Design, Synthesis And Application Of Poly(aryleneethynylene)s (PAE)s

Conjugated polymers mainly refer to the polymers with a large delocalized conjugatedπ bond. The main feature of conjugated polymer is that the electron and energy can migratethroughout the polymer backbone. Thus the tiny external interference may affect thefluorescence properties of the whole backbone of the polymer. Compared with smallmolecules, fluorescent conjugated polymers as sensing materials may achieve highersensitivity due to the signal amplification effect, since energy and electron can migrate inthree-dimensional space. In addition, from a perspective of materials, conjugated polymershave many advantages compared to small molecules: such as strength, stability, tunablestructure, etc. Therefore, more and more attention has been paid to conjugated polymers.We present the preparation of a series of conjugated polymers, using combinatorialsynthesis of different monomers, based on Sonogashira coupling. The monomers werefrom3different synthetic routes and which resulted in7different conjugated polymers.This paper mainly focused on the synthesis of these fluorescent conjugated polymers, thestudy of their photophysical properties and the research on sensor array and fluorescenceencoded microspheres based on these polymers. The detailed work is carried out mainly onthree parts as following:First, Pattern-based strategy is an emerging field of interest for effective sensingapplications. Seven different conjugated polymers from combinatorial synthesis werecombined into a sensor array, and seven metal cations were selected as representativeanalytes. The response patterns for each cation were constructed by collecting theindividual fluorescence responses from seven polymers in the array. Each ion owns acharacteristic pattern. Some of them have similar modes of response with subtledifferences, while some patterns are distinctively different. The family/period the metalcations belong to and the charges/electronic configurations they possess may account forsuch similarity/difference in the pattern.Second, the fluorescence encoded microspheres in uniform size were prepared by coating these polymers onto SPSDVB microspheres (35μm in the diameter) and APGMAmicrospheres (5μm in the diameter). According to the maximum wavelength offluorescence emission, the above synthesized conjugated polymers were divided into twocategories: one with relatively shorter wavelength emission and another with relativelylonger wavelength emission. By tuning the molar ratio of two different types of polymers,a series of35μm SPSDVB and5μm APGMA fluorescence encoded microspheres wereprepared. Monodispersity and eveness of microspheres, before and after coating, weredemonostrated by fluorescence microscopy and scanning electronic microscopy (SEM).The photophysical properties of the spheres were studied by using solid absorption andsolid fluorescence measurements. The high-throughput flow cytometry was used tocharacterize the efficiency of encoding of the microsphere. The stabilities of encodingmicrospheres were investigated, such as thermal stability, photostability and solventresistance. The results showed that the properties of the fluorescent microspheres are stableenough when used under the regular condition for practical applications.In the research of life science, carboxyl groups can be used for coupling with manybiological molecules. Among previously synthesized conjugated polymers, two conjugatedpolymer containing ester side groups were used to prepare polymers with carboxyl groupsafter hydrolysis. Through the reaction of carboxyl and amino group on the APGMAmicrospheres, the conjugated polymers was immobilized onto the microspheres viacovalent bonding, with carboxyl groups available for biconjugation; to further confirm thecarboxyl group can be used to react with biological molecules, FITC fluorescent dyelabeled bovine serum albumin (BSA-FITC) was reacted with the microspheres to formcovalent bond with the fluorescent conjugated polymer microspheres. Characterization byflow cytometry proved that BSA-FITC is very firmly immobilized onto the microspheresafter many times of washing. For comparison, BSA-FITC on the microsphere via physicaladsorption can be very easily washes off.