Preparation And Charactriaztion Of Mussel-inspired Nano Electromagnetic Composites With Hybrid Hydrogels

Hydrogels are three-dimensional networks polymer formed by physical and chemical crosslinking of water-soluble polymer or hydrophilic polymer.It is widely used in tissue engineering because of structural resemblance to natural soft tissue.However,traditional hydrogels have some disadvantages,such as poor mechanical properties and inadequate function.Integration of different nano-materials into hydrogels can endow new structures or functions to the hydrogels so as to broaden their applications in various biomedical fields.This study developed nanocomposite hydrogels with an electromagnetic nanomaterial.The main content includes the following parts:As a nano-material,Fe₃O₄ NPs can be used as a nano-reinforcement phase to synthesize composite hydrogels.However,Fe₃O₄ NPs is easy to agglomerate in hydrogel network,which results in poor mechanical properties.Moreover,previous reported Fe₃O₄ NPs composited hydrogels did not have adhesiveness.These shortages limite the applications of Fe₃O₄ NPs composited hydrogels.In this part,a mussel-inspired polydopamine-Fe₃O₄ NPs?PDA-Fe₃O₄NPs?was developed to produce nanocomposite hydrogels.First,the PDA-Fe₃O₄ NPs were produced by introducing dopamine?DA?monomers to mediate the nucleation and growth of Fe₃O₄ NPs during the process of Fe₃O₄ NPs precipitation.In this process,DA monomers were polymerized into PDA,which controled the size and morphology of Fe₃O₄ NPs as well as improved the dispersion stability.Second,PDA-Fe₃O₄ NPs was employed as nano-reinforcements to incorporat in the hydrogels and obtain PDA-Fe₃O₄-polyacrymide?PDA-Fe₃O₄-PAM?hydrogels.The catechol groups on PDA chain and amino group on PAM chain formed hydrogen bonds,which improved the toughness and recoverability of composite hydrogels.In addition,PDA endowed hydrogel with excellent tissue adhesiveness and cell affinity,which broadened the application of Fe₃O₄ NPs composite hydrogels in tissue engineering.Nano-electromagnetic composites have both magnetic and electrical properties,and play important role in the area of new functional composite materials.The traditional methods for preparing nano-electromagnetic composites require harsh conditions and damage the structure and properties of nano-electromagnetic composites.Note that the catechol groups can interact with majority of substances under mild conditions by covalent or non-covalent bonds.Inspired by catechol chemistry,PDA-Fe₃O₄-CNT nano-electromagnetic composites was fabricated with both good magnetic properties and high conductivity.Fe₃O₄ NPs were in situ generated on the surface of CNT through the mediation of catechol groups.SEM and TEM results proved that the catechol groups was a necessary condition for the formation of nano-electromagnetic composites.XRD analysis showed that catechol groups would not damage the structure of CNT and the crystallinity of Fe₃O₄ NPs.In addition,magnetic hysteresis loop analysis showed that the nano-electromagnetic composites still had high paramagnetic properties.This mussel-inspired method for the preparation of nano-electromagnetic composites have some advantages,such as mild conditions,high yield,and maintaining the properties of CNT and Fe₃O₄ NPs.This study provided new way for the preparation of nano-electromagnetic composites,and cound be generalized to prepare other functional nanomaterials.In human body,there are hierarchical and oriented structures such as muscles and neuron,which showed anisotropic properties that accommodated challenge in the external environment.Anisotropic hydrogels have hierarchical structures similar to biological tissues and play an important role in tissue engineering.In this part,PDA-Fe₃O₄-CNT-PAM hydrogels with anisotropic mechanical properties and conductivity were developed.The hydrogel consisted of oriented PDA-Fe₃O₄-CNT nano-electromagnetic composites,which were integrated in PAM networks with directional structures by the assistance of external magnetic field.Various analysis,including EDS line scanning and mapping,CLSM,infrared laser diffraction,proved that the formation of oriented structures in PAM hydrogels.The nano-electromagnetic composites improve the mechanical properties of hydrogel.In addition,the hydrogel had good biocompatibility due to the cell affinity and tissue adhesiveness of catechol groups.The hydrogel can regulate the directional growth behavior of C2C12 cells under electrical stimulation.In summary,the mussel inspired anisotropic PDA-Fe₃O₄-CNT-PAM hydrogel has attractive properties,such as anisotropic mechanical properties and conductivity,cell affinity and tissue adhesiveness,and can serve as a potent multifunctional biomaterials for mimicking oriented tissues.