The Research Of Preparation Of Fluorescent Polydopamine Nanodots And Optical Sensor

Due to its high sensitivity,simpleness,speedness and low cost,the fluorescent sensor has drawn more and more attention,and has been used in the field of detection,diagnosis,and biological imaging and so on.Therefore,people have developed lots of nanomaterials including fluorescent inorganic nanomaterials and fluorescent organic nanomaterials.As a kind of organic nanomaterials,polydopamine has good water solubility,good biocompatibility,and easy to modify.It has been widely usedin the field of functional nanomaterials,sensor,catalyst,and so on.However,the research on fluorescentpolydopamine nanomaterials are relatively less.Exploring the synthesis stable and controllable fluorescent polydopamine nanodots,is significant to broaden the biological application.In this research,we focuson exploring suitable approaches to prepare the polydopamine nanodots,comfirming the composition,morphology,valence by characterization,and building the sensing systems,the main partsare as follows:Chapter 1 OverviewThis chapter mainly introduces the formation mechanism,synthesis methods,surface modification and biological applications of polydopamine nanomaterials especially fluorescent polydopamine.Finally,we summarize and discuss the significance of research.Chapter 2 Rapid synthesis of fluorescent polydopamine nanodots and its application on sensing alkaline phosphataseIn this chapter,we using KMnO₄ as the oxidant to synthese the homogeneously distributed fluorescent polydopamine nanodots（PDA-NDs）,it is fast（¹4 min）and environmentally friendly.We have charaterazed the PDA-NDs with TEM、FTIR、XPSand so on.KMnO₄ can react with ascorbic acid through redox reaction.On the other hand,ascorbic acidcan be obtained by hydrolysis of alkaline phosphatase（ALP）.Based on these,a sensitive method was developed to quantify the activity of ALP through real-time formation of fluorescent PDA-NDs.The fluorometric signal via the concentration of ALP is linear from 1 to 50 mU?m L-1ALP activity,and the limit of the detection is as low as 0.94 mU?m L^-1.Chapter 3 Synthesis of fluorescent polydopamine nanodots with Cu/GMP and its application on sensing acetylcholinesterase activityIn this chapter,the Cu/GMP can mimic laccase,that can be used to oxidize dopamine,and successfully got the dispersive fluorescence polydopamine nanodots.The characterization of Cu/GMP and PDA-NDs was confirmed by TEM,XPS,UV and so on.The hydrolysis of acetylthiocholine can produce thiocholine by acetylcholinesterase.Based on the specificity of the Cu/GMP and thiol groups,it has influence on the dopamine oxidation,which can realize detection of acetylcholinesterase activity.The method has a good response beween 0.5-30mU·mL^-1 range of acetylcholinesterase activity,and the detection limit is 0.28mU·mL^-1.Chapter 4 Synthesis of fluorescent polydopamine nanodots with Pt-Cu nanoflower nanozymeIn this chapter,we prepared the Pt-Cu nanoflower alloys through the hydrothermal method.We have characterized the morphology and structure.Based on the research of the Pt-Cu nanoflower,we have found it can mimic peroxidase excellently.With the aid of high catalytic activity of Pt-Cu nanoflower,the fluorescence polydopamine nanodotswere prepared under moderate condition,with the uniform distributed nanosize and good fluorescence properties.This work has smartly applied the nanozyme to the synthesis of new nanomaterials,and will help to broaden its application of fluorescence polydopamine.