Preparation And Performance Study Of Ratio Fluorescent Oxygen Nanoprobe

A collection of luminescent metal complexes have been widely used as oxygen probes in biomedicine field,including Ir(Ⅲ)complexes,Pt(Ⅱ)-porphyrins and Ru(Ⅱ)complexes.However,most reported optical oxygen nanoprobes depend on single luminescent wavelength,which could be easily influenced by incident lamp,detector and unevenly distributed of nanoprobe.To allow more reliable detection,adding another luminescent free of oxygenation as reference will calibrate the signal as ratiometric luminescence.Lanthanide chelates have unique optical properties,such as narrow emission bands,large Stokes and/or anti-Stokes shifts,whose luminescence is rarely influenced by oxygen,which could be a great reference of oxygen sensors.Metal complexes have lower stability with attack of cationic groups or biomolecules in complicated physiological environment.Encapsulation of luminescent metal complexes in polymeric nanoparticles(NPs)affords an alternative yet simple solution.Modified by particle matrix or surface coupling groups could offer protection to fluorescent molecules.In this work,a bipyridine-branched hydrophobic copolymer was prepared as matrix and coordinated with Ru-and Tb-complex respectively,which was then doped into polymeric nanoparticles(NPs)by a reprecipitation method,followed by further study of their ratiometric luminescence,oxygen sensitivity and biocompatibility.The main research is as follows:1、[Tb(ACAC)3]3+ was synthesized as a precursor,and then coordinated to the side chain of co-polymer including polystyrene and bipyridine to yield the final metallopolymer(Tb-Poly).The structure was supported by’H NMR data,UV-Vis absorbance and fluorescence spectrophotometer.The coordinated band formed successfully between Tb complex and co-polymer.2、Based on the metallopolymer Tb-Poly and Ru-Poly,ratiometric luminescent oxygen nanosensors(Ru-Tb NPs)were prepared by reprecipitation method.The resultant Ru(Ⅱ)-Tb(Ⅲ)NPs have a typical size of～100 nm with positive surface in aqueous solution.Nanoparticles exhibit green-red dual－wavelength emission characteristics at excitations of 300 nm and 450 nm,respectively.The red emission is strongly quenched by increased dissolved oxygen while the green emission is stable.The relationship between ratiometric luminescent intensity and concentration of oxygen was expressed by the linear Stern-Volmer equation.And the temperature sensitivity of nanoparticles was studied.3、Cytotoxicity of Ru-Tb NPs was tested by MTT assay on living Hela cells.The results show that a dosage of<33[tg/mL renders slight growth inhibition of cells.The cellular uptake and penetration of these Ru-Tb NPs were investigated in vitro by confocal luminescence imaging in two-dimensional(2D)monolayer cells and three-dimensional(3D)multicellular spheroids(MCs).