Development Of Double Network Colloid Gel For 3D Bioprinting

Colloidal gels are composed of particulate network dispersed in liquid;this is different in comparison to conventional polymeric gels characterized by a continuous polymer network.By introducing reversible colloidal interactions,we can render colloidal gels of shear-thinning and self-healing;such fascinating mechanical properties make these gels appealing in regard of applications in regenerative medicine,for instance,as injectable fillers,or 3D bioprinting inks.However,colloidal gels generally are mechanically weak,restricting their widespread applications in reconstruction of load-bearing tissues/organs.Here,we present a novel strategy of generating highly strong colloidal gels based on a double-network design.Polyethylene glycol diacrylate(PEGDA)as a continuous phase with high mechanical strength has been introduced to cooperate with the self-healing colloid network as dispersed phase.The colloidal network is capable of dissipating the destructive energy.Through the double-network design,the mechanical properties of the colloidal gels have been substantially enhanced.By using confocal microscopy,we analyze the microscopic structure of the colloidal network and observe the effect of the structural features on the viscoelastic properties of the gels.This allows us to further optimize the mechanical behavior of the gels by tailoring the preparation parameters.Specifically,highly strong colloidal gels with Young's modulus of 1.6 MPa and fracture strain of 250% can be achieved.We further demonstrate that the double-network colloidal gel can be used as printable extracellular matrix for 3D construction of cellularized tissue mimics.Rat bone marrow stromal stem cells are mixed in the gels and printed into scaffolds with delicate microstructure,which allows cell attachment,spreading,proliferation and osteogenic differentiation.In general,we here by develop a class of colloidal gels of enhanced mechanical properties,desired printability,and biocompatibility,which have shown great potential in applications in tissue engineering and regenerative medicine.