon nanotube and graphene. This kind of nanomaterial has successfully overcome some defects of traditional semiconductor quantum dots. It is highly evaluated not only for the excellent optical performance and small size effect, but also the great biocompatibility and ease to achieve surface functionalization. Carbon dots can be widely used in the field of biochemical sensing, fluorescent probes, environmental testing, photocatalytic technology, drug carriers and so on. In this dissertation, we mainly deseribe the Preparation and application of CDs. Firstly, hetero atom doping carbon dots with brilliant fluorescent quantum yield and other fluorescence properties were prepared by citric acid and amino compounds. Secondly, the surface functionalized CDs were applied to the detection of metal ions and molecules. Lastly, the small molecule rhodamine based fluorescence probe immobilized to CDs, design and synthesis of a fluorescent molecular probe modified functional materials1 We synthesized two kinds of carbon dots using citric acid with 1, 2-ethylenediamine （NCD） and N-（b-aminoethyl）-g-aminopropyl methyldimethoxy silane （SiCD） respectively. The quantum yields of NCD and SiCD are as high as 65.5% and 55.4%. Both of NCD and SiCD can be obviously quenched by Hg2+ at fairly low concentrations. On this basis, two selective and sensitive fluorescence probes have been developed for the detection of trace Hg2+ in the aqueous media. The sensors could be applied for in vitro imaging of Hg+ ions in living cells with satisfying resolution.2 We investigated for the first time the fluorescence interactions between the methyldimethoxy silane functionalized SiCD and quercetin （QCT） in detail and have found QCT can selectively and sensitively detect QCT in aqueous solution. On this basis, a rapid, selective, and sensitive sensing method based on the SiCD fluorescence probe has been developed for the detection of trace QCT in water. A linear range of F455 versus QCT concentration was obtained within 0-40 μM, while the limit of detection of 79 nM was obtained.3 We report a simple, aqueous based synthesis approach preparing N2CD using citric acid with diethylenetriamine. The quantum yields of the N2CD are as high as 86%. A new strategy for constructing an FRET based ratiometric chemosensor for Al³⁺ detection was established and possessed both high sensitivity and selectivity by combining advantages of N2CD and QCT. The FRET ratiometric fluorescence approach is developed with N2CD as donor and QCT-Al conjugate as acceptor. I Moreover, the FRET ratiometric fluorescence system based on the N2CD /QCT-A1³⁺ was applied for fluorescent test papers with satisfying resolution.4 A rhodamine derivatives bearing cyanuric chloride （Rh-1） was synthesized, and has been proved as a selective fluorescent and colorimetric chemosensor for detecting Al+. Being capped with amino group, Rh-1 has been covalently linked on surface of N2CD and construct a new fluorescent detect platform （Rh-CD）. Rh-CD does not only keep the detection performence of Rh-1, but also have excellent water solubility and biocompatibility.