,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,*,Energy Transfer Mediated Fluorescence from Blended Conjugated Polymer Nanoparticles,Changfeng Wu,Hongshang Peng,Yunfei Jiang,and Jason McNeill*,Energy Transfer Mediated Fluor,1,Abstract,Nanoparticles consisting of a derivative of the blue-emitting conjugated polymer polyfluorene doped with,green-,yellow-,and red-emitting conjugated polymers were prepared by a,reprecipitation,method.,The,nanoparticles can be described as a system of,densely packed chromophores,that exhibit,efficient,energy,transfe,r from the host to the dopant polymers.,2,Abstract Nanoparticles cons,Abstract,Fluorescence quenching analysis of the host polymer as a,function of the dopant concentration indicates that one energy acceptor molecule can effectively quench,90%,of the fluorescence of a nanoparticle consisting of 100-200 host conjugated polymer molecules.,A nanoparticle,energy transfer model,was developed that successfully describes,the quenching behavior of a small number,of highly efficient energy acceptors per nanoparticle.,3,Abstract Fluorescence quench,Abstract,The fluorescence brightness of the blended polymer,nanoparticles was determined to be much,higher,than that of inorganic quantum dots and dye-loaded silica,particles of similar dimensions.,The combination of,high,fluorescence brightness,and,tunable fluorescence,of,these blended,nanoparticles,is promising for ultrasensitive,fluorescence-based assays.,4,Abstract4,Contents,1.Introduction,2.Experimental Section,3.Results and Discussion,4.Conclusions,5,Contents1.Introduction2.Expe,1.Introduction,Highly fluorescent nanoparticles have attracted much attention,due to a variety of fluorescence-based applications such as,biosensing,imaging,and high-through,put assays.,Conjugated polymers are known,to possess,high,absorption,coefficients,and,high fluorescence,efficiency,which have led to a wide range of applications in,optoelectronic thin film devices.,However,the use of conjugated polymer,nanoparticles in fluorescence labeling is still a largely unexplored,area.,6,1.Introduction Highly flu,1.Introduction,Energy transfer in nanoscale systems has recently been demonstrated,as the basis of molecular beacons for efficient,biomolecule detection.,Here we report on energy transfer mediated,fluorescence from,conjugated polymer nanoparticles,consisting of,polyfluorene,(PF),doped with three different conjugated polymer acceptors.,7,1.Introduction Energy tran,2.Experimental Section,2.1 Materials,2.2 Nanoparticle Preparation,2.3 Characterization Methods,8,2.Experimental Section2.1 Mate,2.1.Materials,Host,PF,：,poly(9,9-dihexylfluorenyl-2,7-diyl),(,MW 55 000,polydispersity,2.7),Dopants,PFPV,：,poly9,9-dioctyl-2,7-divinylenefluorenylene-alt-co-2-methoxy-5-(2-,ethylhexyloxy)-1,4-phenylene,(,MW 270 000,polydispersity 2.7),PFBT,：,poly(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-2,1,3-thiadiazole),(MW 10 000,polydispersity 1.7),MEH-PPV,：,poly2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene,(,MW 200 000,polydispersity7.0),THF,：,Tetrahydrofuran(anhydrous,99.9%),9,2.1.MaterialsHost9,2.2.Nanoparticle Preparation,THF,+,polymer,inert atmosphere,stirring,overnight,filtered,c=,40 ppm,homogeneous solutions,+,dopant,(,0 to 10 wt%,),diluted,stirred,Preparation of the aqueous,dispersion of blended conjugated polymer nanoparticles,10,2.2.Nanoparticle PreparationT,2.2.Nanoparticle Preparation,8 mL of deionized,water,nanoparticle dispersions,suspension,2 mL,of,solution,mixture,added quickly,sonicating,filtered,partial vacuum evaporation,The resulting nanoparticle dispersions,are clear and,stable for months with no signs of aggregation.,11,2.2.Nanoparticle Preparation8,2.3.Characterization Methods,Morphology and size distribution,of the polymer blend nanoparticles were characterized,by atomic force microscopy(,AFM,).,The UV-vis absorption spectra were recorded,with a Shimadzu,UV-2101PC,scanning spectrophotometer,using,1 cm quartz cuvettes.,Fluorescence spectra were collected with,a,commercial fluorometer,(Quantamaster,PTI,Inc.),using a 1,cm quartz cuvette.,12,2.3.Characterization MethodsM,3.Results and Discussion,Diagram,3.1.Nanoparticle Size and Morphology,3.2.Optical Properties,3.3.Nanoparticle Energy Transfer Model,13,3.Results and DiscussionDiagra,3.1.Nanoparticle Size and Morphology,(a)Chemical structures of the conjugated polymers,14,3.1.Nanoparticle Size and Mor,3.1.Nanoparticle Size and Morphology,(b)a representative AFM image of blend nanoparticles dispersed on silicon substrate,(c)histogram of particle height data taken from AFM image,15,3.1.Nanoparticle Size and Mor,3.2.Optical Properties,(d)photograph of fluorescence emission from,aqueous suspensions of the blend nanoparticles taken under a UV lamp(365 nm).,16,3.2.Optical Properties(d)pho,3.2.Optical Properties,Figure 2.,(Left),Normalized absorption and fluorescence emission spectra of,conjugated polymers,PF,PFPV,PFBT,and MEH-PPV,in