3D printing of hydrogel nanocomposites: A symbiotic union for advanced biomedical applications

Hydrogels have emerged as thriving materials for developing biomedical devices due to their biocompatibility and hydrophilic nature, encompassing various fields from biomedical engineering and pharmaceuticals to wound care and tissue scaffolding. Nevertheless, traditional hydrogels are beset with poor mechanical strength, limited controlled release of medicines, and irreversible chain breakage, all of which compromise their efficacy in practice. The desirable performance of hydrogels can be notably lifted upon incorporating nanomaterials, yielding tunable functions for devising next-generation biocompatible structures. Despite the alluring prospects offered by hydrogel nanocomposites, the processing of these materials is still in its infancy and remains full of challenges to produce personalized, tangible items. Herein, we endeavor to bridge the gap between hydrogel nanocomposites for biomedical applications with additive manufacturing processing, providing a useful guideline for comparing and selecting viable three-dimensional (3D) printing approaches. We review the background of synthesizing hydrogel nanocomposites along with the key concepts toward biomedical applications, featuring a survey on the recent reports on 3D printing of hydrogel nanocomposites for developing customized tissues, drug delivery, bioadhesives, wound dressing, and biosensors.