The
fixation of hydrogels to biological tissues is a major challenge
conditioning the development of implants and surgical techniques.
Here, coatings of procoagulant nanoparticles are devised which use
the presence of blood to create adhesion between hydrogels and soft
internal organs. Those nanostructured coatings are simply adsorbed
at the hydrogel surfaces and can rapidly activate the formation of
an interfacial blood clot acting as an adhesive joint. This concept
is demonstrated on pig liver capsules with model poly(ethylene-glycol)
membranes that are intrinsically poorly adhesive. In the absence of
blood, ex vivo peeling tests show that coatings with aggregates of
bare silica nanoparticles induce a 2- to 4-fold increase in adhesion
energy as compared to the uncoated membrane (3 ± 2 J m–2). This effect is found to scale with the specific surface area of
the coating. The highest adhesion energies produced by these nanoparticle-coated
membranes (10 ± 5 J m–2) approach the value
obtained with cyanoacrylate glue (33 ± 11 J m–2) for which tearing of the tissue is observed. Ex vivo pull-off tests
show an adhesion strength of coated membranes around 5 ± 1 kPa,
which is significantly reduced when operating in vivo (1.0 ±
0.5 kPa). Nevertheless, when blood is introduced at the interface,
the in vivo adhesion strength can be improved remarkably with silica
coatings, reaching 4 ± 2 kPa after 40 min contact. In addition,
these silica-coated membranes can seal and stop the bleeding produced
by liver biopsies very rapidly (<30 s). Such a combination of coagulation
and particle bridging opens promising routes for better biointegrated
hydrogel implants and improved surgical adhesives, hemostats, and
sealants.