Fluorescent Conjugated Polymer PPESO3: A Novel Synthetic Route and the Application for Sensing Protease Activities

A facile synthetic route for preparing fluorescent conjugated polymer PPESO 3 has been proposed. Compared with a commonly used synthetic procedure, not only is the newly developed procedure simplified but also the dealkylation step with BBr 3 is avoided. Therefore, the preparing difficulty and danger are reduced, which is obviously beneficial to the preparation and application of PPESO 3 and other PPEs with similar structure. Also, the nonspecific bindings between PPESO 3 and proteins were investigated. Encouraged by the results, a rather simple but effective sensor system to assay protease activity was developed. This sensor took advantage of the nonspecific interactions of the ionic conjugated polymers with proteins and the enzyme-catalyzed hydrolysis of proteins. It was known that bovine serum albumin (BSA) could enhance the fluorescence of PPESO 3 with an apparent blue shift of the peak emission wavelength. Such phenomena have been successfully utilized to monitor trypsin and pepsin activities in this study for the first time.