Shear-thinning hydrogels are suitable biomaterials for
catheter-based
minimally invasive therapies; however, the tradeoff between injectability
and mechanical integrity has limited their applications, particularly
at high external shear stress such as that during endovascular procedures.
Extensive molecular crosslinking often results in stiff, hard-to-inject
hydrogels that may block catheters, whereas weak crosslinking renders
hydrogels mechanically weak and susceptible to shear-induced fragmentation.
Thus, controlling molecular interactions is necessary to improve the
cohesion of catheter-deployable hydrogels. To address this material
design challenge, we have developed an easily injectable, nonhemolytic,
and noncytotoxic shear-thinning hydrogel with significantly enhanced
cohesion via controlling noncovalent interactions. We show that enhancing
the electrostatic interactions between weakly bound biopolymers (gelatin)
and nanoparticles (silicate nanoplatelets) using a highly charged
polycation at an optimum concentration increases cohesion without
compromising injectability, whereas introducing excessive charge to
the system leads to phase separation and loss of function. The cohesive
biomaterial is successfully injected with a neuroendovascular catheter
and retained without fragmentation in patient-derived three-dimensionally
printed cerebral aneurysm models under a physiologically relevant
pulsatile fluid flow, which would otherwise be impossible using the
noncohesive hydrogel counterpart. This work sheds light on how charge-driven
molecular and colloidal interactions in shear-thinning physical hydrogels
improve cohesion, enabling complex minimally invasive procedures under
flow, which may open new opportunities for developing the next generation
of injectable biomaterials.