Design and translation of injectable biomaterials

Injectable biomaterials, including bulk materials and particulate materials, can be delivered in a minimally invasive way and may provide alternative treatment options for conditions that currently require surgical procedures. However, the design and translation of injectable biomaterials can be complex, as the injectability of a biomaterial is determined by its properties and injection conditions, which can change in the translation from the bench to the clinic. In this Review, we highlight parameters that affect the injectability of biomaterials, outlining design considerations for both injectable bulk and particle materials, and examining safety and testing considerations. We then discuss different delivery routes and applications of injectable biomaterials, including subcutaneous, nervous tissue, intraocular, intracardiac, intramuscular and intravascular injection, in addition to orthopaedic applications, highlighting clinically approved approaches and promising preclinical outcomes. Moreover, we survey applications of injectable biomaterials related to women’s health, and provide an outlook on the translational challenges and opportunities of injectable biomaterials.