Novel Balanced Charged Alginate/PEI Polyelectrolyte Hydrogel that Resists Foreign-Body Reaction

Foreign-body reaction (FBR) has been a long-term obstacle for implantable biomedical devices and materials, especially to those that require mass/signal transport between the implants and the body. However, currently, very limited biomaterials can mitigate FBR. In this work, we develop a balanced charged polyelectrolyte hydrogel that can efficiently resist FBR and collagenous capsule formation in a mouse model. Using this new strategy, we can easily tune the antifouling properties of the polyelectrolyte hydrogels by changing the ratio of negatively charged alginate and positively charged poly(ethylene imine). We find that at the optimum ratio where the net charge of hydrogel is neutral, the adhesion of proteins, cells, bacteria, and fresh blood on its surface can be significantly inhibited, indicating its excellent antifouling properties. In vivo studies show that after being implanted subcutaneously, this balanced charged hydrogel can prevent the capsule formation for at least 3 months. Furthermore, immunofluorescent staining results indicate that this balanced charged hydrogel elicits negligible inflammation, significantly reducing macrophage migration to the tissue–implant interface. This flexible and versatile approach holds a great promise for designing a wide spread of new antifouling hydrogels and using as immunoisolation materials for biomedical applications.