The Preparation And Applications Of Fluorescent Sensors Based On Water-soluble Conjugated Polymer

Conjugated polymers (CPs) have attracted considerable attentions in highsensitive bio-and chemo-sensors due to the exceptional features they exhibit inaqueous solution, like low toxicity, high fluorescence quantum yields, unique solutionbehavior, the ability to interact electrostatically with other charged species, and anextraordinarily high sensitivity to fluorescence quenchers. In comparison to otherattractive fluorescent probes, like quantum dots and small molecule dyes, conjugatedpolymers possess superior signal amplification and superquenching properties owingto the conjugated polymer backbone, which is described as "molecular wire" toprovide extended electron communication and transport. According to these advantags,we focus on the synthesis and application of a water-soluble fluorescent conjugatedpolymer in this paper.In the chapter1, we described the attractive properities of fluorescent conjugatedpolymers and synthesis of a water-soluble fluorescent conjugated polymer PPESO3.Then we focused on the fluorescent conjugated polymers’ applications in chem-andbio-sensors.In the chapter2, a simple and sensitive Hg2+sensor based on the water-solublefluorescent conjugated polymer multilayer films was developed. The multilayer filmswere fabricated successfully utilizing layer-by-layer self-assembly technology via theelectrostatic interaction between polycation electrolyte PDDA and sulfonic groupanion surrounded conjugated polymer PPESO3. In the presence of Hg2+, thephotoluminescence (PL) of PDDA/PPESO3multilayer films quenched effectivelywithout obvious maximum PL emission wavelength shift. The proposed film sensor was successfully applied for the determination of Hg2+in several water samples withsatisfactory reproducibility and accuracy.In the chapter3, we report on a simple and sensitive water-soluble fluorescentconjugated polymer for use in a choline biosensor. Choline is oxidized by the enzymecholine oxidase (ChOx), and the hydrogen peroxide (H2O2) formed is used to oxidizecatechol via catalysis by horseradish peroxidase. The product of oxidation acts as aquencher of the photoluminescence of a fluorescent conjugated polymer. Thebiosensor was successfully applied to the determination of choline in milk sampleswith satisfactory reproducibility and accuracy.In the chapter4, a simple, sensitive, label-free fluorescence sensor for thedetection of adenosine triphosphate was developed, which was based on thewater-soluble fluorescent conjugated polymer. Cu2+could efficiently quench thephotoluminescence (PL) intensity of fluorescent conjugated polymer PPESO3due tothe strong electrostatic interaction and electron transfer between PPESO3and Cu2+.However, the addition of adenosine triphosphate (ATP) could disrupt thepolymer-metal complex, leading to the recovery of the polymer’s fluorescence. Theproposed method was successfully applied to the detection of ATP in human serumsample with satisfactory results. Moreover, considering that ATP could be hydrolyzedby alkaline phosphatase (ALP) and the released Cu2+could quench the fluorescenceof PPESO3, the enzyme activity of ALP was also studied.