Biological & Soft Matter Seminar: Creating adhesion at hydrogel-tissue interfaces

Zoom: https://us02web.zoom.us/j/88904888353?pwd=dDIwaXRxSjlsVElkR0dXdTNPTGhnZz09

Abstract: 

The fixation of hydrogels to soft biological tissues is of outmost interest for numbers of biomedical applications but it is a highly challenging task due to the fragile and wet nature of both hydrogels and tissues. Here, we explore how physical mechanisms occurring at hydrogel-tissue interfaces can be exploited to design bioadhesive hydrogels that are relevant for clinical applications. For that, ex vivo and in vivo experiments were devised to measure the adhesion between model polyethylene glycol hydrogel films and the surface of porcine livers. In a first study, we find that a transition from a lubricated contact to an adhesive contact is governed by the transport of liquid across the tissue-hydrogel interface. We show that this transition corresponds to a draining of the interface, which is well described by a simple model taking into account the microanatomy of tissues. This interfacial wetting effect explains the strong decrease in adhesion observed between ex vivo and in vivo conditions and suggests a new route to improve adhesion using superabsorbent hydrogel meshes. In a second study inspired by the pioneering works by Leibler and coworkers, we investigate how tissue-hydrogel adhesion can be created using particles that bridge the interface by adsorbing on both gels and tissues. Ex vivo and in vivo experiments show how adhesion depends on the contact parameters, coating properties as well as on the hydration of tissues. We find that in the presence of blood, the particle bridging effect combined to the procoagulant properties of silica nanoparticles provide a way to enhance the adhesion strength by inducing the rapid formation of a clot at the interface. These results and methods shed a new light on the design of predictive bioadhesion tests and on the strategies to control the fixation and biointegration of hydrogel based-devices.