Preparation And Application Of The Conductive Hydrogel In Electrochemical Biosensors

The gel is a kind of polymer material with the three-dimensional porous structure,which was constituted by polymerization and crosslinking of the related monomers.It can be divided into solid gel,hydrogel and aerogel according to the difference of the dispersion medium.Compared to the traditional gel,the functionalized gel and its application in various fields caused the extreme focus of the researchers widely in recent years.As a kind of functionalized gel,the conductive gel is synthesized by the traditional gel with some conductive material,which combined with the excellent properties of the original gel and showed a good electrical conductivity.It has been widly used in the flexible electronics,electronic skin,electrochemical sensor,etc.This thesis can be divided into four chapters.Chapter?,Introduction.Chapter ?,Preparation,characterization and properties of a nanocomposite conductive hydrogel.Chapter ?,Preparation of a nanocomposite conductive hydrogel and its application in uric acid electrochemical biosensors.Chapter ?,Construction and detection application of direct electron transfer glucose electrochemical biosensor based on highly assembled ionic microgel-oxidized graphene.Chapter?: IntroductionDefining and classifying of the gel in briefly.This paper focuses on the classification,application and research of the conductive gel.Chapter ? : Preparation,characterization and properties of a nanocomposite conductive hydrogel.The sodium styrene sulfonate(Na SS)was used as monomer,N,N'-methylene diacrylamide(BIS)was cross-linking agent,a chemical crosslinked structure was formed after the addition of the initiator of potassium persulfate(KPS).The polyionic liquids was semi-interconnected in the net of the P(Na SS)by electrostatic attraction.Then the poly(vinyl alcohol)(PVA)solution was also added into above-obtained net,the physical cross-linking between PVA chains were formed after freezing,the gold nanoparticles with good conductivity were fixed in the hydrogel by in-situ reduction,the conductive hydrogel which possess double-network was obtained in this time.As a result of the existence of various weak bonds in the gel,the prepared conductive hydrogel showed good self-healing property and thermoplastic property.The morphology of the hydrogel was observed by scanning electron microscopy(SEM),transmission electron microscopy(TEM),the conductivity was measured by four point probe tester,the mechanical and self-healing properties were performed using a universal material testing machine.All of the results demonstrated that our hydrogel has good conductivity and self-healing properties,which can realize the repeated self-healing and the repeated plasticity and has a variety of applications.Chapter ?: Preparation of a nanocomposite conductive hydrogel and its application in uric acid electrochemical biosensors.Monomers of aniline and 3-aminophenylboronic acid hydrochloride were polymerized under acid condition to form conductive polymer chains bearing hydroxyls.Then,the chitosan was added to cross-link with the conductive polymer chains via hydrogen bonding to form hydrogel with a 3D-microstructure.The composite metal nanoparticles of Au@Mn O2 NPs were also mixed into the hydrogel matrix during polymerization.The obtained nanocomposite conductive hydrogel was modified on the electrode and used for uric acid sensing.The unique three-dimensional porous structure of the conductive hydrogel provided a large space for immobilization of the enzyme and protected the bioactivity as well as possible.Electric catalytic oxidation of H2O2 can be realized fastly through the composite metal nanoparticles.A series of electrochemical tests demonstrated that our conductive hydrogel can detect uric acid efficiently.Chapter ?: Glucose electrochemical biosensor of direct electron transferring based on highly assembled microgel-GO.A kind of ionic microgel with three-dimensional and porous structure was prepared and assembled with oxidized grapheme.As a result of the same charges between microgels and the heterogeneous charges between microgel and graphene oxide make them assembled regularly and formed a special 2D microgel film without aggregation.The glucose oxidase was also added and assembled with them byelectrostatic interaction and then formed a unique three-dimensional framework.The microgel film provided a scaffold for enzyme immobilization and preserved the bioactivity as well as possible,the physical immobilization of the enzyme is more friendly comparing with chemical cross-linking and more firmly comparing with encapsulation.A series of electrochemical tests showed that the glucose electrochemical biosensor based on direct electron transfer can realize the efficient detection of glucose without any mediums.