Research On Coordination Electrodeposition Of Chitosan With Graphene And Gelatin/Chitosan Core-shell Capsule

Chitosan has good biocompatibility,biodegradability and film-forming properties.It can be used in electrodeposition and preparation of capsules.Chitosan has good application prospects in the fields of biosensor,drug delivery and controlled release.The co-deposition of chitosan with graphene can be realized by electrodeposition of chitosan.At present,the co-deposition of graphene and chitosan is based on cathodic electrodeposition,which has some problems.For example,graphene disperses poorly in most common solvent and the reduction of graphene in the deposited film is not complete.Besides,there are some defects and bubbles on the surface of the deposited film.Capsules can be applied to the stimuli-responsive release system.Under the stimulation of external environment,the release of the encapsulated material can be controlled.In order to develop a new electrodeposition technology of graphene and chitosan,the composite films of modified graphene and chitosan were prepared by coordination electrodeposition.On the other hand,gelatin/chitosan core-shell capsules with temperature stimulus response were fabricated to realize the controlled release of capsules.In the first part,2-hydroxypropyltrimethyl ammonium chloride chitosan modified reduced graphene oxide(HACC-rGO)dispersed well in chitosan solution was first prepared.The mixed solution of HACC-rGO and chitosan was used as the deposition solution,and the HACC-rGO/chitosan nanocomposite films deposited on copper(or silver)electrodes(or substrates)were prepared by coordination electrodeposition of HACC-rGO and chitosan.Moreover,the spatiotemporal control of coordination electrodeposition and the electrochemical detection ability of composite films were investigated.At the same time,the HACC-rGO/CS composite film prepared by coordination electrodeposition was compared with the HACC-rGO/CS composite film prepared by cathodic electrodeposition.The morphology and structure of the composite film were characterized by scanning electron microscopy(SEM)and thermogravimetric analysis(TGA).Compared with the composite film prepared by cathodic electrodeposition,the surface of the composite film prepared by coordination electrodeposition is smooth and uniform,and there is no bubble.The composite film has sufficient strength to be completely peeled from the electrode.In addition,HACC-rGO/CS nanocomposite coatings or films with different shapes can be prepared conveniently and controllably by using the spatiotemporal control of electrodeposition.Films with different thickness can be obtained by changing the deposition time.Moreover,HACC-rGO/CS composite film has electrochemical detection ability.In the second part,gelatin/chitosan core-shell capsules were prepared,based on the thermally responsive sol-gel transitions of gelatin and the electrostatic interaction of chitosan with sodium dodecylbenzene sulfonate.The encapsulantion properties of the core-shell capsules for different materials were investigated.It was found that the core-shell capsules could simultaneously encapsulate dyes,fluorescent materials,nanoparticles and other substances,and the encapsulanted materials were not contaminated in each other.Then,cyclodextrin was loaded into gelatin microsphere located in the capsule core.The effects of temperature and cyclodextrin on the morphology of the capsule were studied.The apparent morphology of gelatin/chitosan core-shell capsule was characterized by scanning electron microscope.The results show that the capsule can be deformed or even destroyed above the sol-gel transition temperature of gelatin.Sodium salicylate was used as a model drug to be loaded into gelatin/chitosan core-shell capsule.The drug release study showed that cyclodextrin could be released from the gel sphere and destroyed the capsule wall above the sol-gel transition temperature of gelatin,which accelerated the release rate of drugs in capsules.The release rate of drugs in capsules can be adjusted by changing the content of cyclodextrin in gel sphere.In addition,the core-shell capsules can be used in the field of chemical detection,due to their temperature stimuli-responsive property.Therefore,the core-shell capsule has a good application prospect in the fields of drug delivery,controlled release and chemical detector.