Biosensors Based On Electrochemiluminescence And DNA Aptamers

This thesis is concentrated on designing and fabricating biosensors,and multi-techniques are combined,as follows:1.Electrochemiluminescence sensor.The coupling of organic cation exchange polymer (Nafion) with negative polyelectrolyte(PSS) provides an effective approach to immobilize ECL reagent-Ru(bpy)3²⁺ to fabricate the solid-state sensor.Compared with the pure Nafion film,the interfusion of PSS into Nafion takes some advantages.On one hand,it could enhance the stability of ECL sensor due to the strong ability of ion exchange;on the other hand,it could greatly overcome the drawback of slow mass transfer duo to changing the compact construction of Nafion film,which results in the improvement of detection sensitivity.The solid-state ECL sensor based on the Nafion/PSS composite film also enhanced the ECL intensity of Ru(bpy)3²⁺ and exhibited good ECL stability,because the composite film immobilized a large amount of Ru(bpy)3²⁺.In addition,this kind of immobilization approach was simple,effective,and timesaving.2.Fluorescence aptasensor.A simple,selective and sensitive fluorescent aptasensor for adenosine triphosphate(ATP) detection by using a dye-labeled aptamer and single-walled carbon nanotubes(SWNTs) was developed.This design is based on the noncovalent interaction of aptamer with SWNTs byπ-stacking between the nucleotide bases and the SWNT sidewalls.As to ATP,a sensitive detection limit of 4.5 nM was obtained.In addition, the aptasensor can be used to detect ATP in real samples since prominent fluorescence signal were obtained in cellular ATP assays.Therefore,this method can be used to detect ATP simply,selectively and sensitively,which might provide a promising method for cellular ATP assay in vivo in the future.