Synthesis And Characterization Of Highly Fluorescent Polymer Nanodots And Their Applications

Fluorescent polymer nanodots(PNDs)have a wide range of applications in many fields such as fluorescence imaging and biosensing,due to their excellent properties such as small particle size and high brightness.In this dissertation,some kinds of PNDs have been synthesized by using non-conjugated natural product,chiral tartaric acid(TA),as the carbon source.Their applications on the bioscience field were also studied.The main contents are as follows:(1)The PNDs derived from tartaric acid were prepared by solvothermal method using oleic acid as the reaction media.The morphology and structure of PNDs was characterized by transmission electron microscope(TEM),elemental analysis(EA),X-ray photoelectron spectroscopy(XPS),mass spectrum(MS)and so on.The results indicated that the as-prepared PNDs possessed small particle size(about 3.40 nm),high water-solubility,high dispersity because of the abundant amount of oxygen on the surface of particles.The products showed stable optical properties and show high fluorescence quantum yields(QYs)without any surficial decoration.The circular dichroism spectra showed that some chiral centers of the precursors may be maintained and the obtained products still possessed certain chirality,which may open up new and exciting possibilities in the chiral domain.(2)Nitrogen-doped photoluminescent PNDs were synthesized by adding ethylenediamine(EDA)to modify the surface of PNDs.The effects of synthetic conditions to the fluorescence properties of PNDs were discussed.The chemical structure of PNDs was characterized by EA,FTIR,XPS,MS and so on.The results indicated that the fluorescence intensity and quantum yields(18.12%)had a larger increase as a result of the introduce of amino group.Based on the stable fluorescence properties of the PNDs,a novel probe for the detection of Cu2+has been established.Under the optimal conditions,a good linear relationship was obtained between Cu2+and PNDs when the concentration of copper ion was in the range of 1.0×10-7 M?2.5×10-5 M(linear correlation coefficient r>0.99)and the limit of detection was 1.6×10-8 M(3S/N).This method had high selectivity and sensitivity,and can be used to assay the trace copper in real samples.(3)Composite PNDs were prepared from hybrid carbon sources,chiral tartaric acid and citric acid.The obtained PNDs with obvious absorption peak emitted bright blue-green light and the QYs could reach 48.7%.The characterization of EA,FTIR,XPS and MS showed that some new ester groups or amide groups are generated in the compounds.The CD signals reduced significantly in the products.The obtained PNDs exhibited low cytotoxicity,and could be introduced into the target cells for in vitro bioimaging.The confocal fluorescence microscopy showed that the green light was observed,indicated that the PNDs could penetrated easily into the cell membrane and cytoplasm.The fluorescent polymer nanodots are expected to provide promising applications in biological labeling,biosensor,optoelectronics and other potential biomedical fields.