Emerging Liquid Metal Biomaterials: From Design to Application

Abstract

Liquid metals (LMs) as emerging biomaterials possess unique advantages including their favorable biosafety, high fluidity, and excellent electrical and thermal conductivities, thus providing a unique platform for a wide range of biomedical applications ranging from drug delivery, tumor therapy, and bioimaging to biosensors. The structural design and functionalization of LMs endow them with enhanced functions such as enhanced targeting ability and stimuli responsiveness, enabling them to achieve better and even multifunctional synergistic therapeutic effects. Herein, the advantages of LMs in biomedicine are presented. The design of LM‐based biomaterials with different scales ranging from micro‐/nanoscale to macroscale and various components is explored in‐depth to promote the understanding of structure–property relationships, guiding their performance optimization and applications. Furthermore, the related advanced progress in the development of LM‐based biomaterials in biomedicine is summarized. Current challenges and prospects of LMs in the biomedical field are also discussed.

Gallium-Based Liquid Metal Materials for Antimicrobial Applications

“…For example, the mechanical strength provided by the oxide layer plays a role in the mechanical destruction of bacteria [ 136 ]. It has been proposed that the oxide layers provide a versatile platform that can anchor graft molecules [ 21 , 137 , 138 ], such as silanes [ 139 ] and phosphates [ 140 ]. Based on this property, antimicrobial drugs or even antibiotics can be anchored to the Ga nanoparticles to achieve synergistic antimicrobial effects.…”

“…In recent years, it has attracted considerable attention from researchers in various fields, attributed to its combined metallic properties and flexibility as a fluidic material as well as its excellent biocompatible property [ 5 ]. The applications of LM are mainly focused on wearable electronics [ 6 , 7 , 8 ], microfluidics [ 9 , 10 ], robotics [ 11 ], and thermal conductor materials [ 12 ], while recent research has suggested that LM also exhibits biological activities in biomedical therapeutics [ 13 , 14 , 15 , 16 ], primarily including tumor hyperthermia, drug delivery, biological imaging, and antibacterial behavior [ 17 , 18 , 19 , 20 , 21 ].…”

Liquid Metal-Doped Conductive Hydrogel for Construction of Multifunctional Sensors

“…Liquid metal (LM) has metallic and fluidic properties and has shown promising applications in soft and stretchable electronics, microfluidics, soft composites, catalysis, batteries, and biomedicines. − Numerous applications of LM have been explored, and interest in the utilization of the micro/nanodroplets of LM, which enabled particular properties related to flexibility, shape transformability, thermal properties, stimuli responsiveness, self-healing, and size-dependent behaviors, has been growing. − Embedding flexible LM into soft polymer matrices has enabled the creation of a variety of polymer–LM soft functional composites with a distinct combination of electrical, thermal, and mechanical properties. Compared with the traditional rigid conductive filler, the flexible LM can greatly improve the electrical conductivity of the hydrogel and reduce the internal stress caused by a mismatch in mechanical properties at the interface between the filler and hydrogel. , Nevertheless, it remains challenging to incorporate LM into water-confined polymer matrices to prepare conductive hydrogels with satisfactory mechanical properties.…”

Actively Triggerable Metals via Liquid Metal Embrittlement for Biomedical Applications

“…[12] For biomedical applications, eutectic gallium indium (EGaIn) is an ideal stimulus because it is liquid at room temperature and has been explored extensively in biointerfacing applications like skin-integrated electronics and drug delivery, possessing demonstrated biocompatibility in various formats. [13][14][15][16][17][18] Gallium alloys like EGaIn are known to severely embrittle aluminum, which can be used to construct biomedical structures and devices that withstand significant mechanical loads during their functional lifetime while retaining the ability to be eliminated non-invasively at end-of-life (Figure 1C). Aluminum is also regularly ingested from food consumption at an average rate of 10 mg day −1 , though normal consumption can reach levels as high as 1 g day −1 since aluminum is a common component of pharmaceutical products.…”