Vat Photopolymerization of Liquid Metal Nanoparticle‐Integrated Hydrogels

Abstract Hydrogels are water‐rich, cross‐linked polymers widely applied in biomedicine, tissue engineering, wound healing, and 3D bioprinting due to their biocompatibility and structural versatility. Additive manufacturing, particularly vat photopolymerization (VPP) methods such as stereolithography (SLA) and digital light processing (DLP), has enabled high‐resolution fabrication of complex hydrogel architectures. However, the precision and performance of VPP‐printed hydrogels remain constrained by light scattering, uncontrolled polymerization kinetics, and the poor solubility or toxicity of conventional photo‐absorbers. Here, polymer‐coated liquid metal nanoparticles (pLMNPs) are introduced as multifunctional additives that address these challenges. Prepared using reversible addition−fragmentation chain‐transfer (RAFT) polymer coatings in aqueous solution, pLMNPs exhibit excellent colloidal stability and are uniformly distributed within the hydrogel resins. Their incorporation improves light focusing, reduces scattering, and regulates polymerization kinetics, enabling enhanced print fidelity. Through dynamic covalent bonding between Ga and abundant carboxylic acids/amines on gelatin methacryloyl (GelMA), LMNPs reinforce hydrogel networks, nearly doubling both Young's modulus and compressive toughness. Beyond structural enhancement, pLMNPs impart photothermal responsiveness and antibacterial activity while remaining stable in aqueous media. This work establishes a versatile nanoparticle‐assisted strategy for VPP‐based 3D printing of hydrogels, offering new opportunities for the design of high‐resolution, mechanically robust, and multifunctional hydrogels for biomedical implants and wearable devices.