Preparation Of Polythiophene Based Hydrogel For Cardiac Tissue Engineering

In this thesis,two different conductive hydrogels(CH)were prepared by a simple “one-step” strategy.These hydrogels were composed of rigid and hydrophobic conductive polythiophene and flexible and hydrophilic natural polymer with good biocompatibility.Physicochemical properties of the CH conductive hydrogels were comprehensively evaluated,including the degree of swelling,mechanical strength and electrical properties.The CH conductive hydrogels and their porous sponge scaffold after lyophilization were used as the substrates for the culture of brown adipose stem cells(BADSCs),which could promote the adhesion,proliferation,growth and differentiation of BADSCs under the externally electrical stimulation.Preparation and performance evaluation of a double network polythiophene based conductive hydrogel: In order to overcome the issue encountered in the traditional “two-step” method to prepare conductive hydrogel that conductive components are not homogeneously mixed,homogenously electrical double network(HEDN)hydrogels were formatted via two different and simultaneously occurred reactions in dimethyl sulfoxide(DMSO)solution,which did not interfere each other.1H NMR and FTIR is used to study the formation of the HEDN hydrogel.In this study,we investigate the swelling properties,mechanical strength and electrical conductivity of the HEDN hydrogel.The results suggested that the physical and chemical properties of HEDN could be regulated by adjusting the feeding ratio between PTAA and MAAG network.The compression strength of the double network hydrogel was between 22.7 kPa and 493.1 kPa,and the electrical conductivity was in the order of magnitude of 10-4 S·cm-1,which was in agreement with the reported electrical conductivity of the myocardium tissue,and was suitable for the application of myocardial tissue engineering materials.In order to prove the capacity of the conductive hydrogel to promote the adhesion,proliferation and differentiation into the myocardial cells(MCs)of BADSCs,further biological evaluation on the material was carried out.The results demonstrated that brown adipose derived stem cells both grew well on the surface of HEDN with or without the electrical stimulation.Not only could HEDN promote the survival and proliferation of adipose derived stem cells,but also could enhance the effect of electrical stimulation on cell differentiation,and enhance the differentiation of BADSCs into MCs.BADSCs grown on the surface of HEDN withelectrical stimulationcould express more cardiac specific protein(Cardiactroponin T and ?-actinin),and formed a more ordered cardiac muscle cell network.At the same time,the expression of calcium channel protein(Connexin 43)also increased significantly,which showed that the conductive hydrogel was beneficial for the signal transduction between cells.The electrical stimulation can enhance this process.Preparation and performance evaluation of a polythiophene based electrically conductive porous scaffold: In order to enhance the conductivity and easily processing properties of myocardial tissue engineering scaffold material,this paper also selected poly 3,4-ethoxylene dioxythiophene(PEDOT)with good conductive properties and sodium alginate with good mechanical strength.PEDOT-Alginate electrical hydrogel(PAEH)was prepared by “one step” method in the aqueous phase and porous sponge scaffolds(PAMCS)was then prepared after lyophilization.In this study,the swelling,mechanical strength,electrical properties and protein adsorption capacity(hydrophilic or hydrophobic properties)of the hydrogel as well as the micro pore structure and degradation propertiesof porous sponge scaffoldwere both investigated.The results showed that PAEH hada storage modulus of more than 100 kPa,an electrical conductivity in the order of magnitudes of 10-2 S·cm-1 and a better capacitance performance.At the same time,PAEH had a good ability to adsorb protein,which is good for cell adhesion on its surface.The physicochemical properties of materials could also be regulated by adjusting the feed ratiobetween PEDOT and alginate.PAMCS scaffold material was endowed a better degradation performance,and it is suitable for cardiac tissue engineering.The biological properties of PAMCS porous sponge were further studied in this paper.The results suggested that alginate scaffold material combined with PEDOT had strong hydrophobicity and was more benefical for cell adhesion compared to pure sodium alginate hydrogel.It is can be seen that cells well and uniformly attached in PAMCS sponge scaffold.The experiment results of the differentiation of BADSCs into MCs showed that PAMCS scaffold could enhance the differentiation of the stem cells in electrical stimulation conditions.