Construction Of Polypyrrole Conductive Hydrogel And Its Biomedical Application

Conductive hybrid hydrogel combining advantageous physical properties of hydrogel and the electronic conductivity of intrinsically conductive materials is a popular option for biomedical materials,which are widely used for tissue engineering material,artificial skin,bioelectronics,wearable biosensors for human health recording.In general,the most popular preparation strategy for conductive hybrid hydrogel is incorporating metal nanoparticles,ionic liquids,graphene,carbon nanotubes（CNTs）and conducting polymers into the 3D networks of hydrogels.However,among the different types of conductive components,CNTs,graphene and nanoparticles are prone to self-aggregation,uneven distribution,and unchangeable morphology because of their inherent disadvantages,which limit the further development of the conductive hydrogels.Recently,conducting polymers（CPs）such as polyaniline（PANI）and polypyrrole（PPy）have drawn considerable attention due to their tunable nanostructures,good biocompatibility,high electrical conductivity,redox activity,and stimulus responsiveness.Among them,PPy is the most popular biomedical materials.However,the rigid and hydrophobic polymeric chains of conducting polymers tend to twist and entangle in water,then PPy need to be fabricated during the polymerization process.Thus,preparing conductive polymer hydrogels（CPHs）with high conductivity and mechanical property for biomedical applications,is the key to develop its application in biomedical field.In this study,we firstly prepared the nanocomposite polypyrrole conductive hydrogels（NPCHs）by directly blending the PPy nanofibers with gelatin methacrylate（GelMA）,and the cell experiments in vitro were carried out to evaluate the biocompatibility and the effect of angiogenesis.Next,we further prepared the elastomeric conductive hybrid hydrogels（ECHs）with continuous PPy conductive networks using the in situ oxidative polymerization strategy,the resulting ECHs exhibited excellent biocompatibility,electrical performance and elastomeric mechanical properties,the force or strain sensitive resistance test was carried to verify its effectiveness as an implantable sensor.1.Preparation of nanocomposite PPy conductive hydrogel and its application in angiogenesis.A free template method to modify PPy with dopamine（DA）is used,PPy nanofiber with good water dispersibility and high conductivity（1.0 S/cm）was obtained from 0.032 DA/Py mole ratio.The NPCHs was synthetized by simplely blending the PPy nanofibers with GelMA,it exhibited uniform composition and stable electrical properties.Through cell culture on the surface of the hydrogel,the results showed the cell adhesion,spreading and proliferation performance could be effected by the materials,and the angiogenesis effect in basal medium was also observed,which established the basis for its application in tissue repair materials.2.Preparation of elastomeric conductive hybrid hydrogels by in situ oxidative polymerization and its application in strain sensor.We report an efficient in situ polymerization strategy based on continuous conductive networks to achieve high conductive ECHs.DA was chosen as the dopant and mediator to regulate the growth of conducting PPy within elastomeric GelMA-polyacrylamide（PAM）double-network hydrogels.Due to its interconnected porous structure and unique continuous conductive path,the resulting ECHs showed good elastomeric mechanical property by cyclic compressive test,dynamic piezoresistive response,relatively high conductivity(7.07?10^-4S/cm),stable electrical properties,high force and strain sensitivity,fast response time（410ms）,and excellent biocompatibility,making it an ideal selection for implantable strain sensors.