Studies On Structural Designs Of Phosphonium-based Self-assemblies And Their Applications In Biosensors

Quaternary phosphonium based ionic liquid,as a new type of functional material,has been widely used in organic synthesis,electrochemistry,extraction and separation,functional materials,biology and medicine,etc.After the starting material of ethyl paraben,ethyl gallate or ethyl protocatechuate was sequentially alkylated with11-bromo-1-undecene,ester reduction and acyl chlorination,a series of new quaternary phosphonium-based ionic liquids were designed and synthesized by a nucleophilic addition and borohydrogenation of triphenylphosphine and tributylphosphine,followed by a substitution reaction with?meth?acryloyl chloride.The structures and properties of the ionic liquids were characterized by nuclear magnetic resonance?NMR?,thermogravimetric analyzer?TGA?,polarized optical microscope?POM?,differential scanning calorimetry?DSC?and X-ray diffraction?XRD?.The results show that the quaternary phosphonium salts prepared here are of correct structures with good thermal stability,but the molecular structure has some influence on its thermal stability.The thermal stability of tetraalkylphosphonium salts is obviously higher than that of alkyltriphenylphosphonium salts.The number of long alkyl chains and the type of?methyl?acryloyl chloride have little influence on the thermal stability.The melting point of alkyl triphenylphosphosphonium salt is higher than that of alkyl tributylphosphosphonium salt because of the?-?conjugate action of benzene ring.Some quaternary phosphonium salts exhibit a pattern texture under POM,and the lamellar structure of the quaternary phosphonium salts was confirmed by XRD.Biosensors,as a means of analysis and detection,have been widely applied in immunoassay,electrochemical reaction,biochemical reagents,food safety and water quality detection.In this thesis,a biosensor was constructed by an introduction of Zr⁴⁺into the tDNA skeleton using an ATRP reaction to realize the specific detection of tDNA.This thesis work has verified the experimental feasibility of the impedance signal changes in each stage.By optimizing the reaction time of ATRP,it was found that the impedance signal could be maximized when the reaction time was set up for15 min.When the concentration of tDNA used in this experiment is 1 nM,the sensitivity is relatively high,and the performance of the biosensor is pretty good.