Preparation And Bioapplications Of Carbon Dots

Carbon dots(Cdots),as a kind of fluorescent materials,have broad applications in biomedicine,biosensor and optoelectronics.In this paper,we synthesised carbon dots of super fluorescence characteristics,and then developed probes based on carbon dots for detection of biomolecules.In the first part,we report a facile-green strategy for synthesising large-scale of fluorescent N,P doped carbon dots(N,P-Cdots)with an absolute quantum yield of 66.08 % by the simple one-step thermal decomposition.In the synthesis process,citric acid was selected as carbon precursor and tryptophan(Trp)was N-doped and passivation reagent,and organic polar solvents with high boiling point,i.e.ethylene glycol and glycerol,were used as reacting medium.TEM,FITR,XPS,UV Abosorption Spectroscopy and Fluorescence Excitation-Emission Spectrometer have been utilized to characterize its structure and optical properties.And then we took advantage of the superior fluorescence characteristic of the as-prepared N,P-Cdots to selectively detect the cancer mark of Carcinoembryonic antigen(CEA)with high sensitivity based on the fluorescence quenching mechanism.Finally we successfully developed a strategy for supersensitive fluorimetric detection of cancer markers using the N,P-Cdots which have a good consistency and stability.In the second part,we report a strategy to synthesis Gd-doped carbon dots(Gd-Cdots)of super-high quantum yield with a microwave assisted hydrothermal method.The Gd-Cdots,with a diameter of 4~8 nm,can be purified easily with conventional centrifugal techniques.Carbon microparticles(CMPs)have also been synthesized with a similar procedure.Meanwhile,we demonstrated a novel “ turn-off-on ”fluorescent biosensor,which has been developed for highly sensitive detection of glucose using Gd-doped carbon dots as probes and CMPs as quenchers.The proposed biosensor has exhibited low-cost and non-toxic properties,with high sensitivity and good specificity.In addition,the results in real blood samples further confirmed it as a promising application in diabetes diagnosis.