Ga-based liquid metal (LM), particularly gallium-based alloys, uniquely combines metallic conductivity with fluidic flexibility, offering attractive opportunities for biomedical technologies that are difficult to achieve with conventional solid-state metals. This review first summarizes the expanding applications of LM in microfluidics, flexible electronics, biosensing, drug delivery, and thermal therapy, highlighting the functional advantages arising from its fluidity, deformability, and electrical conductivity. However, the limitations that hinder broader biomedical implementation remain: although the native gallium oxide layer can stabilize LM structures, it also introduces challenges in oxidation control, wettability, interfacial adhesion, conductivity, and long-term reliability. Against this background, surface engineering is presented as a central strategy for addressing these limitations. We systematically review surface modification approaches based on small molecules, polymers, biological coatings, and related interfacial strategies for improving stability, biocompatibility, and functionality. We further discuss fabrication approaches for integrating surface-engineered LM into wearable platforms, including 3D printing and hydrogel-based architectures. Finally, persistent challenges involving surface tension, adhesion, nanoparticle aggregation, conductivity loss, electrochemical corrosion, mechanical mismatch, biocompatibility, and sterilization are critically evaluated together with corresponding solutions. This application-surface-engineering framework provides a roadmap for designing multifunctional, surface-engineered LM-based systems, while outlining future directions for translating these materials from laboratory studies to clinical and practical biomedical applications.

Adoptive cell therapy continues to encounter diverse hurdles in treating solid tumors, including poor infiltration, an immunosuppressive microenvironment, and tumor immune evasion, necessitating the endowment of effector cells with multiple functionalities. However, conventional cell-engineering techniques, including genetic editing and chemical modification, merely modulate a single functional axis to yield a monofunctional effector cell that can overcome only one physiological barrier, leading to insufficient solid tumor suppression. Recently, membrane-fusogenic liposomes have emerged as a multiplex engineering tool capable of straightforwardly producing multifunctional effector cells to synchronously surmount multiple challenges for effective antitumor efficacy. Through a fusion process, this liposome concurrently achieves immune cell surface functionalization and intracellular delivery of bioactive molecules, thereby endowing effector cells with multiple functionalities within a single step. This minireview summarizes recent advances in the use of fusogenic liposomes for immune cell engineering to boost their therapeutic efficiency on solid tumors. We discuss their design principles, representative applications, and analyze their technical advantages and current limitations. Looking forward, we propose that membrane-fusogenic liposomes hold potential to advance the development of multimodal engineered immune cells for next-generation cancer immunotherapies.