Studies On The Light-Activated Mimic Oxidases And Ratiometric Fluorescent Probes Based On Semiconducting Polymer Dots

Semiconducting polymer dots?Pdots?is mainly composed of one or several?-conjugated polymers.Pdots have the advantages of strong light absorption capacity,high fluorescence brightness,good light stability and good biocompatibility,and are widely used in biosensing,bioimaging and medical diagnosis and treatment.This thesis focuses on two scientific issues:the characteristics and mechanism of Pdots mimic oxidases and the improvement of the light stability of Pdots probes.The mechanism,properties and application of Pdots as mimic oxidases enzyme were studied in detail;a method of functionalizing Pdots with response-type carbon dots is designed to improve the photostability of the probe.Based on the above exploration,two ratio-type fluorescent probes were constructed for the detection of acetylcholinesterase?ACh E?and in vivo pH imaging.The main work includes the following two parts:?1?Light-activated semiconducting polymer dots as mimic oxidase with remarkable catalytic efficiency:characteristics,mechanisms,and applicationsIn this study,we have demonstrated that Pdots hold intrinsic light-activatable oxidase-like activity with ultrahigh catalytic efficiency.Through the results of cyclic voltammetry and control experiments,results indicate that the clew-like nanostructure and excellent electron conductivity of Pdots play important roles for the efficient oxidase-like activity.In addition,the ¹O₂ and O₂^·-are the main reactive species for substrate oxidation.Using Pdots as mimic oxidase and fluorophore,a ratiometric sensing system has been constructed for AChE detection.From this study,we conclude that Pdots with adjustable clew-like nanostructures can be viewed as an ideal material for nanoenzyme mimics and provide wide range of potential applications.?2?Ratiometric pH sensing and biological imaging with carbon dots-coated PdotsIn this paper,blue light-emission carbon dots were synthesized by simple hydrothermal method.Blue light-emission carbon dots are used for pH detection.CDs@Pdots nanocomposites are synthesized by electrostatic adsorption.The material shows good water solubility and high fluorescence stability.Interestingly,this material can also achieve in vitro ratio pH detection,it shows wide detection range?pH 2.32 to pH 11.13?and high sensitivity.Cell imaging and zebrafish imaging have broadened the application of nano-compatible materials and are expected to enable simple ratio fluorescence detection in practical biological applications.